1999 Vol. 17, No. S1
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Display Method:
1999, 17(S1): 663-667.
Abstract:
The rare earth mineral monazite ((Ce,La,Th)P04)is usually found in magmatic rocks or related meta-morphosed rocks as one of seldom associated minerals. Sometimes the monazite can be found in elastic rocks or placer. Although the authigenic monazite has been found in bauxite deposits or karstification sediments,but it is the first time that discovery of authigenic monazite in Precambrian sedimentary rock of Dalian area China. The authigenic monazite is found in the Shisanlitai Formation of Precambrian Sinian System of the Jin-shitan Beach,Dalian area. This formation is composed of abundant reddish stromatolite limestone. The authigenic monazite has been found in the intercalated green mudstone between limestone beds. It was supposed that Cynobacteria biomineralization promoted formation of the authigenic monazite. The authigenic monazite-bearing mudstone is consisted entirely of illite (sericitized) by X-ray diffraction determination. Exactly the authigenic monazite is involved in the hematite veinlets of the illite mudstone. The electron scanning image analysis of monazite shows subhedral crystal form in l0um diameter. The chemical composition of the authigenic monazite is determined by electron-probe analysis (Wave Spectrum Analysis) as follows(%): Ce2O3 33.28,La2O3 9.52, Nd2O3 17.26,P2O5 30.04,ThO2 2.73,Pr2O3 3.12,Sm2O3 2.01, Gd2O3 0.59,UO2 0.19,Fe2O3 0.34,SiO2 0.56,CaO 0.14,Al2O3 0.08,TiO2 0.11,Na2O 0.01,total 99.98. Therefore,the authigenic monazite belongs to Ce,La,Nd, monazite varities. The significance of the discovery of autaigenic monazite in Precambrian sedimentary rock are discussed in this paper,e. g.,the favourable sedimentary environment of authigenic monazite, the poesibie origin of rare earth elements of the famous Baiyun Obo rare earth minerral deposits and so nn. Besides,the discovery of auhi-genic monazite shows the possibility of isotopic age determination by U,Th-Pb method for the non-fossil Precambrian strata.
The rare earth mineral monazite ((Ce,La,Th)P04)is usually found in magmatic rocks or related meta-morphosed rocks as one of seldom associated minerals. Sometimes the monazite can be found in elastic rocks or placer. Although the authigenic monazite has been found in bauxite deposits or karstification sediments,but it is the first time that discovery of authigenic monazite in Precambrian sedimentary rock of Dalian area China. The authigenic monazite is found in the Shisanlitai Formation of Precambrian Sinian System of the Jin-shitan Beach,Dalian area. This formation is composed of abundant reddish stromatolite limestone. The authigenic monazite has been found in the intercalated green mudstone between limestone beds. It was supposed that Cynobacteria biomineralization promoted formation of the authigenic monazite. The authigenic monazite-bearing mudstone is consisted entirely of illite (sericitized) by X-ray diffraction determination. Exactly the authigenic monazite is involved in the hematite veinlets of the illite mudstone. The electron scanning image analysis of monazite shows subhedral crystal form in l0um diameter. The chemical composition of the authigenic monazite is determined by electron-probe analysis (Wave Spectrum Analysis) as follows(%): Ce2O3 33.28,La2O3 9.52, Nd2O3 17.26,P2O5 30.04,ThO2 2.73,Pr2O3 3.12,Sm2O3 2.01, Gd2O3 0.59,UO2 0.19,Fe2O3 0.34,SiO2 0.56,CaO 0.14,Al2O3 0.08,TiO2 0.11,Na2O 0.01,total 99.98. Therefore,the authigenic monazite belongs to Ce,La,Nd, monazite varities. The significance of the discovery of autaigenic monazite in Precambrian sedimentary rock are discussed in this paper,e. g.,the favourable sedimentary environment of authigenic monazite, the poesibie origin of rare earth elements of the famous Baiyun Obo rare earth minerral deposits and so nn. Besides,the discovery of auhi-genic monazite shows the possibility of isotopic age determination by U,Th-Pb method for the non-fossil Precambrian strata.
1999, 17(S1): 675-680.
Abstract:
The superlarge Fe-Nb-REE ore deposit at Baiyun Obo is one of the most large Nb-REE ore deposits in the world,which is hosted by dolomite in the Baiyun Obo Formation of Middle Prpterozoic age. In this paper the tectonic setting,regional geology,regional distribution,occurrence,petrology, mineralogy and C-,O-,Sr-isotopic geochemistry of the ore-bearing dolomite in Baiyun Obo, Inner Mongolia,China are studied. The ore-bearing dolomite is only located in the Baiyun Obo Formation of Middle Proterozoic age. It shows some features of normal marine sedimentary carbonate, such as special time-stratigraphic distribution,stratiform and lens shaped, laminated and bedded structures, conformable contact and synchronous fold with wall rocks; and some features of magmatic carbonatite,such as distribution along deep fault,thin dolomite vein cutting wall rocks in heading wall, so the dolomite is neither the normal marine sedimentary carbonate northe magmatic carbonatite. The dolomite distributed along regional fault in stratiform,stratifold and lentiform was controlled by second tectonic basin. The dolomite thickness in center is much larger, and the thickness in marginal is much smaller or thin out. The dolomite displays special "eye-type" structure,e. g massive strucure in the center part, banded and laminated in the margin. The dolomite shows "two-end structures",e. g. stratiform body is located in upper part and vein in lower part,in which the stratigraphic position of the vein dolomite is not overstep the stratigraphic position of the stratiform dolomite. The ore-bearing dolomite have 8180 per mil values between +6.4 and +16.5,andδ13Cvalues between-4.7 and +1.4,which is located between the normal marine sedimentary and magmatic car- bonates. 87Sr/86Sr data have confirmed this conclution. To sum up,authors believes that the dolomite was formed by hydrothermal venting which was circulating in submarine.
The superlarge Fe-Nb-REE ore deposit at Baiyun Obo is one of the most large Nb-REE ore deposits in the world,which is hosted by dolomite in the Baiyun Obo Formation of Middle Prpterozoic age. In this paper the tectonic setting,regional geology,regional distribution,occurrence,petrology, mineralogy and C-,O-,Sr-isotopic geochemistry of the ore-bearing dolomite in Baiyun Obo, Inner Mongolia,China are studied. The ore-bearing dolomite is only located in the Baiyun Obo Formation of Middle Proterozoic age. It shows some features of normal marine sedimentary carbonate, such as special time-stratigraphic distribution,stratiform and lens shaped, laminated and bedded structures, conformable contact and synchronous fold with wall rocks; and some features of magmatic carbonatite,such as distribution along deep fault,thin dolomite vein cutting wall rocks in heading wall, so the dolomite is neither the normal marine sedimentary carbonate northe magmatic carbonatite. The dolomite distributed along regional fault in stratiform,stratifold and lentiform was controlled by second tectonic basin. The dolomite thickness in center is much larger, and the thickness in marginal is much smaller or thin out. The dolomite displays special "eye-type" structure,e. g massive strucure in the center part, banded and laminated in the margin. The dolomite shows "two-end structures",e. g. stratiform body is located in upper part and vein in lower part,in which the stratigraphic position of the vein dolomite is not overstep the stratigraphic position of the stratiform dolomite. The ore-bearing dolomite have 8180 per mil values between +6.4 and +16.5,andδ13Cvalues between-4.7 and +1.4,which is located between the normal marine sedimentary and magmatic car- bonates. 87Sr/86Sr data have confirmed this conclution. To sum up,authors believes that the dolomite was formed by hydrothermal venting which was circulating in submarine.
1999, 17(S1): 687-690.
Abstract:
The Characteristics of fluorescence alteration of some typical coals from China has been investigated by means of laser microprobe. The results show that there are three fluorescence alteration patterns for telocolli- nite. They are positive alteration, negative alteration and negative -positive alteration,depending on the thermal maturation levels of these samples. They occur at VRo less than 0.60%,more than 1.10%,0.60-1.10%,respectively. Two alteration parameters:I4oo and R have been selected to differentiate the fluorescence alteration between Chinese coals and Australian coals. The results indicated that the R-I curve of the Chinese coals is quite similar to that of the Australian coals. However, I400 of telocollinite in the Chinese coals is higher than that of the Australian coals, up to 1000-2000 relative intensity units. The measured VRo of the Chinese coals is different from EqVRo(equivalent vitrinite reflectance) which was derived from their fluorescence parameters in the R-I-VRo model based on the Australian coals, with a higher EqVRo value by 0.0l%-0.04%.According to this,a R-I-VRo model based on the fluorescence characteristics of the Chinese coals has been suggested. This model can be used to correct the measuring vitrinite reflectance for source rocks from Chinese petroliferous basins more correctly than the model of the Australian model. A case study was given for some typical samples from Tuha Basin. The results are plotted to this model. It presents that EqVRo is very close to the measured VRo.
The Characteristics of fluorescence alteration of some typical coals from China has been investigated by means of laser microprobe. The results show that there are three fluorescence alteration patterns for telocolli- nite. They are positive alteration, negative alteration and negative -positive alteration,depending on the thermal maturation levels of these samples. They occur at VRo less than 0.60%,more than 1.10%,0.60-1.10%,respectively. Two alteration parameters:I4oo and R have been selected to differentiate the fluorescence alteration between Chinese coals and Australian coals. The results indicated that the R-I curve of the Chinese coals is quite similar to that of the Australian coals. However, I400 of telocollinite in the Chinese coals is higher than that of the Australian coals, up to 1000-2000 relative intensity units. The measured VRo of the Chinese coals is different from EqVRo(equivalent vitrinite reflectance) which was derived from their fluorescence parameters in the R-I-VRo model based on the Australian coals, with a higher EqVRo value by 0.0l%-0.04%.According to this,a R-I-VRo model based on the fluorescence characteristics of the Chinese coals has been suggested. This model can be used to correct the measuring vitrinite reflectance for source rocks from Chinese petroliferous basins more correctly than the model of the Australian model. A case study was given for some typical samples from Tuha Basin. The results are plotted to this model. It presents that EqVRo is very close to the measured VRo.
1999, 17(S1): 699-705.
Abstract:
Donghe sandstone is typical shore-shallow-sea facies quartz sandstone with burial depth ranging from 3500 to 5100m and the largest thickness 129 meter formed during late Devonian (or early Carboniferous) in Tarim basin. Although it has great depth, it still has better reserroir quality (Porosity is about 20% and permeability 200 ×10-3μm2 ) and that is quite rare in the world. Different vie wpoints on its genesis yet exist.Some believe that the well-developped porosity was formed by dissolwtion of calcite cement in late diagenesis,but the others think it is primary proe retained after compaction and cementation. On the basis of mrmeraus data collected from casting section,thin section and SEM,the anthor draw a conclusion that pare in Dongre sandstone is chiefly primary porosity retained. after compaction and cementation; and the proofs are as follows:First,tire cornpaciion intensity on porasity is not strong and pore fillings come mainly from autirigenic clay,quartz and calcite nriner}als ilr wtrich tire clayfilm is the most common infillins form,and next clay fill,quartz overgrowth as well as carbonate fill. The carbonate cement is abundantly distributed around the sardbody, but irl the middle they present in spot,grutneleuse and laminae. Second dissolotion is raot well developped in the sandstone snd they mainly take place in class, quartz overgrowth and quartz grain us vela as feldspars while the carboncate cereut shows no any dissolution and they are not the remains produced by intersive dissaieaion. Under the background of the remained intergranular pore,the mixed pares formed by the remained primary pore and the secondary dissalution pore. Dissolution has the eminent contribution to the sandstone permeability. By quantitative analysis on tire evolution of porosity and related physical property parametevs,the author believe that the primary pore. suchas the pare with well-developped clove film and substrate loss porosity 17.82% by canpaction,and the other forms of loss by filling and compaction is 20%,27 % and 34.3%, respectively. The secondary dissalution can increase part of porosity by 1.49%. The protection condition of primary porasity has close relatian to the intgerated gealagicalfactors.
Donghe sandstone is typical shore-shallow-sea facies quartz sandstone with burial depth ranging from 3500 to 5100m and the largest thickness 129 meter formed during late Devonian (or early Carboniferous) in Tarim basin. Although it has great depth, it still has better reserroir quality (Porosity is about 20% and permeability 200 ×10-3μm2 ) and that is quite rare in the world. Different vie wpoints on its genesis yet exist.Some believe that the well-developped porosity was formed by dissolwtion of calcite cement in late diagenesis,but the others think it is primary proe retained after compaction and cementation. On the basis of mrmeraus data collected from casting section,thin section and SEM,the anthor draw a conclusion that pare in Dongre sandstone is chiefly primary porosity retained. after compaction and cementation; and the proofs are as follows:First,tire cornpaciion intensity on porasity is not strong and pore fillings come mainly from autirigenic clay,quartz and calcite nriner}als ilr wtrich tire clayfilm is the most common infillins form,and next clay fill,quartz overgrowth as well as carbonate fill. The carbonate cement is abundantly distributed around the sardbody, but irl the middle they present in spot,grutneleuse and laminae. Second dissolotion is raot well developped in the sandstone snd they mainly take place in class, quartz overgrowth and quartz grain us vela as feldspars while the carboncate cereut shows no any dissolution and they are not the remains produced by intersive dissaieaion. Under the background of the remained intergranular pore,the mixed pares formed by the remained primary pore and the secondary dissalution pore. Dissolution has the eminent contribution to the sandstone permeability. By quantitative analysis on tire evolution of porosity and related physical property parametevs,the author believe that the primary pore. suchas the pare with well-developped clove film and substrate loss porosity 17.82% by canpaction,and the other forms of loss by filling and compaction is 20%,27 % and 34.3%, respectively. The secondary dissalution can increase part of porosity by 1.49%. The protection condition of primary porasity has close relatian to the intgerated gealagicalfactors.
1999, 17(S1): 718-722.
Abstract:
Syngenetic clast in sedimentary rock is a fragment which develops in the sedimentary pr0ocess where weakly consolidated argillaceous or silty sediments formed just a little earlier were re-eroded to fragments. It is a cepositional structural phenomenon representing a turbulent sedimentary environment. It is first time that some syngenetic clasts are discovered in the Dabeiwu area, Northeast Jiangxi,where eprmetamorphic classic rocks of Shuangqiaoshan Group of Middle Proterozoic erathem outcropped. The syngenetic clasts,mainly occur in the argillite,consist about 2-10 % of the sedimentary rocks. They have a well-rounded shape of circular or ellipsoid,and being as sand-size particle fragment with a diameter of 0.5-2.0mm. The inner fragments of the syngenetic clast are fine-silty feldspar and quartz,their size are a little more coarse than that of the sedimentary rocks around the syngenetic class. There is a closed conta:a relation and a well-defined boundary between syngenetic clast and the sedimentary rocks. Clearly,the discovery of the syngenetic clast provides a strong support to the view that the Shuangqiaoshan Group is a turbidite.Because of the closed contact relation and a little difference between syngenetic class and the sedimentary rocits, the syngenetic clast is a good strain-measuring marker. The defor:natione of syngenerir rlast in the area ttxe classified to three types.(laser deformation with Flinn coefficient K<0.5,shear deformation with 0.52.0. Each of them diatrihutes regularhr at certain place. Based on the deformation feature of the syngenetic chat,the authors believe that the Shuangqiaoahtan Group in this area has under-gone two phases Df deformation, (laser deformation and ductile shear deformation. The former is the regional fold deformation with a flaser rate among strata of 23.1%-45.3% calculated from the strain axial rate Kxz(1.58-2.51)of the syngenetic clast. According to distribution of ductilt shear deformed syngenetic clast and other shear deformaripn marker, Dabeiwu ductile shear zone developed in epi-metasnorphic elastic rncira is confirmed with,shear strain of 1.01-2.13 and the largest shear transposition of 0.6-0.8 km. As particles different from the sedimentary rocks with a little higher ponasity attd pertneability caused by their coarser inner-fragments,the syngenetic clasts play an important role in the dynamic differential materials in the course of rock deformation and become to he growth points of the ayntectonic siderite porphyroblasts.
Syngenetic clast in sedimentary rock is a fragment which develops in the sedimentary pr0ocess where weakly consolidated argillaceous or silty sediments formed just a little earlier were re-eroded to fragments. It is a cepositional structural phenomenon representing a turbulent sedimentary environment. It is first time that some syngenetic clasts are discovered in the Dabeiwu area, Northeast Jiangxi,where eprmetamorphic classic rocks of Shuangqiaoshan Group of Middle Proterozoic erathem outcropped. The syngenetic clasts,mainly occur in the argillite,consist about 2-10 % of the sedimentary rocks. They have a well-rounded shape of circular or ellipsoid,and being as sand-size particle fragment with a diameter of 0.5-2.0mm. The inner fragments of the syngenetic clast are fine-silty feldspar and quartz,their size are a little more coarse than that of the sedimentary rocks around the syngenetic class. There is a closed conta:a relation and a well-defined boundary between syngenetic clast and the sedimentary rocks. Clearly,the discovery of the syngenetic clast provides a strong support to the view that the Shuangqiaoshan Group is a turbidite.Because of the closed contact relation and a little difference between syngenetic class and the sedimentary rocits, the syngenetic clast is a good strain-measuring marker. The defor:natione of syngenerir rlast in the area ttxe classified to three types.(laser deformation with Flinn coefficient K<0.5,shear deformation with 0.52.0. Each of them diatrihutes regularhr at certain place. Based on the deformation feature of the syngenetic chat,the authors believe that the Shuangqiaoahtan Group in this area has under-gone two phases Df deformation, (laser deformation and ductile shear deformation. The former is the regional fold deformation with a flaser rate among strata of 23.1%-45.3% calculated from the strain axial rate Kxz(1.58-2.51)of the syngenetic clast. According to distribution of ductilt shear deformed syngenetic clast and other shear deformaripn marker, Dabeiwu ductile shear zone developed in epi-metasnorphic elastic rncira is confirmed with,shear strain of 1.01-2.13 and the largest shear transposition of 0.6-0.8 km. As particles different from the sedimentary rocks with a little higher ponasity attd pertneability caused by their coarser inner-fragments,the syngenetic clasts play an important role in the dynamic differential materials in the course of rock deformation and become to he growth points of the ayntectonic siderite porphyroblasts.
1999, 17(S1): 728-733.
Abstract:
Being one of the most important oil source rock in Biyang depression,the lacustrine carbonate rock is,here,mainly composed of dolomite,representing the characteristics of lacustrine carbonate rocks formed in the course of soda lake evolution Under the hot and semi-arid paleoclimate,the upper and lower part of the lower Tertiary are coarse elastic rocks which formed fluvial and Lacustrine fades in interval. The middle part Hetaoyuan Formation consists mainly of lacustrine muddy shale,carbonate and alkaline rocks except fan delta and delta deposits. The depositional model of lacustrine carbonate rocks evoluted to the soda lake:(1)The fan delta fades and delta fades are distributed along the south and north margin of the depression respectively,for the abundant supplement of elastics and low salinity(3‰-6‰)are generally not favorable for the formation of carbonate deposition,only forming lots of authigenic calcite and little authigenic dolomite minerals dispersing in mudstone and sandstone or the cements of sandstones. Particularly,in delta fades during flood-interval period or in interchannel deposits,the authigenic ferrodolomite and lime mudstone sheet increases with some lime mud shell oolites,intraclast sandstone and cryptoalgal laminated rocks intercalation deposited;(2)The salinity of lake water in Lake-shore and lake-bay facies,especially in the latter is high,the authigenic calcites and lime mudstone,ferrodolostone are widespread,in these fades,meanwhile,true ooid-and superficial ooid-bearing grain carbonate rock increases as well;(3)Carbonate rocks in shallow Lake facies are well developed,and the total thickness of carbonate rocks is about 300-600 m. The lithology are mainly grey-black,brown-grey dolomite mudstone,ferrodolostone and ooid-intraclast-bearing dolomite mudstone except alkaline-bearing lumps and lime mudstone deposition in the near-shore shollow lake fades;(4)Deeper lake facies,excluding turbidite deposition,are short of supplement of fresh water and elastics in deeper water depth and stable depositional environment. The salinity of lake water is high. Dolomite mudstone deposition is the thickest and about 700-900 m. The lithology are mainly black,grey-black dolomite mudstone,ferrod-lostone and dolomitic muddy shale lamllar interbedded. These are the typical characteristics of lacustrine carbonate-type oil source rock. Nowadays,the oil field has been found here;(5)The salinity of alkaline lake facies is very high (30‰-60‰),all kinds of carbonate rock,especially lime mudstone and ferrocalcite rock,are well developed and lamellar interbedded with alkaline layers and elastic rocks. Carbonate rocks formed excellent evaporite-bearing carbonate-type oil source rock.
Being one of the most important oil source rock in Biyang depression,the lacustrine carbonate rock is,here,mainly composed of dolomite,representing the characteristics of lacustrine carbonate rocks formed in the course of soda lake evolution Under the hot and semi-arid paleoclimate,the upper and lower part of the lower Tertiary are coarse elastic rocks which formed fluvial and Lacustrine fades in interval. The middle part Hetaoyuan Formation consists mainly of lacustrine muddy shale,carbonate and alkaline rocks except fan delta and delta deposits. The depositional model of lacustrine carbonate rocks evoluted to the soda lake:(1)The fan delta fades and delta fades are distributed along the south and north margin of the depression respectively,for the abundant supplement of elastics and low salinity(3‰-6‰)are generally not favorable for the formation of carbonate deposition,only forming lots of authigenic calcite and little authigenic dolomite minerals dispersing in mudstone and sandstone or the cements of sandstones. Particularly,in delta fades during flood-interval period or in interchannel deposits,the authigenic ferrodolomite and lime mudstone sheet increases with some lime mud shell oolites,intraclast sandstone and cryptoalgal laminated rocks intercalation deposited;(2)The salinity of lake water in Lake-shore and lake-bay facies,especially in the latter is high,the authigenic calcites and lime mudstone,ferrodolostone are widespread,in these fades,meanwhile,true ooid-and superficial ooid-bearing grain carbonate rock increases as well;(3)Carbonate rocks in shallow Lake facies are well developed,and the total thickness of carbonate rocks is about 300-600 m. The lithology are mainly grey-black,brown-grey dolomite mudstone,ferrodolostone and ooid-intraclast-bearing dolomite mudstone except alkaline-bearing lumps and lime mudstone deposition in the near-shore shollow lake fades;(4)Deeper lake facies,excluding turbidite deposition,are short of supplement of fresh water and elastics in deeper water depth and stable depositional environment. The salinity of lake water is high. Dolomite mudstone deposition is the thickest and about 700-900 m. The lithology are mainly black,grey-black dolomite mudstone,ferrod-lostone and dolomitic muddy shale lamllar interbedded. These are the typical characteristics of lacustrine carbonate-type oil source rock. Nowadays,the oil field has been found here;(5)The salinity of alkaline lake facies is very high (30‰-60‰),all kinds of carbonate rock,especially lime mudstone and ferrocalcite rock,are well developed and lamellar interbedded with alkaline layers and elastic rocks. Carbonate rocks formed excellent evaporite-bearing carbonate-type oil source rock.
1999, 17(S1): 742-746.
Abstract:
The paper focuses on sequence stratigraphy of the Sinian in Western Henan Province. Based on the theory of sequence stratigraphy,three type I sequences have been identified, in which the first two sequences correlate to the Huanglianduo Formation and Dongjia Formation,respectively,and the third one includes both the Luoquan and Dongpo Formations. After establishing their sequence isochronic framework,the author analyzes systematically the distribution patterns and genetic relations of the strata and sedimentary facies zones within the framework,and then proposes that the formation of the Sinian sequences and their system tracts in the study area was controlled primarily by the relative sea-level changes. The sediments which deposited within the same sea-level changes,although they have different sedimentary environments and different components, are isochrononic and can be correlated. Finally,the author proposes a method how to drove the curves of relative sea-level changes. Based on the research result,the author concludes that the theory of sequence stratigraghy can be generally applied to the Precambian,such as the Sinian,by identifying the key boundaries,especially the sequence boundary (SB) and the maximum flooding surface (mls),and analyzing the features of the parasequences,parasequence sets and system tracts within a sequence. The method establishes a good base for the classification and correlation of the strata study. But the hierarchy of the sequence cannot be precisely determined because of low-studying-level and short of accurate dating,therefore further studies are necessary.
The paper focuses on sequence stratigraphy of the Sinian in Western Henan Province. Based on the theory of sequence stratigraphy,three type I sequences have been identified, in which the first two sequences correlate to the Huanglianduo Formation and Dongjia Formation,respectively,and the third one includes both the Luoquan and Dongpo Formations. After establishing their sequence isochronic framework,the author analyzes systematically the distribution patterns and genetic relations of the strata and sedimentary facies zones within the framework,and then proposes that the formation of the Sinian sequences and their system tracts in the study area was controlled primarily by the relative sea-level changes. The sediments which deposited within the same sea-level changes,although they have different sedimentary environments and different components, are isochrononic and can be correlated. Finally,the author proposes a method how to drove the curves of relative sea-level changes. Based on the research result,the author concludes that the theory of sequence stratigraghy can be generally applied to the Precambian,such as the Sinian,by identifying the key boundaries,especially the sequence boundary (SB) and the maximum flooding surface (mls),and analyzing the features of the parasequences,parasequence sets and system tracts within a sequence. The method establishes a good base for the classification and correlation of the strata study. But the hierarchy of the sequence cannot be precisely determined because of low-studying-level and short of accurate dating,therefore further studies are necessary.
1999, 17(S1): 752-757.
Abstract:
The Neozoic Era stratra deposits are mainly terrigenous clastics which formed in arid or semiarid regions in Kuche down warping region in Tarim basin. There are six lithologic associations during Neogene period in Kuche depression. The lithologic asociation during Paleogene period is FA6+FA5+FA1+FA3+FA2. The main lithologic association during Jidike period in the north area is FAl+FA2+FA5,and in the south area is FA5+FA6. The main lithologic association during Kongchong period in the north area is FA1+FA2+FA3,and in the south area is FA5+FA4. The main lithologic association during Kuche period in the north area is FA1+FA2+FA3,and in the east and south area is FA5. The sedimentary system is regarded as terminal fans by petrology,sedimentary structure and the depositional sequence. The model includes a tripartite zonation of terminal fans into feeder, distributary and basinal zones. The feeder zone is characterized by a down- stream decrease in both the scale and frequency of channel deposits,which are mainly replaced by sheetflood deposits. The basinal zone is made up of floodbasin,playa mudflat or aeolian-origined deposits. The lithologic type is mainly terrigenous clastics. The content of quartz is 10.1%-58.5%,of the terminal fan lithic fragment is 58%-84.3%,interstitial materials is 19. 2%-39.4%,cement is 1%-18%,that include anhydrite,calcite, dolomite and analcidite. The primary pore typs are primary intergranular pore,matrix micropore,shrinkage pore,intercrystal pore and inner granular pore. The secondary pore type include intergranular solution pore,granular solution pore,fracture etc. Integrated with the diagenesis,reservoir space,porosity and permeability,the reservoir quality of lower Tertiary stratra is poor and the better reservoir during Neogene period developped in the northern area in Kuche down warping region.
The Neozoic Era stratra deposits are mainly terrigenous clastics which formed in arid or semiarid regions in Kuche down warping region in Tarim basin. There are six lithologic associations during Neogene period in Kuche depression. The lithologic asociation during Paleogene period is FA6+FA5+FA1+FA3+FA2. The main lithologic association during Jidike period in the north area is FAl+FA2+FA5,and in the south area is FA5+FA6. The main lithologic association during Kongchong period in the north area is FA1+FA2+FA3,and in the south area is FA5+FA4. The main lithologic association during Kuche period in the north area is FA1+FA2+FA3,and in the east and south area is FA5. The sedimentary system is regarded as terminal fans by petrology,sedimentary structure and the depositional sequence. The model includes a tripartite zonation of terminal fans into feeder, distributary and basinal zones. The feeder zone is characterized by a down- stream decrease in both the scale and frequency of channel deposits,which are mainly replaced by sheetflood deposits. The basinal zone is made up of floodbasin,playa mudflat or aeolian-origined deposits. The lithologic type is mainly terrigenous clastics. The content of quartz is 10.1%-58.5%,of the terminal fan lithic fragment is 58%-84.3%,interstitial materials is 19. 2%-39.4%,cement is 1%-18%,that include anhydrite,calcite, dolomite and analcidite. The primary pore typs are primary intergranular pore,matrix micropore,shrinkage pore,intercrystal pore and inner granular pore. The secondary pore type include intergranular solution pore,granular solution pore,fracture etc. Integrated with the diagenesis,reservoir space,porosity and permeability,the reservoir quality of lower Tertiary stratra is poor and the better reservoir during Neogene period developped in the northern area in Kuche down warping region.
1999, 17(S1): 763-768.
Abstract:
Sampling the 1674 in Haojiatai,Xiaochangliang and Donggutuo sections in Nihewan bain based on the field works, and studying their quality susceptibility value and analysing their grain size characteristics. The results show that the change of susceptibility value and grain-size profile of lacustrine sediments relect the change of paleoclimate to some extent. The high values of susceptilbility and low fraction of fine grain indisate the cold and dry weather or the elevation of the basin,vice versa. In addition,the fine floating grain fraction between 0.2μm and 7.5μm may compare with isotope stage,which may good service fixing the high frequency age and studying the paleoclimate change in lacustrine sediments.
Sampling the 1674 in Haojiatai,Xiaochangliang and Donggutuo sections in Nihewan bain based on the field works, and studying their quality susceptibility value and analysing their grain size characteristics. The results show that the change of susceptibility value and grain-size profile of lacustrine sediments relect the change of paleoclimate to some extent. The high values of susceptilbility and low fraction of fine grain indisate the cold and dry weather or the elevation of the basin,vice versa. In addition,the fine floating grain fraction between 0.2μm and 7.5μm may compare with isotope stage,which may good service fixing the high frequency age and studying the paleoclimate change in lacustrine sediments.
1999, 17(S1): 775-781.
Abstract:
The area of the Yellow Sea is about 417 thousands square kilometres and is divided into north and South two parts according to the boundary line between the Chengshantou of Shandong Province and the Bailing Islands of Korea. Of which the North Yellow Sea is about 100 thousands square kilometres. The South Yellow Sea is three times as much as the North Yellow Sea. China began to study the sediments of the Yellow Sea from the 1950s and have got much scientific achievement. After 1970s,Institute of Oceanology,the Chinese Academy of Sciences the Tongji University First Institute of Oceanography,state Oceanic Administration had investigated and studied the surface and core samples from the Yellow Sea in varying degrees early or late. After the late 1980s,the previous Institute of Marine Geology,Ministry of Geology and Mineral Resources had made a study of the sequence of bedding and the stratigraphic correlation in the Quaternary.Above-mentioned study laid a foundation for the study of the South Yellow Sea. In this paper,the numbers of different microfossils and the distribution character of associations the sedimentary character the relationship among the microfossils planktonic foraminifera、calcareous nanoplank-fossils and Black Stream、the warm current of the Yellow Sea、the cold water mass、the coastal current of the Yellow Sea have been studied by means of the analysis of microfossils in the surface sediments from the South Yellow Sea. At same time,according to the data of size,the types of the surface sediments have been divided as follows:in the middle-west areas of the South Yellow Sea,1. clay 2. silt clay 3. fine-sand and silt 4. sand-gravel and mixtum,and in the east area,the sediments are arranged for inturn sand 、mud sand、sand mud and mud from the north to the south. In addition,the material resource in the surface sediments from the South Yellow Sea might be summed up following:1. the material cources of the Yellow River 2. the material sources of the Changjiang 3. the material sources of the remnant sand 4. the material sources of the Hanjiang and ]in- jiang etc. (Korean). 5. the material sources of eolian depos.
The area of the Yellow Sea is about 417 thousands square kilometres and is divided into north and South two parts according to the boundary line between the Chengshantou of Shandong Province and the Bailing Islands of Korea. Of which the North Yellow Sea is about 100 thousands square kilometres. The South Yellow Sea is three times as much as the North Yellow Sea. China began to study the sediments of the Yellow Sea from the 1950s and have got much scientific achievement. After 1970s,Institute of Oceanology,the Chinese Academy of Sciences the Tongji University First Institute of Oceanography,state Oceanic Administration had investigated and studied the surface and core samples from the Yellow Sea in varying degrees early or late. After the late 1980s,the previous Institute of Marine Geology,Ministry of Geology and Mineral Resources had made a study of the sequence of bedding and the stratigraphic correlation in the Quaternary.Above-mentioned study laid a foundation for the study of the South Yellow Sea. In this paper,the numbers of different microfossils and the distribution character of associations the sedimentary character the relationship among the microfossils planktonic foraminifera、calcareous nanoplank-fossils and Black Stream、the warm current of the Yellow Sea、the cold water mass、the coastal current of the Yellow Sea have been studied by means of the analysis of microfossils in the surface sediments from the South Yellow Sea. At same time,according to the data of size,the types of the surface sediments have been divided as follows:in the middle-west areas of the South Yellow Sea,1. clay 2. silt clay 3. fine-sand and silt 4. sand-gravel and mixtum,and in the east area,the sediments are arranged for inturn sand 、mud sand、sand mud and mud from the north to the south. In addition,the material resource in the surface sediments from the South Yellow Sea might be summed up following:1. the material cources of the Yellow River 2. the material sources of the Changjiang 3. the material sources of the remnant sand 4. the material sources of the Hanjiang and ]in- jiang etc. (Korean). 5. the material sources of eolian depos.
1999, 17(S1): 789-793.
Abstract:
The piston core PC5794,698cm long,was recovered from the East Pacific Ocean. It is composed of Quaternary and early Miocene in stratigraphy. 55 nannofossils ooze samples of early Miocene(698-140cm,24.06-22.06Ma)were collected in the interval of 5cm,and the 87Sr/86Sr Isotope-MS,ICP and chemical method respectively. The fluctuations of 87Sr/86Sr and CaC03 through time display two and an half short-term cycles which are opposite in direction. The cycles are significant to paleoceanography. (1) The positive and negative cycles of 87Sr/86Sr reflect the increased trends of chemical weathering of old crust and volcanic activities in ocean respectively, while the positive and negative CaC03 cycles are constant with warming and cooling trends of paleoclimate. In general,the temperatures of air were lower in the eras of strong volcanic activity. (2) Compared to middle and late Miocene,the influences of the Antarctic Bottom Water to sedimentation and water of east Pacific were less important in early Miocene. But the Antarctic Bottom Water formed CaC03 dissolution and high contents of benthic foraminifera.
The piston core PC5794,698cm long,was recovered from the East Pacific Ocean. It is composed of Quaternary and early Miocene in stratigraphy. 55 nannofossils ooze samples of early Miocene(698-140cm,24.06-22.06Ma)were collected in the interval of 5cm,and the 87Sr/86Sr Isotope-MS,ICP and chemical method respectively. The fluctuations of 87Sr/86Sr and CaC03 through time display two and an half short-term cycles which are opposite in direction. The cycles are significant to paleoceanography. (1) The positive and negative cycles of 87Sr/86Sr reflect the increased trends of chemical weathering of old crust and volcanic activities in ocean respectively, while the positive and negative CaC03 cycles are constant with warming and cooling trends of paleoclimate. In general,the temperatures of air were lower in the eras of strong volcanic activity. (2) Compared to middle and late Miocene,the influences of the Antarctic Bottom Water to sedimentation and water of east Pacific were less important in early Miocene. But the Antarctic Bottom Water formed CaC03 dissolution and high contents of benthic foraminifera.
1999, 17(S1): 798-804.
Abstract:
The Luhuo rift occurs in the internal parts of the Songpan-Ganzi massif,western Sichuan,which was bounded by the deep-seated Jiajilong-Quesuo fault and Seda fault. The boundary faults dipped northeastward and southwestward respectively, which constituted the garben-like type sea basin. Teh Luhuo rift is character- istically different from the neighboring parts in that there are basic volcanic rocks and calcareous breccias.Through the classificaiton and correlation of strata and formation analysIs,it is determined that there are turbidity formation,(volcanic) melange formation and bassyal sea carbon-silicon-mud formation in the Luhuo rift. The turbidite formation is the chief formation in the Triassic system. The Bouma sequence,various bedding structures are existed in the rock series. The granulometric analysis result as well as the lower maturities of composition and texture suggests the origin of turbidity fluid. Compared with the chemical composition of major elements and rare earth elements for graywack and slate in different distinct tectonic environments, it can be revealed that the continental island-arc source for the provenance of the Triassic turbidite in the rift.The melange formation and/or volcanic melange formation was olistostrome formed by short-distance transportation and deposition,which occur as stratified between age-determined marine strata. The bassyal sea carbon-silicon-mud formation consists of purple radiolaria-bearing silicon mudstone,gray,gray-purple and purple sponge-spiculte-bearing micrite, and silty mudstone. There are horizontal bedding and quasi-boxwork in mi-crite,which shows less hydrodynamic condition and starved calm bassyal environment. Combined with other data related to tectonic activity,vilcanoic and magmatic intrusive,the evolution from beginning,development to closing of the Luhuo rift may be divided into four stages as follows. 1)Primary rifting(in late-Permian) in which carbonate rock formation, clastic formation and tholeiite formtation were developed, accompanied with stratified basic-ultrabasic intrusive bodes,2)Deposition depression stage(from early-Triassic to late stage of late-Triassic) during which bassyal sea carbon-silicon-mud formation,melange formation nad turbidite formation were developed,3)Intense rifting stage (in the middle stage of late-Triassic)in which the volcanic melange formation was developed, accompanied with the intrusion of basic-ultrbasic dykes, and 4 ) Withering stage(in the late stage of late-Triassic) in which the turbidite formation was formed.
The Luhuo rift occurs in the internal parts of the Songpan-Ganzi massif,western Sichuan,which was bounded by the deep-seated Jiajilong-Quesuo fault and Seda fault. The boundary faults dipped northeastward and southwestward respectively, which constituted the garben-like type sea basin. Teh Luhuo rift is character- istically different from the neighboring parts in that there are basic volcanic rocks and calcareous breccias.Through the classificaiton and correlation of strata and formation analysIs,it is determined that there are turbidity formation,(volcanic) melange formation and bassyal sea carbon-silicon-mud formation in the Luhuo rift. The turbidite formation is the chief formation in the Triassic system. The Bouma sequence,various bedding structures are existed in the rock series. The granulometric analysis result as well as the lower maturities of composition and texture suggests the origin of turbidity fluid. Compared with the chemical composition of major elements and rare earth elements for graywack and slate in different distinct tectonic environments, it can be revealed that the continental island-arc source for the provenance of the Triassic turbidite in the rift.The melange formation and/or volcanic melange formation was olistostrome formed by short-distance transportation and deposition,which occur as stratified between age-determined marine strata. The bassyal sea carbon-silicon-mud formation consists of purple radiolaria-bearing silicon mudstone,gray,gray-purple and purple sponge-spiculte-bearing micrite, and silty mudstone. There are horizontal bedding and quasi-boxwork in mi-crite,which shows less hydrodynamic condition and starved calm bassyal environment. Combined with other data related to tectonic activity,vilcanoic and magmatic intrusive,the evolution from beginning,development to closing of the Luhuo rift may be divided into four stages as follows. 1)Primary rifting(in late-Permian) in which carbonate rock formation, clastic formation and tholeiite formtation were developed, accompanied with stratified basic-ultrabasic intrusive bodes,2)Deposition depression stage(from early-Triassic to late stage of late-Triassic) during which bassyal sea carbon-silicon-mud formation,melange formation nad turbidite formation were developed,3)Intense rifting stage (in the middle stage of late-Triassic)in which the volcanic melange formation was developed, accompanied with the intrusion of basic-ultrbasic dykes, and 4 ) Withering stage(in the late stage of late-Triassic) in which the turbidite formation was formed.
1999, 17(S1): 811-814.
Abstract:
Through research of gaseous hydrocarbon geochemistry of thermal simulating experiment and productive gaseous matter of nature evolution process from coal- measure source rocks, author think changeable of methane carbon isotope (δ13C1) are been from light t weight along with add of degrees in course thermal evolution of coal-measure source rocks. The changeable range of ethane carbon isotope(δ13C2) are rather narrow from-28.3‰ to-20‰(PDB). δ13C2 value ware-28‰±(Ro=0.45%-0.65%)is the lower thermal evolution stage of coal-measure source rocks, when the rocks ware getting into mainly hydrocarbon-generating stages (Ro=0.6%-1.5%)δ13C2 value of the gases are generally distributed -26‰ - -23‰,along with going step further evolution of the rocks,ethane carbon isotope ware gradualty got weight and δ13C2 vaice or generally large than -20‰. It is not the only characteristics of mixed-source gathered of differentially stem from gases that partial opposites sequence of the carbon isotope,on condition that specified styles of organisic,hydrocarbon source rocks have to from for its oneself vcolution.On the lower evolution stages of the rocks,it is mainly may decided by organic mather-source that gaseous hydrocarban carbon isntope are crccLlrrdr: features of partial opposites seqence and ethane carbon isotope value relatively lower,the features are related to geochemical compositions of primary soluble organic matter.
Through research of gaseous hydrocarbon geochemistry of thermal simulating experiment and productive gaseous matter of nature evolution process from coal- measure source rocks, author think changeable of methane carbon isotope (δ13C1) are been from light t weight along with add of degrees in course thermal evolution of coal-measure source rocks. The changeable range of ethane carbon isotope(δ13C2) are rather narrow from-28.3‰ to-20‰(PDB). δ13C2 value ware-28‰±(Ro=0.45%-0.65%)is the lower thermal evolution stage of coal-measure source rocks, when the rocks ware getting into mainly hydrocarbon-generating stages (Ro=0.6%-1.5%)δ13C2 value of the gases are generally distributed -26‰ - -23‰,along with going step further evolution of the rocks,ethane carbon isotope ware gradualty got weight and δ13C2 vaice or generally large than -20‰. It is not the only characteristics of mixed-source gathered of differentially stem from gases that partial opposites sequence of the carbon isotope,on condition that specified styles of organisic,hydrocarbon source rocks have to from for its oneself vcolution.On the lower evolution stages of the rocks,it is mainly may decided by organic mather-source that gaseous hydrocarban carbon isntope are crccLlrrdr: features of partial opposites seqence and ethane carbon isotope value relatively lower,the features are related to geochemical compositions of primary soluble organic matter.
1999, 17(S1): 820-824.
Abstract:
The advanced analytic techniques of thermal stimulation/on-line stable carbon mass spectrum and thermal stimulation/gas chromatography have been used to determine the light hydrocarbon distribution and the δ13C ratio of benzene and toluene of source rock and natural gas. The analytic results indicate that I、Ⅱ-type kerogen of lower Paleozoic limestone can generate more abundant benzene and touene of light hydrocarbon at the high stage of evolution .The δ13C ratios of benzene and toluene of light hydrocarbon mainly vary with kerogen type and have little relation to the maturity. The δ13C ratios of benzene and toluene of light hydrocarbon of source rock between Lower Paleozoic and Upper Paleozoic in Erdos basin are about-27‰ and- 22‰,Vrespectively. It indicates that the δ13C ratios of benzene and toluene vary apparently. The δ13C ratios of benzene and toluene of natural gas between Lower Paleozoic and Upper Paleozoic are-18.64‰--18. 61‰ and-23.71‰--17.15‰,-28.99‰--20.09‰ and-26.59‰--22.03‰ respectively .The direct correlation between source rock and natural gas has been taken according to the characteristics of light hydrocarbon distribution and δ13C ratios of benzene and toluene .Natural gas of Lower Paleozoic sources from source rock of Lower Paleozoic mainly.
The advanced analytic techniques of thermal stimulation/on-line stable carbon mass spectrum and thermal stimulation/gas chromatography have been used to determine the light hydrocarbon distribution and the δ13C ratio of benzene and toluene of source rock and natural gas. The analytic results indicate that I、Ⅱ-type kerogen of lower Paleozoic limestone can generate more abundant benzene and touene of light hydrocarbon at the high stage of evolution .The δ13C ratios of benzene and toluene of light hydrocarbon mainly vary with kerogen type and have little relation to the maturity. The δ13C ratios of benzene and toluene of light hydrocarbon of source rock between Lower Paleozoic and Upper Paleozoic in Erdos basin are about-27‰ and- 22‰,Vrespectively. It indicates that the δ13C ratios of benzene and toluene vary apparently. The δ13C ratios of benzene and toluene of natural gas between Lower Paleozoic and Upper Paleozoic are-18.64‰--18. 61‰ and-23.71‰--17.15‰,-28.99‰--20.09‰ and-26.59‰--22.03‰ respectively .The direct correlation between source rock and natural gas has been taken according to the characteristics of light hydrocarbon distribution and δ13C ratios of benzene and toluene .Natural gas of Lower Paleozoic sources from source rock of Lower Paleozoic mainly.
1999, 17(S1): 836-838.
Abstract:
An analysis is made about alkanes in TSP in Taiyuan city by GC-MS and GCC-MS.The result shows the following distribution features of ulkanes in TSP:There is an app+rent difference Letween winter and summer,i. e. distribution feature in winter takes the form of single-peak-group normal distribution,from lower carbon numbers to higher carbon numbers,high peak zone in the middle and lower peak zones of two ends.The maximum carbon number is C23. Starting from C26,odd-number carbon superiority is not apparnet. During the non-heating period the feature of alkane distribution:a normal distribution peak group from lower cabron numbers to higher carbon numbers to higher carbon numbers,i.e.C24-C21;from C21-C22,another normal distribtution peak group takes the from of twin-peak group distribution,having maximum carbon number at the highest peak C29. After C26 odd-number superiority is relatively apparent. There is sharp difference between different functional zones constituted by an alkanse series carbon isutapes,i. e. industrial area of Taiyuan steel-22.6‰,commercial residential area of Taiuan No. 4 lane-27.9‰,chemical industrial area of chemical fertilizer plant-32.98‰.The above distribution feature is closely related to the source of pollutants. The pollutants in the heating period mainly come from fossil fuels,dust and the products from combustion. The situation is mainly due to coal for winter heating,coal for industrial production consumption and coal mine production. Besides, Taiyuan city's affection by winter's reverse temperature is comparatively big. The air stability is big. The air exchange between the down town and the outskirts and the boundary villages is difficult. Besides,the germs in winter are not so active and a few of the current organic matters such as high-class plants, etc. enter atmosphere. The source of organic pollutants taken from the samples in summer ; except for mainly from fossil fuels,few from germs and current organic matter,e. g. High-class plants,the main reason is that in summer reverse temperature phenomea relatively small and the air stability gets smaller. It is easy for the air in outskirts and villages to disperse towards the city to make the curret organic matters such as high-class plants,etc. Be transported to down town and to make the different functional areas of alkanes distribution have less difference. Ralatively speaking,the organic pollution in Taiyuan city on the whole is severely influenced by the residues coming from combusted fossil fuels,it is only in summer that a few natural pollution sources exist. Concretely speaking, in different functional area : The industrial area of Taiyuan steel is mainly polluted by coal. the pollution constituents in the residential area in Taiyuan No. 4 lane is complex,i. e.products from combusted coal automobile tail-gas exhaustion and flying dust drained from daily life. The pollutants in the chemical industrial area of No. 1 power plant mainly come from chemical pollution,coal combustion and current high-class organic matters in the outskirts.
An analysis is made about alkanes in TSP in Taiyuan city by GC-MS and GCC-MS.The result shows the following distribution features of ulkanes in TSP:There is an app+rent difference Letween winter and summer,i. e. distribution feature in winter takes the form of single-peak-group normal distribution,from lower carbon numbers to higher carbon numbers,high peak zone in the middle and lower peak zones of two ends.The maximum carbon number is C23. Starting from C26,odd-number carbon superiority is not apparnet. During the non-heating period the feature of alkane distribution:a normal distribution peak group from lower cabron numbers to higher carbon numbers to higher carbon numbers,i.e.C24-C21;from C21-C22,another normal distribtution peak group takes the from of twin-peak group distribution,having maximum carbon number at the highest peak C29. After C26 odd-number superiority is relatively apparent. There is sharp difference between different functional zones constituted by an alkanse series carbon isutapes,i. e. industrial area of Taiyuan steel-22.6‰,commercial residential area of Taiuan No. 4 lane-27.9‰,chemical industrial area of chemical fertilizer plant-32.98‰.The above distribution feature is closely related to the source of pollutants. The pollutants in the heating period mainly come from fossil fuels,dust and the products from combustion. The situation is mainly due to coal for winter heating,coal for industrial production consumption and coal mine production. Besides, Taiyuan city's affection by winter's reverse temperature is comparatively big. The air stability is big. The air exchange between the down town and the outskirts and the boundary villages is difficult. Besides,the germs in winter are not so active and a few of the current organic matters such as high-class plants, etc. enter atmosphere. The source of organic pollutants taken from the samples in summer ; except for mainly from fossil fuels,few from germs and current organic matter,e. g. High-class plants,the main reason is that in summer reverse temperature phenomea relatively small and the air stability gets smaller. It is easy for the air in outskirts and villages to disperse towards the city to make the curret organic matters such as high-class plants,etc. Be transported to down town and to make the different functional areas of alkanes distribution have less difference. Ralatively speaking,the organic pollution in Taiyuan city on the whole is severely influenced by the residues coming from combusted fossil fuels,it is only in summer that a few natural pollution sources exist. Concretely speaking, in different functional area : The industrial area of Taiyuan steel is mainly polluted by coal. the pollution constituents in the residential area in Taiyuan No. 4 lane is complex,i. e.products from combusted coal automobile tail-gas exhaustion and flying dust drained from daily life. The pollutants in the chemical industrial area of No. 1 power plant mainly come from chemical pollution,coal combustion and current high-class organic matters in the outskirts.
1999, 17(S1): 846-853.
Abstract:
Natural gas hydrates have become an exciting national and international research issue. Gas hydrates,also called gas clathrates,naturally occur in solids comprised of water molecules forming a rigid lattice of cages with most of the cages, each containing a molecule of natural gas,mainly methane. Natural gas hydrates exists worldwide in the polar region,normally associated with onshore and offshore permafrost,and in sediment of outer continental and insular margins. The role that methane hydrates will play in contributing to the world's energy needs will depend on the availability,producibility,and cost of extracting methane from the hydrate phase. The generally accepted estimates of the total amount of methane that in gas hydrates is about twice the total methane of all fossil fuels (i. e. gas,oil,coal, etc.)combined.However, if even a small portion of the suspected gas hydrate accumulation is producible, hydrates would have a significant impact as an energy resource. The total amount of methane in gas hydrates likely exceeds 1019g methane carbon. Three important research areas clearly emerge as common themes in all gas hydrate research plans:(l)hydrates as an energy resource, (2) hydrates as agent of global change,and (3) hydrates as a factor in seafloor stability and geohazards. Because natural gas hydrates represent a large amount of methane within 2000m of the earth's surface, they are considered to be an unconventional,unproven source of fossil fuel.Because gas hydrates are metastable,changes of pressure and temperature affect their stability. Destabilized gas hydrates beneath the seafloor lead to geologic hazards such as submarine slumps and slides,examples of those are found worldwide. Destabilized gas hydrates may also affect climate through the release of methane,a "greenhouse" gas,which may enhance global warming and be an important factor in global climate change. I thought that in each of these aspects an imposing need arises for study that is both technically demanding and of public interest. Here we briefly review those three themes and their underlying scientific opportunitres.
Natural gas hydrates have become an exciting national and international research issue. Gas hydrates,also called gas clathrates,naturally occur in solids comprised of water molecules forming a rigid lattice of cages with most of the cages, each containing a molecule of natural gas,mainly methane. Natural gas hydrates exists worldwide in the polar region,normally associated with onshore and offshore permafrost,and in sediment of outer continental and insular margins. The role that methane hydrates will play in contributing to the world's energy needs will depend on the availability,producibility,and cost of extracting methane from the hydrate phase. The generally accepted estimates of the total amount of methane that in gas hydrates is about twice the total methane of all fossil fuels (i. e. gas,oil,coal, etc.)combined.However, if even a small portion of the suspected gas hydrate accumulation is producible, hydrates would have a significant impact as an energy resource. The total amount of methane in gas hydrates likely exceeds 1019g methane carbon. Three important research areas clearly emerge as common themes in all gas hydrate research plans:(l)hydrates as an energy resource, (2) hydrates as agent of global change,and (3) hydrates as a factor in seafloor stability and geohazards. Because natural gas hydrates represent a large amount of methane within 2000m of the earth's surface, they are considered to be an unconventional,unproven source of fossil fuel.Because gas hydrates are metastable,changes of pressure and temperature affect their stability. Destabilized gas hydrates beneath the seafloor lead to geologic hazards such as submarine slumps and slides,examples of those are found worldwide. Destabilized gas hydrates may also affect climate through the release of methane,a "greenhouse" gas,which may enhance global warming and be an important factor in global climate change. I thought that in each of these aspects an imposing need arises for study that is both technically demanding and of public interest. Here we briefly review those three themes and their underlying scientific opportunitres.
1999, 17(S1): 668-674.
Abstract:
Antlsraxolite is very common in Longtoushan reef limestone region. The main mode of occurrence of anthraxolite is in karst cavities,primary holes of reef limestone and in calcite veins. Some anthraxolite is discovered in cassiterite-sulphide ore bodies and in contact plane between granite- parphgy and reef limestone. Studies about anthraxolite and conditions of source- reservior-caprock association indicate that there was oil-gas migration and reservior in the reef in past geological history .The composition feature of stable isotopic and fluid inclusion shows a close relation between organic matter and polymetallic mineralization. One of the main period of petroleum evolution had a bearing on the seafloor exhalative sedimentary mineralization in Devo- nion. The final damage of oil-gas field related to magmatic activity in late Yenchan period. Organic matter played an impartant pole in polymetallic mineralization:Thermal brine containing organic matter promoted some ore-forming elements to be activated and migrate from strata,and at the same time to form hot-water karst in reef limestone which is the main space for mineralization and provide sulphur to controll to the physicochemical condition of ore-forming environment. On the other hand, submarine hot-water activity in Devonion and intrusion of magma in Yenchan period provided power for oil- gas evolution and migration of brine containing organic matter. Eventually the heat of magma accelerated the degradation and metamor-phism of organic matter. Light component volatilized and much anthraxolite remained.
Antlsraxolite is very common in Longtoushan reef limestone region. The main mode of occurrence of anthraxolite is in karst cavities,primary holes of reef limestone and in calcite veins. Some anthraxolite is discovered in cassiterite-sulphide ore bodies and in contact plane between granite- parphgy and reef limestone. Studies about anthraxolite and conditions of source- reservior-caprock association indicate that there was oil-gas migration and reservior in the reef in past geological history .The composition feature of stable isotopic and fluid inclusion shows a close relation between organic matter and polymetallic mineralization. One of the main period of petroleum evolution had a bearing on the seafloor exhalative sedimentary mineralization in Devo- nion. The final damage of oil-gas field related to magmatic activity in late Yenchan period. Organic matter played an impartant pole in polymetallic mineralization:Thermal brine containing organic matter promoted some ore-forming elements to be activated and migrate from strata,and at the same time to form hot-water karst in reef limestone which is the main space for mineralization and provide sulphur to controll to the physicochemical condition of ore-forming environment. On the other hand, submarine hot-water activity in Devonion and intrusion of magma in Yenchan period provided power for oil- gas evolution and migration of brine containing organic matter. Eventually the heat of magma accelerated the degradation and metamor-phism of organic matter. Light component volatilized and much anthraxolite remained.
1999, 17(S1): 681-686.
Abstract:
This paper dealt with the weathering and evolution of primary and clay minerals in ferrallite derived from basalt and granite in the south China .In the intensive weathered iatosol derived from basalt,the heavy min- erals mainly existed in the particle fractions of 10-50μm and 50-100μm,accounting for 35%-90%. In the feeble weathered red soils and lateritic red soils derived from basalt, the heavy minerals are lagely distributed in the particle fraction of 100-250μm,making up 10%-20%. However, the light minerals take the leading position in the ferrallite derived from granite. The kaolinite content in the lateritic red soils and red soils derived. from basalt are less than that in the clay fraction (<2μm)in the red soils are less than that in the latosol and iateritic red soils derived from basalt. The kaolinite contents in clay fraction in the lateritic red soils,red soils and yellow soils derived from granite are 54%,42 % and 35 %, respectively .According to the weathering of feldspar in the red and yellow soils derived from basalt and granite,the weathering process is subject to the climate Londitions and parent materials,therefore,the cimate and parent materials control the distribution of feldspar in various particle fractions .The wE:athering order among different feldspars is that ;Na-feldspar≥K-feldspar≥Ca-feldspar.
This paper dealt with the weathering and evolution of primary and clay minerals in ferrallite derived from basalt and granite in the south China .In the intensive weathered iatosol derived from basalt,the heavy min- erals mainly existed in the particle fractions of 10-50μm and 50-100μm,accounting for 35%-90%. In the feeble weathered red soils and lateritic red soils derived from basalt, the heavy minerals are lagely distributed in the particle fraction of 100-250μm,making up 10%-20%. However, the light minerals take the leading position in the ferrallite derived from granite. The kaolinite content in the lateritic red soils and red soils derived. from basalt are less than that in the clay fraction (<2μm)in the red soils are less than that in the latosol and iateritic red soils derived from basalt. The kaolinite contents in clay fraction in the lateritic red soils,red soils and yellow soils derived from granite are 54%,42 % and 35 %, respectively .According to the weathering of feldspar in the red and yellow soils derived from basalt and granite,the weathering process is subject to the climate Londitions and parent materials,therefore,the cimate and parent materials control the distribution of feldspar in various particle fractions .The wE:athering order among different feldspars is that ;Na-feldspar≥K-feldspar≥Ca-feldspar.
1999, 17(S1): 691-698.
Abstract:
The Dingjiazhai Fm. aged Asselian-Sakmarian pseudoconformably overlies the Pumenqian Fm. aged the Lower Carboniferous. The Dingjiazhai Fm. in the Dingjiazhai section at Shidian County mainly comprises 3 parts in ascending order:1. the pebble-bearing layer at the lower part;2. siltstones and black shales at the middle part in which trace fossils Palaeophycus sp.,Taenidium serpentinum?,have been found,3. muddy siltstones and biocalcarenites at the upper part. A thin purple mudstone occurs at its topmost in which the trace fossil Dendrotichnium sp.,is present. According to the palaeontological, petrological and ichnological features, six main sedimentological facies are distinguished from the upper part of Pumenqian Fm. to the Dingjiazhai Fm. . They are tidal flat fades,margin facies and lagoon facies which were located in the restricted platform,sand bar or shoal facies,basin facies of shallow water and open marine platform which belonged to open marine environments. The Dingjiazhai Fm. in the Jinji section of Baoshan region consists of the pebble-bearing layer at its lower part and mudstones and muddy siltstones at its middle and upper part. Palaeo-phycus sp. B and Tisoa jinjiensis are main trace fossils present in the mudstones and muddy siltstones overlying the pebble-bearing layer. The vertical U-shaped structures of Tisoa jinjiensis are similar to those of Areni-colites. The trace fossil assemblage can be attributed to the Skolithos ichnofacies. As indicated by Frey&Pemberton (1984),the environments which the,Skolithos ichnofacies represents are characterized by shifting substrates, moderate to high-energy conditions and episodic erosion or deposition. On the basis of petrological studies on the pebble-bearing layer,it can be divided into two beds:the lower pebble bed and the upper brecdated limestone. The pebbles with better rounding in the former are elliptical and flat and mainly consist of siltstones,quartzites,silicolites and lithic sandstones. The breccia in the latter are briefly composed of lime-stones whose carbonate microfacies are similar to those of the underlying Pumenqian Fm. . The cementation of the brecciated limestone is much better than that of the lower pebble bed. The authors consider that the origin of the pebble-bearing layer at the lower part of the Dingjiazhai Fm. is not related to glaciation. The lower pebble bed was deposited in the normal littoral environments and the upper brecciated limestone was de- rived from the debris flow. The palaeoecologic features of biota (corals, fusulinids,spores) also indicate that the organisms lived in warm marine environments. Many geologists have regarded striated clasts, dropstones, three-fold sequence and periglacial marine biota as main evidences of glacial origin of the Dingjiazhai Fm. .This paper puts forward different viewpoints against their conclusions. The striated clasts are not only prod- acts of glacial process. They can be produced by many other geological processes such as faults,debris flow,landslip,landfall, mountain flood and even wind action. The photos of striated clasts (Fan&Fang,1992) do not show any typical characters generated by glaciation. They have better roundness and lack evident worn planes. The direction of striates is different from that of long axis of clasts. Some Chinese and foreign geologists misunderstand that the dropstones are able to stab the stratification when they fall down. In fact,when the dropstones fall down and come into contact with the surface of deposits,the power of dropstones is not strong enough to crash the stratification and only can bend it. The local concentration of pebbles and coarse clasts and the occurrence of till pellets can be regarded as products of ice-berg raft. Unfortunately,these phenomena have not been found in the Dingjiazhai Fm. Wopfner (1994) suggest that the three-fold sequence consisting of 1. diamictites and coarse elastics;2. pebbly mudstones and laminites and 3. black pyritic mudstones respectively correspond to the deposits in glacial advance,glacial retreat and deglacialtion which are observed in many Gondwana areas. Howerver,the stratigraphic sequences and regional dstribution of the Dingjiazhai Fm. in Baoshan region are so simple that they can not be attributed to the mentioned above three-fold sequence related to glaciation. Eurydesma-Deltopecten fauna characterized by lower diversity are typical periglacial marine biota. The main members of this fauna include bivalves Megadesmus;Myonia,braehiopods Trigonotreta, Cyrtella,Arc-titreta, Tomiospsis;gastropods Keeneia, I'eruispira. The specimen Eurydesma in the Dingjiazhai Fm, is an error of identification. It has been acted as an important proof of the presence of periglacial marine biota. Fang and Lin (1990) restudied this specimen and identified it as Schizodus. The most members of brachiopods are attributed to the Tethyan type. Only Cyrtella belongs to the Gondwana type. As mentioed above,the hypothesis of glacial origin of the Dingjiazhai Fm. at Baoshan region is truthless.
The Dingjiazhai Fm. aged Asselian-Sakmarian pseudoconformably overlies the Pumenqian Fm. aged the Lower Carboniferous. The Dingjiazhai Fm. in the Dingjiazhai section at Shidian County mainly comprises 3 parts in ascending order:1. the pebble-bearing layer at the lower part;2. siltstones and black shales at the middle part in which trace fossils Palaeophycus sp.,Taenidium serpentinum?,have been found,3. muddy siltstones and biocalcarenites at the upper part. A thin purple mudstone occurs at its topmost in which the trace fossil Dendrotichnium sp.,is present. According to the palaeontological, petrological and ichnological features, six main sedimentological facies are distinguished from the upper part of Pumenqian Fm. to the Dingjiazhai Fm. . They are tidal flat fades,margin facies and lagoon facies which were located in the restricted platform,sand bar or shoal facies,basin facies of shallow water and open marine platform which belonged to open marine environments. The Dingjiazhai Fm. in the Jinji section of Baoshan region consists of the pebble-bearing layer at its lower part and mudstones and muddy siltstones at its middle and upper part. Palaeo-phycus sp. B and Tisoa jinjiensis are main trace fossils present in the mudstones and muddy siltstones overlying the pebble-bearing layer. The vertical U-shaped structures of Tisoa jinjiensis are similar to those of Areni-colites. The trace fossil assemblage can be attributed to the Skolithos ichnofacies. As indicated by Frey&Pemberton (1984),the environments which the,Skolithos ichnofacies represents are characterized by shifting substrates, moderate to high-energy conditions and episodic erosion or deposition. On the basis of petrological studies on the pebble-bearing layer,it can be divided into two beds:the lower pebble bed and the upper brecdated limestone. The pebbles with better rounding in the former are elliptical and flat and mainly consist of siltstones,quartzites,silicolites and lithic sandstones. The breccia in the latter are briefly composed of lime-stones whose carbonate microfacies are similar to those of the underlying Pumenqian Fm. . The cementation of the brecciated limestone is much better than that of the lower pebble bed. The authors consider that the origin of the pebble-bearing layer at the lower part of the Dingjiazhai Fm. is not related to glaciation. The lower pebble bed was deposited in the normal littoral environments and the upper brecciated limestone was de- rived from the debris flow. The palaeoecologic features of biota (corals, fusulinids,spores) also indicate that the organisms lived in warm marine environments. Many geologists have regarded striated clasts, dropstones, three-fold sequence and periglacial marine biota as main evidences of glacial origin of the Dingjiazhai Fm. .This paper puts forward different viewpoints against their conclusions. The striated clasts are not only prod- acts of glacial process. They can be produced by many other geological processes such as faults,debris flow,landslip,landfall, mountain flood and even wind action. The photos of striated clasts (Fan&Fang,1992) do not show any typical characters generated by glaciation. They have better roundness and lack evident worn planes. The direction of striates is different from that of long axis of clasts. Some Chinese and foreign geologists misunderstand that the dropstones are able to stab the stratification when they fall down. In fact,when the dropstones fall down and come into contact with the surface of deposits,the power of dropstones is not strong enough to crash the stratification and only can bend it. The local concentration of pebbles and coarse clasts and the occurrence of till pellets can be regarded as products of ice-berg raft. Unfortunately,these phenomena have not been found in the Dingjiazhai Fm. Wopfner (1994) suggest that the three-fold sequence consisting of 1. diamictites and coarse elastics;2. pebbly mudstones and laminites and 3. black pyritic mudstones respectively correspond to the deposits in glacial advance,glacial retreat and deglacialtion which are observed in many Gondwana areas. Howerver,the stratigraphic sequences and regional dstribution of the Dingjiazhai Fm. in Baoshan region are so simple that they can not be attributed to the mentioned above three-fold sequence related to glaciation. Eurydesma-Deltopecten fauna characterized by lower diversity are typical periglacial marine biota. The main members of this fauna include bivalves Megadesmus;Myonia,braehiopods Trigonotreta, Cyrtella,Arc-titreta, Tomiospsis;gastropods Keeneia, I'eruispira. The specimen Eurydesma in the Dingjiazhai Fm, is an error of identification. It has been acted as an important proof of the presence of periglacial marine biota. Fang and Lin (1990) restudied this specimen and identified it as Schizodus. The most members of brachiopods are attributed to the Tethyan type. Only Cyrtella belongs to the Gondwana type. As mentioed above,the hypothesis of glacial origin of the Dingjiazhai Fm. at Baoshan region is truthless.
1999, 17(S1): 712-717.
Abstract:
Oolitic pyrite ores,a special ore-type,occur in the Gaobanhe massive sulfide deposit in the Proterozoic rift in the Yanshan region. The pyrite oolides have cores consisting of compacted trangular laminae,cemented by filamentous thermophilous microorganism,of sulfur-addicted bacteria and as many as 10-20 incrustations composed of pyrite and lesser galena. In the oolitic pyrite,there are 1.43%-2.59% of highly sapropelic organic materials,plenty of organism-marking materials, normalized iroamyl dialkene and methyl heptadecyl,and large amounts of phytane and pristane. The oolitic pyrite is similar to hot-water depositions of modern oceanic rifts with respect to its composition of micro and REE-elements, showing a bacterium or algae-built sedimentary texture under microscope. Further studies indicate these organisms were flourishing in a reduced environment colse to the vents of hot water on sea bdes,essentially because of the suspended regime caused by the vent pulsation. This regime helped the thermophilous microoganism to grow around the pyrite intraclasts and bacterial groups and to take up mineral materials from the vent hot water. In a word,a series of mechanisms including submar8ine ezhalation,vent pulsation,microorganic adsorption and reduction,and the lide contributed considerably to formation of the oolitic pyrite.
Oolitic pyrite ores,a special ore-type,occur in the Gaobanhe massive sulfide deposit in the Proterozoic rift in the Yanshan region. The pyrite oolides have cores consisting of compacted trangular laminae,cemented by filamentous thermophilous microorganism,of sulfur-addicted bacteria and as many as 10-20 incrustations composed of pyrite and lesser galena. In the oolitic pyrite,there are 1.43%-2.59% of highly sapropelic organic materials,plenty of organism-marking materials, normalized iroamyl dialkene and methyl heptadecyl,and large amounts of phytane and pristane. The oolitic pyrite is similar to hot-water depositions of modern oceanic rifts with respect to its composition of micro and REE-elements, showing a bacterium or algae-built sedimentary texture under microscope. Further studies indicate these organisms were flourishing in a reduced environment colse to the vents of hot water on sea bdes,essentially because of the suspended regime caused by the vent pulsation. This regime helped the thermophilous microoganism to grow around the pyrite intraclasts and bacterial groups and to take up mineral materials from the vent hot water. In a word,a series of mechanisms including submar8ine ezhalation,vent pulsation,microorganic adsorption and reduction,and the lide contributed considerably to formation of the oolitic pyrite.
Reservoir Characters of Classic Rocs of the Shanxi Formation at Yi-Meng Area,Northern of Ordos Basin
1999, 17(S1): 723-727.
Abstract:
sandy-conglomerated braided channel of middle fan, the point-sandbar deposit ofmeandering river and the distributor channel sand of the delta-plain are the main sandstone reservoir of the shanxi formation at the Yi-Meng area. The sand bodies are consisted of quartz sandstone and lithic sandstone with abundant impurity and lithic fragment. It is characterized by the low porosity,low permeability,the heterogeneities and secondary pores predominantly. Their physical property are associated with its depositional micro-facies:the physical property of the point-sandbar deposit,the distributor channel deposit and sandy-conglomerated braided channel gradually become worse and worse. Based on the relationship between pore-throat types,the shanxi formation sandstone reservoir could be classified into four types. Tl}e reservoir of middle porosity and low permeability with solution pore and remainder intergranular porosity is distributed of the point-sandbar deposit and the distributor channel deposit are mainly objective formations of exploration in South Yi-Meng;The reservoir of low porosity and low permeability with intercrystal pore is distributed of the sandy-conglomerated braided channel and can consisted of the lithologic reservoir with tectonic setting;The compacted reservoir with micro-pore and micro-fracture scarcely are discovered oil and gas in the area;The exceed compacted reservoir with no pore and fracture are not discovered oil and gas in the area.
sandy-conglomerated braided channel of middle fan, the point-sandbar deposit ofmeandering river and the distributor channel sand of the delta-plain are the main sandstone reservoir of the shanxi formation at the Yi-Meng area. The sand bodies are consisted of quartz sandstone and lithic sandstone with abundant impurity and lithic fragment. It is characterized by the low porosity,low permeability,the heterogeneities and secondary pores predominantly. Their physical property are associated with its depositional micro-facies:the physical property of the point-sandbar deposit,the distributor channel deposit and sandy-conglomerated braided channel gradually become worse and worse. Based on the relationship between pore-throat types,the shanxi formation sandstone reservoir could be classified into four types. Tl}e reservoir of middle porosity and low permeability with solution pore and remainder intergranular porosity is distributed of the point-sandbar deposit and the distributor channel deposit are mainly objective formations of exploration in South Yi-Meng;The reservoir of low porosity and low permeability with intercrystal pore is distributed of the sandy-conglomerated braided channel and can consisted of the lithologic reservoir with tectonic setting;The compacted reservoir with micro-pore and micro-fracture scarcely are discovered oil and gas in the area;The exceed compacted reservoir with no pore and fracture are not discovered oil and gas in the area.
1999, 17(S1): 734-741.
Abstract:
The discovery and study of Changqing Gas Field in Ordos Basin has shown the gas exploration prospect of Paleozoic,especially the weathered crust gas reservoir of Ordovician System. Ertuokeqianqi is one of the most favorable regions for gas exploration,and it has been paid much attentions for many years. Mainly based on 2-D seismic data and coupled with drilling and well logging data,we studied and described the seismic characteristics of the morphology of the weathered crust of Ordovician,Ertuokeqanqi,Ordos Basin through geological and seismic models. Firstly,through the study of drills,well logs and :sonic synthetic seismograms,we mastered the characteristic essentials of objective formations-the different conic velocity between upper Paleozoic and lower Paleozoic and the two coal formations and their seismic cha-acteristic .At the same time,we also understood the relations of Lithology and Logging parameters, which lays a foundation for developing seismic models. Furthermore,we divided the shapes of the Ordovician weathered crust into four conceptual models,namely, paleotableland,paleopit, paleovalley and paleoslope. Using these models,we elementarily established the corresponding relations between paleogeomorphology and seismic characteristic with the analysis and comparison of geological models,seismic reflection and practical reflection. We have found that the dis- tance between the lower coal formation and Ordovician weathered crust had important relations with the seismic characteristics. Finally,this research is very valuable to interpret and calibrate the weathered crust of Ordovician system on seismic log and to draw the horizontal maps of the relic Ordovician formation over the M55. The maps might reflect the morphology of the weathered crust,and which is helpful to find Ordovician weathered crust gas reservoir and direct the gas exploration in Ertuokepianqi, Ordos Basin.
The discovery and study of Changqing Gas Field in Ordos Basin has shown the gas exploration prospect of Paleozoic,especially the weathered crust gas reservoir of Ordovician System. Ertuokeqianqi is one of the most favorable regions for gas exploration,and it has been paid much attentions for many years. Mainly based on 2-D seismic data and coupled with drilling and well logging data,we studied and described the seismic characteristics of the morphology of the weathered crust of Ordovician,Ertuokeqanqi,Ordos Basin through geological and seismic models. Firstly,through the study of drills,well logs and :sonic synthetic seismograms,we mastered the characteristic essentials of objective formations-the different conic velocity between upper Paleozoic and lower Paleozoic and the two coal formations and their seismic cha-acteristic .At the same time,we also understood the relations of Lithology and Logging parameters, which lays a foundation for developing seismic models. Furthermore,we divided the shapes of the Ordovician weathered crust into four conceptual models,namely, paleotableland,paleopit, paleovalley and paleoslope. Using these models,we elementarily established the corresponding relations between paleogeomorphology and seismic characteristic with the analysis and comparison of geological models,seismic reflection and practical reflection. We have found that the dis- tance between the lower coal formation and Ordovician weathered crust had important relations with the seismic characteristics. Finally,this research is very valuable to interpret and calibrate the weathered crust of Ordovician system on seismic log and to draw the horizontal maps of the relic Ordovician formation over the M55. The maps might reflect the morphology of the weathered crust,and which is helpful to find Ordovician weathered crust gas reservoir and direct the gas exploration in Ertuokepianqi, Ordos Basin.
1999, 17(S1): 747-751.
Abstract:
Based on various information,total 8 allocyclic parasequences are identified in Upper May Member,Central Ordos Basin and most of them are in good coincidence with the Gamma Ray logging curves. In this paper, each parasequence is described in detail. The upper parts of these meter-scale parasequences are mostly deposited in dolomite flat enriched with gypsum,which abound in various evidences of durable exposure. Controlled by sea-level fluctuation,δ13C values in each parasequence ascend and follow by reduction. As shown in parasequence No. 6,δ13C value varies upward from -3.O‰ to -0.7‰,and finally reaches to -1.7‰. But because each parasequence is located at the different part of the third-order sequence,the averages of δ13C values may change. These changes in higher-order sequence show a similar rule as that in parasequences. Different levels of sea-level fluctuation shaped sequences of different levels or even parasequences,thus indicated the similar rules in sequences and parasequences. On the basis of numerous test data, the content of gypsum and salt precipitated in different period of the formation of parasequences seem to change regularly, leading to the porosity and content of remnant gypsum steadily increase. While content of material which can not be dissolved in acid gradually descend,as it was mainly constituted by mud and organic matters. High porosity zone mostly distributes at the top or upper part of exposed parasequences.
Based on various information,total 8 allocyclic parasequences are identified in Upper May Member,Central Ordos Basin and most of them are in good coincidence with the Gamma Ray logging curves. In this paper, each parasequence is described in detail. The upper parts of these meter-scale parasequences are mostly deposited in dolomite flat enriched with gypsum,which abound in various evidences of durable exposure. Controlled by sea-level fluctuation,δ13C values in each parasequence ascend and follow by reduction. As shown in parasequence No. 6,δ13C value varies upward from -3.O‰ to -0.7‰,and finally reaches to -1.7‰. But because each parasequence is located at the different part of the third-order sequence,the averages of δ13C values may change. These changes in higher-order sequence show a similar rule as that in parasequences. Different levels of sea-level fluctuation shaped sequences of different levels or even parasequences,thus indicated the similar rules in sequences and parasequences. On the basis of numerous test data, the content of gypsum and salt precipitated in different period of the formation of parasequences seem to change regularly, leading to the porosity and content of remnant gypsum steadily increase. While content of material which can not be dissolved in acid gradually descend,as it was mainly constituted by mud and organic matters. High porosity zone mostly distributes at the top or upper part of exposed parasequences.
1999, 17(S1): 758-762.
Abstract:
The late Triassic lacustrine in Ordos basin is a large open lake with gentle topography .This paper has firstly reported the lacustrine elastic tempestites in the Triassic Yanchang Formation of the central Ordos basin. The typical tempestite consist of packstones which have a lot of deposition-structural characteristic for differently evolutionary stage of storm. Sedimentary structures of the storm deposits are :a)hummocky cross-stratification are characterized by gentlly curved,low angel cross-lamination. Presently most researchers think that powerful dominant or multidirectional oscillatory flow result in the special character which is most useful and best indicator of the storm sedimentary sequences distinguished from the turbidites., b ) basal division,consisting of one or more of the following:sharp base; oriented directional sole marks ; basal lag of pebbles,or rip-up and deformed resedimented intrabasinal clasts of mudstone. The formation of these structure is related to sediment liquefacion,drainage,reflecting the characteristics of density current. Especially the erosional structure and basal lag of pebbles in turbidite facics are the evidence of storm activity c) planar parallel lamination,d) bioturbated mudstone or fine sandstone .The reservation of escaping structure indicate a quick depositional event. After the storm is over,burrow structure will be developed on the sediment surface,e)lower maturity in texture in sandstone .Lower maturity reflect lower degree of sorting that is a signature of rapid deposit. The typical sequence is concluded. It can be divided into :a) high-discharge form, characterized by block structure,deformed pebble bedding,escaping trace,b ) hiatus, c ) low-discharge,marked by wave-cross ripple mark, burrow trace, lenticular bedding and vein bedding. Storm sedimentary model is given in this paper .We also discuss the structure and paleo-latitude setting of the late Triassic lacustrine tempestites,background of which has been defined as high-level system and was developed in the middle of lake-regressive sequence during the evolution of the basin. The storm deposit transit to deltas or beaches deposits upper and to turbidites offshore. We use the combination of storm facies asso- ciation and geological characters of adjacent areas to modify the former located sedimentary boundary of the Yanchang lake .We futher indicate storm sedimentary ;association developed area as prospective lithologic or structrure-lithological trap.
The late Triassic lacustrine in Ordos basin is a large open lake with gentle topography .This paper has firstly reported the lacustrine elastic tempestites in the Triassic Yanchang Formation of the central Ordos basin. The typical tempestite consist of packstones which have a lot of deposition-structural characteristic for differently evolutionary stage of storm. Sedimentary structures of the storm deposits are :a)hummocky cross-stratification are characterized by gentlly curved,low angel cross-lamination. Presently most researchers think that powerful dominant or multidirectional oscillatory flow result in the special character which is most useful and best indicator of the storm sedimentary sequences distinguished from the turbidites., b ) basal division,consisting of one or more of the following:sharp base; oriented directional sole marks ; basal lag of pebbles,or rip-up and deformed resedimented intrabasinal clasts of mudstone. The formation of these structure is related to sediment liquefacion,drainage,reflecting the characteristics of density current. Especially the erosional structure and basal lag of pebbles in turbidite facics are the evidence of storm activity c) planar parallel lamination,d) bioturbated mudstone or fine sandstone .The reservation of escaping structure indicate a quick depositional event. After the storm is over,burrow structure will be developed on the sediment surface,e)lower maturity in texture in sandstone .Lower maturity reflect lower degree of sorting that is a signature of rapid deposit. The typical sequence is concluded. It can be divided into :a) high-discharge form, characterized by block structure,deformed pebble bedding,escaping trace,b ) hiatus, c ) low-discharge,marked by wave-cross ripple mark, burrow trace, lenticular bedding and vein bedding. Storm sedimentary model is given in this paper .We also discuss the structure and paleo-latitude setting of the late Triassic lacustrine tempestites,background of which has been defined as high-level system and was developed in the middle of lake-regressive sequence during the evolution of the basin. The storm deposit transit to deltas or beaches deposits upper and to turbidites offshore. We use the combination of storm facies asso- ciation and geological characters of adjacent areas to modify the former located sedimentary boundary of the Yanchang lake .We futher indicate storm sedimentary ;association developed area as prospective lithologic or structrure-lithological trap.
1999, 17(S1): 769-774.
Abstract:
The superficial sediment layer in lake,only a few centimeters in thickness,may contain more organic matter,nutrients and anthropogenic pollutants than the entire water-cdumn. The particle sige distribution can be used to indicate the flow direction and energy distribution of the lake. The water energy and flow's feature controlled the nutrients and pollutants distributions in the lake. In the light of research results about particle size distribution,cluster analysis and factor analysis,the author surmises that there are several types of lake flows with different direction and power existing in Erhai Lake.First,there is a flow from Miju River,which is the biggest input river of Erhai Lake,forming the primary dynamic flow. Second,the Cangshan streams along the western side of Lake Erhai forms the radical canal flows from west side to the east,which are diminished gradually,and built fan delta along west side.Third,along the west side,exists lake flows with the direction from north to south;fourth,affecting by the topography of Lake Erhai,there are three relatively big annular flows in Lake Erhai with anticyclone direction. In a word,the flows' features control nowadays size distribution framwork.
The superficial sediment layer in lake,only a few centimeters in thickness,may contain more organic matter,nutrients and anthropogenic pollutants than the entire water-cdumn. The particle sige distribution can be used to indicate the flow direction and energy distribution of the lake. The water energy and flow's feature controlled the nutrients and pollutants distributions in the lake. In the light of research results about particle size distribution,cluster analysis and factor analysis,the author surmises that there are several types of lake flows with different direction and power existing in Erhai Lake.First,there is a flow from Miju River,which is the biggest input river of Erhai Lake,forming the primary dynamic flow. Second,the Cangshan streams along the western side of Lake Erhai forms the radical canal flows from west side to the east,which are diminished gradually,and built fan delta along west side.Third,along the west side,exists lake flows with the direction from north to south;fourth,affecting by the topography of Lake Erhai,there are three relatively big annular flows in Lake Erhai with anticyclone direction. In a word,the flows' features control nowadays size distribution framwork.
1999, 17(S1): 782-788.
Abstract:
It is well known that beachrocks are the characteristic rock of tropics and subtropics beach. They are formed in special geomorphologic locations and sedimentary environment and are formed in special geomor-phologic locations and sedimentary environment and are considered as a kind of good sign to show facies and an important symbol to recover the ancient position of sea level. For this reason,geologists have been paying colse attention to beachrocks. Beachrocks formed in different period are distributed very extensively in the coastal areas and seabed of many islands as well as the southeastern coast of China,but most of them discovered during 1940s-1984s were post-late-Pleistocene beachrocks. The submerged beachrocks on seabed have not been discovered much.During the marine geological survey on the south margin of the East China Sea continental shelf in eary 1990s,a few big and integrted beachrock (olcated about 115m water depth) and bioclastics (between 110m and 241m water depth) samples were collected on the seabed at many places. It was considered that the collected rocks were only a small part of beachrock outcrops. Many beachrocks might be covered by residual sand and there should be an extensive distribution of submerged beach-rock and biiclastic limestone nearby the southern shelf break zone of the East China Sea,which needs further investigations and study in the future. Analysis shows the characters of beachrocks: (1) The rock is mainly composed of terrigenous fragment, bio-clamshell fragment and cement, the three kia}ds of components being not well-distributed.Clamshell content is about 25-45 percent and its composition is simple,mainly including Gastropods and lamellibranchic. The content of other organisms(Foraminifera,Al- gae,Hepatica,Spongy,Coral fragment,for instance) is not much. Terrigenous fragment takes up about 30-60 percent and their grains are proximate edge angle,proximate round or edge angle,main composition being quartz-Next is plagiochasite and k-feldspar etc.In ciment,calcite is the important composition,the next aragonite. Small amount of argillaceous cement is also in it. There are basemental cementation and sandy and silt structure. Especially the rock appears slightly stratified structure. The arrangement of shell fragment presents a bit of directivity,which suggests the trace of certain beach courses. According to the analysis,submerged beachrock is named and is the biolith formed in shore and beach environment. (2) Chemistry compositions:CAO holds 40.40 percent and SiO2 18.76 percent. This content arrangement of different compositions was chiefly caused by random distribution of organism and terrigenous composition during beach-action course and by different position for collecting samples. In addition,MgO content of beachrocks,as well as the difference among fragment composition, granulanity and psephicity of the rocks,can infer the difference of diagenetic environment. (3)ERA chemistry-composition measurement and XRD analysis of the cement indicated that the cement of the rock was mainly low-Mg-c alcite. The crystallizationdegree of the cement was higher. The measurement result of electronic probe of the cement was in accordance with the analysis of XRD. (4)The 14C dating result of the beachrocks is about 20000-21000 a B. C., which indicates that it is the deposit of shore envirnment at low sea level during the last glacial age of late Pleistocene,being to submerged beachrocks of late Pleistocene. In addition,it is considered that the formation and change of beachrocks would vary accompanying the occurrence of varied geologic events and time change in different areas and under the influence of circumstances and so on. Beachrocks in different morphologic positions also show various characters. It is much com- plicated to certificate it accurately and study its variation and differences.
It is well known that beachrocks are the characteristic rock of tropics and subtropics beach. They are formed in special geomorphologic locations and sedimentary environment and are formed in special geomor-phologic locations and sedimentary environment and are considered as a kind of good sign to show facies and an important symbol to recover the ancient position of sea level. For this reason,geologists have been paying colse attention to beachrocks. Beachrocks formed in different period are distributed very extensively in the coastal areas and seabed of many islands as well as the southeastern coast of China,but most of them discovered during 1940s-1984s were post-late-Pleistocene beachrocks. The submerged beachrocks on seabed have not been discovered much.During the marine geological survey on the south margin of the East China Sea continental shelf in eary 1990s,a few big and integrted beachrock (olcated about 115m water depth) and bioclastics (between 110m and 241m water depth) samples were collected on the seabed at many places. It was considered that the collected rocks were only a small part of beachrock outcrops. Many beachrocks might be covered by residual sand and there should be an extensive distribution of submerged beach-rock and biiclastic limestone nearby the southern shelf break zone of the East China Sea,which needs further investigations and study in the future. Analysis shows the characters of beachrocks: (1) The rock is mainly composed of terrigenous fragment, bio-clamshell fragment and cement, the three kia}ds of components being not well-distributed.Clamshell content is about 25-45 percent and its composition is simple,mainly including Gastropods and lamellibranchic. The content of other organisms(Foraminifera,Al- gae,Hepatica,Spongy,Coral fragment,for instance) is not much. Terrigenous fragment takes up about 30-60 percent and their grains are proximate edge angle,proximate round or edge angle,main composition being quartz-Next is plagiochasite and k-feldspar etc.In ciment,calcite is the important composition,the next aragonite. Small amount of argillaceous cement is also in it. There are basemental cementation and sandy and silt structure. Especially the rock appears slightly stratified structure. The arrangement of shell fragment presents a bit of directivity,which suggests the trace of certain beach courses. According to the analysis,submerged beachrock is named and is the biolith formed in shore and beach environment. (2) Chemistry compositions:CAO holds 40.40 percent and SiO2 18.76 percent. This content arrangement of different compositions was chiefly caused by random distribution of organism and terrigenous composition during beach-action course and by different position for collecting samples. In addition,MgO content of beachrocks,as well as the difference among fragment composition, granulanity and psephicity of the rocks,can infer the difference of diagenetic environment. (3)ERA chemistry-composition measurement and XRD analysis of the cement indicated that the cement of the rock was mainly low-Mg-c alcite. The crystallizationdegree of the cement was higher. The measurement result of electronic probe of the cement was in accordance with the analysis of XRD. (4)The 14C dating result of the beachrocks is about 20000-21000 a B. C., which indicates that it is the deposit of shore envirnment at low sea level during the last glacial age of late Pleistocene,being to submerged beachrocks of late Pleistocene. In addition,it is considered that the formation and change of beachrocks would vary accompanying the occurrence of varied geologic events and time change in different areas and under the influence of circumstances and so on. Beachrocks in different morphologic positions also show various characters. It is much com- plicated to certificate it accurately and study its variation and differences.
1999, 17(S1): 794-797.
Abstract:
The abundance and distribution of amino acids in sediments are closely related to the organism amounts and sedimentary environment. However organism amounts are controlled by the climatic condition during sedimentary period. Thus, the abundance and distribution of amino acids in sediments can indicate the situa- tion of paleoclimate. In this paper,amino acids from a sedimentary core section (0-440 cm) of Nansha Sea area have been examined. Results show that 17 kinds of amino acids are present in this core section;amino acid contents are from 925 to 2343 ug/g; acidic amino acid to neutral amino acid ratios are from 0.48 to 0.71. The section variation of amino acid contents and composition of amino acids show alkalic sedimentary environment and the four cold-warm evolutions of paleoclimate during this sedimentary period,respectively.These imply that abundance and composition of amino acids can be used as an good indicator of sedimentary paleoenvironment.
The abundance and distribution of amino acids in sediments are closely related to the organism amounts and sedimentary environment. However organism amounts are controlled by the climatic condition during sedimentary period. Thus, the abundance and distribution of amino acids in sediments can indicate the situa- tion of paleoclimate. In this paper,amino acids from a sedimentary core section (0-440 cm) of Nansha Sea area have been examined. Results show that 17 kinds of amino acids are present in this core section;amino acid contents are from 925 to 2343 ug/g; acidic amino acid to neutral amino acid ratios are from 0.48 to 0.71. The section variation of amino acid contents and composition of amino acids show alkalic sedimentary environment and the four cold-warm evolutions of paleoclimate during this sedimentary period,respectively.These imply that abundance and composition of amino acids can be used as an good indicator of sedimentary paleoenvironment.
1999, 17(S1): 805-810.
Abstract:
On the basis of the theory of plate tectonics, according to the organic relationship between the successful model of basi:xai dynamic types and the geological conditions,main gas-bearing basins in China are classified into six groups and nine sub-groups comprising fifteen kinds by which the gas-bearing geological factors of all kinds of basins are studied, which show that in the east of China marginal sea have advantage geological conditions becoming middle or even big gas fields and intracontinental rift basins may find many small and middle gas fields some of which are possibly combined with each other so that they can form middle or big gas fields,that the important zones of middle or big gas fields in the west of China are craton transformed basins.
On the basis of the theory of plate tectonics, according to the organic relationship between the successful model of basi:xai dynamic types and the geological conditions,main gas-bearing basins in China are classified into six groups and nine sub-groups comprising fifteen kinds by which the gas-bearing geological factors of all kinds of basins are studied, which show that in the east of China marginal sea have advantage geological conditions becoming middle or even big gas fields and intracontinental rift basins may find many small and middle gas fields some of which are possibly combined with each other so that they can form middle or big gas fields,that the important zones of middle or big gas fields in the west of China are craton transformed basins.
1999, 17(S1): 815-819.
Abstract:
Shiyanghe and Heihe rivers,situated in the east part of Hexi Corridor,Gansu province,are two typical rivers in the arid and semi-arid area. According to the groundwateic helium isotope composition,most samples collected from these two river basins are of meteoric characteristics. Theirδ3He values range from -93.8%-181.4%, but most of them are close to the atmosphere helium with δ3He ranging between-20-+200%3He/20Ne distribute in the range of 4.65×10-7-7.43×10-7, which is slightly higher than that of the air, indicating that their origin is mainly from the meteoric water. In the northwest of Wuwei basin,Shiyanghe river the He3/He4 values of groundwater is lower than atmosphere helium in 1-2 magnitude of orders,implying that the mixing of radiogenic helium from adjacent granite bodies in which abundant minerals containing U and Th are observed. The decay of U and Th can produce a large amount of 4He resulting in the excess of helium in the groundwater. The eminent accumulation of radiogenic helium shows that the circulation period of groundwater in this area could be 1000 years. Along the hidden fault in the front of the Qilian Mountains can observe the much higher 3He/4He values with δ3He ranging from 70%-180 %, indicating that the eminent contribution of mantle helium which implies that the Fault is still active.
Shiyanghe and Heihe rivers,situated in the east part of Hexi Corridor,Gansu province,are two typical rivers in the arid and semi-arid area. According to the groundwateic helium isotope composition,most samples collected from these two river basins are of meteoric characteristics. Theirδ3He values range from -93.8%-181.4%, but most of them are close to the atmosphere helium with δ3He ranging between-20-+200%3He/20Ne distribute in the range of 4.65×10-7-7.43×10-7, which is slightly higher than that of the air, indicating that their origin is mainly from the meteoric water. In the northwest of Wuwei basin,Shiyanghe river the He3/He4 values of groundwater is lower than atmosphere helium in 1-2 magnitude of orders,implying that the mixing of radiogenic helium from adjacent granite bodies in which abundant minerals containing U and Th are observed. The decay of U and Th can produce a large amount of 4He resulting in the excess of helium in the groundwater. The eminent accumulation of radiogenic helium shows that the circulation period of groundwater in this area could be 1000 years. Along the hidden fault in the front of the Qilian Mountains can observe the much higher 3He/4He values with δ3He ranging from 70%-180 %, indicating that the eminent contribution of mantle helium which implies that the Fault is still active.
1999, 17(S1): 832-835.
Abstract:
In this paper,low mature mudstone and limestone from Carboniferous System in Tarim Basin have been studied by the thermal simulating experiment. The results show that amount of gaseous hydrocarbon become more and more with increasing simulation temperature and begin increasing rapidly at 400℃. The yield of gaseous hydrocarbon at 450℃ is 834.94m3/tCotg for mudstone and 483.23m3/tCotgfor limestone,indicating that mudstone has higher yield of gaseous hydrocarbon than limestone under the relative high values simulating temperature. The yields of methane, ethane and hydrogen reach the largest at 400℃.The carbon isotopic values of methan.es are from-36.5‰ to-31.7‰ for mudstone and from-37.5‰ to-34.0‰ for limestone. These values show that urethanes formed by source rocks from Carboniferous System in Tarim Basin has a heavy carbon isotopic composition. The largest yield of liquid hydrocarbon is 27.12kg/tCotg for mudstone and 18.69kg/tCotg for limestone. Their corresponding simulating temperature is 300℃ and 350℃, respective1y. This shows that oil-forming high peak value of limestone is higher than that of mudstone. These data reflect that Carboniferous mudstone and limestone have different process of hydrocarbon Qeneration and evolution. Therefore,in the region of distribution of low generation,and natural gases from Carboniferous mature source rock mudstone is source rock should have a heavy important to hydrocarbon carbon isotopic composition.
In this paper,low mature mudstone and limestone from Carboniferous System in Tarim Basin have been studied by the thermal simulating experiment. The results show that amount of gaseous hydrocarbon become more and more with increasing simulation temperature and begin increasing rapidly at 400℃. The yield of gaseous hydrocarbon at 450℃ is 834.94m3/tCotg for mudstone and 483.23m3/tCotgfor limestone,indicating that mudstone has higher yield of gaseous hydrocarbon than limestone under the relative high values simulating temperature. The yields of methane, ethane and hydrogen reach the largest at 400℃.The carbon isotopic values of methan.es are from-36.5‰ to-31.7‰ for mudstone and from-37.5‰ to-34.0‰ for limestone. These values show that urethanes formed by source rocks from Carboniferous System in Tarim Basin has a heavy carbon isotopic composition. The largest yield of liquid hydrocarbon is 27.12kg/tCotg for mudstone and 18.69kg/tCotg for limestone. Their corresponding simulating temperature is 300℃ and 350℃, respective1y. This shows that oil-forming high peak value of limestone is higher than that of mudstone. These data reflect that Carboniferous mudstone and limestone have different process of hydrocarbon Qeneration and evolution. Therefore,in the region of distribution of low generation,and natural gases from Carboniferous mature source rock mudstone is source rock should have a heavy important to hydrocarbon carbon isotopic composition.
1999, 17(S1): 839-845.
Abstract:
The radiant heat transportation at desert interface includes solar radiant heat flux,long wave radiant heat flux and desert surface heat flux. Based on the natural and climatic conditions of Gurbantunggut Desert,the author has measured and analyzed the heat budget on different underlying areas .The following results are mainly obtained: (1) The heat transportation on sand-shifting desert and on sand-fixed desert is different limited by individual surface feature,sand layer nature and air temperature etc. (2)The reflectivity and the long wave radiation on sand-shifting area are all larger than that on sand-fixed area. (3)The heat flux through sand layer increases with the layer going down;while heat transportation value changes with an inverse trend. (4)The heat transportation from earth to atmosphere on different desert types are in forms of sensible heat at daytime and latent heat at night which constitutes special response and feedback transfer process to solar radiant heat on desert area. In the meantime,the author has analyzed the changing properties of physical climate parameters in desert region according to measured data and heat balance equation of earth surface;and modeled the heat transfer process at earth-atmosphere interface.
The radiant heat transportation at desert interface includes solar radiant heat flux,long wave radiant heat flux and desert surface heat flux. Based on the natural and climatic conditions of Gurbantunggut Desert,the author has measured and analyzed the heat budget on different underlying areas .The following results are mainly obtained: (1) The heat transportation on sand-shifting desert and on sand-fixed desert is different limited by individual surface feature,sand layer nature and air temperature etc. (2)The reflectivity and the long wave radiation on sand-shifting area are all larger than that on sand-fixed area. (3)The heat flux through sand layer increases with the layer going down;while heat transportation value changes with an inverse trend. (4)The heat transportation from earth to atmosphere on different desert types are in forms of sensible heat at daytime and latent heat at night which constitutes special response and feedback transfer process to solar radiant heat on desert area. In the meantime,the author has analyzed the changing properties of physical climate parameters in desert region according to measured data and heat balance equation of earth surface;and modeled the heat transfer process at earth-atmosphere interface.
