1989 Vol. 7, No. 2
column
Display Method:
1989, 7(2): 1-13.
Abstract:
Qaidam Basin is a typical Tertiary inland salt lake containing oils and gases.There is a complete sequence of oil maturation: from immature to highmature.Under such background, the oil source correlation, concerning the evaluation of resource volumes in different stages of hydrocarbon generation, is of great importance. According to the analysing data of 35 rock samples and 23 oils and on the basis of the comprehensive geochemical study, the paper discussed the oil souce beds of different ages via biomarkers, the correlation of oils and source rocks in different layers as well as in different evolution stages. GC/ MS analysis was undertaken by Finnigan-Mat YSQ-45 GC-MS-computer system. The methods of oil source correlation include: 1. carbon isotopic composition 2.bulk distribution of cyclic biogenetic compounds 3.distribution of steranes with different carbon numbers 4.combination of source indicators with maturity indicators to discriminate source rocks 5.fingerprint types of oils and rocks The results revealed that methods 1 and 2 can distinguesh the oils of Tertiary sources from those of Jurassic sources. As for the Tertiary oil-source correlation, methods 4 and 5 should be used because the hydrocarbon precusors are stable. The present study suggests that the Tertiary possessed good source rocks; the sterane carbon number distribution of source rocks shows " V" ?shaped fingerprint and C27 predominance. Relatively, the Eocene- Oilgocene source rocks are better than the Miocene rocks, their boundary value of ( C27+ C28) / C29 is 1.6. Our study, in which the oil source correlation was investigated through the whole hydrocabon generation process proved that the hydrocarbons generated in different stages, i.e., crude oils of different maturity, can be correlated to their source rocks.It was confirmed that crude oils found in Qaidam Basin by now are mostly low-mature.However, the mature and high-mature hydrocarbons are rarely found.That means, the basin is still of great resource potential.
Qaidam Basin is a typical Tertiary inland salt lake containing oils and gases.There is a complete sequence of oil maturation: from immature to highmature.Under such background, the oil source correlation, concerning the evaluation of resource volumes in different stages of hydrocarbon generation, is of great importance. According to the analysing data of 35 rock samples and 23 oils and on the basis of the comprehensive geochemical study, the paper discussed the oil souce beds of different ages via biomarkers, the correlation of oils and source rocks in different layers as well as in different evolution stages. GC/ MS analysis was undertaken by Finnigan-Mat YSQ-45 GC-MS-computer system. The methods of oil source correlation include: 1. carbon isotopic composition 2.bulk distribution of cyclic biogenetic compounds 3.distribution of steranes with different carbon numbers 4.combination of source indicators with maturity indicators to discriminate source rocks 5.fingerprint types of oils and rocks The results revealed that methods 1 and 2 can distinguesh the oils of Tertiary sources from those of Jurassic sources. As for the Tertiary oil-source correlation, methods 4 and 5 should be used because the hydrocarbon precusors are stable. The present study suggests that the Tertiary possessed good source rocks; the sterane carbon number distribution of source rocks shows " V" ?shaped fingerprint and C27 predominance. Relatively, the Eocene- Oilgocene source rocks are better than the Miocene rocks, their boundary value of ( C27+ C28) / C29 is 1.6. Our study, in which the oil source correlation was investigated through the whole hydrocabon generation process proved that the hydrocarbons generated in different stages, i.e., crude oils of different maturity, can be correlated to their source rocks.It was confirmed that crude oils found in Qaidam Basin by now are mostly low-mature.However, the mature and high-mature hydrocarbons are rarely found.That means, the basin is still of great resource potential.
1989, 7(2): 21-28.
Abstract:
In factors of controlling sedimentation，effect of regional tectonic is the most important. On the one hand tectonic action opens up terrigenous fragmental materials，and the other hand it offers sediroental places .Fragmental composition and its time-space changes.therefore. in a certain degree. can reflect effectively in- tensity，nature, and continued -turned times of regional tectonic action.In the case of continental cratons that stages of ebolution is unclear it is specially significance.Based on the research of regional petrology，thespaper ，taking Jinzi area in Liaoning as a point of architectonic pattern of Sino-Korean Platform, place emphasis on studing of sandstones in relation to tectics from Mid Protcrozoic to Mesozoic. Probenance terranes corre- sponding to plate tectonic units subdibided recently by Dickinson and others are adopted in the paper Fragmental composition of sandstones in this area shows the following changes:feldspar一quartz (Mid-Late Proterozoic) deribed mainly from crystal rocks of continental basement: lithec fragment-quartz (Late Paleozoic)，from continental basement and pre-sediments getting into recycles; and fdld-spar-lithec fragment (Mespzoic)，from mother rocks around basin and products of bolcanic cycles.K20/Na20rate of sandstones is lower and its maturity reduces with changing of times. The threekinds of fragmental ebolution present basically the two facts:l.non-stability of fagmental composition is increasing;2.probenances of sedimentary materialtend to dibersity. Analysis of tectonic setting of sandstones with QFL and QmFLt diagrams shows that fragmental points were distributed over bsement uplift and transition area of continental blocks due to high conten of feldspar in early Changchengian of Mid Proterozoic in Jinxi, It displays that settlement of Yanliao Basin during Mid Proterozoic was accompanide uplift action of the shanhaiguan ancient Iand.Feldspar-riched sands from base- ment accumulated mainly to the Xingcheng一Huludao yoked basin near uplift area. Quartz content of sand- stones generally tends to increase from Changchengian to Qingbeikouan of Late Proteozoic，which tectonic ac- tion of sedimental area develops towards stabilfty.In the area high mature quartz sands formde mat shape were widely distributed over the western liaoning, Bohai Gulf，and the eastern Liaoning.This is resuly that strand line is slowly moved Forward in stable condition and quartz sands belong to products of continental cratonization. Because chert and other lithic Cragments increawe, the points of Permian sandstones Fall mainly to field of recycled orogens. According to analysis of regional stratigraphy and tectonics，this kind of sub-stable Crag- ments deribed closing of Inner Mongolia geosyneline in Late Paleozoic. Based on the analysis of focal folds， volcan actibity，and intrusion of neutral-acid magma, Permian sandston fragments distrubuted on recucled orogens hint that possessed one kind of“orogenic” character in evolution of“sino- Korean Plat- form” in sometime.Affected by plate collision of neighbour areas，probenance of the foreland uplift lay under the doub- 1e controls of continental blocks and orogenie bewlts during late period of Late Paleozoic in the western Liaon- ing.In this problem.it is not quite definite to classify on Dickinson′s probenances. In Early-Mid Triassic time，fragments were mainly distributed between continents and magmatic arcs， which show tectonic property of intense basin depression.To compare Triassic fragmental composition wigh Late Paleozoic one、associations of mother rock are different; but with Jurassic one，similar.It shows that the regional tectonec property of controlling probenances habe changed in initial stage of Mesozoec and tha Triassic time was a transitional time from eratonec enbironment to actibe continental margin in this area.From Jurassis to Cretaceousm，Volcanic debris came repeadly into sedimental cycles and increase gradually，It rebealed that this area hs been completely inbolbed in the field of actibe continental matgin，and eben more in- tenser. In summary，Jinxi area underwent two large-scale ebolutional stages of sedimentary-tectonic cycle from sub- stable craton to actibe continental margins，including basement uplift，cratonization, recycled sedimentation, and intense depression and fault subsidence. Both Q/F+L and F/L balues indicate that periodic interval of sedimentary reformational history was shortened and reformational intensity became reduced on the evolution of times. It eomfirrns that tectonic actibity of the crust in the area tectonics on sedimentation proceed from the insied to the outside Among the， the F/Lratios of two times in the early proterozoic and the early Mid Mesozoic re larger tha others.The both predict beginning of two large-scale sedimentary-tectonee cycles belong to the types of sub-stable craton and active continental margin.
In factors of controlling sedimentation，effect of regional tectonic is the most important. On the one hand tectonic action opens up terrigenous fragmental materials，and the other hand it offers sediroental places .Fragmental composition and its time-space changes.therefore. in a certain degree. can reflect effectively in- tensity，nature, and continued -turned times of regional tectonic action.In the case of continental cratons that stages of ebolution is unclear it is specially significance.Based on the research of regional petrology，thespaper ，taking Jinzi area in Liaoning as a point of architectonic pattern of Sino-Korean Platform, place emphasis on studing of sandstones in relation to tectics from Mid Protcrozoic to Mesozoic. Probenance terranes corre- sponding to plate tectonic units subdibided recently by Dickinson and others are adopted in the paper Fragmental composition of sandstones in this area shows the following changes:feldspar一quartz (Mid-Late Proterozoic) deribed mainly from crystal rocks of continental basement: lithec fragment-quartz (Late Paleozoic)，from continental basement and pre-sediments getting into recycles; and fdld-spar-lithec fragment (Mespzoic)，from mother rocks around basin and products of bolcanic cycles.K20/Na20rate of sandstones is lower and its maturity reduces with changing of times. The threekinds of fragmental ebolution present basically the two facts:l.non-stability of fagmental composition is increasing;2.probenances of sedimentary materialtend to dibersity. Analysis of tectonic setting of sandstones with QFL and QmFLt diagrams shows that fragmental points were distributed over bsement uplift and transition area of continental blocks due to high conten of feldspar in early Changchengian of Mid Proterozoic in Jinxi, It displays that settlement of Yanliao Basin during Mid Proterozoic was accompanide uplift action of the shanhaiguan ancient Iand.Feldspar-riched sands from base- ment accumulated mainly to the Xingcheng一Huludao yoked basin near uplift area. Quartz content of sand- stones generally tends to increase from Changchengian to Qingbeikouan of Late Proteozoic，which tectonic ac- tion of sedimental area develops towards stabilfty.In the area high mature quartz sands formde mat shape were widely distributed over the western liaoning, Bohai Gulf，and the eastern Liaoning.This is resuly that strand line is slowly moved Forward in stable condition and quartz sands belong to products of continental cratonization. Because chert and other lithic Cragments increawe, the points of Permian sandstones Fall mainly to field of recycled orogens. According to analysis of regional stratigraphy and tectonics，this kind of sub-stable Crag- ments deribed closing of Inner Mongolia geosyneline in Late Paleozoic. Based on the analysis of focal folds， volcan actibity，and intrusion of neutral-acid magma, Permian sandston fragments distrubuted on recucled orogens hint that possessed one kind of“orogenic” character in evolution of“sino- Korean Plat- form” in sometime.Affected by plate collision of neighbour areas，probenance of the foreland uplift lay under the doub- 1e controls of continental blocks and orogenie bewlts during late period of Late Paleozoic in the western Liaon- ing.In this problem.it is not quite definite to classify on Dickinson′s probenances. In Early-Mid Triassic time，fragments were mainly distributed between continents and magmatic arcs， which show tectonic property of intense basin depression.To compare Triassic fragmental composition wigh Late Paleozoic one、associations of mother rock are different; but with Jurassic one，similar.It shows that the regional tectonec property of controlling probenances habe changed in initial stage of Mesozoec and tha Triassic time was a transitional time from eratonec enbironment to actibe continental margin in this area.From Jurassis to Cretaceousm，Volcanic debris came repeadly into sedimental cycles and increase gradually，It rebealed that this area hs been completely inbolbed in the field of actibe continental matgin，and eben more in- tenser. In summary，Jinxi area underwent two large-scale ebolutional stages of sedimentary-tectonic cycle from sub- stable craton to actibe continental margins，including basement uplift，cratonization, recycled sedimentation, and intense depression and fault subsidence. Both Q/F+L and F/L balues indicate that periodic interval of sedimentary reformational history was shortened and reformational intensity became reduced on the evolution of times. It eomfirrns that tectonic actibity of the crust in the area tectonics on sedimentation proceed from the insied to the outside Among the， the F/Lratios of two times in the early proterozoic and the early Mid Mesozoic re larger tha others.The both predict beginning of two large-scale sedimentary-tectonee cycles belong to the types of sub-stable craton and active continental margin.
1989, 7(2): 45-50.
Abstract:
Based on the lithological texture, optic features, cathodoluminescence, trace elements and inclusion temperature measurment the Yangxin series of the Lower Permian (which is exposed on Ermei, Hanwang and Baoxing of south-west Sichuan) with a cumulative thickness of approximate 100m combined with the occurrence of the dolomite and its vertical petrographic complex, horizontal distribution and the deposition and burial history, the author proposes that the dolomite in this region was originated from bioclastic limestone of beach facies which deposited under the control of the Ermeishan-Washan ancient fault during early stage. It is beneficial to form mixing dolomite by presh and marinewater because of it frequntly expose and submerge from sea level and sequentially form the diagenesis of uplifting and downgoing of earthcurst, folding and faulting in geohistorical process. Especially the Dongwu movent soon happened after the deposition of Yangxin series, it made the earth crust uprise, leading these strata to expose and denude, and the Baoxing, northwest portion of the region was the highest and denuded deeply while its southeast portion, the Hanwang and Daxin denuded less with 100-150m in remains thickness (the Lower Permian) more than that of Baoxing, it was the depression at that time, thus making the fresh water in west side of the highland flow along the Ermeishan- Wasan fault and its accompanying fractures towards the depression, wherever there reserved 5% of seawatcr in rocks, there would promote dolomitization to take place. Subsequently the volcanic eruption, basalt' s mass flowed out, and hydrothermal activity from eaeth crust in that region, these major geological events deeply influenced the strata in Ermei, Hanwang and Baoxing, changed the physical and chemical conditions of rocks increased the geotherm and the composition of pore water was also changed, and simultaneously provides the ions of various elements as calcium and magnesium etc. thus a favorable condition for continuous dolomitization was possessed. Owing to the long term subsidence of earth crust, the Yangxin series of the Lower Permian in that area deeply buried under several thousand meters and sustained a number of reworkings by deep burial, such as the increase of geothermal gradient composition change of pore water, transformation of organic matter into hydrocarbon etc. which also provides conditions for continuous dolomitiaztion. Until the later Indo-China movement, the dolomite was sustained such dynamic action as intensive compression and tension, making them eproduces such "strain textures" as tight contact between crystals in a zigzag form, not show crystal, but show sheet-connected orange in color under cathoaluminescence, a general extinction, and mechanical twincrystals etc. They are further to evolve into the present dolomite with extremely inhomogeneous in of silt fine to medium and coarse crystals, bu it is maine the medium-coarse crystals in which there coexist with the euhedral, semieuhedral and anhedral crystals the anhedral one is the main, this is a result of superposition of various diagenetic condition and various types dolomitizations, it made the dolomite crystals to enlarge the porosity to decrease and the reservoir capacity to worsen.
Based on the lithological texture, optic features, cathodoluminescence, trace elements and inclusion temperature measurment the Yangxin series of the Lower Permian (which is exposed on Ermei, Hanwang and Baoxing of south-west Sichuan) with a cumulative thickness of approximate 100m combined with the occurrence of the dolomite and its vertical petrographic complex, horizontal distribution and the deposition and burial history, the author proposes that the dolomite in this region was originated from bioclastic limestone of beach facies which deposited under the control of the Ermeishan-Washan ancient fault during early stage. It is beneficial to form mixing dolomite by presh and marinewater because of it frequntly expose and submerge from sea level and sequentially form the diagenesis of uplifting and downgoing of earthcurst, folding and faulting in geohistorical process. Especially the Dongwu movent soon happened after the deposition of Yangxin series, it made the earth crust uprise, leading these strata to expose and denude, and the Baoxing, northwest portion of the region was the highest and denuded deeply while its southeast portion, the Hanwang and Daxin denuded less with 100-150m in remains thickness (the Lower Permian) more than that of Baoxing, it was the depression at that time, thus making the fresh water in west side of the highland flow along the Ermeishan- Wasan fault and its accompanying fractures towards the depression, wherever there reserved 5% of seawatcr in rocks, there would promote dolomitization to take place. Subsequently the volcanic eruption, basalt' s mass flowed out, and hydrothermal activity from eaeth crust in that region, these major geological events deeply influenced the strata in Ermei, Hanwang and Baoxing, changed the physical and chemical conditions of rocks increased the geotherm and the composition of pore water was also changed, and simultaneously provides the ions of various elements as calcium and magnesium etc. thus a favorable condition for continuous dolomitization was possessed. Owing to the long term subsidence of earth crust, the Yangxin series of the Lower Permian in that area deeply buried under several thousand meters and sustained a number of reworkings by deep burial, such as the increase of geothermal gradient composition change of pore water, transformation of organic matter into hydrocarbon etc. which also provides conditions for continuous dolomitiaztion. Until the later Indo-China movement, the dolomite was sustained such dynamic action as intensive compression and tension, making them eproduces such "strain textures" as tight contact between crystals in a zigzag form, not show crystal, but show sheet-connected orange in color under cathoaluminescence, a general extinction, and mechanical twincrystals etc. They are further to evolve into the present dolomite with extremely inhomogeneous in of silt fine to medium and coarse crystals, bu it is maine the medium-coarse crystals in which there coexist with the euhedral, semieuhedral and anhedral crystals the anhedral one is the main, this is a result of superposition of various diagenetic condition and various types dolomitizations, it made the dolomite crystals to enlarge the porosity to decrease and the reservoir capacity to worsen.
1989, 7(2): 71-77.
Abstract:
The Pingxi mining district is located in the eastern part of shanxi province and in the northeastern margin of Qinshue Field. It is a large one which is being built, its area is about 336.5km2. The age of the coalbearing formation is Permo- Carboniferous.This paper probes into the sedimentary environment of Taiyuan Formation in this area. Taiyuan Formation is one of the main coal-bearing formations in this area, which mainly consists of grey and dark-grey limestones, argillites, sandy-argillites, siltites; light-grey and grey-yellow sandstones and coal seams, being about 120 mthick. By the analysis of vertical sequence, Hthologic characteristics, sedimentary structure feature of grain size distribution, trace elements, fossils, sand-body geometry shape and paleocurrent, Taiyuan Formation in this area is considered to be a set of the coal-bearing deposits represented by thd deltas, tidal flat and subtidal carbonate sediments, which occurred in the margin of Hua-bei Epicontinental Sea during the Late Carboniferous. The lower part of Taiyuan Formation is represented by sediments of a tidal system, while the middle and upper part of Taiyuan Formation are composed of sdeiments of the deltaic system. Two basic kinds of deltas have been recognized in this area, namely, high-construction lobate delta and high-destructive tide-dominated delta. There are three limestone seams in Taiyuan Formation, namely "Sijieshi" "Qianshi", and "Houshi" limestones, which are much like in lithologic characteristics and consist mainly of bioclastic micrites. The analysis of paleoenvironments shows that these limestones in this area are carbonate sediments formed in the subtidal low-energy zone.
The Pingxi mining district is located in the eastern part of shanxi province and in the northeastern margin of Qinshue Field. It is a large one which is being built, its area is about 336.5km2. The age of the coalbearing formation is Permo- Carboniferous.This paper probes into the sedimentary environment of Taiyuan Formation in this area. Taiyuan Formation is one of the main coal-bearing formations in this area, which mainly consists of grey and dark-grey limestones, argillites, sandy-argillites, siltites; light-grey and grey-yellow sandstones and coal seams, being about 120 mthick. By the analysis of vertical sequence, Hthologic characteristics, sedimentary structure feature of grain size distribution, trace elements, fossils, sand-body geometry shape and paleocurrent, Taiyuan Formation in this area is considered to be a set of the coal-bearing deposits represented by thd deltas, tidal flat and subtidal carbonate sediments, which occurred in the margin of Hua-bei Epicontinental Sea during the Late Carboniferous. The lower part of Taiyuan Formation is represented by sediments of a tidal system, while the middle and upper part of Taiyuan Formation are composed of sdeiments of the deltaic system. Two basic kinds of deltas have been recognized in this area, namely, high-construction lobate delta and high-destructive tide-dominated delta. There are three limestone seams in Taiyuan Formation, namely "Sijieshi" "Qianshi", and "Houshi" limestones, which are much like in lithologic characteristics and consist mainly of bioclastic micrites. The analysis of paleoenvironments shows that these limestones in this area are carbonate sediments formed in the subtidal low-energy zone.
1989, 7(2): 89-98.
Abstract:
The bauxite-bearing rock cerise in the western Henan exists in Middle or Upper Carboniferous, and covers discordant upon the carbonate rock of Middle Ordovician or Upper Cambrian.This paper deals with the vertical ，lateral changes and their distribution of facies, mineral associations, chemical composition，texture and structure, trace metals, size fraction and the determination of gravel orientation of the ore-bearing rock se- ries. Vertically, the ore-bearing series makes up a circle of transgression to regression which is composed of the secondary circle in the initial stage of transgression of the Carboniferous.It is shown that the ferrous clay rocks below is fresh water or brackish water deposit, formed in the backshore mud(lat area in the early peroid of the transgression; the bauxite deposits belongs to the normal sea water or freshening seawater deposit, and formed in the foreshore and nearshore district in the largest period of transgression, but meanwhile there forms clay deposits in the north of western Henan; the clay shale above dcposiged in the freshening seawatcr circum- stance in the backshore mudflat district in the period of regression; sequcntly. somewhere developed swamps and formed battie with coal line/coal bed; afterward the seawater withdrawn from the region temporarily. Laterally, in the sedimentary period of bauxite deposits, the relief feature in this area was lower in northeast and higher is southwest, the sedimentary basin behaved trianglarly and opened towards east, there developed a series of ancient islamds, which in some degree segrated the sedimentary environment.One tributa ry of the seawater flow. being larger than that one, flowed northeasterward from Hebi and Anyang district, then turning to west; the other one came from Yongcheng in the eastern area.The sedimentary environment controlled the distribution of the ore deposit and rocks.There mainly developed two layers of carbonate rocks in Hebi and Anyang district. which formed in the shelf sea; in the northern area--Jiaozuo-Kaifeng there is the nearshore and offshore environment, in which formed clay rocks and fine fragmental clay deposits; in the southern area there is the shore circumstance, in foreshore and nearshore deposited bauxite. Because of the segretion of relief feature, the southern shore environment could be subdvided into live subfacics, which are Yanshi-Xinyang -Gong County open shore subfacies, Songshan-Qishan lagoon and bay sudfacies between is- lands, Sanmenzia-Shan County-Mianchi bay subfacies, Xinan semi-closed lagoon subfacies, and Ruyong Lushan-Baofeng lagoon subfacies. The richer bauxite deposits lie mainly in the semi-closed lagoon and bay subfacies, where exist a stronger karstification. In some areas the bauxite deposit is characterised by grading bedding, massive bedding, parallel cross bedding and basement-sustaining texture, which indicates that the bauxite belongs to dense-flow sediments. And through the bauxite appeared in the shore circumstance, possessing fragment-pisolite-oolite hybrid fez- ture, pseudo-thin wrapper pisolite-oolite texture. rolling bedding, lenticular bedding and depending on grading analysis, we have a conclusion that some bauxite may be a sort of nearshore storm sediment. The bauxite formed upon the weathering crust which had as long as 150 million years time developping.It had simple mineral association(diaspore, kaolinite, illinite, etc.)and chem ical composition. The ore- forming material was transported in fine fragment and colloidal state, and then deposited in the sedimentary basin and again fransported mechanically Based on size fraction, it is indicated that most bauxite deposited in a torrential dynamical condition. All these processes happened in the steady tectonic background--platform stage. The bauxite formed in a specific mud coast, and had little land-derived frag- ment (quartz, feldspar, mica) contaminating.From Jurassic, because the district entered a new tectonic stage-一diwa (geodepression) stage, the ore-bearing rock series was raised up near land surface, and suf- fered from transforming and leaching of underground water, which resulted in silicon and iron in orebodies removed and bauxite becomed richer.The sedimentary environment as a base of ore-forming controlled mineral associations.The mineral associations (e.g. diaspore-kaolinite combination) formed in favorable surrounding (e.g. semi-closed bay or lagoon facies) liable to be leached and richened. So we have a conclusion that the rich- er bauxite is closely related to the favorable sedimentary environment. Finally, this paper points out that depending on sedimentary facies, bauxite can be found out in the shore fades, and richer bauxite in the semi-closed lagoon and bay subfacies. The ore all distributes in the edge of ancient land or island. Another factor controlling metalogenesis and richening is the karstilication, which has been discussed in other paper. This paper also points out the areas proably beaing orebodies.
The bauxite-bearing rock cerise in the western Henan exists in Middle or Upper Carboniferous, and covers discordant upon the carbonate rock of Middle Ordovician or Upper Cambrian.This paper deals with the vertical ，lateral changes and their distribution of facies, mineral associations, chemical composition，texture and structure, trace metals, size fraction and the determination of gravel orientation of the ore-bearing rock se- ries. Vertically, the ore-bearing series makes up a circle of transgression to regression which is composed of the secondary circle in the initial stage of transgression of the Carboniferous.It is shown that the ferrous clay rocks below is fresh water or brackish water deposit, formed in the backshore mud(lat area in the early peroid of the transgression; the bauxite deposits belongs to the normal sea water or freshening seawater deposit, and formed in the foreshore and nearshore district in the largest period of transgression, but meanwhile there forms clay deposits in the north of western Henan; the clay shale above dcposiged in the freshening seawatcr circum- stance in the backshore mudflat district in the period of regression; sequcntly. somewhere developed swamps and formed battie with coal line/coal bed; afterward the seawater withdrawn from the region temporarily. Laterally, in the sedimentary period of bauxite deposits, the relief feature in this area was lower in northeast and higher is southwest, the sedimentary basin behaved trianglarly and opened towards east, there developed a series of ancient islamds, which in some degree segrated the sedimentary environment.One tributa ry of the seawater flow. being larger than that one, flowed northeasterward from Hebi and Anyang district, then turning to west; the other one came from Yongcheng in the eastern area.The sedimentary environment controlled the distribution of the ore deposit and rocks.There mainly developed two layers of carbonate rocks in Hebi and Anyang district. which formed in the shelf sea; in the northern area--Jiaozuo-Kaifeng there is the nearshore and offshore environment, in which formed clay rocks and fine fragmental clay deposits; in the southern area there is the shore circumstance, in foreshore and nearshore deposited bauxite. Because of the segretion of relief feature, the southern shore environment could be subdvided into live subfacics, which are Yanshi-Xinyang -Gong County open shore subfacies, Songshan-Qishan lagoon and bay sudfacies between is- lands, Sanmenzia-Shan County-Mianchi bay subfacies, Xinan semi-closed lagoon subfacies, and Ruyong Lushan-Baofeng lagoon subfacies. The richer bauxite deposits lie mainly in the semi-closed lagoon and bay subfacies, where exist a stronger karstification. In some areas the bauxite deposit is characterised by grading bedding, massive bedding, parallel cross bedding and basement-sustaining texture, which indicates that the bauxite belongs to dense-flow sediments. And through the bauxite appeared in the shore circumstance, possessing fragment-pisolite-oolite hybrid fez- ture, pseudo-thin wrapper pisolite-oolite texture. rolling bedding, lenticular bedding and depending on grading analysis, we have a conclusion that some bauxite may be a sort of nearshore storm sediment. The bauxite formed upon the weathering crust which had as long as 150 million years time developping.It had simple mineral association(diaspore, kaolinite, illinite, etc.)and chem ical composition. The ore- forming material was transported in fine fragment and colloidal state, and then deposited in the sedimentary basin and again fransported mechanically Based on size fraction, it is indicated that most bauxite deposited in a torrential dynamical condition. All these processes happened in the steady tectonic background--platform stage. The bauxite formed in a specific mud coast, and had little land-derived frag- ment (quartz, feldspar, mica) contaminating.From Jurassic, because the district entered a new tectonic stage-一diwa (geodepression) stage, the ore-bearing rock series was raised up near land surface, and suf- fered from transforming and leaching of underground water, which resulted in silicon and iron in orebodies removed and bauxite becomed richer.The sedimentary environment as a base of ore-forming controlled mineral associations.The mineral associations (e.g. diaspore-kaolinite combination) formed in favorable surrounding (e.g. semi-closed bay or lagoon facies) liable to be leached and richened. So we have a conclusion that the rich- er bauxite is closely related to the favorable sedimentary environment. Finally, this paper points out that depending on sedimentary facies, bauxite can be found out in the shore fades, and richer bauxite in the semi-closed lagoon and bay subfacies. The ore all distributes in the edge of ancient land or island. Another factor controlling metalogenesis and richening is the karstilication, which has been discussed in other paper. This paper also points out the areas proably beaing orebodies.
1989, 7(2): 117-124.
Abstract:
Qaidam Basin is situated in the northern border of the Qinghai-Tibet plateau and is ond of the largest inland basin in the world.In this basin, it is enriched in borate deposits.According to their genesis, it can be divided into two types: sedimentary origin and mineralizing water. On the basis of the conditions of its formation, the former may be divided into five subtypes: lacustrine-chemical deposit, lacustrine marsh deposit, deposit of resedimentary origin of oilfield water, deposit of mineralized water and salted soil; The latter may be further classified into four subtypes: brine of the recent salt lake, water of oilfield, mineralized water and water of the mud volcano. The occurrence of ore body and mineral association are different in each one. The lacustrine-chemical borate deposit is the most important among them. There are elevben minerals of borate have been found so far in Qaidam Basin.They are ulexite, pinnoite, inderite, kurnakovite, carboborite, hungtsaoite, macallisterite, inyoite, hydroboracitc, borax, and nodleite.Among them, carboborite, and hungtsaoite were the first found in the world.. The mineralizing water are distributed very wide in Qaidam Basin and it is higher in grade of boron.On account of the boron associated with element K, Li, Mg, I, especially in the brine of salt lake, so it became mineral resource with comprehensive utilization value. According to tje origin and the space distribution of the borate deposits, it may be divided into five minerogcnetic belts in Qaidam Basin as follows: 1, The minerogenetic belt of lacustrine-chemical sedimentary borate of intermont basin on the northern margin of the basin. 2, The minerogenetic belt of sedimentary borate in the region of intermontane valley on the southern of Qilian Mountain. 3.The minerogenetic region of lacustrine marsh-chemical sedimentary borate of the front depression of the mountain on the eastern side of Tirtiary uplift region of the western basin. 4. The minerogenetic belt of resedimented borate of oilfield water and B- bearing oilfield water on the Tertiary uplift of the western basin. S.The minerogenetic belt of lacustrine marsh-chemical sedimented borate on the southern of the basin. 6.The minerogcnetic belt If B-bearing brine associated with K-Mg salt in the Meso-Cenozoic depression belt of the centre basin.
Qaidam Basin is situated in the northern border of the Qinghai-Tibet plateau and is ond of the largest inland basin in the world.In this basin, it is enriched in borate deposits.According to their genesis, it can be divided into two types: sedimentary origin and mineralizing water. On the basis of the conditions of its formation, the former may be divided into five subtypes: lacustrine-chemical deposit, lacustrine marsh deposit, deposit of resedimentary origin of oilfield water, deposit of mineralized water and salted soil; The latter may be further classified into four subtypes: brine of the recent salt lake, water of oilfield, mineralized water and water of the mud volcano. The occurrence of ore body and mineral association are different in each one. The lacustrine-chemical borate deposit is the most important among them. There are elevben minerals of borate have been found so far in Qaidam Basin.They are ulexite, pinnoite, inderite, kurnakovite, carboborite, hungtsaoite, macallisterite, inyoite, hydroboracitc, borax, and nodleite.Among them, carboborite, and hungtsaoite were the first found in the world.. The mineralizing water are distributed very wide in Qaidam Basin and it is higher in grade of boron.On account of the boron associated with element K, Li, Mg, I, especially in the brine of salt lake, so it became mineral resource with comprehensive utilization value. According to tje origin and the space distribution of the borate deposits, it may be divided into five minerogcnetic belts in Qaidam Basin as follows: 1, The minerogenetic belt of lacustrine-chemical sedimentary borate of intermont basin on the northern margin of the basin. 2, The minerogenetic belt of sedimentary borate in the region of intermontane valley on the southern of Qilian Mountain. 3.The minerogenetic region of lacustrine marsh-chemical sedimentary borate of the front depression of the mountain on the eastern side of Tirtiary uplift region of the western basin. 4. The minerogenetic belt of resedimented borate of oilfield water and B- bearing oilfield water on the Tertiary uplift of the western basin. S.The minerogenetic belt of lacustrine marsh-chemical sedimented borate on the southern of the basin. 6.The minerogcnetic belt If B-bearing brine associated with K-Mg salt in the Meso-Cenozoic depression belt of the centre basin.
1989, 7(2): 14-20.
Abstract:
In Devonian period, southern Hunan was situated in the east margin of Hunan, Guangdong, Guangxi neritic shelf basin.During the middle__late Devonian epoch, the carbonate sediments were dominant in this area, which may be divided into two facies area: the platform and the platform__basin, and six such facies types as the restricted platform; open platform; reef; shelf, platform basin with slope margin and platform __basin. 250 samples of fresh carbonate rocks for this study were collected from seven sections of various localities and facies types.The contents of elements in carbonate rocks are detected by ICP__AES (model JA__1160). The strontium is one of the important trace elemint in carbonate rocks.The average Sr contents and Sr / Ca × 1000 ratio in different sedimentary facies are vary widely.The tendency of this varition is closely related to sedimentary environments, i.e.the Sr/ Ca× 1000 ratio tends to increase gradually form restricted platform to open platform to shelf and to platform__basin; and from shallow to bathyal, which is fromO.27 to 0.88 to 0.95__1.18 to 2.37.In the lagoon of restricted platform, the Sr/ Ca×1000 ratio of primary dolomites is higher than that of diagenetic dolomites. Several authers have noted that many ancent carbonate rodks have a wide range and a bimodal dstrivution of Sr and given various explanation for it. We agree upon the idea suggested by J.Veizer et al. (1973, 1974), who hold that in the different sedimentary environments the primary carbonate minerals are different, and the Sr content of these minerals is also various. During the diagenetic process, the content decrease with the neomorphism from instable aragonite aragonite and high-Mg calcite into stable low-Mg calcite, but the Sr content in low- Mg calcite is not to change due to it is stable. Thus a bimodal strontium distribution of carbonate rodks in various fades is caused, and may be a indicator for environments.
In Devonian period, southern Hunan was situated in the east margin of Hunan, Guangdong, Guangxi neritic shelf basin.During the middle__late Devonian epoch, the carbonate sediments were dominant in this area, which may be divided into two facies area: the platform and the platform__basin, and six such facies types as the restricted platform; open platform; reef; shelf, platform basin with slope margin and platform __basin. 250 samples of fresh carbonate rocks for this study were collected from seven sections of various localities and facies types.The contents of elements in carbonate rocks are detected by ICP__AES (model JA__1160). The strontium is one of the important trace elemint in carbonate rocks.The average Sr contents and Sr / Ca × 1000 ratio in different sedimentary facies are vary widely.The tendency of this varition is closely related to sedimentary environments, i.e.the Sr/ Ca× 1000 ratio tends to increase gradually form restricted platform to open platform to shelf and to platform__basin; and from shallow to bathyal, which is fromO.27 to 0.88 to 0.95__1.18 to 2.37.In the lagoon of restricted platform, the Sr/ Ca×1000 ratio of primary dolomites is higher than that of diagenetic dolomites. Several authers have noted that many ancent carbonate rodks have a wide range and a bimodal dstrivution of Sr and given various explanation for it. We agree upon the idea suggested by J.Veizer et al. (1973, 1974), who hold that in the different sedimentary environments the primary carbonate minerals are different, and the Sr content of these minerals is also various. During the diagenetic process, the content decrease with the neomorphism from instable aragonite aragonite and high-Mg calcite into stable low-Mg calcite, but the Sr content in low- Mg calcite is not to change due to it is stable. Thus a bimodal strontium distribution of carbonate rodks in various fades is caused, and may be a indicator for environments.
1989, 7(2): 29-33.
Abstract:
A simple reproducible, rapid, and high precise probability density method of difference spectrum for quantative analysis testing of mineral mixtures is discussed.It is particularly simple to use in that requires no selection of peaks and more complicated calculation like least-squares curve-fitting1-4, and requires only to solve mean values known and unknown spectra ratio in full frequancies range. In all samples tested, this method produces results as good as.
A simple reproducible, rapid, and high precise probability density method of difference spectrum for quantative analysis testing of mineral mixtures is discussed.It is particularly simple to use in that requires no selection of peaks and more complicated calculation like least-squares curve-fitting1-4, and requires only to solve mean values known and unknown spectra ratio in full frequancies range. In all samples tested, this method produces results as good as.
1989, 7(2): 35-43.
Abstract:
Study on the carbonate constituent of 121 deep sea sediments (water depth: 280-4420m.) taken from the central South China Sea has been carried out. The carbonate content of deep sea sediments of the South China Sea ranges from 1.72 to 91.77%.In the continent slope region the average value is 33.77%.In the deep sea plain region the average value is 5.63%. Deep water carbonates of the South China Sea are made almost entirely of biogenous skeletal materials, these include mainly foraminifera, coccolith, bryozoan and mollusc shells, prodominately composed of planktonic unicellular remains. The grain size parameters of carbonate sediment are significantly influnced by various types of biogenous particle. The general tendency of the foraminiferal abundance shows a progressive increase with increasing water depth away form the coast. The number of benthic foraminifera per gram of the sediments ranges from hundreds to more than ten, the number of plankton is from thousands to a few. The distribution of ratio between the aboundance of planktonic and benthic foram in the entire population is regular. The ratio is about 2 : 1 in the edge of outer shelf, 30 : 1 in the slope with depth less than 3000m.; finally, less than 1 : 20 in the deep water central basin of the South China Sea. The species diversity of benthic foraminifera is very high. According to the distributhion of benthic forams, it may be divided into four assemblages i.e Uvigerina schwageri-Cibicides praecinctus assemblage in the edge of the outer shelf, Siphouvigerina ampullacea-Ceratobulimina pacifica assemblage in the upper slope, Cibicides wuellerstorfi assemblage in the middle and lower slope as well as Trochammina globigeriniformis assemblage in the deep sea basin. Their assemblage characteristics are controlled by submarine topo-graphical-geomrphological feature and also related to water mass. The species diversity of planktonic foraminifera is lower, the common species are only 33. According to the range of water depth, it may be divided into three zones of the assemblage, i.e Gloligerinoidesruber-G. sacculifer assemblage with water depth less than 2000m., Neoglo-boquadrina Dutertrei assemblage with the depth range from 2000m to 2900m, and Pulleniatina Obliquiloculate assemblage with the depth range from 2900m to 3420m. These assemblage characteristics are obviously controlled by water depth associated with selective dissolution (or differential dissolution). The concentration of calcareous nannoplankton per ten fields of vision over a slide in the sediments ranges from about thousand to zero. The surface sediments are dominated by the species of Emiliania huxley and Gephyrocapsa oceanica. The others, such as pelecypods shell fragments, echinoids, crinoids and ophiuroids ct al, are less than 1% in the sediments. Except for northern rise area of Nansha Islands, deep water carbonate is mainly composed of bryozoans there. Based on the type and relative aboundance of bio-carbonate skeletal constituents and the carbonate content, four assemblage provinces of calcareous organism can be divided in the central South China Sea: ( I ) Foraminifera-Molluscs assemblage province. It occurs in the outer edge of the northern shelf of the South China Sea with the depth of less than 200m. The average percentage of the carbonate is 22.00% ; (II ) Planktonic foraminifera-Calcareous nonnoplankton assemblage province. It occurs in the multi-terraced slopes of the north-western area of the South China Sea, with the depth of less than 3500m to 4000m. The average percentage of the carbonate is 33.77% (III) Benthic foraminifera assemblage province. It occurs in the deep sea plain of the South China Sea with the depth of more than deep sea plain of the South China Sea with the depth of more than 3500m to 4000m. The average carbonate percentage is 5. 63%. ( IV ) Bryozoan-Foraminifera-Mulluscs assemblage province. It occurs in northern rise area of Nansha Islands. The distributive depth is approximately 3000m. The carbonate content is high to 91.77%. The major characteristi
Study on the carbonate constituent of 121 deep sea sediments (water depth: 280-4420m.) taken from the central South China Sea has been carried out. The carbonate content of deep sea sediments of the South China Sea ranges from 1.72 to 91.77%.In the continent slope region the average value is 33.77%.In the deep sea plain region the average value is 5.63%. Deep water carbonates of the South China Sea are made almost entirely of biogenous skeletal materials, these include mainly foraminifera, coccolith, bryozoan and mollusc shells, prodominately composed of planktonic unicellular remains. The grain size parameters of carbonate sediment are significantly influnced by various types of biogenous particle. The general tendency of the foraminiferal abundance shows a progressive increase with increasing water depth away form the coast. The number of benthic foraminifera per gram of the sediments ranges from hundreds to more than ten, the number of plankton is from thousands to a few. The distribution of ratio between the aboundance of planktonic and benthic foram in the entire population is regular. The ratio is about 2 : 1 in the edge of outer shelf, 30 : 1 in the slope with depth less than 3000m.; finally, less than 1 : 20 in the deep water central basin of the South China Sea. The species diversity of benthic foraminifera is very high. According to the distributhion of benthic forams, it may be divided into four assemblages i.e Uvigerina schwageri-Cibicides praecinctus assemblage in the edge of the outer shelf, Siphouvigerina ampullacea-Ceratobulimina pacifica assemblage in the upper slope, Cibicides wuellerstorfi assemblage in the middle and lower slope as well as Trochammina globigeriniformis assemblage in the deep sea basin. Their assemblage characteristics are controlled by submarine topo-graphical-geomrphological feature and also related to water mass. The species diversity of planktonic foraminifera is lower, the common species are only 33. According to the range of water depth, it may be divided into three zones of the assemblage, i.e Gloligerinoidesruber-G. sacculifer assemblage with water depth less than 2000m., Neoglo-boquadrina Dutertrei assemblage with the depth range from 2000m to 2900m, and Pulleniatina Obliquiloculate assemblage with the depth range from 2900m to 3420m. These assemblage characteristics are obviously controlled by water depth associated with selective dissolution (or differential dissolution). The concentration of calcareous nannoplankton per ten fields of vision over a slide in the sediments ranges from about thousand to zero. The surface sediments are dominated by the species of Emiliania huxley and Gephyrocapsa oceanica. The others, such as pelecypods shell fragments, echinoids, crinoids and ophiuroids ct al, are less than 1% in the sediments. Except for northern rise area of Nansha Islands, deep water carbonate is mainly composed of bryozoans there. Based on the type and relative aboundance of bio-carbonate skeletal constituents and the carbonate content, four assemblage provinces of calcareous organism can be divided in the central South China Sea: ( I ) Foraminifera-Molluscs assemblage province. It occurs in the outer edge of the northern shelf of the South China Sea with the depth of less than 200m. The average percentage of the carbonate is 22.00% ; (II ) Planktonic foraminifera-Calcareous nonnoplankton assemblage province. It occurs in the multi-terraced slopes of the north-western area of the South China Sea, with the depth of less than 3500m to 4000m. The average percentage of the carbonate is 33.77% (III) Benthic foraminifera assemblage province. It occurs in the deep sea plain of the South China Sea with the depth of more than deep sea plain of the South China Sea with the depth of more than 3500m to 4000m. The average carbonate percentage is 5. 63%. ( IV ) Bryozoan-Foraminifera-Mulluscs assemblage province. It occurs in northern rise area of Nansha Islands. The distributive depth is approximately 3000m. The carbonate content is high to 91.77%. The major characteristi
1989, 7(2): 51-60.
Abstract:
The " knotty nodule" of Dalong Formation of Late Permian in Northern Sichuan and Sorthern Shaanxi Province are composed of siliceous-rich nodules and clay-rich matrix. They may have two differ sedimentary sequence: One is type of Northern Sichuan, which is mainly distributed to Northern Jiangyou, Guangyuan, and Western Wangcang region in Northern Sichuan: The other is type of Sorthern Shaanri, which is distributed to Xixiang region in Sorthern Shaanxi (Fig.l). The "knotty nodule" and the surrounding rocks are dark colored thin to medium-thin bedding micritic limestone, siliceous micritic limestone, radiolarias siliceous rock, siliceous rock, argillaceous limestone and shale (or mudstone) etc. with horizontal and rhythms bedding, part rich in organic ous materials and pyrites (or nodule). In the "knotty nodule, " the biota is characterized as abundance planktonic faunas such as radiolarias, ammonoids, condonts and thin-shelled brachiopods and a few foraminifers, ostracods, calcisphers and sponge- spiculite etc. According to sedimentary characterxs and faunal studies, the" knotty nodule" and the surrounding rocks may suggest deposition in outer shelf to basin environment, with waterdepth in the 100 to 200m or 300 to 500m range and under normal salinities. In accordance with origin and texture, the"knotty nodule" may be divided into three types, e.g. knotty nodule (discontinuous), continuous knotty nodule and flaser knotty nodule (or flaser structures). The knotty nodule is mainly distributed to upper part of Dalong Formation in Xixiang, Shaanxi Province.It is composed of dispersion nodules and rich in lime-muddy matrix. These nodules arc dark grey siliceous-bering micritic limestone, and usually are irregular and lenticle nodules. The continuous knotty nodule is distributed to upper and lower part of Dalong Formation in Guangyuan, Sichuan Province. They are silica-rich siliceous micritic limestone, radiolarias siliceous rock, in which the nodules preceded to the interlocking coalescence to nodules layer of semi-continuous or continuous. In general, the continuous knotty nodules inerleaved with more distortional siliceous shale layers and exhibit a certain rhythm structure. The flaser knotty nodule consist of small lime-siliceous ellipsoidal bodies or lenses (or flaser nodule) surrounded by siliceous- rich solution seams. The most flaser nodules are the comparatively high degree of preferred orientation, and nearly parallel to bedding. In many cases, both flaser nodules and the adjacent solution seams have abundent radiolarias. Within these nodules, the radiolarias are random bioturbated fabric, that it was locked in place by early cementation, whereas in the surrounding solution seams of nodules have the preferred alignment of radiolarias elongate grams. These are formed by the surrounding matrix remained unlithification during burial and may even have flowe plasticully around the hardened nodule during compaction. The solution seams may cut across primary depositional features such as bedding planes and omission surface, and they cut and truncate burrows. In many flaser knotty nodules, the solution seams form a secondary matrix to nodules, and seams are distorted around or cemented nodules. Carbon and oxygen isotope data (table 2, Fig. 4) indicated that the " knotty nodule" and the surrounding rocks were formed by submarine diagenesis cementation, which were in the direction of equilibrium with ambient colder bottom water than the surrounding sediment. This data is very similar to carbon and oxygen isotopes of the nodule, chalk nodule and hardground by the Cretaceous-Tertiary of the Caribbean (Deep Sea Drilling Project) and by the Cretaceous of the Northwest-European (Fig. 5) As noted above, from the characters of sedimentary, carbon and oxygen isotopes in the "knotty nodule" lead to the following conclusions about their origin: 1, The knotty nodule produced by sea floor early diagentic cementation, in which the pause in pelagic sedimention and closer to the sediment-water interface. 2, The continuous knott
The " knotty nodule" of Dalong Formation of Late Permian in Northern Sichuan and Sorthern Shaanxi Province are composed of siliceous-rich nodules and clay-rich matrix. They may have two differ sedimentary sequence: One is type of Northern Sichuan, which is mainly distributed to Northern Jiangyou, Guangyuan, and Western Wangcang region in Northern Sichuan: The other is type of Sorthern Shaanri, which is distributed to Xixiang region in Sorthern Shaanxi (Fig.l). The "knotty nodule" and the surrounding rocks are dark colored thin to medium-thin bedding micritic limestone, siliceous micritic limestone, radiolarias siliceous rock, siliceous rock, argillaceous limestone and shale (or mudstone) etc. with horizontal and rhythms bedding, part rich in organic ous materials and pyrites (or nodule). In the "knotty nodule, " the biota is characterized as abundance planktonic faunas such as radiolarias, ammonoids, condonts and thin-shelled brachiopods and a few foraminifers, ostracods, calcisphers and sponge- spiculite etc. According to sedimentary characterxs and faunal studies, the" knotty nodule" and the surrounding rocks may suggest deposition in outer shelf to basin environment, with waterdepth in the 100 to 200m or 300 to 500m range and under normal salinities. In accordance with origin and texture, the"knotty nodule" may be divided into three types, e.g. knotty nodule (discontinuous), continuous knotty nodule and flaser knotty nodule (or flaser structures). The knotty nodule is mainly distributed to upper part of Dalong Formation in Xixiang, Shaanxi Province.It is composed of dispersion nodules and rich in lime-muddy matrix. These nodules arc dark grey siliceous-bering micritic limestone, and usually are irregular and lenticle nodules. The continuous knotty nodule is distributed to upper and lower part of Dalong Formation in Guangyuan, Sichuan Province. They are silica-rich siliceous micritic limestone, radiolarias siliceous rock, in which the nodules preceded to the interlocking coalescence to nodules layer of semi-continuous or continuous. In general, the continuous knotty nodules inerleaved with more distortional siliceous shale layers and exhibit a certain rhythm structure. The flaser knotty nodule consist of small lime-siliceous ellipsoidal bodies or lenses (or flaser nodule) surrounded by siliceous- rich solution seams. The most flaser nodules are the comparatively high degree of preferred orientation, and nearly parallel to bedding. In many cases, both flaser nodules and the adjacent solution seams have abundent radiolarias. Within these nodules, the radiolarias are random bioturbated fabric, that it was locked in place by early cementation, whereas in the surrounding solution seams of nodules have the preferred alignment of radiolarias elongate grams. These are formed by the surrounding matrix remained unlithification during burial and may even have flowe plasticully around the hardened nodule during compaction. The solution seams may cut across primary depositional features such as bedding planes and omission surface, and they cut and truncate burrows. In many flaser knotty nodules, the solution seams form a secondary matrix to nodules, and seams are distorted around or cemented nodules. Carbon and oxygen isotope data (table 2, Fig. 4) indicated that the " knotty nodule" and the surrounding rocks were formed by submarine diagenesis cementation, which were in the direction of equilibrium with ambient colder bottom water than the surrounding sediment. This data is very similar to carbon and oxygen isotopes of the nodule, chalk nodule and hardground by the Cretaceous-Tertiary of the Caribbean (Deep Sea Drilling Project) and by the Cretaceous of the Northwest-European (Fig. 5) As noted above, from the characters of sedimentary, carbon and oxygen isotopes in the "knotty nodule" lead to the following conclusions about their origin: 1, The knotty nodule produced by sea floor early diagentic cementation, in which the pause in pelagic sedimention and closer to the sediment-water interface. 2, The continuous knott
1989, 7(2): 79-88.
Abstract:
The upper member of the Late Permian coal formation is a set of shallow water delta deposits in studied area. The sedimentary environments of the coal seams belong to three facies. In the upper member of the coal formation there are ten coal seams and the main seams are number 3. 6 and 12. The layers of the coal seams are stable. Their thickness varies obviously and the structures are from simple to complex. The anamal and plant fossils are contained both in seam tops and floors. There is 1-2 clayrock with cash in the seam. The coal seams contain: water (Wf) 0.81-2.47%, ash (A8) 9.16-26.42%, volatile (Vr) 26.47-41.63*5, gelatinlayer (Y) 8.0-42.5mm, the total surfur content (SQ8) 0.103-3.935%. The R0max of the vitrinite (0.76-1.11%,) shows that the metamorphic grade of the coal is II-IIIstage. The coal -forming matters are mostly gelatificated, so that thick cell-walls are common. The maceral mainly consists of the nonstructural gelatinized matrix and vitrain. Barkinite, cutinite and sporinite are commonly seen. Fusain and xylovitrain-fusain are locally gathered as lens. Also there are a certain amount of transitional macerals in the coal. All of the macerals can be found in broken and crumbled occurences ect. The occurcnces of mineral impurities in the coal which assume as clastic, nodular, filled and lenticular forms are comples and variable. The peat swamp facies which formed the main coal scams are unstable environments covered by relatively deep water, in which the water level and medium properties are changable. The peat swamp faeies in the studied area belong to two types of coal facies: The upper delta facies and the coalffacies from upper-lower delta transitional zone to lower delta. In accordance with genetical marks, The peat swamp facies can be subdivided into eight kinds. The coal seam number 3 is a good example to show the characters and changes in the peat swamps facies as it was forming.
The upper member of the Late Permian coal formation is a set of shallow water delta deposits in studied area. The sedimentary environments of the coal seams belong to three facies. In the upper member of the coal formation there are ten coal seams and the main seams are number 3. 6 and 12. The layers of the coal seams are stable. Their thickness varies obviously and the structures are from simple to complex. The anamal and plant fossils are contained both in seam tops and floors. There is 1-2 clayrock with cash in the seam. The coal seams contain: water (Wf) 0.81-2.47%, ash (A8) 9.16-26.42%, volatile (Vr) 26.47-41.63*5, gelatinlayer (Y) 8.0-42.5mm, the total surfur content (SQ8) 0.103-3.935%. The R0max of the vitrinite (0.76-1.11%,) shows that the metamorphic grade of the coal is II-IIIstage. The coal -forming matters are mostly gelatificated, so that thick cell-walls are common. The maceral mainly consists of the nonstructural gelatinized matrix and vitrain. Barkinite, cutinite and sporinite are commonly seen. Fusain and xylovitrain-fusain are locally gathered as lens. Also there are a certain amount of transitional macerals in the coal. All of the macerals can be found in broken and crumbled occurences ect. The occurcnces of mineral impurities in the coal which assume as clastic, nodular, filled and lenticular forms are comples and variable. The peat swamp facies which formed the main coal scams are unstable environments covered by relatively deep water, in which the water level and medium properties are changable. The peat swamp faeies in the studied area belong to two types of coal facies: The upper delta facies and the coalffacies from upper-lower delta transitional zone to lower delta. In accordance with genetical marks, The peat swamp facies can be subdivided into eight kinds. The coal seam number 3 is a good example to show the characters and changes in the peat swamps facies as it was forming.
1989, 7(2): 105-110.
Abstract:
The evaporite of the sedimentary basin of the upper Yangtze Platform has a wide distribution, which covers an area of 4 x 5km2 particularly developes in Sichuan Basin. The evaporites occured from Feixianguan and Jialinjiang Formation of Lower Triassic, Leikoupo Formation of Middle Triassic. The thikness of anhydrite bed is 100-500m. This paper provides a great deal of data of δ34S, and established a δ34S column of Triassic evaporite in Sichuan Basin by analysing samples from deep bore. Stratigraphic column of δ34S value indicates that δ34S value of anhydrite in the fourth member of Leikoupo Formation (namely T214) rages 14.5-18.9‰, commonly 16.5‰, T2I319.7-23.2‰, average 21.78‰, which is close to the isotopic value of sea sulphate. In T2l127.1-29.5‰.In the Fifth member of Jialinjiang For- mation (namely T1j5) δ34S value 26.1- 28.6‰, T1j4 28.0-28.5‰ commonly. But the δ34S value of T1j2 32.4-43.9‰, shows an abnomal high value. As mentioned above, the sulfur isotope data are imoprtant for geologic research. (1) In contemporary beds or a certain sedimentary basin. δ34S value varies very limited. So sulfur isotope may serve to stratigraphic division and correlation. (2) δ34S value in the Triassic column decreases gradually from 34.9‰ at the lower to 14.5‰ at the upper. (3) According to the view of modern sedimentary the deviation of sulfur isotope between evaporite and sea sulphate varies less than 1.6‰. The evaporation experiments on sea water indicate that in chloride sedimentary stage (such as carnallite etc.) the brine is bare of δ34S evidently. This represents the Salinization trend of the ancient saline lake and suggests that T2l4might be the higher deposition stage of salt-mineral. (4) In the upper and middle part of Jialinjiang Formation δ34S value fix at about 28% constantly. In an anhydrite bed. δ34S is poor at some place. While a new sedimentary cycle start, δ34S value shows a new circulation from higher to lower. It may be proved that the dissolved sulphate of the ancient salt lake was supplied constantly. This may gives support to the hypothesis of shallow salt lake model. In other warde, in the lake of Early Triassic, the evaporative sedimentation of Sichuan Basin was a shalow water enviroment. (5) Comparing with sulfur isotopic data worldwide, δ34S value of the marine Triassic evaporite of Sichuan Basin has some character of the high abnomal value, and it is necessary to modify the sulfur isotopic curve prevailing all over th wold based on the data provided in the present paper.
The evaporite of the sedimentary basin of the upper Yangtze Platform has a wide distribution, which covers an area of 4 x 5km2 particularly developes in Sichuan Basin. The evaporites occured from Feixianguan and Jialinjiang Formation of Lower Triassic, Leikoupo Formation of Middle Triassic. The thikness of anhydrite bed is 100-500m. This paper provides a great deal of data of δ34S, and established a δ34S column of Triassic evaporite in Sichuan Basin by analysing samples from deep bore. Stratigraphic column of δ34S value indicates that δ34S value of anhydrite in the fourth member of Leikoupo Formation (namely T214) rages 14.5-18.9‰, commonly 16.5‰, T2I319.7-23.2‰, average 21.78‰, which is close to the isotopic value of sea sulphate. In T2l127.1-29.5‰.In the Fifth member of Jialinjiang For- mation (namely T1j5) δ34S value 26.1- 28.6‰, T1j4 28.0-28.5‰ commonly. But the δ34S value of T1j2 32.4-43.9‰, shows an abnomal high value. As mentioned above, the sulfur isotope data are imoprtant for geologic research. (1) In contemporary beds or a certain sedimentary basin. δ34S value varies very limited. So sulfur isotope may serve to stratigraphic division and correlation. (2) δ34S value in the Triassic column decreases gradually from 34.9‰ at the lower to 14.5‰ at the upper. (3) According to the view of modern sedimentary the deviation of sulfur isotope between evaporite and sea sulphate varies less than 1.6‰. The evaporation experiments on sea water indicate that in chloride sedimentary stage (such as carnallite etc.) the brine is bare of δ34S evidently. This represents the Salinization trend of the ancient saline lake and suggests that T2l4might be the higher deposition stage of salt-mineral. (4) In the upper and middle part of Jialinjiang Formation δ34S value fix at about 28% constantly. In an anhydrite bed. δ34S is poor at some place. While a new sedimentary cycle start, δ34S value shows a new circulation from higher to lower. It may be proved that the dissolved sulphate of the ancient salt lake was supplied constantly. This may gives support to the hypothesis of shallow salt lake model. In other warde, in the lake of Early Triassic, the evaporative sedimentation of Sichuan Basin was a shalow water enviroment. (5) Comparing with sulfur isotopic data worldwide, δ34S value of the marine Triassic evaporite of Sichuan Basin has some character of the high abnomal value, and it is necessary to modify the sulfur isotopic curve prevailing all over th wold based on the data provided in the present paper.
1989, 7(2): 125-128.
Abstract:
The microstructure and composition of phosphahic pebbles in phosphorites in Zhongyicun Member of Meishucun Section, Jinning, Yunnan Province have been carefully investigated by electron microscope. The investigations revealed that the composition of pebble phosphorites can be divided three different levels: pebble phosphorites consist of phosphatic pebbles and cement materials; phosphatic pebbles consist of phosphatic oolites, phosphatic microglobules and phosphatic amorphous aggregates are composed of phosphatic microcrystals and amorphous grains and non-phosphatic micrograins.The phosphatic amorphous grains and microcrystals are the most fundamental amd the smallest grains of phosphatic matters possibly observed under electron microscope. By the investigations of electron microscope, the followimg three stages of formation of pebble phosphorites are proposed: (1) Stage of formation of phosphatic amorphous grain aggregates and phosphatic microcrystals which were crystallized out from sea water; (2) Stage of formation of phosphatic pbbles; (3) Stage of formation of pebble phosphorites. The sedimentary environment of pebble phosphorites belongs to neritic deposit
The microstructure and composition of phosphahic pebbles in phosphorites in Zhongyicun Member of Meishucun Section, Jinning, Yunnan Province have been carefully investigated by electron microscope. The investigations revealed that the composition of pebble phosphorites can be divided three different levels: pebble phosphorites consist of phosphatic pebbles and cement materials; phosphatic pebbles consist of phosphatic oolites, phosphatic microglobules and phosphatic amorphous aggregates are composed of phosphatic microcrystals and amorphous grains and non-phosphatic micrograins.The phosphatic amorphous grains and microcrystals are the most fundamental amd the smallest grains of phosphatic matters possibly observed under electron microscope. By the investigations of electron microscope, the followimg three stages of formation of pebble phosphorites are proposed: (1) Stage of formation of phosphatic amorphous grain aggregates and phosphatic microcrystals which were crystallized out from sea water; (2) Stage of formation of phosphatic pbbles; (3) Stage of formation of pebble phosphorites. The sedimentary environment of pebble phosphorites belongs to neritic deposit
