1997 Vol. 15, No. 1
column
Display Method:
1997, 15(1): 1-6.
Abstract:
Six sequence named IV 1-IV 4, Chl, Ch2 withan average duration of 1.02. 0 M a canrecog一nized in the mid-lower Naxing Formation of the Lower Carboniferous at Yalai, Nyalam，south Tibet, Inwhich three sequences with type卫basal boundary surface and three with type平could be divided bythe system tract, texture and the relationship of sequence, and all of them are of slow transgression tofast regression. Thei
Six sequence named IV 1-IV 4, Chl, Ch2 withan average duration of 1.02. 0 M a canrecog一nized in the mid-lower Naxing Formation of the Lower Carboniferous at Yalai, Nyalam，south Tibet, Inwhich three sequences with type卫basal boundary surface and three with type平could be divided bythe system tract, texture and the relationship of sequence, and all of them are of slow transgression tofast regression. Thei
1997, 15(1): 13-19.
Abstract:
43 trace fossil ichnogenera have been found in Devonian Shujiaba Formation distributed in thenorthern belt of West Qinling Mountains, and they areAcanthorhaphe Arthophcus, Belorhaphe，Bostri -cophyton, Buthotrephis, Cochilidznus, Chondrites, Cosmorhaphe, Dictyodora，Fucusopsis, Glockeria，Gordia，Gran ula ria，Helicolithus, Helminthoida，Helminthopsis, Lennea，Loph octen ium，Megagrap tort，Neonereites, Nereies, Palaeohelminthoida，Paleod ictyon，Planolites, Protopaleodictyon,,Protovirgular-is，Rhabdoglyphus, Rhobdoichnus, Rusophycus(?)，Saerichnites, Sagittichnus, Scolicia，Skol ithos,Spirophycus,Spirorhaphe,Squamodictyon,Subloren,Subularia,Subhyllochorda，Taphrhelminthoida, Taphrhelminthopsis, Tuberculichnus, Urohelminthoida.All the host rocks of trace fossils mentioned aboveare to rbidi to depo sit s, s o i t iseasy toseethere exists a close link between the formation of trace fossil and turbidity process. According tothatthetime of pre- and post-turbiditynized, and they are current event, twsharply different fossil assemblages canbe recog-1) Trace fossil assenblag a fo rmed befo re turbidi ty ev entThey are produced in a low-energy abyssal environment in the interval of tubidity process, with twotypical feature① animals live and seek for food horizontally in the surface deposits,and trace fossil sa remainly preserved in the Te mudstone surfac of the Bouma sequence;②Generally, they appear incurve,snake and network shapesof which overAnd they are the typical members of "Nereites”features.70% ichnogeneraareformed before the turbidity event.fades with high degree of differentiation and abundance2) Trace fossil assemblage formed after turbidity eventThey are of lowabundance and degreespanning fadesty peof differentiation, and are characterized by the irregular”shalloww ater”and”members, generally preserved in the sandstone parts of thesequence or piercing sandstone. They are not in the leading role among the fossils discovered.Although the abundance and degree of differentiation of trace fossils formed before the turbidityevent :ire g ready higher than that formed after the event, they are of equivalently important role in theturbidite measure for their appearrance reflects the replacement of "fastlow-fast”sedimentation rate,i. e the whole process of the formation is a complete turbidite depositional sequence. Thus we canlink the two sharply lifferent trace fossil assemblages in accordance with their origin, and use them as apaleoichnological indicator of bethyal byssal turbidite measure.
43 trace fossil ichnogenera have been found in Devonian Shujiaba Formation distributed in thenorthern belt of West Qinling Mountains, and they areAcanthorhaphe Arthophcus, Belorhaphe，Bostri -cophyton, Buthotrephis, Cochilidznus, Chondrites, Cosmorhaphe, Dictyodora，Fucusopsis, Glockeria，Gordia，Gran ula ria，Helicolithus, Helminthoida，Helminthopsis, Lennea，Loph octen ium，Megagrap tort，Neonereites, Nereies, Palaeohelminthoida，Paleod ictyon，Planolites, Protopaleodictyon,,Protovirgular-is，Rhabdoglyphus, Rhobdoichnus, Rusophycus(?)，Saerichnites, Sagittichnus, Scolicia，Skol ithos,Spirophycus,Spirorhaphe,Squamodictyon,Subloren,Subularia,Subhyllochorda，Taphrhelminthoida, Taphrhelminthopsis, Tuberculichnus, Urohelminthoida.All the host rocks of trace fossils mentioned aboveare to rbidi to depo sit s, s o i t iseasy toseethere exists a close link between the formation of trace fossil and turbidity process. According tothatthetime of pre- and post-turbiditynized, and they are current event, twsharply different fossil assemblages canbe recog-1) Trace fossil assenblag a fo rmed befo re turbidi ty ev entThey are produced in a low-energy abyssal environment in the interval of tubidity process, with twotypical feature① animals live and seek for food horizontally in the surface deposits,and trace fossil sa remainly preserved in the Te mudstone surfac of the Bouma sequence;②Generally, they appear incurve,snake and network shapesof which overAnd they are the typical members of "Nereites”features.70% ichnogeneraareformed before the turbidity event.fades with high degree of differentiation and abundance2) Trace fossil assemblage formed after turbidity eventThey are of lowabundance and degreespanning fadesty peof differentiation, and are characterized by the irregular”shalloww ater”and”members, generally preserved in the sandstone parts of thesequence or piercing sandstone. They are not in the leading role among the fossils discovered.Although the abundance and degree of differentiation of trace fossils formed before the turbidityevent :ire g ready higher than that formed after the event, they are of equivalently important role in theturbidite measure for their appearrance reflects the replacement of "fastlow-fast”sedimentation rate,i. e the whole process of the formation is a complete turbidite depositional sequence. Thus we canlink the two sharply lifferent trace fossil assemblages in accordance with their origin, and use them as apaleoichnological indicator of bethyal byssal turbidite measure.
1997, 15(1): 25-30.
Abstract:
The two unconformities developed on the tops of Lower Ordovician Liangjashan Fm(U F1)and M a-jagou or the Middle Ordovician Fengfeng Fm(UF2) are essential boundaries that controlled the formationand distribution of the Early Paleozoic karstification related reservoirs. U F1 and U F2 have beeninterpret-ed to represent short and long terms of tectonic uplift, respectively，but the new evidence led us to con-clude that they were crested by different original mechanisms and therefore the related reservoirs shouldbe predicted in different ways. UF1 was commonly interpreted as the result of southern upwarping ofbasement, but sequence stratigraphic analysis supports its origin of eustatic sealevel changes. Sealeve1fall can produce a tilted karst denudation plane dipping basinward by truncating horizontal strata. TheU F1 cut Liangjashan Fm. in the NW and gradually went down to the top of Upper Cambrian Series inthe S Etherefore, the related reservoirs〔orrespon dingly developed in these different strata from NW to SESp atially，the most favorable regional reservoirs should be located in the central area of N. China,where the carbonate sediments experienced dolotion with the following light leaching. UF2was cre-ated by global event that resulted in the intraplate downward flexure, and subsequent perispheral bulge.The younger strata(Fengfeng Fm.)were protected in the concave belt of central N.China and erodedaway by the meterior water along the bulge. As a result, the potential regional reservoirs related rocksof Fengfeng Fm. and the potential regional reservoirs related to U F2 are likely to distribute along the pe-ripheral uplift belts, especially around the remanent Fengfeng Fm.
The two unconformities developed on the tops of Lower Ordovician Liangjashan Fm(U F1)and M a-jagou or the Middle Ordovician Fengfeng Fm(UF2) are essential boundaries that controlled the formationand distribution of the Early Paleozoic karstification related reservoirs. U F1 and U F2 have beeninterpret-ed to represent short and long terms of tectonic uplift, respectively，but the new evidence led us to con-clude that they were crested by different original mechanisms and therefore the related reservoirs shouldbe predicted in different ways. UF1 was commonly interpreted as the result of southern upwarping ofbasement, but sequence stratigraphic analysis supports its origin of eustatic sealevel changes. Sealeve1fall can produce a tilted karst denudation plane dipping basinward by truncating horizontal strata. TheU F1 cut Liangjashan Fm. in the NW and gradually went down to the top of Upper Cambrian Series inthe S Etherefore, the related reservoirs〔orrespon dingly developed in these different strata from NW to SESp atially，the most favorable regional reservoirs should be located in the central area of N. China,where the carbonate sediments experienced dolotion with the following light leaching. UF2was cre-ated by global event that resulted in the intraplate downward flexure, and subsequent perispheral bulge.The younger strata(Fengfeng Fm.)were protected in the concave belt of central N.China and erodedaway by the meterior water along the bulge. As a result, the potential regional reservoirs related rocksof Fengfeng Fm. and the potential regional reservoirs related to U F2 are likely to distribute along the pe-ripheral uplift belts, especially around the remanent Fengfeng Fm.
1997, 15(1): 37-42.
Abstract:
as a river dominated delta deposit. It develops three kinds of subfacies delta above一water plain,deltain-ner front and delta outer front. On the basis of this,it can be subdivided into eight kinds of microfaciessurficial distributary channel, interchannel area, interchannel swamp, subaqueous distributary channel,debouch bar，inter distributary bay，sheet sand and delta front mud. The plane distribution feature of sedimentary fades is that from northwest to southeast, delta plain,delta inner front, delta outer front appear in order. Different microfacies overlie and interlace with eachother.Distributary channel sandbody and debouch bar sandbody the main sandbody framework of delta. Combining research results of crofacies analysis on a single well with plane distribution featuresof sedimentary microfacies, the sedimentary model of the Putaohua reservior in the Yushulin oilfield isbuilt finally. It objectively shows sedimentary featuers of the Putaohuaerervior and provides acertaingeological evidence for further oilfiekl development.
as a river dominated delta deposit. It develops three kinds of subfacies delta above一water plain,deltain-ner front and delta outer front. On the basis of this,it can be subdivided into eight kinds of microfaciessurficial distributary channel, interchannel area, interchannel swamp, subaqueous distributary channel,debouch bar，inter distributary bay，sheet sand and delta front mud. The plane distribution feature of sedimentary fades is that from northwest to southeast, delta plain,delta inner front, delta outer front appear in order. Different microfacies overlie and interlace with eachother.Distributary channel sandbody and debouch bar sandbody the main sandbody framework of delta. Combining research results of crofacies analysis on a single well with plane distribution featuresof sedimentary microfacies, the sedimentary model of the Putaohua reservior in the Yushulin oilfield isbuilt finally. It objectively shows sedimentary featuers of the Putaohuaerervior and provides acertaingeological evidence for further oilfiekl development.
1997, 15(1): 48-53.
Abstract:
An analytical technique for the simultaneous determination of He and Ar contents and isotopic tom-positions in rocks by static mass spectrometer has heen developed. The gases in rocks are extracted bymelting at 1 600℃.The purification of noble gases、an be made out by。titanium sponge Better at600℃，two Zr-Al Betters, and a Ti subliming Better. Heavier noble gases, such as argon, krypton andxenon are absorbed in a charcoal trap held at liquid nitrogen temperature. The purified helium and neonfractions are admitted to the mass spectrometer for helium measurement. After that, pumping out the Heand Ne, the charcoal trap is heated, and then the released(Ar+ Kr+ Xe)fractionis admitted to the massspectrometer for argon measurement. The air with constant isotopic compositions of noble gases is con-sidered as a standard sample. The average sensitivities of4He，20Ne and 36 Ar are(9. 00 +0.35）×10-10，(1. 4 01+0. 03 2）×10 -9 and(1. 76+0. 21）×10-10 cm3 STP,respectively. The blank levels of the sys-tem fo r4He and 36Ar are 1. 3860 ×109 and 4. 08×10-11cm3STP, respectively. Measured He and Ar con-tents and isotopic compositionsinedogites are given in this paper. Itis the first report on He and Arisotopic compositions in rocks in China.
An analytical technique for the simultaneous determination of He and Ar contents and isotopic tom-positions in rocks by static mass spectrometer has heen developed. The gases in rocks are extracted bymelting at 1 600℃.The purification of noble gases、an be made out by。titanium sponge Better at600℃，two Zr-Al Betters, and a Ti subliming Better. Heavier noble gases, such as argon, krypton andxenon are absorbed in a charcoal trap held at liquid nitrogen temperature. The purified helium and neonfractions are admitted to the mass spectrometer for helium measurement. After that, pumping out the Heand Ne, the charcoal trap is heated, and then the released(Ar+ Kr+ Xe)fractionis admitted to the massspectrometer for argon measurement. The air with constant isotopic compositions of noble gases is con-sidered as a standard sample. The average sensitivities of4He，20Ne and 36 Ar are(9. 00 +0.35）×10-10，(1. 4 01+0. 03 2）×10 -9 and(1. 76+0. 21）×10-10 cm3 STP,respectively. The blank levels of the sys-tem fo r4He and 36Ar are 1. 3860 ×109 and 4. 08×10-11cm3STP, respectively. Measured He and Ar con-tents and isotopic compositionsinedogites are given in this paper. Itis the first report on He and Arisotopic compositions in rocks in China.
1997, 15(1): 59-64.
Abstract:
Special petroleum geological and geochemical conditions lead to a special type of oils formed in theMiddle Jurassic coal-shale strata in the Minhe basin. The oils are characterized by a higher Pr/Ph ratio(2. 65-3. 15)，very low sterane/hopane ratio(0. 03)，higher C27 /C29 α α α strerane ratio(1. 07 )，higherTs /Tm value(1. 09)，higher abundance of C29 Ts and rearranged hopane series, higher abundance ofbiphenyl series and alkyl tetrahydrogen naphthalenes, and high value of dibenzofuran/dibenzothiophene,etc. Many types of oil shales with very different oil potentials occur in the Middle Jurassic coal-sh alestrata. Most of them areformed in weakly oxidizing freshwater sedimentary environments, with higherPr/Ph ratios(averaging 1. 98) and very low values of sterane/hopane and dibenzofuran /dibenzothiophone as main evidence. Some oil shales show higher abundance of C29Ts and rearranged hopanes, re-Electing that these oil shales are the predominant contributor to the Minhe oil. It‘s also proved that theoil shales contain reworked sedimentary organic matter by organic geochemistry, organic petrology andkerogen TGA and DTG analysis. Source rock maturation and oil}gas generation are also affected by ab-normal geothermal energy.
Special petroleum geological and geochemical conditions lead to a special type of oils formed in theMiddle Jurassic coal-shale strata in the Minhe basin. The oils are characterized by a higher Pr/Ph ratio(2. 65-3. 15)，very low sterane/hopane ratio(0. 03)，higher C27 /C29 α α α strerane ratio(1. 07 )，higherTs /Tm value(1. 09)，higher abundance of C29 Ts and rearranged hopane series, higher abundance ofbiphenyl series and alkyl tetrahydrogen naphthalenes, and high value of dibenzofuran/dibenzothiophene,etc. Many types of oil shales with very different oil potentials occur in the Middle Jurassic coal-sh alestrata. Most of them areformed in weakly oxidizing freshwater sedimentary environments, with higherPr/Ph ratios(averaging 1. 98) and very low values of sterane/hopane and dibenzofuran /dibenzothiophone as main evidence. Some oil shales show higher abundance of C29Ts and rearranged hopanes, re-Electing that these oil shales are the predominant contributor to the Minhe oil. It‘s also proved that theoil shales contain reworked sedimentary organic matter by organic geochemistry, organic petrology andkerogen TGA and DTG analysis. Source rock maturation and oil}gas generation are also affected by ab-normal geothermal energy.
1997, 15(1): 71-76.
Abstract:
Wudalianchi volcanic group is located in Heilongjiang Province in northeastern China. There are 14volcanoes, 12 of which erupted in the Middle Pleistocene and another two，the Laoheishan volcano andHuoshaoshan volcano，erupted between 1 719 and 1 721 in historic record. Both Laoheishan volcano andHuoshaoshan volcano consist of airfall tephra which is mainly composed of basaltic scoria, bomb, vokan-is cake and a few and lithic fragments. Based on the authors'study, the Laoheishan airborn tephra forms a scoria cone and a fallout sheet,respectively. 1) The Laoheishan basaltic scoria cone is a round haped cone with oilt top, its altitude is 515. 9m，higher than surrounding ground(162 m)，and its base area is 1. 25 km2，the diameter of crater takinga funnel shape is 370 -400 m. The Laoheishan scoria cone consists of loose, semiconsolidated to consoli-dated tephra. The grain size of the scoria cone is much bigger than that of the tephra sheet. The averagemaximum diameter of basaltic scoriais 11. 3一22. 3 cm at different points on the scoria cone. The grainsize of basaltic bomb and driblet, in general, ranges from 0. 2 to 2 m，the diameter of the biggest oneis over 3 m and the average maximum diameter of lithic clasts including the granite and basalt fragmentseffused at the early stage is 1. 8-3. 8 cm at different points on the scoria cone. 2) The distribution pattern of fallout tephra of the tephra sheet is fan haped. the apex of the fan islocated at the crater of the Laoheishan volcano. The airfall tephra is mainly settled down in SSE of thescoria cone, which reveals a strong NNW wind while the Laoheishan volcano erupted. The dispersal ofthe fallout tephra is not far away from the source, the distribution area of the tephrais limited, only 16kmz, which shows the eruption column is not too high. The thickness of the tephra decreases rapidlyoutwards from the source and the average maximum scoria size, the average maximum lithic size and themedian diameter of tephra within the tephra sheet deposit decrease exponentially away from the eruptivesource. The airfall tephra deposits of the tephra sheet can be devided into two parts, either of which hasstratigraphical sequences from the layer of lithic fragments to the l from the base of the Laoheishan scoria cone, which shows a pulsating eruption of the Laoheishan vol- cano. Meanwhile, it is supposed that the two tage explosions of the Laoheishan volcano are in accordante with 1 719 and 1 720 eruptions, respectively.3)According to the isopach map of the Laoheishan tephra sheet deposit,and by the Froggatt volume-thickness plot method,the volume 0.0063km3 of the tephra sheet deposit and by the Froggatt volume-thickness plot method[8]，the volume 0. 0063 km3of the tephra sheet deposit is calculated and it ismuch less than that of the scoria cone of the Laoheishan volcano (0.、 68km3), showing the tephra of theLaoheishan volcano belongs to a cone-building deposit. with the aid of the Walker[4]and Fisher [6]plotmethods, the Laoheishan volcanic eruption is considerde to belong to the Strombolian type, and basedon a higher value of F%，the author suggests that the Iaoheishan volcano erupts with strong explosiveforte. 4) The Laoheishan volcano and Huoshaoshan volcano are dorment ones and there is a possibility forboth of them to erupt again, for there are frequent microseisms and small seisms in the Wu dalianchi areanow adays.
Wudalianchi volcanic group is located in Heilongjiang Province in northeastern China. There are 14volcanoes, 12 of which erupted in the Middle Pleistocene and another two，the Laoheishan volcano andHuoshaoshan volcano，erupted between 1 719 and 1 721 in historic record. Both Laoheishan volcano andHuoshaoshan volcano consist of airfall tephra which is mainly composed of basaltic scoria, bomb, vokan-is cake and a few and lithic fragments. Based on the authors'study, the Laoheishan airborn tephra forms a scoria cone and a fallout sheet,respectively. 1) The Laoheishan basaltic scoria cone is a round haped cone with oilt top, its altitude is 515. 9m，higher than surrounding ground(162 m)，and its base area is 1. 25 km2，the diameter of crater takinga funnel shape is 370 -400 m. The Laoheishan scoria cone consists of loose, semiconsolidated to consoli-dated tephra. The grain size of the scoria cone is much bigger than that of the tephra sheet. The averagemaximum diameter of basaltic scoriais 11. 3一22. 3 cm at different points on the scoria cone. The grainsize of basaltic bomb and driblet, in general, ranges from 0. 2 to 2 m，the diameter of the biggest oneis over 3 m and the average maximum diameter of lithic clasts including the granite and basalt fragmentseffused at the early stage is 1. 8-3. 8 cm at different points on the scoria cone. 2) The distribution pattern of fallout tephra of the tephra sheet is fan haped. the apex of the fan islocated at the crater of the Laoheishan volcano. The airfall tephra is mainly settled down in SSE of thescoria cone, which reveals a strong NNW wind while the Laoheishan volcano erupted. The dispersal ofthe fallout tephra is not far away from the source, the distribution area of the tephrais limited, only 16kmz, which shows the eruption column is not too high. The thickness of the tephra decreases rapidlyoutwards from the source and the average maximum scoria size, the average maximum lithic size and themedian diameter of tephra within the tephra sheet deposit decrease exponentially away from the eruptivesource. The airfall tephra deposits of the tephra sheet can be devided into two parts, either of which hasstratigraphical sequences from the layer of lithic fragments to the l from the base of the Laoheishan scoria cone, which shows a pulsating eruption of the Laoheishan vol- cano. Meanwhile, it is supposed that the two tage explosions of the Laoheishan volcano are in accordante with 1 719 and 1 720 eruptions, respectively.3)According to the isopach map of the Laoheishan tephra sheet deposit,and by the Froggatt volume-thickness plot method,the volume 0.0063km3 of the tephra sheet deposit and by the Froggatt volume-thickness plot method[8]，the volume 0. 0063 km3of the tephra sheet deposit is calculated and it ismuch less than that of the scoria cone of the Laoheishan volcano (0.、 68km3), showing the tephra of theLaoheishan volcano belongs to a cone-building deposit. with the aid of the Walker[4]and Fisher [6]plotmethods, the Laoheishan volcanic eruption is considerde to belong to the Strombolian type, and basedon a higher value of F%，the author suggests that the Iaoheishan volcano erupts with strong explosiveforte. 4) The Laoheishan volcano and Huoshaoshan volcano are dorment ones and there is a possibility forboth of them to erupt again, for there are frequent microseisms and small seisms in the Wu dalianchi areanow adays.
1997, 15(1): 85-91.
Abstract:
Bused on analysis of the habitat type of the Early Triassic twenty communities of,Jianghan Basinand the crosswextendance of communities of every age, the Early Triassic evolution of sea level andpaleogeography are discussed in this paper, furthermore the Early Triassic ecosgstem is divided into sixevolution wry stages. Based on the study of the Early Triassic。ostratigraphy of,Jianghan Basin, the au-thorn have firstly established the Early Triassic ecostratigraphic system of,Jianghan Basin, which con-twins twenty community zones, ten community formations and three community groups. Their distribu-ti on s, compositions, ecologic environment evolutions aswell as top and bottom boundary lines are ex-pounded in this paper as well.
Bused on analysis of the habitat type of the Early Triassic twenty communities of,Jianghan Basinand the crosswextendance of communities of every age, the Early Triassic evolution of sea level andpaleogeography are discussed in this paper, furthermore the Early Triassic ecosgstem is divided into sixevolution wry stages. Based on the study of the Early Triassic。ostratigraphy of,Jianghan Basin, the au-thorn have firstly established the Early Triassic ecostratigraphic system of,Jianghan Basin, which con-twins twenty community zones, ten community formations and three community groups. Their distribu-ti on s, compositions, ecologic environment evolutions aswell as top and bottom boundary lines are ex-pounded in this paper as well.
1997, 15(1): 98-103.
Abstract:
Irregular illite/smectite interstratified clay minerals(I /S)occur frequently in sedimentary strata.Three pure I/S samples from the sedimentary strata in Xinjing, China are analysed in this paper, and it can be seen that the illite layer in I/S has the thickness of 1. 00 nm, but the smectite layer has two typesin thickness, that is，1. 5 nm for a smectite layer with two layers of interlayer water molecule and 1.25-1. 26 nm for a smectite layer with a single layer of interlayer water molecule. It〔an be concludedfrom the above results that, during diagenesis, the smectite layers in I/S transform to illite layer by twosteps, that is，smectite layer with two layers of interlayer water smectite layer with one layer of inter-layer water illite layer. It can also be seen that the layer linking probabilities of the I/S are betweenthose of wholly random interstratification and those of simplely physical mixture of two types of crystal-liter, i. e.，pII.I. PII.I,PII.I <1. 0. The structural formulae are calculated for I4 pure I/S samplesfrom the drills of the Fuyu oilfield in Olin Province according to their electron probe quantitative analyz-ing results. By regression analysis of 14 variables including elements and cbarge distribution among te-trahedral, octehedral, interlayer sheets of the I/S sampsles as well as X一ray diffraction results(ra ti o oftwo type layers) and the sample burial depth, it is concluded that along with the continuing of diagenesis(increasing of burial depths)，the contents of illite layers in I/S obviously incrase correlation coefficientbeing 0. 85)，and the substitutions of A1 for Si in the tetrahedral sheet and the tetrahedral charge as wellas the layer、barge also increase(the coefficients being 0. 77, 0. 077, 0. 085, respectively)·By plo t tingof the contents of Siversus K and Na+2Ca versus K per formula, it can be seen that the illite layer inthe I/S of sedimentary strata has a chemical co mpo sition chracteristic of muscovite with the layer charge of 0. 30of 0. 75, and the smectite layer has a〔hracter of montomorillonite with the layer charge of 0. 30
Irregular illite/smectite interstratified clay minerals(I /S)occur frequently in sedimentary strata.Three pure I/S samples from the sedimentary strata in Xinjing, China are analysed in this paper, and it can be seen that the illite layer in I/S has the thickness of 1. 00 nm, but the smectite layer has two typesin thickness, that is，1. 5 nm for a smectite layer with two layers of interlayer water molecule and 1.25-1. 26 nm for a smectite layer with a single layer of interlayer water molecule. It〔an be concludedfrom the above results that, during diagenesis, the smectite layers in I/S transform to illite layer by twosteps, that is，smectite layer with two layers of interlayer water smectite layer with one layer of inter-layer water illite layer. It can also be seen that the layer linking probabilities of the I/S are betweenthose of wholly random interstratification and those of simplely physical mixture of two types of crystal-liter, i. e.，pII.I. PII.I,PII.I <1. 0. The structural formulae are calculated for I4 pure I/S samplesfrom the drills of the Fuyu oilfield in Olin Province according to their electron probe quantitative analyz-ing results. By regression analysis of 14 variables including elements and cbarge distribution among te-trahedral, octehedral, interlayer sheets of the I/S sampsles as well as X一ray diffraction results(ra ti o oftwo type layers) and the sample burial depth, it is concluded that along with the continuing of diagenesis(increasing of burial depths)，the contents of illite layers in I/S obviously incrase correlation coefficientbeing 0. 85)，and the substitutions of A1 for Si in the tetrahedral sheet and the tetrahedral charge as wellas the layer、barge also increase(the coefficients being 0. 77, 0. 077, 0. 085, respectively)·By plo t tingof the contents of Siversus K and Na+2Ca versus K per formula, it can be seen that the illite layer inthe I/S of sedimentary strata has a chemical co mpo sition chracteristic of muscovite with the layer charge of 0. 30of 0. 75, and the smectite layer has a〔hracter of montomorillonite with the layer charge of 0. 30
1997, 15(1): 112-117.
Abstract:
The cropper ore provenance effect by sedimentation of,Jiapela Formation of Upper Triassic; in the East Tibet is first putforward by the authors based on the latest data and research from srtatigraphy，sedimentology, geochemistry of trace ele-menu and rare earth elements，and so on. And the relationship between the proveper ore was been principally affected bysedimentation in Late Triassic，and its forming environment was anactive continental margin. The chondrite normalizedpattern of REEfrom cropper sandstones and mudstones of,Jiapela Formation is different from theYulong granite- porphyryin the content of REE and oblique type from the pattern.
The cropper ore provenance effect by sedimentation of,Jiapela Formation of Upper Triassic; in the East Tibet is first putforward by the authors based on the latest data and research from srtatigraphy，sedimentology, geochemistry of trace ele-menu and rare earth elements，and so on. And the relationship between the proveper ore was been principally affected bysedimentation in Late Triassic，and its forming environment was anactive continental margin. The chondrite normalizedpattern of REEfrom cropper sandstones and mudstones of,Jiapela Formation is different from theYulong granite- porphyryin the content of REE and oblique type from the pattern.
1997, 15(1): 123-127.
Abstract:
The Study area, one of the most important gold-producing areas in China and abundant in gold andplacer gold reservoirs, is located in the northwest area of the Jiao Dong peninsula. The authors havemainly researched sedimentary features, the theories and methods of sedimentology and hydrodynamics,placer gold accumulation and hydrodynamics conditions of modern rivers in the area, by means of pointedo ut th at placer gold in river accum ulation is ady namic process in close relation with mechanicalmineral-ization and related to special river hydrodynamics. The underflow of the transverse circulation is greatlyimportant to the formation of step gentle slope dip face of river valley and placer gold accumulation.
The Study area, one of the most important gold-producing areas in China and abundant in gold andplacer gold reservoirs, is located in the northwest area of the Jiao Dong peninsula. The authors havemainly researched sedimentary features, the theories and methods of sedimentology and hydrodynamics,placer gold accumulation and hydrodynamics conditions of modern rivers in the area, by means of pointedo ut th at placer gold in river accum ulation is ady namic process in close relation with mechanicalmineral-ization and related to special river hydrodynamics. The underflow of the transverse circulation is greatlyimportant to the formation of step gentle slope dip face of river valley and placer gold accumulation.
1997, 15(1): 135-140.
Abstract:
1997, 15(1): 141-151.
Abstract:
Bused 0n the sealing mechanism of the hydrocarbon concentration caprock and its geological condi-ti on s, and bymeans of determiing the period that the sealing ability of hydrocarbon concentration caprock formedsource rocks, and investigating the matching relationship of that with the gas expulsion period ofauthors have disscussed the sealing efficiency of the hydrocarbon concentrationcaprock, i. e.，only the sealing period is earlier than or near the expulsion period of sourcerocks can the hydrocarbon concentration caprock seal the gas expelled by source rocks in diffusive phase,if notthe sealing efficiency of the hydrocarbon concentratio n caprock is bad. This paper analysed the efficiencyof the hydrocarbon concentration caprock of the Qingsankou formation mudstone which seals the gasfrom Jurassic system and expounded the significance of sealing efficiency in the evaluation of gasprospectrve resources.
Bused 0n the sealing mechanism of the hydrocarbon concentration caprock and its geological condi-ti on s, and bymeans of determiing the period that the sealing ability of hydrocarbon concentration caprock formedsource rocks, and investigating the matching relationship of that with the gas expulsion period ofauthors have disscussed the sealing efficiency of the hydrocarbon concentrationcaprock, i. e.，only the sealing period is earlier than or near the expulsion period of sourcerocks can the hydrocarbon concentration caprock seal the gas expelled by source rocks in diffusive phase,if notthe sealing efficiency of the hydrocarbon concentratio n caprock is bad. This paper analysed the efficiencyof the hydrocarbon concentration caprock of the Qingsankou formation mudstone which seals the gasfrom Jurassic system and expounded the significance of sealing efficiency in the evaluation of gasprospectrve resources.
1997, 15(1): 156-160.
Abstract:
It is effective to determine thrust events of provenance, tectonic setting and provenance strata cor re-sponding to basin sediments according to the clast dispersal style and the components of sediments inforeland basins. Test and study on the Upper Triassic stratigraphic section of the Ankou region in thesouthwestern margin of Ordos show that the provenanc es of stratigraphy are a set of meta lastics andmeta}olcanics which are Chenjiahe Formation(O3ch)and Huluhe Formation(Z- O2hl)〔ontributed inteh eastern Qilian fold-thrust belt. The provenance of the Upper Jurassic conglomerate in the south-western margin is Longshan Formation(Pt2ln)·The dispersal style of the Upper Triassic is the blended clast composition, and thedispersal style of the both of the Upper Triassic and the Upper Jurassic is theinverted dust composition which is the sedimentary response to two times of large thrusting. The analy-sis on the QmFLt triangular diagram representing the sandstone components of the Upper Triassic in theAnkou region shows that the Late Triassic basin in the southwestern margin of Ordos is a foreland basinlocated in the foreland of a collision orogen and the provenance is the fold-thrust massif of the recycledo rogen which is the eastern Qilian orogen.
It is effective to determine thrust events of provenance, tectonic setting and provenance strata cor re-sponding to basin sediments according to the clast dispersal style and the components of sediments inforeland basins. Test and study on the Upper Triassic stratigraphic section of the Ankou region in thesouthwestern margin of Ordos show that the provenanc es of stratigraphy are a set of meta lastics andmeta}olcanics which are Chenjiahe Formation(O3ch)and Huluhe Formation(Z- O2hl)〔ontributed inteh eastern Qilian fold-thrust belt. The provenance of the Upper Jurassic conglomerate in the south-western margin is Longshan Formation(Pt2ln)·The dispersal style of the Upper Triassic is the blended clast composition, and thedispersal style of the both of the Upper Triassic and the Upper Jurassic is theinverted dust composition which is the sedimentary response to two times of large thrusting. The analy-sis on the QmFLt triangular diagram representing the sandstone components of the Upper Triassic in theAnkou region shows that the Late Triassic basin in the southwestern margin of Ordos is a foreland basinlocated in the foreland of a collision orogen and the provenance is the fold-thrust massif of the recycledo rogen which is the eastern Qilian orogen.
1997, 15(1): 168-171.
Abstract:
By analyzing the Characteristics of granular and chemical compositions of the Xiaotang profile, he change of Holocene climate in the plain area of northern Taklimakan Desert has been revealed. The sedi-mentary fades mainly consists of clay formed by fluvial washing and aeolian layer caused by wind. Claymaterials coincide with the typical fades of modern river, while the aeolian deposit is similar to the fea-tures of present driftgand. Movement and conversion of elements in sedimentary layers are clowly relat-ed with the climate and hydrographic dandlitions at that time. The- dry and high temperature- dry climate since Holocene has been crented under the background of global climate with impact of localdesert landscape. meanwhile, the windy and dry climate is produced. It is objectively recorded in sedi-mentary fades.
By analyzing the Characteristics of granular and chemical compositions of the Xiaotang profile, he change of Holocene climate in the plain area of northern Taklimakan Desert has been revealed. The sedi-mentary fades mainly consists of clay formed by fluvial washing and aeolian layer caused by wind. Claymaterials coincide with the typical fades of modern river, while the aeolian deposit is similar to the fea-tures of present driftgand. Movement and conversion of elements in sedimentary layers are clowly relat-ed with the climate and hydrographic dandlitions at that time. The- dry and high temperature- dry climate since Holocene has been crented under the background of global climate with impact of localdesert landscape. meanwhile, the windy and dry climate is produced. It is objectively recorded in sedi-mentary fades.
1997, 15(1): 7-12.
Abstract:
The method of solvent extraction was employed to obtain concentrated oxygen一contaiing com-pounds from the Gudao crude oil and they were then separated by column chromatography packed withsilica to get organosilicon compounds and other fractions. The organosilicon compounds were separatedand identified by IR electron spectrum and GC一M S method.
The method of solvent extraction was employed to obtain concentrated oxygen一contaiing com-pounds from the Gudao crude oil and they were then separated by column chromatography packed withsilica to get organosilicon compounds and other fractions. The organosilicon compounds were separatedand identified by IR electron spectrum and GC一M S method.
1997, 15(1): 20-24.
Abstract:
A set of very typical turbidite sequence is developed in the middle of Kuqa depression. Among therocks, mark structures showing turbidty features frequently occur and have charaterlstic Bouma se-quence. Turbidity deposits passing through the scarp zone of braid delta front in the northeast Kuqa de-pression enter the centre of the basin. As the Late Triassic is a stable subsiding stage of the depressionand the landform of lakebed is smooth, turbidte sequenceis relatively thinner and only D turbiditefaciesis developed. Obviously it is a very typical distal turbidite. Hydrocarbon source rocks of deep lake faciesand reservoirs of braid deltas and cap rocks associated with turbidite are well developed. It has beenproved that M esozoic strata have good potentials for exploration of oil and gas in this region.
A set of very typical turbidite sequence is developed in the middle of Kuqa depression. Among therocks, mark structures showing turbidty features frequently occur and have charaterlstic Bouma se-quence. Turbidity deposits passing through the scarp zone of braid delta front in the northeast Kuqa de-pression enter the centre of the basin. As the Late Triassic is a stable subsiding stage of the depressionand the landform of lakebed is smooth, turbidte sequenceis relatively thinner and only D turbiditefaciesis developed. Obviously it is a very typical distal turbidite. Hydrocarbon source rocks of deep lake faciesand reservoirs of braid deltas and cap rocks associated with turbidite are well developed. It has beenproved that M esozoic strata have good potentials for exploration of oil and gas in this region.
1997, 15(1): 31-36.
Abstract:
The paper introduces the theory and method of high一resolution sequence stratigraphy based on thecontrol of baselevel rise and fall. On the basis of fades analysis the method is used to deduce a single di-rection of accommodation migration, stacking patterns of strata, baselevel rise，and f all and s u dace to ca-tion of sequences by volumetric partition of sediment and facies differentiation, and to divide various or-ders of baselevel cycles(i. e. sequences) and to correlate thecycles order by order from long一termcyclesto short- term ones. After that, the authors apply the method for detail division and correlation of LatePaleo zoic coal-bearing series mainly composed of continental sediments in the Datong region，NorthShanxi, and clarify some vague conclusions and searches for the relationship between coal accumulationand high一resolution sequence. The result of the study indicates that the method can be widely used toimprove the precision of division and correlation of strata, and that it is an effective way to research intocontinental sequence stratigraphy. In addition, this approa his also very useful in correlation and predica-ti on of res erv airs.
The paper introduces the theory and method of high一resolution sequence stratigraphy based on thecontrol of baselevel rise and fall. On the basis of fades analysis the method is used to deduce a single di-rection of accommodation migration, stacking patterns of strata, baselevel rise，and f all and s u dace to ca-tion of sequences by volumetric partition of sediment and facies differentiation, and to divide various or-ders of baselevel cycles(i. e. sequences) and to correlate thecycles order by order from long一termcyclesto short- term ones. After that, the authors apply the method for detail division and correlation of LatePaleo zoic coal-bearing series mainly composed of continental sediments in the Datong region，NorthShanxi, and clarify some vague conclusions and searches for the relationship between coal accumulationand high一resolution sequence. The result of the study indicates that the method can be widely used toimprove the precision of division and correlation of strata, and that it is an effective way to research intocontinental sequence stratigraphy. In addition, this approa his also very useful in correlation and predica-ti on of res erv airs.
1997, 15(1): 43-47.
Abstract:
In recent 20 years, while having payed attention to studying the modern barrier island sedimentarysystems, reople have made some researches on sedimentary characteristics of washover fans associatedwith barrier island and pointed out that there are many washover fans in ancient barrier island sedimen-tart' sequences, which opens up a new field for oil- gas exploration. Directed by modern sedimentary the-ory, authors studied the Carborriferous washover fans ind barrier island in the Donghetang area of theTarim basin by full uses of geological, logging and seismic data. The washover fan can be divided intosandstone type and limestone type. The former consists of siltstone,fine sandstone and brown mudstonewith graded and parrallel beddings. In the sandstone, quartz and chert content is 8070一9070，there aresome normal and multicrystal oolites in it. The latter is made up of brecciated tearing debris, fine silt andquartz, chert, coarse silt, which are associated with grey brown siltstone and grey green arenaceous lime-stone vertically. Grain probability curves of the washover fan almost are characterized by two segmentswith high content of suspension substance which is up to 30%.The thickness of sandstone typewashover fan vertical sedimentary structure sequence, which can be describedas“Bouma sequence AE,AAA and ABE'，i s 40-60 cm. The washover fan of limestone type shows massive structure as a whole,and there developed limestone brecciated with various sizeand shape, suspending among lime mud andsilty sand, and sedimentary thickness is about 1 m, which ismud. Affected by storm factor, tempestuous current carryingassociated with normal tidal flat lagoona great deal of basinal debris passed overbarrier island and formed washover fans extended toward lagoon about 1 kilometer in length and about10 square kilometerin area in atidal flat lagoon environment at the back of barrier island. The washoverhas good reservoir potential and pinches out quickly laterally, therefore, it‘s favorable for formidip pinch一outoil- gas po of w hi ch has been found in the Carboniferous stfata in the Lunnan area of the Tarim basin.
In recent 20 years, while having payed attention to studying the modern barrier island sedimentarysystems, reople have made some researches on sedimentary characteristics of washover fans associatedwith barrier island and pointed out that there are many washover fans in ancient barrier island sedimen-tart' sequences, which opens up a new field for oil- gas exploration. Directed by modern sedimentary the-ory, authors studied the Carborriferous washover fans ind barrier island in the Donghetang area of theTarim basin by full uses of geological, logging and seismic data. The washover fan can be divided intosandstone type and limestone type. The former consists of siltstone,fine sandstone and brown mudstonewith graded and parrallel beddings. In the sandstone, quartz and chert content is 8070一9070，there aresome normal and multicrystal oolites in it. The latter is made up of brecciated tearing debris, fine silt andquartz, chert, coarse silt, which are associated with grey brown siltstone and grey green arenaceous lime-stone vertically. Grain probability curves of the washover fan almost are characterized by two segmentswith high content of suspension substance which is up to 30%.The thickness of sandstone typewashover fan vertical sedimentary structure sequence, which can be describedas“Bouma sequence AE,AAA and ABE'，i s 40-60 cm. The washover fan of limestone type shows massive structure as a whole,and there developed limestone brecciated with various sizeand shape, suspending among lime mud andsilty sand, and sedimentary thickness is about 1 m, which ismud. Affected by storm factor, tempestuous current carryingassociated with normal tidal flat lagoona great deal of basinal debris passed overbarrier island and formed washover fans extended toward lagoon about 1 kilometer in length and about10 square kilometerin area in atidal flat lagoon environment at the back of barrier island. The washoverhas good reservoir potential and pinches out quickly laterally, therefore, it‘s favorable for formidip pinch一outoil- gas po of w hi ch has been found in the Carboniferous stfata in the Lunnan area of the Tarim basin.
1997, 15(1): 54-58.
Abstract:
The Xiangchuan regionis referred to Shoushan County，Sichuan Province and the western and middle parts of Hunan Province where Sinian-Cambrian bedded cher is are w ell-dev eloped. T he orgyic car-bon content in the chert samples is relatively high, ranging from 0. 06 to 9. 00% and averaging 1. 91%.The linear positive relationship between organic carbon concentrations and some trace element contentsis not clear. Microscopic studies of the kerogen from the chert samples show that the main componentsprobably take place; and 3) that the chert is formed in a shallow continertal-margin stagnant basin.results sug-gent that the primary mother materials basically belong to Type一I amorphous kerogen. On the Van Krevelen diagram，all samples fall into the metagenesis field. Stable carbon isotopes of kerogen from the chert samples range from一29. 30 t0，一3 5. 84%.Analysis of thefeatures of organic petrology mentionedabove suggests 1)that organisms and their degraded products contribute much to the formation of chert, 2) that in the formation of the chert a scalled elimination of impurity matters”processes may
The Xiangchuan regionis referred to Shoushan County，Sichuan Province and the western and middle parts of Hunan Province where Sinian-Cambrian bedded cher is are w ell-dev eloped. T he orgyic car-bon content in the chert samples is relatively high, ranging from 0. 06 to 9. 00% and averaging 1. 91%.The linear positive relationship between organic carbon concentrations and some trace element contentsis not clear. Microscopic studies of the kerogen from the chert samples show that the main componentsprobably take place; and 3) that the chert is formed in a shallow continertal-margin stagnant basin.results sug-gent that the primary mother materials basically belong to Type一I amorphous kerogen. On the Van Krevelen diagram，all samples fall into the metagenesis field. Stable carbon isotopes of kerogen from the chert samples range from一29. 30 t0，一3 5. 84%.Analysis of thefeatures of organic petrology mentionedabove suggests 1)that organisms and their degraded products contribute much to the formation of chert, 2) that in the formation of the chert a scalled elimination of impurity matters”processes may
1997, 15(1): 65-70.
Abstract:
he Hetaoyuan Formation in the Tertiary Biyang depression is completely a lacustrine regressives ys tem，but it has some microcyclic variations in microfacies during evolution. These characteristics canbe shown obviously from the abundance of trace elements and their ratios. Based on variation charactersof contents of 16 trace elements such as Ti，Sr, Nb, Ba, etc.and 7 trace elements ratios such as Sr/Ba,Fe /M n, M g / Ca,etc·obtained from mudstones, shales and carbonates, and in terms of some data suchas paleosalinity and lithofacies, this paper made a systematical study of paleodimate under which theHetaoyuan Formation was deposited. As a result, four characteristic paleoclimate types can be grouped,i. e.，temperate-humid, dry一umid alternation, hot-dry and humid-emiarid. It is hoped that this result can provide some clues for the petroleum and gas exploration in the Biyang depression.
he Hetaoyuan Formation in the Tertiary Biyang depression is completely a lacustrine regressives ys tem，but it has some microcyclic variations in microfacies during evolution. These characteristics canbe shown obviously from the abundance of trace elements and their ratios. Based on variation charactersof contents of 16 trace elements such as Ti，Sr, Nb, Ba, etc.and 7 trace elements ratios such as Sr/Ba,Fe /M n, M g / Ca,etc·obtained from mudstones, shales and carbonates, and in terms of some data suchas paleosalinity and lithofacies, this paper made a systematical study of paleodimate under which theHetaoyuan Formation was deposited. As a result, four characteristic paleoclimate types can be grouped,i. e.，temperate-humid, dry一umid alternation, hot-dry and humid-emiarid. It is hoped that this result can provide some clues for the petroleum and gas exploration in the Biyang depression.
1997, 15(1): 77-79.
Abstract:
C14dating and isotope determination of C. H nad O H have been adopte for the staglamite in ruijing cave, LinAn, zhejiang by means of C14dating and stable isotope geochemistiy. The records of paleoclimateevolution from 5 to 1×10 4 a B. P. obtained from Hangzhou area show that there were obviously three periodic paleoclimate changes during the preiodwith the highest Tempdratuer 14.96℃，the lowest 6.6℃periodic paleoclimate changes during the preiod with the highest temand the biggest temperatwre differener about 8℃ and the mean 3-5℃The period was just in thestage of Daliice age, but the age was not a continuous low-temperature stage and it had, at least, threetemperature fluctuation, which is in line with isotopic paleotemperatnre of the staglamite measured byus. In addidon, We have correlated the paleoclimate changesfrom 5 to 1×104 a B Pwith the synch ronological sealevd changer of the coastal area in Southwest China. The result shows that thay are basically cojcident,i. e.，when the temperature rises. the sealevel rises too and the femperaturefalls,and the sealevel falls as well.
C14dating and isotope determination of C. H nad O H have been adopte for the staglamite in ruijing cave, LinAn, zhejiang by means of C14dating and stable isotope geochemistiy. The records of paleoclimateevolution from 5 to 1×10 4 a B. P. obtained from Hangzhou area show that there were obviously three periodic paleoclimate changes during the preiodwith the highest Tempdratuer 14.96℃，the lowest 6.6℃periodic paleoclimate changes during the preiod with the highest temand the biggest temperatwre differener about 8℃ and the mean 3-5℃The period was just in thestage of Daliice age, but the age was not a continuous low-temperature stage and it had, at least, threetemperature fluctuation, which is in line with isotopic paleotemperatnre of the staglamite measured byus. In addidon, We have correlated the paleoclimate changesfrom 5 to 1×104 a B Pwith the synch ronological sealevd changer of the coastal area in Southwest China. The result shows that thay are basically cojcident,i. e.，when the temperature rises. the sealevel rises too and the femperaturefalls,and the sealevel falls as well.
1997, 15(1): 92-97.
Abstract:
Silliceous rocks, carbonate rocks and volcanic rocks are widespread in the upper Maokou formationof Early Perenan in the centry part of Guizhou Province. Based on the synthetic analysis of tectorrics,petrology geocchemistry and sequence stratigraphy，the tectonic setting is supposed to be fault-con-trololed continental margin. Under the condition of this tectonic setting, the characteristics of sequencestratigraphy is different from those of passive continental margins and foreland basins aswell as from theother tectonic unit. The sequencoe bounding surface of the fault ontrol ed continental margin can bedlis-tinguished by the sudden lithologic mange, which implies tectonic changes. The tiferal differentiation ofthe depositional system tract in each sequence has a relationship with the strength of upper crustult caused by deep magmatism. Based on the basic characteristics of tectonics and sedimentology，the secondmember of the Maokou formation could be clasisfied into one parasequence group with two parase-quences, and each of them takes the amfs as its base, including condensed section and progradationalhighstand system tract; it is explained as a sequence stratigraphic architecture of the broken carbonateplatform w hich can be further divided into remnant platform, prograd ational isolated platform，platfo rmtrough of fault trough and ramp facies, etc·The example of the sepuence stratigraphic analysis on thefault ontrolled continental margin is raised by combining tectonism，of sedimentary sysyten together.the formation of sequence stratigraphic architecture and the variation.
Silliceous rocks, carbonate rocks and volcanic rocks are widespread in the upper Maokou formationof Early Perenan in the centry part of Guizhou Province. Based on the synthetic analysis of tectorrics,petrology geocchemistry and sequence stratigraphy，the tectonic setting is supposed to be fault-con-trololed continental margin. Under the condition of this tectonic setting, the characteristics of sequencestratigraphy is different from those of passive continental margins and foreland basins aswell as from theother tectonic unit. The sequencoe bounding surface of the fault ontrol ed continental margin can bedlis-tinguished by the sudden lithologic mange, which implies tectonic changes. The tiferal differentiation ofthe depositional system tract in each sequence has a relationship with the strength of upper crustult caused by deep magmatism. Based on the basic characteristics of tectonics and sedimentology，the secondmember of the Maokou formation could be clasisfied into one parasequence group with two parase-quences, and each of them takes the amfs as its base, including condensed section and progradationalhighstand system tract; it is explained as a sequence stratigraphic architecture of the broken carbonateplatform w hich can be further divided into remnant platform, prograd ational isolated platform，platfo rmtrough of fault trough and ramp facies, etc·The example of the sepuence stratigraphic analysis on thefault ontrolled continental margin is raised by combining tectonism，of sedimentary sysyten together.the formation of sequence stratigraphic architecture and the variation.
1997, 15(1): 104-111.
Abstract:
Dune rock is a special type of rocks in tropic and subtropic areas. Although dune rock is similar tobeach rock in the external figure, their origins and features are quite different. By the study on some rep-resentative outcrops of dune rocks in Shidao (Xisha Islands)，Wenchang and Linggao(Hainan Island)，Qingzhou Island(Yangjian, Guangdong) and Guang- Ao(Shantou, Guangdong)，the author makes asummary to the sedimentological, petrological characteristics of dune rocks and their differences frombeach rocks. Dune rocks in South China are formed by the cementation of island limesands and coastal bioclasticdensands. which can be dstributed in the zone(with an altitude over bom).Th ere are high angle plate cros s一bedding, megatrough cro ss一bedding, conv ex cross- bedding, pares- parallel bedding, megatrough croc s一bedding, conv ex cross- bedding, Parallel bedding, and cacting tubes(mould) of tree roots in therocks. The elastic materials of dune rock inherit the characters of the beach sands, but also carry on thefeatures of eolian sands.Some of them contain the collision sediments or bodies of terrestrial organisms. The grains of dune rocks which are, in general, middle- fine sands arewell sorted with variableand negative Ywhich are quite different from those of beach sands. The cement miner一als and fabrics, Peculiar in the fresh water vadose environment, are welldevoloped in dune rocks. Al-though the Ca Mg} and Sr contents and proportions in dune rocks are different from those of beachrocks, they can be very similar to those of uplift beach rocks. So，the author considers that the main way to recognize dune rocks is to study their outcropo ccur-rence, sedimentary structure, granulometry，cement and〔ement fabric，etc·
Dune rock is a special type of rocks in tropic and subtropic areas. Although dune rock is similar tobeach rock in the external figure, their origins and features are quite different. By the study on some rep-resentative outcrops of dune rocks in Shidao (Xisha Islands)，Wenchang and Linggao(Hainan Island)，Qingzhou Island(Yangjian, Guangdong) and Guang- Ao(Shantou, Guangdong)，the author makes asummary to the sedimentological, petrological characteristics of dune rocks and their differences frombeach rocks. Dune rocks in South China are formed by the cementation of island limesands and coastal bioclasticdensands. which can be dstributed in the zone(with an altitude over bom).Th ere are high angle plate cros s一bedding, megatrough cro ss一bedding, conv ex cross- bedding, pares- parallel bedding, megatrough croc s一bedding, conv ex cross- bedding, Parallel bedding, and cacting tubes(mould) of tree roots in therocks. The elastic materials of dune rock inherit the characters of the beach sands, but also carry on thefeatures of eolian sands.Some of them contain the collision sediments or bodies of terrestrial organisms. The grains of dune rocks which are, in general, middle- fine sands arewell sorted with variableand negative Ywhich are quite different from those of beach sands. The cement miner一als and fabrics, Peculiar in the fresh water vadose environment, are welldevoloped in dune rocks. Al-though the Ca Mg} and Sr contents and proportions in dune rocks are different from those of beachrocks, they can be very similar to those of uplift beach rocks. So，the author considers that the main way to recognize dune rocks is to study their outcropo ccur-rence, sedimentary structure, granulometry，cement and〔ement fabric，etc·
1997, 15(1): 118-122.
Abstract:
A uranium deposit is the largest paleokarst type U deposit in loth scale and tonnage in China. Thedeposit is formed below a fossil cave and in a faulting}olution breccia system in the Lower Carbonifer-ous limestone. The temperature of mineralizing fluids ranges from 1810℃to 1500 ℃Four U一Pb ages forpitchblende and whole rock ores, 135, 131, 119 and 65 Ma, have been determined, which are obviouslyyounger than those of the wall rocks. Sulfur isotope data show that the δ34 S values of pyrites from theores range from 1.00 ‰to一15. 3‰with a mean value of一6.87‰,closel to those of pyrites fromthe wall rocks(1. 00‰一15.60‰，mean- 7.06‰)，suggesting that the wall rocks are the source ofsulfur for mineralization. The five analyzed samples of calcites from the ores have δ13 Cvalues between 0.34‰and-3.19‰(mean一1.50‰).The similarity between the average carbon isotope composition of the ores(一1.50‰)and the wall rocks(0.53‰)is interpreted to result from an isotope exchange between the wall rock and mineralizing fluid. The lead isotope composition of pyrites from the ores andwhole}ock of Lower Carboiferous sugggests that the source of lead and urarnum in the deposit is vari-ous in strata of the ore field.The value of δ18O and δD for mineralizing fluids range from 1.5‰o 7.3‰ and from一30.4‰to一84.9‰,of metamorphic and meteoric waters.respectively, indicating that the mineralizing fluid is a mixed waterThe mineralizing process is clowly related to development historyof regional tectordic movemnets and multi-episode paleokarstification. Thus, it is named as hydrothermalreworked paleokarst type uranium deposit.
A uranium deposit is the largest paleokarst type U deposit in loth scale and tonnage in China. Thedeposit is formed below a fossil cave and in a faulting}olution breccia system in the Lower Carbonifer-ous limestone. The temperature of mineralizing fluids ranges from 1810℃to 1500 ℃Four U一Pb ages forpitchblende and whole rock ores, 135, 131, 119 and 65 Ma, have been determined, which are obviouslyyounger than those of the wall rocks. Sulfur isotope data show that the δ34 S values of pyrites from theores range from 1.00 ‰to一15. 3‰with a mean value of一6.87‰,closel to those of pyrites fromthe wall rocks(1. 00‰一15.60‰，mean- 7.06‰)，suggesting that the wall rocks are the source ofsulfur for mineralization. The five analyzed samples of calcites from the ores have δ13 Cvalues between 0.34‰and-3.19‰(mean一1.50‰).The similarity between the average carbon isotope composition of the ores(一1.50‰)and the wall rocks(0.53‰)is interpreted to result from an isotope exchange between the wall rock and mineralizing fluid. The lead isotope composition of pyrites from the ores andwhole}ock of Lower Carboiferous sugggests that the source of lead and urarnum in the deposit is vari-ous in strata of the ore field.The value of δ18O and δD for mineralizing fluids range from 1.5‰o 7.3‰ and from一30.4‰to一84.9‰,of metamorphic and meteoric waters.respectively, indicating that the mineralizing fluid is a mixed waterThe mineralizing process is clowly related to development historyof regional tectordic movemnets and multi-episode paleokarstification. Thus, it is named as hydrothermalreworked paleokarst type uranium deposit.
The Features of the Sanshui Relict Basin and Its Conditions of Petroleum Geology, Guangdong Province
1997, 15(1): 141-146.
Abstract:
The sanshui basin, formed in the Huananincro-plate uting Cretaceous and Paleogene,is a typical oneof Mez0-Cnozois relict basins in the Pearl River Delta area, Guangdong Province. The major structuraldeformation in the basin is characterized by a number of small scale extensional faults which are mainlypostdepositional. In this paper, the evolution of the Sanshui basin and its relict fertures, its deformationstyles and trap patterns as well as the perspect of petroleum exploration in this type of basins are dis-cussed based on analyses of structures, strata, depositional envitonments and facies and the maturity ofsource rocks as well as the comparison of strata between the Sanshui basin and its neighbouring area.
The sanshui basin, formed in the Huananincro-plate uting Cretaceous and Paleogene,is a typical oneof Mez0-Cnozois relict basins in the Pearl River Delta area, Guangdong Province. The major structuraldeformation in the basin is characterized by a number of small scale extensional faults which are mainlypostdepositional. In this paper, the evolution of the Sanshui basin and its relict fertures, its deformationstyles and trap patterns as well as the perspect of petroleum exploration in this type of basins are dis-cussed based on analyses of structures, strata, depositional envitonments and facies and the maturity ofsource rocks as well as the comparison of strata between the Sanshui basin and its neighbouring area.
1997, 15(1): 152-155.
Abstract:
Between Tianshan and kunlun一Aerjin Mountains lies Tarim Basin, the largest sedimentary basin inchina. The basin has undergone the formation of basement during pre Siian and development sincePhanerozoic and it is agiant complex basin with the histry of a Paleozoic origina lcraton basin overlain bya Mesozoic-Cenozoic foreland basin. The craton basin had been subjected to a rift in nian, a marginalaulacogen in Cambrian-Ordovician and an intracratonic depression basin in Silurian-Permian. The Paleo-wic Erachem is mainly a set of〔arbonate rocks and clastic rocks of marinefacies and the sedimentary anddepressi ng centers experienced several times of shifting during Paleozoic.The Louer Paleowic is thickerin the east than in the west and the Upper Paleozoic is thinner in the east than in the west. All resultedfrom the control of the plate evolution and tectonic framework in Paleozoic.
Between Tianshan and kunlun一Aerjin Mountains lies Tarim Basin, the largest sedimentary basin inchina. The basin has undergone the formation of basement during pre Siian and development sincePhanerozoic and it is agiant complex basin with the histry of a Paleozoic origina lcraton basin overlain bya Mesozoic-Cenozoic foreland basin. The craton basin had been subjected to a rift in nian, a marginalaulacogen in Cambrian-Ordovician and an intracratonic depression basin in Silurian-Permian. The Paleo-wic Erachem is mainly a set of〔arbonate rocks and clastic rocks of marinefacies and the sedimentary anddepressi ng centers experienced several times of shifting during Paleozoic.The Louer Paleowic is thickerin the east than in the west and the Upper Paleozoic is thinner in the east than in the west. All resultedfrom the control of the plate evolution and tectonic framework in Paleozoic.
1997, 15(1): 161-167.
Abstract:
Early Palaeozoic carbonate platform of South Qinling Mt. was developed on the north passive mar-gin of the Yangtze plate. Cambrian and Ordovician carbonate stratigraphy, more than 2000 metres inthickness, is outcropped between Shanyang-Fengzhen Fault and Ningshan-Baihe Fault(Fig. 1).Fiv a fu-ties associations are recogrrized, including anoxic /dysaerobic facies association(A1)，deeper ramp /slopefacies association(A 2)，Shoal facies association(A3)，lagoon and tidal}lat facies association(A 4) andmixed shelf facies association(Fig. 2)·Evolution of the carbonate platform is divided into three phases(Fig.3).Middle Cambrian-Early Ordovician rimmed shelf phase is characterised by oc currence of asouth edge builtup of shoal facies association up to 500 metres in thickness and a south slope of nodularlim es tone,micritic limestone, clay shale and breccias. Inner platform deposits are composed of cyclic la-goonal massive dolostone and laminated dolostone, recording small-scale sea-level changer. Evident fallin sea level resulted from tectonic uplift led to existence of late Early Ordovician palaeokarst and karstconglomerates, which are cupped by Middle-Late Ordovician mixed shelf facies association of the thirdphase containing a transgressive and regressive cyde.Horizontal distributinn of facies zones proves lee side of platform northward and wind side sonth-w ard. It als oimpli esprobably submergedthat there was a possible ancient land on north side of platform(Fig.4)，but it wasunder Shanyang-Fengzhen Fault afterwards.
Early Palaeozoic carbonate platform of South Qinling Mt. was developed on the north passive mar-gin of the Yangtze plate. Cambrian and Ordovician carbonate stratigraphy, more than 2000 metres inthickness, is outcropped between Shanyang-Fengzhen Fault and Ningshan-Baihe Fault(Fig. 1).Fiv a fu-ties associations are recogrrized, including anoxic /dysaerobic facies association(A1)，deeper ramp /slopefacies association(A 2)，Shoal facies association(A3)，lagoon and tidal}lat facies association(A 4) andmixed shelf facies association(Fig. 2)·Evolution of the carbonate platform is divided into three phases(Fig.3).Middle Cambrian-Early Ordovician rimmed shelf phase is characterised by oc currence of asouth edge builtup of shoal facies association up to 500 metres in thickness and a south slope of nodularlim es tone,micritic limestone, clay shale and breccias. Inner platform deposits are composed of cyclic la-goonal massive dolostone and laminated dolostone, recording small-scale sea-level changer. Evident fallin sea level resulted from tectonic uplift led to existence of late Early Ordovician palaeokarst and karstconglomerates, which are cupped by Middle-Late Ordovician mixed shelf facies association of the thirdphase containing a transgressive and regressive cyde.Horizontal distributinn of facies zones proves lee side of platform northward and wind side sonth-w ard. It als oimpli esprobably submergedthat there was a possible ancient land on north side of platform(Fig.4)，but it wasunder Shanyang-Fengzhen Fault afterwards.
1997, 15(1): 172-176.
Abstract:
In this paper, the burial history is recovered by using the back一tripping method according to thevolume model of thickness recovery from Cambrian to Quaternary in the Manjiaer depression, and it isdivided into three periods by means of the original sedimention rate On the basis of the recoery of burialhistory, the hydrocarbon evolution of source rocks in Lower Paleozoic is investigated in accordance withthe calculated results of TTI. The largest scope of hydrocarbon generation and their development are al-so discussed in this paper.
In this paper, the burial history is recovered by using the back一tripping method according to thevolume model of thickness recovery from Cambrian to Quaternary in the Manjiaer depression, and it isdivided into three periods by means of the original sedimention rate On the basis of the recoery of burialhistory, the hydrocarbon evolution of source rocks in Lower Paleozoic is investigated in accordance withthe calculated results of TTI. The largest scope of hydrocarbon generation and their development are al-so discussed in this paper.
