2003 Vol. 21, No. 1
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2003, 21(1): 1-7.
Abstract:
Some sedimentary research fields in China, mainly including sedimentary environments and sedimentary systems, carbonate rocks, clastic diagenesis, sequence stratigraphy, sedimentary basin analysis and modeling, submarine sedimentation in the Chinese seas, oil-gas reservoir sedimentology and ore-deposit sedimentology, are briefly reviewed and prospected in the paper, which is dedicated to celebration of the twentieth anniversary of “Acta Sedimentologica Sinica”.
Some sedimentary research fields in China, mainly including sedimentary environments and sedimentary systems, carbonate rocks, clastic diagenesis, sequence stratigraphy, sedimentary basin analysis and modeling, submarine sedimentation in the Chinese seas, oil-gas reservoir sedimentology and ore-deposit sedimentology, are briefly reviewed and prospected in the paper, which is dedicated to celebration of the twentieth anniversary of “Acta Sedimentologica Sinica”.
2003, 21(1): 10-18.
Abstract:
Sedimentary earth sciences, since its' separation with stratigraphy to become an independent branch of earth sciences in the early years of last century, has passed through three stages from sedimentary petrology, to sedimentology and to sedimentary geology. Sedimentary petrology deals with sedimentary rocks with focus on their characters, classification, occurrence and origin. Sedimentology lays its study interest in the natural processes related to transportation and deposition of sediments. Sedimentary geology deals with the evolution of sediments in a four dimensional framework, i.e. the change of sediments, sedimentary processes and sedimentary environments with time. This paper provides the readers with a historical review and the perspective of the development of this branch of earth sciences based on the background of the revolutions of earth sciences.
Sedimentary earth sciences, since its' separation with stratigraphy to become an independent branch of earth sciences in the early years of last century, has passed through three stages from sedimentary petrology, to sedimentology and to sedimentary geology. Sedimentary petrology deals with sedimentary rocks with focus on their characters, classification, occurrence and origin. Sedimentology lays its study interest in the natural processes related to transportation and deposition of sediments. Sedimentary geology deals with the evolution of sediments in a four dimensional framework, i.e. the change of sediments, sedimentary processes and sedimentary environments with time. This paper provides the readers with a historical review and the perspective of the development of this branch of earth sciences based on the background of the revolutions of earth sciences.
2003, 21(1): 24-30.
Abstract:
The study on origin of sedimentary basins in China followed approach of basin-orogen (range) coupling, including the structural and sedimentary coupling, as well as coupling in deep structure. The structural coupling can be revealed with deformation in the place at which basin and orogen (range) are jointed. The sedimentary coupling implies the tectonic-sedimentary responses that could reconstruct the orogenic process. The coupling in deep structure focuses on lithosphere dynamics revealed by deep structures. Parallel to this, international study on origin of sedimentary basins concentrated on coupling of lithosphere and near-surface processes. Keeping open eyes, integrating different approaches, and co-working in natural laboratories are all important in the future research on sedimentary basins.
The study on origin of sedimentary basins in China followed approach of basin-orogen (range) coupling, including the structural and sedimentary coupling, as well as coupling in deep structure. The structural coupling can be revealed with deformation in the place at which basin and orogen (range) are jointed. The sedimentary coupling implies the tectonic-sedimentary responses that could reconstruct the orogenic process. The coupling in deep structure focuses on lithosphere dynamics revealed by deep structures. Parallel to this, international study on origin of sedimentary basins concentrated on coupling of lithosphere and near-surface processes. Keeping open eyes, integrating different approaches, and co-working in natural laboratories are all important in the future research on sedimentary basins.
2003, 21(1): 38-45.
Abstract:
Based on system research on detrital sediments in different scales, it is found that molasse-like deposits, instable (easy abrasive) detrital grains and mineral-assemblages were developed in the Kuqa depression, the south foot of the Tianshan, in Neogene, especially after Miocene. It is also presented that gradual southward migration of alluvial depositional fronts and depositional depocenters with near east-west strike occurred since Cretaceous. However, evident changes of the above migration trend happen since Pliocene, in which large-scale southward migration of alluvial depositional systems but relative northward migration of depositional depocenters occurred simultaneously, and current north depositional boundary is near present basin-mountain boundary between Kuqa depression and Tianshan, which attributes to syndepositional normal faults of southward dip. Combined with data from tectonic and paleoclimate reserches, it is explained that the above depositional records resulted from the tectonic transformation processes in Late Cenozoic, in which gravity-extension and gravity-collapse occurred in the shallow tectosphere of the Kuqa depression-Tianshan since Pliocene due to intensive uplift of the Tianshan under continuous extrusion stress in Late Cenozoic. The conclusion on tectonic transformation processes, presented in the paper, revise the past views on Cenozoic dynamic mechanism of structural accommodation, which was explained with sole southward thrusting pattern of the Tianshan under extrusion stress regimes.
Based on system research on detrital sediments in different scales, it is found that molasse-like deposits, instable (easy abrasive) detrital grains and mineral-assemblages were developed in the Kuqa depression, the south foot of the Tianshan, in Neogene, especially after Miocene. It is also presented that gradual southward migration of alluvial depositional fronts and depositional depocenters with near east-west strike occurred since Cretaceous. However, evident changes of the above migration trend happen since Pliocene, in which large-scale southward migration of alluvial depositional systems but relative northward migration of depositional depocenters occurred simultaneously, and current north depositional boundary is near present basin-mountain boundary between Kuqa depression and Tianshan, which attributes to syndepositional normal faults of southward dip. Combined with data from tectonic and paleoclimate reserches, it is explained that the above depositional records resulted from the tectonic transformation processes in Late Cenozoic, in which gravity-extension and gravity-collapse occurred in the shallow tectosphere of the Kuqa depression-Tianshan since Pliocene due to intensive uplift of the Tianshan under continuous extrusion stress in Late Cenozoic. The conclusion on tectonic transformation processes, presented in the paper, revise the past views on Cenozoic dynamic mechanism of structural accommodation, which was explained with sole southward thrusting pattern of the Tianshan under extrusion stress regimes.
2003, 21(1): 52-60.
Abstract:
Basin-Rang coupling is an important geological phenomenon. According to the dynamic mechanism, six types of basin-range coupling can be divided: extensional, compressive, transextensive, transpressive, vertical stress deduced and impact. In this paper, the structural characteristics and typical sedimentation of each types of basin-range coupling are elaborated.
Basin-Rang coupling is an important geological phenomenon. According to the dynamic mechanism, six types of basin-range coupling can be divided: extensional, compressive, transextensive, transpressive, vertical stress deduced and impact. In this paper, the structural characteristics and typical sedimentation of each types of basin-range coupling are elaborated.
2003, 21(1): 75-80.
Abstract:
On the basis of sedimentological and palichnological investigations on the nearly 20 profiles of 9 paleo-pelagic depositional areas in China, some conclusions on the identification of the relationship between ichnocoenose in paleo-pelagic substrates and the oxygen content have been drawn as follows: ①The difference in the relative oxygen content of the pelagic oxygen-depleted substrate produces a different representative ichnofossil association, i.e. the dissolved oxygen content of the oxygen-depleted substrate indicated by Associations A, B and C, which are mainly composed of Megagrapton, Paleodictyon and Protopaleodictyon , of Scalarituba and Phycosiphon , and of Chondrites and Zoophycos , respectively, decreases gradually with different associations; ②The size of ichnofossil burrows usually has a normal relationship with the oxygen content of substrates, namely the diameter of burrows becomes smaller with decreasing of the oxygen content; ③The differentiation of ichnofossils decreases with decreasing of the oxygen content of substrates; ④It should be prudent to apply some individual ichnofossils in identifying the oxygen-depleted environment, for instance, Chondrites and Zoophycos can not be always regarded as an ichnofossil indicator to an oxygen-depleted environment, it is necessary to investigate multiple factors before a conclusion that more accords with the true fact can be drawn.
On the basis of sedimentological and palichnological investigations on the nearly 20 profiles of 9 paleo-pelagic depositional areas in China, some conclusions on the identification of the relationship between ichnocoenose in paleo-pelagic substrates and the oxygen content have been drawn as follows: ①The difference in the relative oxygen content of the pelagic oxygen-depleted substrate produces a different representative ichnofossil association, i.e. the dissolved oxygen content of the oxygen-depleted substrate indicated by Associations A, B and C, which are mainly composed of Megagrapton, Paleodictyon and Protopaleodictyon , of Scalarituba and Phycosiphon , and of Chondrites and Zoophycos , respectively, decreases gradually with different associations; ②The size of ichnofossil burrows usually has a normal relationship with the oxygen content of substrates, namely the diameter of burrows becomes smaller with decreasing of the oxygen content; ③The differentiation of ichnofossils decreases with decreasing of the oxygen content of substrates; ④It should be prudent to apply some individual ichnofossils in identifying the oxygen-depleted environment, for instance, Chondrites and Zoophycos can not be always regarded as an ichnofossil indicator to an oxygen-depleted environment, it is necessary to investigate multiple factors before a conclusion that more accords with the true fact can be drawn.
2003, 21(1): 90-95.
Abstract:
The article presents the viewpoint that lateral structure compression had an important effect on sandstone diagenetic compaction through the study on the relationship amoang the structure deformation,paleostructure stress and sandstone diagenetic compaction of lower Jurassic of Kuqa depression and Cretaceous of Xinan depression in Tarim Basin.The porosity loss caused by lateral structure compression was 2.5%～23.6% percentage of bulk porosity loss of sandstones. The porosity loss to structure compression of Kezilesuer and Wuqiaguo areas were 5.6%～6.6% and 17.6%～23.6% percentage of bulk porosity loss of sandstones because of heavy structure deformation,and one of Tugeerming area was 1.9%～2.1% owing to weak structure deformation in Kuqa depression.Qimeigan area in Xinan depression, located in the middle belt of thrust nappe,had porosity loss to structure compression of 4.9% and 17.6% percentage of bulk porosity loss of sandstones,and Tongyouluke area, located in the front belt of thrust nappe, was very small porosity loss to structure compression.
The article presents the viewpoint that lateral structure compression had an important effect on sandstone diagenetic compaction through the study on the relationship amoang the structure deformation,paleostructure stress and sandstone diagenetic compaction of lower Jurassic of Kuqa depression and Cretaceous of Xinan depression in Tarim Basin.The porosity loss caused by lateral structure compression was 2.5%～23.6% percentage of bulk porosity loss of sandstones. The porosity loss to structure compression of Kezilesuer and Wuqiaguo areas were 5.6%～6.6% and 17.6%～23.6% percentage of bulk porosity loss of sandstones because of heavy structure deformation,and one of Tugeerming area was 1.9%～2.1% owing to weak structure deformation in Kuqa depression.Qimeigan area in Xinan depression, located in the middle belt of thrust nappe,had porosity loss to structure compression of 4.9% and 17.6% percentage of bulk porosity loss of sandstones,and Tongyouluke area, located in the front belt of thrust nappe, was very small porosity loss to structure compression.
2003, 21(1): 106-112.
Abstract:
Ordos basin is located in the west of north china platform, middle Ordovician Majiagou formation is one of most important nature gas reservoirs. In Ordovician the overspread of the southern Helan rift and left strike slipping of the southern overthrust led to rift shoulders being warped and rise in the west and south of Ordos basin, and “L” sharp uplift or names of center uplift was formed. At the same time, as a result of equilibrium activity, in the east of the basin formed an unsymmetrical compensation basin (depression), which is named inner shelf basin. Two different sedimentary models are presented, one is sedimentary model of shelf and another is sedimentary model of distally steeped ramp. The sedimentary model of shelf is extend from east to west and pass through the center of inner shelf basin, which runs through main natural gas reservoirs area of Majiagou formation. The east part of three sub environments, that's to say, inter uplift lecuna and under-water uplift, inner shelf basin, open inner shelf, the latter most located out of the research area. In Majiagou 1,3,5 members depositional stage, the climate was dry and sea level was fall by the evaporation, the L-sharp uplift was close to the sea level or above it, or became the erodedarea, the inner shelf basin became semi-restricted or restricted environment. In the center of the basin deposited anhydrock, halilith and some dolostone compounds, in the basin marginal flat was deposited dolostone interbeded with anhydrock. In 2,4 stages, the climate was moist and sea level raised, the inner shelf basin became dolostone limestone-deposited limestone or dolo-limestone. In Majiagou 6 stage, because most of stratigraphy few wells, there's limestone shelf sedimentary environment. The west shelf lies on the L-sharp uplift, in all of the Majiagou stage was deposited limestone or dolostone. The steep slop, along Helan rift margin, developed carbonate gravity flow stones. However, in submarine through developed turbidites mixed with carbonate and silicon debris. The distally steepened ramp developed in all of Ordovician lies on the south of L-sharp uplift, that's to say, present Weibei uplift area. In 1,3,5 members depositional stage, there is dolstone distally steepened ramp. However, in members 2, 4, 6 present dolostone-limestone distally steepened ramp. According to the sedimentary model, in this paper present lithofaices paleography map from 1 to 6 member of Majiagou formation.
Ordos basin is located in the west of north china platform, middle Ordovician Majiagou formation is one of most important nature gas reservoirs. In Ordovician the overspread of the southern Helan rift and left strike slipping of the southern overthrust led to rift shoulders being warped and rise in the west and south of Ordos basin, and “L” sharp uplift or names of center uplift was formed. At the same time, as a result of equilibrium activity, in the east of the basin formed an unsymmetrical compensation basin (depression), which is named inner shelf basin. Two different sedimentary models are presented, one is sedimentary model of shelf and another is sedimentary model of distally steeped ramp. The sedimentary model of shelf is extend from east to west and pass through the center of inner shelf basin, which runs through main natural gas reservoirs area of Majiagou formation. The east part of three sub environments, that's to say, inter uplift lecuna and under-water uplift, inner shelf basin, open inner shelf, the latter most located out of the research area. In Majiagou 1,3,5 members depositional stage, the climate was dry and sea level was fall by the evaporation, the L-sharp uplift was close to the sea level or above it, or became the erodedarea, the inner shelf basin became semi-restricted or restricted environment. In the center of the basin deposited anhydrock, halilith and some dolostone compounds, in the basin marginal flat was deposited dolostone interbeded with anhydrock. In 2,4 stages, the climate was moist and sea level raised, the inner shelf basin became dolostone limestone-deposited limestone or dolo-limestone. In Majiagou 6 stage, because most of stratigraphy few wells, there's limestone shelf sedimentary environment. The west shelf lies on the L-sharp uplift, in all of the Majiagou stage was deposited limestone or dolostone. The steep slop, along Helan rift margin, developed carbonate gravity flow stones. However, in submarine through developed turbidites mixed with carbonate and silicon debris. The distally steepened ramp developed in all of Ordovician lies on the south of L-sharp uplift, that's to say, present Weibei uplift area. In 1,3,5 members depositional stage, there is dolstone distally steepened ramp. However, in members 2, 4, 6 present dolostone-limestone distally steepened ramp. According to the sedimentary model, in this paper present lithofaices paleography map from 1 to 6 member of Majiagou formation.
2003, 21(1): 118-124.
Abstract:
The authigenic monazite have been discovered for the first time in the Shisanlitai Formation, Sinia System of Precambrian sedimentary rock from Dalian area. That was inspired by the discovery of auhtigenic galena in the Gejiatong Formation. There are listed in this paper same examples of North China, where are abnormal high contents of Ce and REE in the Precambrian sedimentary rocks being expected to find authigenic monazite either in above areas or to offer the possibility using U,Th-Pb isotopic method for geo-age determination. This paper introduces new data of authigenic monazite, which recently have been found in Mid-Proterozoic strata of the Ming Tombs District, Beijing. The electron scattered forms of authigenic monazite are quiet different with crystalline forms of magmatic, metamophzeic, and placer monazite grains. This paper recognizes that high contents of REE, especially, higher LREE of Proterozoic mudstones are deposits near old continental crust. The statistical data of La+Ce+Nd, Yb+Y, and Sm+Gd+Dy ratio and plotting in a triangle diagram with Preterozoic mudstones of the Ming Tombs District, Beijing, Golden Pebble Beach, Dalian, and Liaoning Province shows that those samples with more La+Ce+Nd belong to near old continental crust deposits. This paper compares for the first time with the Proterozoic sedimentary rocks of North China and phosphate rocks of Sinian System of South China showing the later plotted points far away from La+Ce+Nd end point due to the phosphorus element from ocean upwelling. According to analysis of sedimentary environment of the Shisanlitai Formation, Sinian System of Dalian the authigenic monazite should be formed by biomineralization processes. It is demonstrated that local sub-reducing environment under entire oxidation environment created authigenic monazite formation, based on which a reef-back lagoon biomineralization model has been established in this paper. Meanwhile, it is supposed that the Precambrian sedimentary rocks with rich rare earth elements of North China might be the ore-source beds of the huge rare earth mineral deposits of the Baiyun Obo, Inner Mongolia.
The authigenic monazite have been discovered for the first time in the Shisanlitai Formation, Sinia System of Precambrian sedimentary rock from Dalian area. That was inspired by the discovery of auhtigenic galena in the Gejiatong Formation. There are listed in this paper same examples of North China, where are abnormal high contents of Ce and REE in the Precambrian sedimentary rocks being expected to find authigenic monazite either in above areas or to offer the possibility using U,Th-Pb isotopic method for geo-age determination. This paper introduces new data of authigenic monazite, which recently have been found in Mid-Proterozoic strata of the Ming Tombs District, Beijing. The electron scattered forms of authigenic monazite are quiet different with crystalline forms of magmatic, metamophzeic, and placer monazite grains. This paper recognizes that high contents of REE, especially, higher LREE of Proterozoic mudstones are deposits near old continental crust. The statistical data of La+Ce+Nd, Yb+Y, and Sm+Gd+Dy ratio and plotting in a triangle diagram with Preterozoic mudstones of the Ming Tombs District, Beijing, Golden Pebble Beach, Dalian, and Liaoning Province shows that those samples with more La+Ce+Nd belong to near old continental crust deposits. This paper compares for the first time with the Proterozoic sedimentary rocks of North China and phosphate rocks of Sinian System of South China showing the later plotted points far away from La+Ce+Nd end point due to the phosphorus element from ocean upwelling. According to analysis of sedimentary environment of the Shisanlitai Formation, Sinian System of Dalian the authigenic monazite should be formed by biomineralization processes. It is demonstrated that local sub-reducing environment under entire oxidation environment created authigenic monazite formation, based on which a reef-back lagoon biomineralization model has been established in this paper. Meanwhile, it is supposed that the Precambrian sedimentary rocks with rich rare earth elements of North China might be the ore-source beds of the huge rare earth mineral deposits of the Baiyun Obo, Inner Mongolia.
2003, 21(1): 129-132.
Abstract:
The coal resource is the key position in primary energy structure, but it's also the main pollution source to restrict the environments for China. It will be the research hot point to Chinese coal-bearing sedimentology to keep the coordinate development for coal energy requirement and environmental protection. The forntier fields of applied basic research and the middle to long term directions in future on Chinese coal-bearing sedimentology will be as follows: the coupling researches in the variety of coal-forming environments with the complexity of coal properties, the researches in environmental sedimentology with the cleaning properties for coal, the researches in coal reservoirs and the construction of the pool-forming theory systems according to Chinese geological settings, the Milankovitch cycle recognition and the orbital cyclostratigraphy researches in coal-bearing sequences, palaeogeographic reconstruction of coal-accumulated areas by multi-information and digitization. Along the breakthrough in these fontier fields , the environmental protection will be the academic duty in coal-bearing sedimentology and a new aspect of the coordination development for the coal resources and environments will be opened up by coal-bearing sedimentology.
The coal resource is the key position in primary energy structure, but it's also the main pollution source to restrict the environments for China. It will be the research hot point to Chinese coal-bearing sedimentology to keep the coordinate development for coal energy requirement and environmental protection. The forntier fields of applied basic research and the middle to long term directions in future on Chinese coal-bearing sedimentology will be as follows: the coupling researches in the variety of coal-forming environments with the complexity of coal properties, the researches in environmental sedimentology with the cleaning properties for coal, the researches in coal reservoirs and the construction of the pool-forming theory systems according to Chinese geological settings, the Milankovitch cycle recognition and the orbital cyclostratigraphy researches in coal-bearing sequences, palaeogeographic reconstruction of coal-accumulated areas by multi-information and digitization. Along the breakthrough in these fontier fields , the environmental protection will be the academic duty in coal-bearing sedimentology and a new aspect of the coordination development for the coal resources and environments will be opened up by coal-bearing sedimentology.
2003, 21(1): 137-141.
Abstract:
Development history of petroleum sedimentology into China has been divided in three stages, i.e., learning from the foreign countries, founding and practicing stage (1949～1970), enriching and consummating stage of petroleum sedimentology theory (1970～1990), and applying stage with the combination of sedimentology and sequence stratigraphy, seismic, well logging, laboratory and computer technology (1990-now). The current application of petroleum sedimentology in petroleum exploration has also been introduced. The good results generated by the applicaiton of sequence stratigraphy, well-log sedimentology and geophysics in petroleum sedimentology study have been stressed, which bring efficient presentation of sedimentology study in macro- and micro-scale, more comprehensive and precise methods and 3-D visualization to sedimentology study domain.
Development history of petroleum sedimentology into China has been divided in three stages, i.e., learning from the foreign countries, founding and practicing stage (1949～1970), enriching and consummating stage of petroleum sedimentology theory (1970～1990), and applying stage with the combination of sedimentology and sequence stratigraphy, seismic, well logging, laboratory and computer technology (1990-now). The current application of petroleum sedimentology in petroleum exploration has also been introduced. The good results generated by the applicaiton of sequence stratigraphy, well-log sedimentology and geophysics in petroleum sedimentology study have been stressed, which bring efficient presentation of sedimentology study in macro- and micro-scale, more comprehensive and precise methods and 3-D visualization to sedimentology study domain.
2003, 21(1): 148-154.
Abstract:
It is typically developed lacus subaqueous fan of Shuangyang Formation in Moliqing fault subsidence of Yitong Basin in Eocene. According to core, well-logging and seismic data, associated with grading analysis and other methods, lacus subaqueous fan is divided into inner fan, middle fan and out fan. From bottom to top a integrated prograding lacus subaqueous fan is consisted of out fan, middle fan and inner fan subfacies in vertical , and it has the features that show thicker, coarser towards up. Inner fan can be further separated into channel, channel levee and slump deposits, middle fan is classified into braided channel, braided interchannel and suppafan lobes, and out fan is consisted of classic turbidites and lacustrine mudstone. Subaqueous fan is mainly formed at the side of steep slope controlled by contemporary fault, and some formed at the front of fan-delta. Primary factors which influence the distribution and emergence of subaqueous fan is that movements of contemporary fault bring steep landform, episode movements of which make up of the burst mechanics of subaqueous gravity flow forming. Subaqueous fan of steep slope mainly occurs at the zone of steep slope, stable subaqueous fan mostly emerges at the front of fan-delta, meanwhile climate is a favorable factor for stable subquous fan. Base-level affects the features of facies orders. It is easily formed prograding subaqueous fan in lowstand systems tracts and regressive systems tracts, there develop regressive subaqueous fan in the transgressive systems tracts as well. The precondition that preserves subaqueous fan is the backwater environment of deeper or deep lacus. The results of statistics show that all that bear industrial petroleum and gas mostly concentrated in the middle fan, and of which is much rich in the braided channel.
It is typically developed lacus subaqueous fan of Shuangyang Formation in Moliqing fault subsidence of Yitong Basin in Eocene. According to core, well-logging and seismic data, associated with grading analysis and other methods, lacus subaqueous fan is divided into inner fan, middle fan and out fan. From bottom to top a integrated prograding lacus subaqueous fan is consisted of out fan, middle fan and inner fan subfacies in vertical , and it has the features that show thicker, coarser towards up. Inner fan can be further separated into channel, channel levee and slump deposits, middle fan is classified into braided channel, braided interchannel and suppafan lobes, and out fan is consisted of classic turbidites and lacustrine mudstone. Subaqueous fan is mainly formed at the side of steep slope controlled by contemporary fault, and some formed at the front of fan-delta. Primary factors which influence the distribution and emergence of subaqueous fan is that movements of contemporary fault bring steep landform, episode movements of which make up of the burst mechanics of subaqueous gravity flow forming. Subaqueous fan of steep slope mainly occurs at the zone of steep slope, stable subaqueous fan mostly emerges at the front of fan-delta, meanwhile climate is a favorable factor for stable subquous fan. Base-level affects the features of facies orders. It is easily formed prograding subaqueous fan in lowstand systems tracts and regressive systems tracts, there develop regressive subaqueous fan in the transgressive systems tracts as well. The precondition that preserves subaqueous fan is the backwater environment of deeper or deep lacus. The results of statistics show that all that bear industrial petroleum and gas mostly concentrated in the middle fan, and of which is much rich in the braided channel.
2003, 21(1): 168-174.
Abstract:
The Late Permian Heshan Formation in the Heshan coal field is a typical carbonate coal measures formed in a shallow water carbonate platform setting. Up to seven coal seams have been preserved with numbers 2, 3A, 3B, 3C, 4A, 4B and 5, in descending order. Four third-order unconformity-bounded sequences have been identified. Sequence Ⅰ is from the bottom of the Heshan Fm to the base of the cherts beneath coal Seam 4B. Sequence Ⅱ is from the cherts beneath Seam 4B to the base of Seam 4A; Sequence Ⅲ is from base of Seam 4A to the base of the bauxitic mudstone beneath Seam 2; Sequence Ⅳ is from the base of the bauxitic mudstone beneath Seam 2 to the top of the Heshan Formation. Sequences Ⅰ, Ⅱ, and Ⅳ are strongly controlled by regional differential subsidence. Sequence Ⅲ shows cyclicity of the coal and carbonate rocks, with extensive distribution in the central Guangxi area, reflecting strong control by sea level changes. Within the Sequence Ⅲ, four fourth-order sequences are recognised, each consisting of a basal transgressive coal seam and overlying highstand tidal flat and open platform limestones. In the Heshan coalfield, fourth-order sequences and coals within the Sequence Ⅲ thin first and then thicken upwards, with the thinnest being the fourth-order sequence with coal Seam 3B. As a result, the thickest coal in the carbonate platform setting is formed at the transgressive surface and the thinnest coal is formed at the bottom of the maximum flooding zone.
The Late Permian Heshan Formation in the Heshan coal field is a typical carbonate coal measures formed in a shallow water carbonate platform setting. Up to seven coal seams have been preserved with numbers 2, 3A, 3B, 3C, 4A, 4B and 5, in descending order. Four third-order unconformity-bounded sequences have been identified. Sequence Ⅰ is from the bottom of the Heshan Fm to the base of the cherts beneath coal Seam 4B. Sequence Ⅱ is from the cherts beneath Seam 4B to the base of Seam 4A; Sequence Ⅲ is from base of Seam 4A to the base of the bauxitic mudstone beneath Seam 2; Sequence Ⅳ is from the base of the bauxitic mudstone beneath Seam 2 to the top of the Heshan Formation. Sequences Ⅰ, Ⅱ, and Ⅳ are strongly controlled by regional differential subsidence. Sequence Ⅲ shows cyclicity of the coal and carbonate rocks, with extensive distribution in the central Guangxi area, reflecting strong control by sea level changes. Within the Sequence Ⅲ, four fourth-order sequences are recognised, each consisting of a basal transgressive coal seam and overlying highstand tidal flat and open platform limestones. In the Heshan coalfield, fourth-order sequences and coals within the Sequence Ⅲ thin first and then thicken upwards, with the thinnest being the fourth-order sequence with coal Seam 3B. As a result, the thickest coal in the carbonate platform setting is formed at the transgressive surface and the thinnest coal is formed at the bottom of the maximum flooding zone.
2003, 21(1): 183-190.
Abstract:
Simulation experiment is an important part in the study on organic geochemistry. It is also an important means for the research of oil and gas geochemistry. According to the analysis of component and isotope composition of pyrolytic gases generated from simulation of coal and its main macerals, we replenish and perfect the predecessor's cognition of isotopic composition in pyrolytic gases generated from simulation in this paper. Moreover, we contrastively study the fractional characteristics of carbon isotope in coal-type gases and pyrolytic gases, and the result shows that they have favourable consistency. Basing on careful simulation, we can gain the decisive index of coal-type gases generated from different coal-bearing sedimentary basin. To the contrast of carbon isotopic composition between natural gases and simulation gases, what the most important is how to deal with the isotopic analysis data. According to the carbon isotope analysis of the simulation series products, we obtain the relationship between methane, ethane carbon isotopic composition and evolution stage in natural gas with single source, and the relationship between methane carbon isotope and ethane carbon isotope in evolution process. All of these results have an important significance to judgie gases of mixed sources.
Simulation experiment is an important part in the study on organic geochemistry. It is also an important means for the research of oil and gas geochemistry. According to the analysis of component and isotope composition of pyrolytic gases generated from simulation of coal and its main macerals, we replenish and perfect the predecessor's cognition of isotopic composition in pyrolytic gases generated from simulation in this paper. Moreover, we contrastively study the fractional characteristics of carbon isotope in coal-type gases and pyrolytic gases, and the result shows that they have favourable consistency. Basing on careful simulation, we can gain the decisive index of coal-type gases generated from different coal-bearing sedimentary basin. To the contrast of carbon isotopic composition between natural gases and simulation gases, what the most important is how to deal with the isotopic analysis data. According to the carbon isotope analysis of the simulation series products, we obtain the relationship between methane, ethane carbon isotopic composition and evolution stage in natural gas with single source, and the relationship between methane carbon isotope and ethane carbon isotope in evolution process. All of these results have an important significance to judgie gases of mixed sources.
2003, 21(1): 8-9.
Abstract:
A brief review on the important influences of “Acta Sedimentologica Sinica” in the recent twenty year development of the Chinese sedimentology since the birth of the Journal is given in this paper.
A brief review on the important influences of “Acta Sedimentologica Sinica” in the recent twenty year development of the Chinese sedimentology since the birth of the Journal is given in this paper.
2003, 21(1): 19-23.
Abstract:
Dynamics of basin fluid is a synthetical discipline to study the flow processes of fluid and kinetic and dynamic processes of fluid-rock interaction in sedimentary basin by the integrated geological, geophysical and geochemical means and computer modeling techniques, which focuses on the integrated research of history of temperature, pressure and geochemistry fields under the framework of fluid carrier network. Basin fluid system pays a very important role on the variation of mineral composition and redistribution of energy in sedimentary basin, which also controls the process of generation, migration and accumulation of hydrocarbon, and the formation of ore deposits. Hence, the study on dynamics of basin fluid has been paid attention to by a lot of scientists at home and a broad. For last 10 years, some important advances in dynamics of basin fluid include flow patterns, carrier network, fluid-rock interaction, analysis means tracing fluid flow, and computer modeling in sedimentary basin. With the application of new theories and technology, the study on basin fluid will bring a greater increase in resource exploration.
Dynamics of basin fluid is a synthetical discipline to study the flow processes of fluid and kinetic and dynamic processes of fluid-rock interaction in sedimentary basin by the integrated geological, geophysical and geochemical means and computer modeling techniques, which focuses on the integrated research of history of temperature, pressure and geochemistry fields under the framework of fluid carrier network. Basin fluid system pays a very important role on the variation of mineral composition and redistribution of energy in sedimentary basin, which also controls the process of generation, migration and accumulation of hydrocarbon, and the formation of ore deposits. Hence, the study on dynamics of basin fluid has been paid attention to by a lot of scientists at home and a broad. For last 10 years, some important advances in dynamics of basin fluid include flow patterns, carrier network, fluid-rock interaction, analysis means tracing fluid flow, and computer modeling in sedimentary basin. With the application of new theories and technology, the study on basin fluid will bring a greater increase in resource exploration.
2003, 21(1): 31-37,65.
Abstract:
Early Cretaceous sedimentary system in the back-arc area of the Gangdese magmatic arc, central Tibet, western China, is characterized by a distinct change from clastics to carbonates in an ascending order. An intensive marine transgression occurred in this area during middle Cretaceous time, which led to accumulation of a massive succession of platform limestone in the southern margin of the Qiangtang terrain and the Lhasa terrain. The trend of eustasy in this area is quite different from that in the Tarim and Simao basins, where a coeval marine regression was in progress. Sandstones (Q78F11L11) in early Early Cretaceous were mainly derived from northern orogen but, upwards, they were gradually dominated by a (southern) magmatic arc provenance. Both bimodal volcanic rocks and bimodal volcanic debris were sometimes found within the middle Cretaceous sedimentary sequences in the southern margin of the back-arc area. An early Cretaceous back-arc rifting event is thus proposed regarding the Gangdese magmatic arc. This back-arc rifting gave rise to the Shyok marginal sea that was floored by oceanic basement, in the back-arc area of the Ladakh-Kohistan arcs. We believe that, during (early-) middle Cretaceous time, the entiresouthern Eurasian margin could have been active, leading to a series of back-arc rift basins. Some basins may have ultimately been floored by oceanic crust while others remained underlain by continental or transitional basement, much like the present western Pacific margin. There is no mechanism and no paleogeographic and topographic evidence to support the view that the Tibetan plateau had intensely been elevated by the end of Early Cretaceous time.
Early Cretaceous sedimentary system in the back-arc area of the Gangdese magmatic arc, central Tibet, western China, is characterized by a distinct change from clastics to carbonates in an ascending order. An intensive marine transgression occurred in this area during middle Cretaceous time, which led to accumulation of a massive succession of platform limestone in the southern margin of the Qiangtang terrain and the Lhasa terrain. The trend of eustasy in this area is quite different from that in the Tarim and Simao basins, where a coeval marine regression was in progress. Sandstones (Q78F11L11) in early Early Cretaceous were mainly derived from northern orogen but, upwards, they were gradually dominated by a (southern) magmatic arc provenance. Both bimodal volcanic rocks and bimodal volcanic debris were sometimes found within the middle Cretaceous sedimentary sequences in the southern margin of the back-arc area. An early Cretaceous back-arc rifting event is thus proposed regarding the Gangdese magmatic arc. This back-arc rifting gave rise to the Shyok marginal sea that was floored by oceanic basement, in the back-arc area of the Ladakh-Kohistan arcs. We believe that, during (early-) middle Cretaceous time, the entiresouthern Eurasian margin could have been active, leading to a series of back-arc rift basins. Some basins may have ultimately been floored by oceanic crust while others remained underlain by continental or transitional basement, much like the present western Pacific margin. There is no mechanism and no paleogeographic and topographic evidence to support the view that the Tibetan plateau had intensely been elevated by the end of Early Cretaceous time.
2003, 21(1): 46-51.
Abstract:
The Yecheng foreland basin is a part of the southwest sag of the Tarim Basin and contains late Cenozoic molassic deposits with great thickness. The phased evolution of the basin mirrors the uplift of the Kunlun mountains. The sedimentary environment during the Miocene was characterized by low-gradient meandering rivers, and became distal fan during the Early Pliocene. Significant change in the sedimentary environment occurred in the Late Pliocene, when the deposits were dominated by debris flow material. The basin became a proximal alluvial fan under arid climatic regime. Changes in the sedimentary environment indicate the uplift of the northern Tibetan Plateau since the Late Pliocene.
The Yecheng foreland basin is a part of the southwest sag of the Tarim Basin and contains late Cenozoic molassic deposits with great thickness. The phased evolution of the basin mirrors the uplift of the Kunlun mountains. The sedimentary environment during the Miocene was characterized by low-gradient meandering rivers, and became distal fan during the Early Pliocene. Significant change in the sedimentary environment occurred in the Late Pliocene, when the deposits were dominated by debris flow material. The basin became a proximal alluvial fan under arid climatic regime. Changes in the sedimentary environment indicate the uplift of the northern Tibetan Plateau since the Late Pliocene.
2003, 21(1): 61-65.
Abstract:
The present contribution is concerned with the application of tracer methods to marine sediment dynamics, in terms of material source identification, sediment transport rate calculations and the problem of a universal theoretical framework. For the tracing of material sources, mixing models that are originally established for river basin systems should be modified to fit marine environments; in particular, changes in the fingerprinting particles during transport must be considered. In the research field of sediment transport rate determination, artificial tracers have been used, on the basis of the spatial integration method (SIM), the time integration method (TIM), or the continuous injection method (CIM), with the SIM being the most popular. In the application of these methods it is crucial to define the centroid movement and the depth of disturbance. In the case of natural tracers, these methods are no longer applicable because the centroid movement cannot be defined. Nevertheless, in some circumstances, natural tracers can provide information on transport, on the basis of a mathematical model. Further investigations are required in the future to establish a universal theoretical framework for both artificial and natural tracers for sediment transport studies, in which solutions must be found to the problems associated with the differential dynamic behaviors of the tracer and the bulk sediment, deposition rates and the depth of disturbance as functions of the temporal scale, and sediment dispersive processes.
The present contribution is concerned with the application of tracer methods to marine sediment dynamics, in terms of material source identification, sediment transport rate calculations and the problem of a universal theoretical framework. For the tracing of material sources, mixing models that are originally established for river basin systems should be modified to fit marine environments; in particular, changes in the fingerprinting particles during transport must be considered. In the research field of sediment transport rate determination, artificial tracers have been used, on the basis of the spatial integration method (SIM), the time integration method (TIM), or the continuous injection method (CIM), with the SIM being the most popular. In the application of these methods it is crucial to define the centroid movement and the depth of disturbance. In the case of natural tracers, these methods are no longer applicable because the centroid movement cannot be defined. Nevertheless, in some circumstances, natural tracers can provide information on transport, on the basis of a mathematical model. Further investigations are required in the future to establish a universal theoretical framework for both artificial and natural tracers for sediment transport studies, in which solutions must be found to the problems associated with the differential dynamic behaviors of the tracer and the bulk sediment, deposition rates and the depth of disturbance as functions of the temporal scale, and sediment dispersive processes.
2003, 21(1): 81-89.
Abstract:
The IGCP 447 (Proterozoic Molar tooth Carbonates and the Evolution of the Earth) was approved in February, 2001 by the International Geological Correlation Program Scientific Board and marked the new progress of this field. The IGCP project 447 a successor of IGCP 319, aims to investigate the origin and structures of Middle to Late Precambrian microsparites and to assess their global correlation by stressing depositional, palaeoenvironmental, biogeochemical, geotectonical and stratigraphical significance (Episodes, New IGCP Projects was accepted and started in 2001). Molar-tooth carbonates are specialized and peculiarly named early diagenetic sedimentary features. The name of ‘Molar-tooth’ carbonates originated from their tapered, ptygmatically folded texture comparable to an elephant's tooth. Molar-tooth structures (MTS) have a specified time range of 1900 to 550 Ma - (mainly developed in Mesoproterozoic to Neoproterozoic era), To try our best to interpret the origin of these enigmatic structures and their possible use in correlation is a significant object of this research. This project will undertake a thorough survey of the Proterozoic carbonates in China, Arctic Europe (Spitsbergen), Russia (South Siberia), North America (Mackenzie Mountains/Victoria Island.), West Africa and so on. MTS are significant for serving as the key Precambrian biological and geochemical events. They might be a link in the revolutionary changes of the biosphere, which heralded the appearance of the complex multi-cellular animals of the late Precambrian. There are more and more evidences which suggest that MTS probably originated from organic substance. Like a bridge, MTS connected the inorganic world with the organic one and is closely related to the evolution of the paleoseas, the atmosphere and the biosphere. Their development and/or recession are related to the origin of life and the abruption of sedimentary geochemistry of marine carbonates. It was proved by the isotopic age of 87Sr/ 86Sr that the disappearance of the MT carbonate might be possibly occurred in 750 Ma. Based on the research of home and abroad, the Meso-neoproterozoic strata might be of important potential of hydrocarbon generation, and of a better reservoir as well.
The IGCP 447 (Proterozoic Molar tooth Carbonates and the Evolution of the Earth) was approved in February, 2001 by the International Geological Correlation Program Scientific Board and marked the new progress of this field. The IGCP project 447 a successor of IGCP 319, aims to investigate the origin and structures of Middle to Late Precambrian microsparites and to assess their global correlation by stressing depositional, palaeoenvironmental, biogeochemical, geotectonical and stratigraphical significance (Episodes, New IGCP Projects was accepted and started in 2001). Molar-tooth carbonates are specialized and peculiarly named early diagenetic sedimentary features. The name of ‘Molar-tooth’ carbonates originated from their tapered, ptygmatically folded texture comparable to an elephant's tooth. Molar-tooth structures (MTS) have a specified time range of 1900 to 550 Ma - (mainly developed in Mesoproterozoic to Neoproterozoic era), To try our best to interpret the origin of these enigmatic structures and their possible use in correlation is a significant object of this research. This project will undertake a thorough survey of the Proterozoic carbonates in China, Arctic Europe (Spitsbergen), Russia (South Siberia), North America (Mackenzie Mountains/Victoria Island.), West Africa and so on. MTS are significant for serving as the key Precambrian biological and geochemical events. They might be a link in the revolutionary changes of the biosphere, which heralded the appearance of the complex multi-cellular animals of the late Precambrian. There are more and more evidences which suggest that MTS probably originated from organic substance. Like a bridge, MTS connected the inorganic world with the organic one and is closely related to the evolution of the paleoseas, the atmosphere and the biosphere. Their development and/or recession are related to the origin of life and the abruption of sedimentary geochemistry of marine carbonates. It was proved by the isotopic age of 87Sr/ 86Sr that the disappearance of the MT carbonate might be possibly occurred in 750 Ma. Based on the research of home and abroad, the Meso-neoproterozoic strata might be of important potential of hydrocarbon generation, and of a better reservoir as well.
2003, 21(1): 96-105.
Abstract:
Dengying formations 2 and 3 members of upper-Sinian is one of major nature gas reservior in Sichuang basin. In light colour dolostone abound with carbonification blackly non-stromatolite ecologic system cyanobacteria dolostone. It's developed not also in depositional and cementational stage,but also in hypergene diagenetic stage.At the depositional stage, it occure in laminae or surounded the grain growth in all sides.The singel bed thickness of these cyanobacteria dolostones from 1 mm to over 10 cm. And total thickness occupy about 10 percent in 2 and 3 members of Denging formation. Sometimes it show up incontinual small blackly points developed in whitely stromatolite ecologic system cyanobacteria dolostones,suck as stromatalolates, oncolite and others.At the hypergene diagenetic stage,the blackly non-stromatolite ecologic system cyanobactria mainly occurred in many generations linely laminae interbeded with wihite coloure fiber texture dolostone laminae filling the karstic cavity and channel, even in enlargeie dissolived crack.The major sharps of non-stromatolite ecalogic system cyanobactria are sphere,ellipsod and cudgel,occasionally are mushroom,monkhat and others.The colongs presented sharp are string bead,grass cluster,croteh and like the valcanic eruption,etc. All of these sharps show palaeocology of upword groweh or toword the centre of karstic cavity and channel. Degradation in test of modern cyanobactria evidenced that non-stromatolite ecologic system cyanobacteria dolostones is one of hydrocarbon source rock in Dengying formation.
Dengying formations 2 and 3 members of upper-Sinian is one of major nature gas reservior in Sichuang basin. In light colour dolostone abound with carbonification blackly non-stromatolite ecologic system cyanobacteria dolostone. It's developed not also in depositional and cementational stage,but also in hypergene diagenetic stage.At the depositional stage, it occure in laminae or surounded the grain growth in all sides.The singel bed thickness of these cyanobacteria dolostones from 1 mm to over 10 cm. And total thickness occupy about 10 percent in 2 and 3 members of Denging formation. Sometimes it show up incontinual small blackly points developed in whitely stromatolite ecologic system cyanobacteria dolostones,suck as stromatalolates, oncolite and others.At the hypergene diagenetic stage,the blackly non-stromatolite ecologic system cyanobactria mainly occurred in many generations linely laminae interbeded with wihite coloure fiber texture dolostone laminae filling the karstic cavity and channel, even in enlargeie dissolived crack.The major sharps of non-stromatolite ecalogic system cyanobactria are sphere,ellipsod and cudgel,occasionally are mushroom,monkhat and others.The colongs presented sharp are string bead,grass cluster,croteh and like the valcanic eruption,etc. All of these sharps show palaeocology of upword groweh or toword the centre of karstic cavity and channel. Degradation in test of modern cyanobactria evidenced that non-stromatolite ecologic system cyanobacteria dolostones is one of hydrocarbon source rock in Dengying formation.
2003, 21(1): 113-117.
Abstract:
Sandstone-type uranium deposit is one type of uranium deposits with important industrial significance, and is the main target exploration type of China nuclear geology. On the basis of brief introduction to metallogenic geological conditions of sandstone-type uranium geology, this paper discusses the research situation of sandstone-type uranium deposits, especially the research situation and in-situ leaching geological conditions of in-situ leachable sandstone-type uranium deposits. The developing direction of this type of uranium deposits and some important basic geologic study and researching methods are also discussed in the paper.
Sandstone-type uranium deposit is one type of uranium deposits with important industrial significance, and is the main target exploration type of China nuclear geology. On the basis of brief introduction to metallogenic geological conditions of sandstone-type uranium geology, this paper discusses the research situation of sandstone-type uranium deposits, especially the research situation and in-situ leaching geological conditions of in-situ leachable sandstone-type uranium deposits. The developing direction of this type of uranium deposits and some important basic geologic study and researching methods are also discussed in the paper.
2003, 21(1): 125-128,136.
Abstract:
This paper has introduced recent development in research of coal accumulation, coal accumulation center, distribution of coal in sequence stratigraphic framework, coal precursor peat and coal forming environment mire, as well as minerals in coal and coal measures kaolinite. The issues on Late Paleozoic transgression in northern China has been proposed again.
This paper has introduced recent development in research of coal accumulation, coal accumulation center, distribution of coal in sequence stratigraphic framework, coal precursor peat and coal forming environment mire, as well as minerals in coal and coal measures kaolinite. The issues on Late Paleozoic transgression in northern China has been proposed again.
2003, 21(1): 133-136.
Abstract:
In recently twenty years, sedimentary geologists working in oil and gas seemingly concern much the development of stratigraphy (seismic stratigraphy, sequence stratigraphy and high-resolution stratigraphy ), while pay little attention to creation of theory and research of method in the research of lithofacies paleogeographic environment. In fact, there are much abundant contents in research of palegeographic information and its source of driving force and driving mechanism in petrostratigraphic record. The new methods and techniques of extracting information and environment are continuously appearing, and the development of lithofacies paleogeography is still facing many important problems of theory and technique. In this paper, some problems are expounded in lithofacies paleogeography of oil and gas area, which include coupling relationship and their sensibility between the process of structure and distributary model of sedimentary lithofacies, time scale and resolution of reconstruction of lithofacies paleogeography, delicate description and depiction of lithofacies and environmental units, prediction of distribution of lithofacies units, source of information and its symmetry of reconstruction of lithofacies paleogeography, and mapping of digital lithofaies paleogeography.
In recently twenty years, sedimentary geologists working in oil and gas seemingly concern much the development of stratigraphy (seismic stratigraphy, sequence stratigraphy and high-resolution stratigraphy ), while pay little attention to creation of theory and research of method in the research of lithofacies paleogeographic environment. In fact, there are much abundant contents in research of palegeographic information and its source of driving force and driving mechanism in petrostratigraphic record. The new methods and techniques of extracting information and environment are continuously appearing, and the development of lithofacies paleogeography is still facing many important problems of theory and technique. In this paper, some problems are expounded in lithofacies paleogeography of oil and gas area, which include coupling relationship and their sensibility between the process of structure and distributary model of sedimentary lithofacies, time scale and resolution of reconstruction of lithofacies paleogeography, delicate description and depiction of lithofacies and environmental units, prediction of distribution of lithofacies units, source of information and its symmetry of reconstruction of lithofacies paleogeography, and mapping of digital lithofaies paleogeography.
2003, 21(1): 142-147.
Abstract:
The paper discusses the present situation of petroleum exploration and development in China, and the challenges facing to the reservoir geologists. They are the deep sited reservoirs, low permeability reservoirs, carbonate reservoirs and foreland basin reservoirs, which have not been understood well for years. In this paper, based on the experiences from the recent study of reservoirs in mainland China petroleum provinces, the four types of reservoirs are analyzed for several aspects, and the corresponding research directions and methodologies are presented.
The paper discusses the present situation of petroleum exploration and development in China, and the challenges facing to the reservoir geologists. They are the deep sited reservoirs, low permeability reservoirs, carbonate reservoirs and foreland basin reservoirs, which have not been understood well for years. In this paper, based on the experiences from the recent study of reservoirs in mainland China petroleum provinces, the four types of reservoirs are analyzed for several aspects, and the corresponding research directions and methodologies are presented.
2003, 21(1): 155-167.
Abstract:
Sequence stratigraphy has been developed in China for nearly 20 years. By the hard work of Chinese geologists, it went through three development stages which are beginning, high-speed development and mature development. Among the stages the Chinese geologists progressed quite a lot and acquired plentiful achievements especially in the research of regional sequence stratigraphy, theoretical sequence stratigraphy, sequence stratigraphy with mineral controlling, sequence stratigraphy in oil and gas exploration, high-resolution sequence stratigraphy, Milankovitch cycles, continental sequence stratigraphy (including alluvial system and desert aeolian system), applications of new techniques and methods in sequence stratigraphy (seism, well-log, computer simulation, neutron technique, cosmogenic nuclide etc.), dynamic sequence stratigraphy in basin depression and mountain building, sequence stratigraphy in the Tibet plateau and orogenic zones, diagenetic sequence stratigraphy, chemical sequence stratigraphy, tectonic sequence stratigraphy and sequence-lithofacies palaeogeography mapping etc. Based on the analysis of research status of Chinese sequence stratigraphy, it is suggested that Chinese geologist should enhance the application of sequence stratigraphy, and also should pay more attention to the basis research, technique improvement and feature development, in order to devote themselves to the development of sequence stratigraphy.
Sequence stratigraphy has been developed in China for nearly 20 years. By the hard work of Chinese geologists, it went through three development stages which are beginning, high-speed development and mature development. Among the stages the Chinese geologists progressed quite a lot and acquired plentiful achievements especially in the research of regional sequence stratigraphy, theoretical sequence stratigraphy, sequence stratigraphy with mineral controlling, sequence stratigraphy in oil and gas exploration, high-resolution sequence stratigraphy, Milankovitch cycles, continental sequence stratigraphy (including alluvial system and desert aeolian system), applications of new techniques and methods in sequence stratigraphy (seism, well-log, computer simulation, neutron technique, cosmogenic nuclide etc.), dynamic sequence stratigraphy in basin depression and mountain building, sequence stratigraphy in the Tibet plateau and orogenic zones, diagenetic sequence stratigraphy, chemical sequence stratigraphy, tectonic sequence stratigraphy and sequence-lithofacies palaeogeography mapping etc. Based on the analysis of research status of Chinese sequence stratigraphy, it is suggested that Chinese geologist should enhance the application of sequence stratigraphy, and also should pay more attention to the basis research, technique improvement and feature development, in order to devote themselves to the development of sequence stratigraphy.
2003, 21(1): 175-182.
Abstract:
Many authors, from different aspects, have modeled the carbon isotope fractionation effect during gas (methane) generation from organic matters (coals and kerogens) through different approaches. Many models about carbon isotope fractionation have been proposed. At the same time, the effects of catalysis and post-genetic process on gas carbon isotope have also been discussed. But the models can not describe carbon isotopic behavior of thermogenic methane in natural system completely, nor explain the mechanism of its fractionation perfectly. The reason is that the assumptions of the models are not completely suitable to the complexity of natural system. Furthermore, pyrolysis results are used as data source of many models. It is well known that pyrolysis has still a distance with natural process, so that the models, sometimes, can not be applied to real case successfully. To establish more perfect model with chemical kinetic approaches may be a focus in further work. And the effects of catalysis and post-genetic process on carbon isotope fractionation should also be considered.
Many authors, from different aspects, have modeled the carbon isotope fractionation effect during gas (methane) generation from organic matters (coals and kerogens) through different approaches. Many models about carbon isotope fractionation have been proposed. At the same time, the effects of catalysis and post-genetic process on gas carbon isotope have also been discussed. But the models can not describe carbon isotopic behavior of thermogenic methane in natural system completely, nor explain the mechanism of its fractionation perfectly. The reason is that the assumptions of the models are not completely suitable to the complexity of natural system. Furthermore, pyrolysis results are used as data source of many models. It is well known that pyrolysis has still a distance with natural process, so that the models, sometimes, can not be applied to real case successfully. To establish more perfect model with chemical kinetic approaches may be a focus in further work. And the effects of catalysis and post-genetic process on carbon isotope fractionation should also be considered.
