By integrating core observations,logging data and seismic interpretation,this study takes the massive Cretaceous carbonates in the M block of the Santos Basin,Brazil,as an example to establish the sequence filling pat...By integrating core observations,logging data and seismic interpretation,this study takes the massive Cretaceous carbonates in the M block of the Santos Basin,Brazil,as an example to establish the sequence filling pattern of fault-bounded isolated platforms in rift lake basins,reveal the control mechanisms of shoal-body development and reservoir formation,and reconstruct the evolutionary history of lithofacies paleogeography.The following results are obtained.(1)Three tertiary sequences(SQ1-SQ3)are identified in the Lower Cretaceous Itapema-Barra Velha of the M block.During the depositional period of SQ1,the rift basement faults controlled the stratigraphic distribution pattern of thick on both sides and thin in the middle.The strata overlapped to uplift in the early stage.During the depositional period of SQ2-SQ3,the synsedimentary faults controlled the paleogeomorphic reworking process with subsidence in the northwest and uplifting in the northeast,accompanied with the relative fall of lake level.(2)The Lower Cretaceous in the M block was deposited in a littoral-shallow lake,with the lithofacies paleogeographic pattern transiting from the inner clastic shoals and outer shelly shoals in SQ1 to the alternation of mounds and shoals in SQ2-SQ3.(3)Under the joint control of relative lake-level fluctuation,synsedimentary faults and volcanic activity,the shelly shoals in SQ1 tend to accumulated vertically in the raised area,and the mound-shoal complex in SQ2-SQ3 tends to migrate laterally towards the slope-break belt due to the reduction of accommodation space.(4)The evolution pattern of high-energy mounds and shoals,which were vertically accumulated in the early stage and laterally migrated in the later stage,controlled the transformation of high-quality reservoirs from“centralized”to“ring shaped”distribution.The research findings clarify the sedimentary patterns of mounds and shoals and the distribution of favorable reservoirs in the fault-controlled lacustrine isolated platform,providing support for the deepwater hydrocarbon exploration in the subsalt carbonate rocks in the Santos Basin.展开更多
As the largest intermontane basin in the northeastern Tibetan Plateau(TP),the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the TP.In this study,b...As the largest intermontane basin in the northeastern Tibetan Plateau(TP),the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the TP.In this study,based on morphological comparison,fossil fruit of Cyclocarya from the Early Oligocene Shangganchaigou Formation in the Qaidam Basin is assigned as Cyclocarya cf.weylandii.The discovery of Cyclocarya cf.weylandii demonstrates the occurrence of Cyclocarya in the Oligocene sediment in Qaidam Basin.This is the first record of Cyclocarya fossil of Early Oligocene Age in China and indicates that Cyclocarya has existed on the northeastern TP since at least the Early Oligocene.The living analogues of the current fossil now lives in sub-tropical China,where the East Asian Monsoon is prevalent.Integrating the new fossils and previously reported fossil remains of plants and fishes,it can be inferred that the Early Oligocene Qaidam Basin was primarily influenced by westerly circulation and had a relatively warm and humid climate,which was in sharp contrast to the present-day climate in Qaidam Basin.展开更多
A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin.Based on the study of more than 1000 rock samples,nine carbonate microfacies and three terrigenous facies...A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin.Based on the study of more than 1000 rock samples,nine carbonate microfacies and three terrigenous facies were identified.The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin.Three(Gandom Kar area),two(Ardal area),seven(Gardbishe area),five(Shirmard area),two(Kuh-e-Kamaneh area),three(Kuh-e-Balghar area),and six(Murak area)of depositional sequences(3rd order)were identified.The thickness of the lowstand systems tract(LST)due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian.During the Middle Maastrichtian,the shallow and deep marine deposits were formed during the transgressive systems tract(TST)and highstand systems tract(HST)in this basin and the rate of subsidence in the center of this basin(Gardbishe area)is higher than in other areas and the platform was drowned in this area.The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin(except the south part)during the Late Maastrichtian.Paleogeographical studies on the Zagros Basin during the Late Campanian-Maastrichtian showed the following results:shallow marine environments were developed in the southeast of this basin,and the turbidite,delta,and fluvial environments in the northwest were developed more than in other areas.展开更多
There are 9 major coal-accumulating periods during geological history in China,including the Early Carboniferous,Late Carboniferous-Early Permian,Middle Permian,Late Permian,Late Triassic,Early-Middle Jurassic,Early C...There are 9 major coal-accumulating periods during geological history in China,including the Early Carboniferous,Late Carboniferous-Early Permian,Middle Permian,Late Permian,Late Triassic,Early-Middle Jurassic,Early Cretaceous,Paleogene and Neogene.The coal formed in these periods were developed in different coal-accumulating areas(CAA)including the North China,South China,Northwest China,Northeast China,the Qinghai–Tibet area,and China offshore area.In this paper,we investigated depositional environments,sequence stratigraphy,lithofacies paleogeography and coal accumulation pattern of five major coal-accumulating periods including the Late Carboniferous to Middle Permian of the North China CAA,the Late Permian of the South China CAA,the Late Triassic of the South China CAA,the Early-Middle Jurassic of the North and Northwest China CAA,and the Early Cretaceous in the Northeast China CAA.According to distribution of the coal-bearing strata and the regional tectonic outlines,we have identified distribution range of the coal-forming basins,sedimentary facies types and coal-accumulating models.The sequence stratigraphic frameworks of the major coal-accumulating periods were established based on recognition of a variety of sequence boundaries.The distribution of thick coals and migration patterns of the coal-accumulating centers in the sequence stratigraphic framework were analyzed.The lithofacies paleogeography maps based on third-order sequences were reconstructed and the distribution of coal accumulation centers and coal-rich belts were predicted.展开更多
Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to tr...Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels,secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas,whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies indicates that the mapping method reliably predicts the distribution of sweet spots. The application and understanding of the mapping method provide a reference for exploring tight sandstone reservoirs on a regional basis.展开更多
Paleogeography is the merger of lithology,depositional environments,tectonic plate movements,topography,climate patterns and ecosystems(reefs,vegetation)through time(e.g.,Scotese,2014,2016,2017;Blakey,2019).The constr...Paleogeography is the merger of lithology,depositional environments,tectonic plate movements,topography,climate patterns and ecosystems(reefs,vegetation)through time(e.g.,Scotese,2014,2016,2017;Blakey,2019).The construction of paleogeographic maps using tectonic plate reconstructions requires a multi-year community effort that shares databases,standards and computer projection methods.展开更多
The Triassic petrostratigraphic system and chronologic stratigraphic sketch have been updated and perfected in the Qiangtang area, Qinghai-Tibet Plateau based on the integrated 1：250000 regional geological survey and...The Triassic petrostratigraphic system and chronologic stratigraphic sketch have been updated and perfected in the Qiangtang area, Qinghai-Tibet Plateau based on the integrated 1：250000 regional geological survey and the latest research progeny. The first finished 1：3000000 Triassic tectonic lithofacies paleogeographic maps in the Qiangtang area shows that the Triassic tectonic unit in the Qiangtang area can been divided into three parts from north to south： northern Qiangtang block; Longmucuo-Shuanghu suture zone; and southern Qiangtang block. The early-middle Triassic tectonic paleogeography in the Qiangtang area is divides into three sub- units： northern Qiangtang passive continental marginal basin （NQPB）, Longmucuo- Shuanghu residual basin （LSRB） and southern Qiangtang residual basin （SQRB）. The NQPB can be subdivided into four paleogeography units： The Tanggula-Zangxiahe shallow and bathyal sea; The Wangquanhe- Yingshuiquan carbonate platform; The Rejuechaka-Jiangaidarina littoral- shallow sea; and Qiangtang central uplift. The above units of The NQPB possess EW trend, geomorphology high in the south and low in the north, the seawater depth northward. The basinal paleo-current direction is unidirectional, and basinal tectonic subsidence center is in accord with the depo-center, located in the Tanggula-Zangxiahe belt, north of the basin. The sedimentation and tectonic evolution of the NQPB are characterized with passive continental marginal basin. The Qiangtang central orogenic denuded area （ancient land） may be as a sedimentary materials source of the NQPB. SQRB can be divided into two units： Duoma carbonate platform and southern Qiangtang neritic-deep sea. The late Triassic tectonic paleogeography in the Qiangtang area is the framework of the ＂archipelagic-sea＂ as a whole, and it may be divided into three sub-units： northern Qiangtang back- arc foreland basin（NQFB）, Longmucuo-Shuanghu residual basin（LSRB） and southern Qiangtang marginal-sea basin（SQMB）. Thereinto, NQFB can be divided into five paleogeography units： the Zangxiahe-Mingjinghu bathyal basin characterized with the flysch; the Tanggula shallow-sea shelf with the fine-clastics; the Juhuashang platform with carbonates; the Tumenggela-Shuanghu coastal- delta with coal-bearing clastics and the Nadigangri- Geladandong arc with volcanics and tuffs. In transverse section, the NQFB fills is wedge-shaped, and the sediments characterized with thicker in north and thinner in south, and with double materials derived from the Ruolagangri orogenic belt in north and the Shuanghu central orogenic belt in south. The late Triassic depocenter of NQFB is located in the middle of the basin, the Yakecuo-Bandaohu-Quemocuo belt, but the subsidence center in the north, the Zangxiahe- Mingjinghu belt, and basinal tectonic subsidence center not concordant with the depo-center. Late Triassic, the SQMB may be divided into three sub-units： Xiaochaka shallow-sea; Riganpeicuo platform~ and South Qiangtang southern bathyal basin. In transverse section, the basement of the SQMB is characterized with low in the northern and southern, but high in the middle; forming wedge shaped sediments with thicker in the north and thinner in the south; the sedimentary materials derived from the Qiangtang central uplift and Nadigangri arcs in north. The late Triassic subsidence centre of the SQMB is located in the northern （Xiaochaka area）, but the depocenter in the southern （Qixiancuo Suobucha area）. The sedimentation and tectonic evolution of the SQMB are characterized with marginal sea.展开更多
The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are ...The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are well-developed Paleozoic-Cenozoic strata in this basin,and these provide a crucial window to a greater understanding of the amalgamation process and source-to-sink relationships between the Alxa Block and surrounding tectonic units.However,due to intensive post-depositional modification,and lack of subsurface data,several fundamental issues-including the distribution and evolution of the depositional systems,provenance supplies and source-to-sink relationships during the Carboniferous-Permian remain unclear and thus hinder hydrocarbon exploration and limit the geological understanding of this basin.Employing integrated outcrop surveys,new drilling data,and detrital zircon dating,this study examines the paleogeographic distribution and evolution,and provenance characteristics of the Carboniferous-Permian strata in the Bayanhot Basin.Our results show that the Bayanhot Basin experienced a long-term depositional evolution process from transgression to retrogression during the Carboniferous-late Permian.The transgression extent could reach the central basin in the early Carboniferous.The maximum regional transgression occurred in the early Permian and might connect the Qilian and North China seas with each other.Subsequently,a gradual regression followed until the end of the Permian.The northwestern NCC appeared as a paleo-uplift area and served as a sediments provenance area for the Alxa Block at that time.The NCC,Bayanwula Mountain,and NQOB jointly served as major provenances during the Carboniferous-Permian.There was no ocean separation,nor was there an orogenic belt between the Alxa Block and the NCC that provided sediments for both sides during the Carboniferous-Permian.The accretion of the Alxa and North China blocks should have been completed before the Carboniferous period.展开更多
To predict the large-scale source rock and reservoir distribution in Cambrian subsalt formations(Upper Sinian to Mid-Cambrian)in the Tarim Basin,more than 502D seismic lines and 3D data volume acquired latest,22 wells...To predict the large-scale source rock and reservoir distribution in Cambrian subsalt formations(Upper Sinian to Mid-Cambrian)in the Tarim Basin,more than 502D seismic lines and 3D data volume acquired latest,22 wells and some out-crops around this area were used to study the tectonic-lithofacies paleogeography,define the distribution of large scale source rocks and reservoirs,and sort out favorable zones.(1)The basin experienced evolution from ramp to deep-water mud-rich ramp,low-gradient slope,weak rimmed to strong rimmed platform,and the differentiation in the platform was controlled by pre-Cambrian palaeo-rifts.(2)The Luonan-Yubei ancient rift controlled the distribution of source rocks in the Lower Cambrian Yuertusi Formation,and this rift together with the northern depression are the main source rock area.(3)There are three sets of large-scale reservoirs,the Upper Sinian Qigebulake Formation,the Lower Cambrian Xiaorbulake Formation and the Wu-songger Formation,and shoal-mounds,early dolomitization and multi-levels of unconformities controlled reservoir develop-ment.(4)Four favorable zones,the north slope of Tazhong,upper slope of Maigaiti area,Keping-Wensu periphery,and south slope of Tabei,were evaluated.Of them,the north slope of Tazhong is most likely to have exploration breakthrough;the south slope of Tabei is the best area for exploring the Upper Sinian large scale weathering crust dolomite;Maigaiti slope and Kep-ing-Wensu periphery area improved in exploration potentials significantly,and are worth prospecting faster.展开更多
The Mengyejing potash salt deposit(MPSD)is the only pre-Quaternary potash salt deposit in China.The MPSD is located in the southern Simao Basin,southeastern Tibetan Plateau.The MPSD,along with rock salts and clastic r...The Mengyejing potash salt deposit(MPSD)is the only pre-Quaternary potash salt deposit in China.The MPSD is located in the southern Simao Basin,southeastern Tibetan Plateau.The MPSD,along with rock salts and clastic rocks,展开更多
In recent years, natural gas exploration in the Sinian Dengying Formation and shale gas exploration in Doushantuo Formation have made major breakthroughs in the Sichuan Basin and its adjacent areas. However, the sedim...In recent years, natural gas exploration in the Sinian Dengying Formation and shale gas exploration in Doushantuo Formation have made major breakthroughs in the Sichuan Basin and its adjacent areas. However, the sedimentary background of the Doushantuo Formation hasn't been studied systematically. The lithofacies paleogeographic pattern, sedimentary environment, sedimentary evolution and distribution of source rocks during the depositional stage of Doushantuo Formation were systematically analyzed by using a large amount of outcrop data, and a small amount of drilling and seismic data.(1) The sedimentary sequence and stratigraphic distribution of the Sinian Doushantuo Formation in the middle-upper Yangtze region were controlled by paleouplifts and marginal sags. The Doushantuo Formation in the paleouplift region was overlayed with thin thickness, including shore facies, mixed continental shelf facies and atypical carbonate platform facies. The marginal sag had complete strata and large thickness, and developed deep water shelf facies and restricted basin facies.(2) The Doushantuo Formation is divided into four members from bottom to top, and the sedimentary sequence is a complete sedimentary cycle of transgression–high position–regression. The first member is atypical carbonate gentle slope deposit in the early stage of the transgression, the second member is shore-mixed shelf deposit in the extensive transgression period, and the third member is atypical restricted–open sea platform deposit of the high position of the transgression.(3) The second member has organic-rich black shale developed with stable distribution and large thickness, which is an important source rock interval and major shale gas interval. The third member is characterized by microbial carbonate rock and has good storage conditions which is conducive to the accumulation of natural gas, phosphate and other mineral resources, so it is a new area worthy of attention. The Qinling trough and western Hubei trough are favorable areas for exploration of natural gas(including shale gas) and mineral resources such as phosphate and manganese ore.展开更多
The climate paleogeography,especially the climate classifications,helps to interpret the global and regional climate changes and intuitively compare the climate conditions in different regions.However,the application ...The climate paleogeography,especially the climate classifications,helps to interpret the global and regional climate changes and intuitively compare the climate conditions in different regions.However,the application of climate classification in deep time(i.e.,climate paleogeography)is prohibited due to the usually qualitatively constrained paleoclimate and the inconsistent descriptions and semantic heterogeneity of the climate types.In this study,a climate paleogeography knowledge graph is established under the framework of the Deep-Time Digital Earth program(DDE).The hierarchical knowledge graph consists of five paleoclimate classifications based on various strategies.The classifications are described and their strengths and weaknesses are fully evaluated in four aspects:“simplicity,applicability,quantifiability,and comparability”.We also reconstruct the global climate distributions in the Late Cretaceous according to these classifications.The results are compared and the relationships among these climate types in different classifications are evaluated.Our study unifies scientific concepts from different paleoclimate classifications,which provides an important theoretical basis for the application of paleoclimate classifications in deep time.展开更多
The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition ar...The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition area between the ordos basin with full of oil and gas resources in the north and the Qinling Orogenic Belt with rich mineral展开更多
Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan ...Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed,and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed.The Maokou Formation is divided into 3 long-term cycles,namely LSCl,LSC2 and LSC3,which correspond to the Member 1,Member 2 and Member 3 of the Maokou Formation,respectively.Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting,the area had tectonic differentiation in NWW and NE,and sedimentary basement took on episodic settlement from north to south,as a result,the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf.According to the residual thickness,paleokarst geomorphologic units such as karst highland,karst slope and karst depression at different stages were reconstructed.The karst geomorphological units were developed successively on the basis of sedimentary geomorphology.Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation.The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations:high energy grain shoal and karst monadnock,platform margin slope and karst slope.Based on this understanding,the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology.The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.展开更多
By using a large amount of geological and geophysical data, the geological characteristics such as lithofacies and paleogeography of 4981 geological units at thirteen key geological periods or epoches since the Precam...By using a large amount of geological and geophysical data, the geological characteristics such as lithofacies and paleogeography of 4981 geological units at thirteen key geological periods or epoches since the Precambrian in the world have been figured out. The global lithofacies and paleogeography charts have been compiled by ArcGis mapping technology. Combined with the results of plate-paleogeography reconstruction, the lithofacies and paleogeography as well as the prototype basins of these global paleoplates have been restored with the Gplate software. Results show that there are 22 kinds of lithofacies combinations and 10 types of paleogeography units developed since Precambrian. These features of lithofacies and paleogeography as well as their evolution were mainly controlled by the divergent and convergent movements of those plates. Taking the results of the lithofacis and paleogeography at the present and paleoplate location during the seven key geological periods from the Precambrian to Paleozoic for example, during the Late Precambrian and Cambrian, the large-scale disintegration of the Rodinia supercontinent resulted in reduction of uplift denudation area and clastic terrestrial facies area, the expansion of coastal-shallow marine facies and shallow-water carbonate platform. In Devonian, uplift denudation area and clastic terrestrial facies area began to increase and littoral-shallow marine facies area and shallow-water carbonate platform shrank as a result of the formation of Larussia supercontinent. In the Permian, with the formation of the Pangea continent, the development of the global uplift denudation area and clastic terrestrial facies reached its peak, while the littoral and shallow marine facies were very limited in distribution. The lithofacies and paleogeography features and evolution patterns of different stages lay a solid foundation for analyzing the formation conditions of geological elements, such as source rocks, reservoirs and cap rocks for oil and gas accumulation, and revealing the distribution regularity of oil and gas around the world.展开更多
In view of the difficulties in the study of lithofacies paleogeography and the low reliability of the distribution range of sedimentary sand bodies in the prototype basin caused by less deep drilling, complex seismic ...In view of the difficulties in the study of lithofacies paleogeography and the low reliability of the distribution range of sedimentary sand bodies in the prototype basin caused by less deep drilling, complex seismic imaging and low degree of exploration in the southern margin of Junggar Basin, NW China. A new method based on the source to sink idea was used to restore lithofacies paleogeography and predict glutenite distribution. In the restoration, apatite fission track age was used to define range and uplift time of macro-provenance;the range of provenance area and the migration process of lake shoreline were restored based on the quantitative relationship between gravel diameter and transportation distance, tectonic shortening and other geological parameters;drilling cores and field outcrop sedimentary structures were analyzed, and a series of maps of lithofacies paleogeographic evolution and distribution range of glutenite bodies were compiled. It is concluded that from Early Jurassic to Early Cretaceous, in the southern margin of Junggar Basin, the provenance area gradually expanded from south to north, the lake basin expanded, shrunk and expanded, and the paleoclimate changed from humid to drought to humid. The western section always had proximal fan delta deposits from the southern ancient Tianshan provenance developed, and in the middle and eastern sections, the provenance areas evolved from far source to near source, mainly river-delta, braided delta, fan delta and other sediments developed. The boundary between provenance areas of the western and middle sections is speculated to be Hongche fault zone. In an angle open to the northwest with the current basin edge line, the restored ancient lake shoreline controlled the heterogeneity of reservoirs in the delta plain belt and delta front belt on its both sides. The ancient lake shoreline, current stratigraphic denudation line and current basin margin line limit the types and scope of favorable reservoirs.This understanding provides an important geological basis for oil and gas exploration in the deep lower source-reservoir assemblage at the southern margin of Junggar Basin.展开更多
The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation ...The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation in middle-upper Yangtze region were investigated based on outcrops,drilling,log and seismic data.The study shows that,(1)Affected by the breakup of the Rodinia supercontinent,the middle and upper Yangtze areas were in extensional tectonic environment during the depositional period of Dengying Formation.The carbonate platform was structurally differentiated.Intra-platform depressions controlled by syndepositional faults developed,forming a tectonic-paleogeographic pattern of"three platforms with two depressions".(2)During the depositional period of the first and second members of the Dengying Formation,rimmed platforms and intra-platform fault depressions developed in upper Yangtze area and isolated platform developed in middle Yangtze area,and there was the Xuanhan-Kaijiang ancient land block in eastern Sichuan.The depositional period of the third member of the Dengying Formation is the transformation period of tectonic-paleogeographic pattern,when a set of shallow water shelf sediment rich in mud was deposited due to transgression on the background of the eroded terrain formed in EpisodeⅠof Tongwan Movement.The sediment of the fourth member of the Dengying Formation inherited the paleogeographic pattern of the first and second members of the Dengying Formation in general,but the Deyang-Anyue intra-platform fault depression further expanded,and the middle Yangtze platform evolved into two separated platforms.(3)Tectonic-sedimentary differentiation and evolution of carbonate platform in the Sinian gave rise to two types of accumulation assemblages with wide distribution and great exploration potential,which are platform margin and intra-platform.展开更多
Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and...Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei.展开更多
Based on the compilation and analysis of the lithofacies and paleogeography distribution maps at present and paleoplate locations during six key geological periods of the Mesozoic and Cenozoic,the lithofacies and pale...Based on the compilation and analysis of the lithofacies and paleogeography distribution maps at present and paleoplate locations during six key geological periods of the Mesozoic and Cenozoic,the lithofacies and paleogeography features and their development laws were expounded.Based on our previous research results on lithofacies and paleogeography from Precambrian to Paleozoic,we systematically studied the features and evolution laws of global lithofacies and paleogeography from the Precambrian and their effects on the formation of source rocks,reservoirs,cap rocks and the distribution of oil and gas worldwide.The results show that since Precambrian,the distribution areas of uplift erosion and terrestrial clastic deposition tended to increase gradually,and increased significantly during the period of continental growth.The scale of coastal and shallow marine facies area had three distinct cycles,namely,from Precambrian to Devonian,from Carboniferous to Triassic,and from Jurassic to Neogene.Correspondingly,the development of shallow carbonate platform also showed three cycles;the lacustrine facies onshore was relatively developed in Mesozoic and Cenozoic;the sabkha was mainly developed in the Devonian,Permian and Triassic.The Cretaceous is the most important source rock layers in the world,followed by the Jurassic and Paleogene source rocks;the clastic reservoirs have more oil and gas than the carbonate reservoirs;the basins with shale caprocks have the widest distribution,the most abundant reserves of oil and gas,and the evaporite caprocks have the strongest sealing capacity,which can seal some huge oil and gas fields.展开更多
For predicting the distribution of favorable reservoir facies belts of the super-large ancient Anyue carbonate gas field in the Sichuan Basin,through an analysis of structure and lithofacies paleogeography,the lithofa...For predicting the distribution of favorable reservoir facies belts of the super-large ancient Anyue carbonate gas field in the Sichuan Basin,through an analysis of structure and lithofacies paleogeography,the lithofacies paleogeography and sedimentary model of the Sinian Dengying Fm was reconstructed based on the field outcrop,drilling and seismic data.As a result,achievements are made in four aspects.First,the basin and its periphery resided in an extensional tectonic setting in the Sinian.Intense extension led to the formation of the Deyang-Anyue intraplatform rift.The Sichuan Basin was divided into the palaeo-geographic pattern of“two uplifts and four sags”.The“two uplifts”evolved into the platform,and the“four sags”evolved into the slope-basin environment.Second,in the depositional stage of the Deng 2 Member,some favorable reservoir belts developed,such as bioherm-shoal at the continental margin,bioherm-shoal at the rift margin,and bioherm-shoal in the platform.The bioherm-shoal at rift margin developed along both sides of the DeyangeAnyue rift,in a U-shape,with a width of about 5-40 km and a length of about 500 km.It connected with the platform margin belt at the continental margin to the west in the Shifang area,and to the north near Guangyuan area.Third,in the depositional stage of the Deng 4 Member,when the lithofacies paleogeographic features in the Deng 2 Member remained,the platform margin belt at the rift margin evolved into two parts in the east and the west as a result of the continuous southward extensional faulting of the Deyang-eAnyue rift until it finally crossed the basin from north to south.The eastern platform margin belt was located in the Guangyuan-Yanting-Anyue-Luzhou area,showing NS distribution with a length of about 450 km and a width of about 4-50 km.The western platform margin belt mainly developed in the Dujiangyan-Chengdu-Weiyuan-Yibin-Mabian area,showing an eastward arc distribution with a length of about 300 km and a width of 4-30 km.And fourth,the sedimentary model of rimmed platform with double platform margins in the Dengying Fm was established,providing a guidance for predicting the distribution of favorable reservoir facies belts.展开更多
基金Supported by the China National Science and Technology Major Project(2025ZD1403000)CNPC Major Science and Technology Project(2023ZZ19).
文摘By integrating core observations,logging data and seismic interpretation,this study takes the massive Cretaceous carbonates in the M block of the Santos Basin,Brazil,as an example to establish the sequence filling pattern of fault-bounded isolated platforms in rift lake basins,reveal the control mechanisms of shoal-body development and reservoir formation,and reconstruct the evolutionary history of lithofacies paleogeography.The following results are obtained.(1)Three tertiary sequences(SQ1-SQ3)are identified in the Lower Cretaceous Itapema-Barra Velha of the M block.During the depositional period of SQ1,the rift basement faults controlled the stratigraphic distribution pattern of thick on both sides and thin in the middle.The strata overlapped to uplift in the early stage.During the depositional period of SQ2-SQ3,the synsedimentary faults controlled the paleogeomorphic reworking process with subsidence in the northwest and uplifting in the northeast,accompanied with the relative fall of lake level.(2)The Lower Cretaceous in the M block was deposited in a littoral-shallow lake,with the lithofacies paleogeographic pattern transiting from the inner clastic shoals and outer shelly shoals in SQ1 to the alternation of mounds and shoals in SQ2-SQ3.(3)Under the joint control of relative lake-level fluctuation,synsedimentary faults and volcanic activity,the shelly shoals in SQ1 tend to accumulated vertically in the raised area,and the mound-shoal complex in SQ2-SQ3 tends to migrate laterally towards the slope-break belt due to the reduction of accommodation space.(4)The evolution pattern of high-energy mounds and shoals,which were vertically accumulated in the early stage and laterally migrated in the later stage,controlled the transformation of high-quality reservoirs from“centralized”to“ring shaped”distribution.The research findings clarify the sedimentary patterns of mounds and shoals and the distribution of favorable reservoirs in the fault-controlled lacustrine isolated platform,providing support for the deepwater hydrocarbon exploration in the subsalt carbonate rocks in the Santos Basin.
基金supported by the National Natural Science Foundation of China(Nos.42072141and 41702363)the Geological Survey of China(No.DD20221645)。
文摘As the largest intermontane basin in the northeastern Tibetan Plateau(TP),the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the TP.In this study,based on morphological comparison,fossil fruit of Cyclocarya from the Early Oligocene Shangganchaigou Formation in the Qaidam Basin is assigned as Cyclocarya cf.weylandii.The discovery of Cyclocarya cf.weylandii demonstrates the occurrence of Cyclocarya in the Oligocene sediment in Qaidam Basin.This is the first record of Cyclocarya fossil of Early Oligocene Age in China and indicates that Cyclocarya has existed on the northeastern TP since at least the Early Oligocene.The living analogues of the current fossil now lives in sub-tropical China,where the East Asian Monsoon is prevalent.Integrating the new fossils and previously reported fossil remains of plants and fishes,it can be inferred that the Early Oligocene Qaidam Basin was primarily influenced by westerly circulation and had a relatively warm and humid climate,which was in sharp contrast to the present-day climate in Qaidam Basin.
基金the University of Isfahan for the financial support。
文摘A sedimentological investigation was carried out to reconstruct the paleogeography of the Zagros Foreland Basin.Based on the study of more than 1000 rock samples,nine carbonate microfacies and three terrigenous facies were identified.The study reveals that the Maastrichtian succession was deposited in a widespread homoclinal ramp in the High Zagros Basin.Three(Gandom Kar area),two(Ardal area),seven(Gardbishe area),five(Shirmard area),two(Kuh-e-Kamaneh area),three(Kuh-e-Balghar area),and six(Murak area)of depositional sequences(3rd order)were identified.The thickness of the lowstand systems tract(LST)due to activities of local faults and subsidence in the southeast is more than in the central and northwest of the High Zagros Basin during the Early and Early Middle Maastrichtian.During the Middle Maastrichtian,the shallow and deep marine deposits were formed during the transgressive systems tract(TST)and highstand systems tract(HST)in this basin and the rate of subsidence in the center of this basin(Gardbishe area)is higher than in other areas and the platform was drowned in this area.The falling relative sea-level due to activities of local faults led to that marine deposits were absent in all parts of the High Zagros Basin(except the south part)during the Late Maastrichtian.Paleogeographical studies on the Zagros Basin during the Late Campanian-Maastrichtian showed the following results:shallow marine environments were developed in the southeast of this basin,and the turbidite,delta,and fluvial environments in the northwest were developed more than in other areas.
基金This research was supported by the Project for the Survey of Land and Resources in China(1212010633901)National Natural Science Foundation of China(Grant No.41572090)。
文摘There are 9 major coal-accumulating periods during geological history in China,including the Early Carboniferous,Late Carboniferous-Early Permian,Middle Permian,Late Permian,Late Triassic,Early-Middle Jurassic,Early Cretaceous,Paleogene and Neogene.The coal formed in these periods were developed in different coal-accumulating areas(CAA)including the North China,South China,Northwest China,Northeast China,the Qinghai–Tibet area,and China offshore area.In this paper,we investigated depositional environments,sequence stratigraphy,lithofacies paleogeography and coal accumulation pattern of five major coal-accumulating periods including the Late Carboniferous to Middle Permian of the North China CAA,the Late Permian of the South China CAA,the Late Triassic of the South China CAA,the Early-Middle Jurassic of the North and Northwest China CAA,and the Early Cretaceous in the Northeast China CAA.According to distribution of the coal-bearing strata and the regional tectonic outlines,we have identified distribution range of the coal-forming basins,sedimentary facies types and coal-accumulating models.The sequence stratigraphic frameworks of the major coal-accumulating periods were established based on recognition of a variety of sequence boundaries.The distribution of thick coals and migration patterns of the coal-accumulating centers in the sequence stratigraphic framework were analyzed.The lithofacies paleogeography maps based on third-order sequences were reconstructed and the distribution of coal accumulation centers and coal-rich belts were predicted.
基金financially supported by the “13th Five-Year Plan” National Science and Technology Major Projects(No. 2016ZX05002006-005)the National Natural Science Foundation of China (No. 41502147)the Sichuan Provincial University “nonconventional oil and gas” scientific research and innovation team construction plan
文摘Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels,secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas,whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies indicates that the mapping method reliably predicts the distribution of sweet spots. The application and understanding of the mapping method provide a reference for exploring tight sandstone reservoirs on a regional basis.
基金partially supported by the National Natural Science Foundation of China(Grant No.4187020378).
文摘Paleogeography is the merger of lithology,depositional environments,tectonic plate movements,topography,climate patterns and ecosystems(reefs,vegetation)through time(e.g.,Scotese,2014,2016,2017;Blakey,2019).The construction of paleogeographic maps using tectonic plate reconstructions requires a multi-year community effort that shares databases,standards and computer projection methods.
基金supported by the Project of the Mesozoic Tectonic Lithofacies Paleogeographic Mapping and Synthesize Research in Qinghai-Tibet Plateau, China Geological Survey(CGS),Ministry of Land and Resources, Project No-1212010610101the Project of the Typical Stratigraphical Sections Research in Qinghai-Tibet Plateau,CGS , Project No-1212011121257
文摘The Triassic petrostratigraphic system and chronologic stratigraphic sketch have been updated and perfected in the Qiangtang area, Qinghai-Tibet Plateau based on the integrated 1：250000 regional geological survey and the latest research progeny. The first finished 1：3000000 Triassic tectonic lithofacies paleogeographic maps in the Qiangtang area shows that the Triassic tectonic unit in the Qiangtang area can been divided into three parts from north to south： northern Qiangtang block; Longmucuo-Shuanghu suture zone; and southern Qiangtang block. The early-middle Triassic tectonic paleogeography in the Qiangtang area is divides into three sub- units： northern Qiangtang passive continental marginal basin （NQPB）, Longmucuo- Shuanghu residual basin （LSRB） and southern Qiangtang residual basin （SQRB）. The NQPB can be subdivided into four paleogeography units： The Tanggula-Zangxiahe shallow and bathyal sea; The Wangquanhe- Yingshuiquan carbonate platform; The Rejuechaka-Jiangaidarina littoral- shallow sea; and Qiangtang central uplift. The above units of The NQPB possess EW trend, geomorphology high in the south and low in the north, the seawater depth northward. The basinal paleo-current direction is unidirectional, and basinal tectonic subsidence center is in accord with the depo-center, located in the Tanggula-Zangxiahe belt, north of the basin. The sedimentation and tectonic evolution of the NQPB are characterized with passive continental marginal basin. The Qiangtang central orogenic denuded area （ancient land） may be as a sedimentary materials source of the NQPB. SQRB can be divided into two units： Duoma carbonate platform and southern Qiangtang neritic-deep sea. The late Triassic tectonic paleogeography in the Qiangtang area is the framework of the ＂archipelagic-sea＂ as a whole, and it may be divided into three sub-units： northern Qiangtang back- arc foreland basin（NQFB）, Longmucuo-Shuanghu residual basin（LSRB） and southern Qiangtang marginal-sea basin（SQMB）. Thereinto, NQFB can be divided into five paleogeography units： the Zangxiahe-Mingjinghu bathyal basin characterized with the flysch; the Tanggula shallow-sea shelf with the fine-clastics; the Juhuashang platform with carbonates; the Tumenggela-Shuanghu coastal- delta with coal-bearing clastics and the Nadigangri- Geladandong arc with volcanics and tuffs. In transverse section, the NQFB fills is wedge-shaped, and the sediments characterized with thicker in north and thinner in south, and with double materials derived from the Ruolagangri orogenic belt in north and the Shuanghu central orogenic belt in south. The late Triassic depocenter of NQFB is located in the middle of the basin, the Yakecuo-Bandaohu-Quemocuo belt, but the subsidence center in the north, the Zangxiahe- Mingjinghu belt, and basinal tectonic subsidence center not concordant with the depo-center. Late Triassic, the SQMB may be divided into three sub-units： Xiaochaka shallow-sea; Riganpeicuo platform~ and South Qiangtang southern bathyal basin. In transverse section, the basement of the SQMB is characterized with low in the northern and southern, but high in the middle; forming wedge shaped sediments with thicker in the north and thinner in the south; the sedimentary materials derived from the Qiangtang central uplift and Nadigangri arcs in north. The late Triassic subsidence centre of the SQMB is located in the northern （Xiaochaka area）, but the depocenter in the southern （Qixiancuo Suobucha area）. The sedimentation and tectonic evolution of the SQMB are characterized with marginal sea.
基金supported by National Key R&D Program Project of China(Grant No.2017YFC0603106)the Opening Foundation of State Key Laboratory of Continental Dynamics,Northwest University,China(Grant No.201210140)。
文摘The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are well-developed Paleozoic-Cenozoic strata in this basin,and these provide a crucial window to a greater understanding of the amalgamation process and source-to-sink relationships between the Alxa Block and surrounding tectonic units.However,due to intensive post-depositional modification,and lack of subsurface data,several fundamental issues-including the distribution and evolution of the depositional systems,provenance supplies and source-to-sink relationships during the Carboniferous-Permian remain unclear and thus hinder hydrocarbon exploration and limit the geological understanding of this basin.Employing integrated outcrop surveys,new drilling data,and detrital zircon dating,this study examines the paleogeographic distribution and evolution,and provenance characteristics of the Carboniferous-Permian strata in the Bayanhot Basin.Our results show that the Bayanhot Basin experienced a long-term depositional evolution process from transgression to retrogression during the Carboniferous-late Permian.The transgression extent could reach the central basin in the early Carboniferous.The maximum regional transgression occurred in the early Permian and might connect the Qilian and North China seas with each other.Subsequently,a gradual regression followed until the end of the Permian.The northwestern NCC appeared as a paleo-uplift area and served as a sediments provenance area for the Alxa Block at that time.The NCC,Bayanwula Mountain,and NQOB jointly served as major provenances during the Carboniferous-Permian.There was no ocean separation,nor was there an orogenic belt between the Alxa Block and the NCC that provided sediments for both sides during the Carboniferous-Permian.The accretion of the Alxa and North China blocks should have been completed before the Carboniferous period.
基金Supported by the China National Science and Technology Major Project(2016ZX05004-002)PetroChina Science and Technology Major Project(2021DJ0501)。
文摘To predict the large-scale source rock and reservoir distribution in Cambrian subsalt formations(Upper Sinian to Mid-Cambrian)in the Tarim Basin,more than 502D seismic lines and 3D data volume acquired latest,22 wells and some out-crops around this area were used to study the tectonic-lithofacies paleogeography,define the distribution of large scale source rocks and reservoirs,and sort out favorable zones.(1)The basin experienced evolution from ramp to deep-water mud-rich ramp,low-gradient slope,weak rimmed to strong rimmed platform,and the differentiation in the platform was controlled by pre-Cambrian palaeo-rifts.(2)The Luonan-Yubei ancient rift controlled the distribution of source rocks in the Lower Cambrian Yuertusi Formation,and this rift together with the northern depression are the main source rock area.(3)There are three sets of large-scale reservoirs,the Upper Sinian Qigebulake Formation,the Lower Cambrian Xiaorbulake Formation and the Wu-songger Formation,and shoal-mounds,early dolomitization and multi-levels of unconformities controlled reservoir develop-ment.(4)Four favorable zones,the north slope of Tazhong,upper slope of Maigaiti area,Keping-Wensu periphery,and south slope of Tabei,were evaluated.Of them,the north slope of Tazhong is most likely to have exploration breakthrough;the south slope of Tabei is the best area for exploring the Upper Sinian large scale weathering crust dolomite;Maigaiti slope and Kep-ing-Wensu periphery area improved in exploration potentials significantly,and are worth prospecting faster.
文摘The Mengyejing potash salt deposit(MPSD)is the only pre-Quaternary potash salt deposit in China.The MPSD is located in the southern Simao Basin,southeastern Tibetan Plateau.The MPSD,along with rock salts and clastic rocks,
基金Supportd by the China National Science and Technology Major Project(2016ZX05004-001)
文摘In recent years, natural gas exploration in the Sinian Dengying Formation and shale gas exploration in Doushantuo Formation have made major breakthroughs in the Sichuan Basin and its adjacent areas. However, the sedimentary background of the Doushantuo Formation hasn't been studied systematically. The lithofacies paleogeographic pattern, sedimentary environment, sedimentary evolution and distribution of source rocks during the depositional stage of Doushantuo Formation were systematically analyzed by using a large amount of outcrop data, and a small amount of drilling and seismic data.(1) The sedimentary sequence and stratigraphic distribution of the Sinian Doushantuo Formation in the middle-upper Yangtze region were controlled by paleouplifts and marginal sags. The Doushantuo Formation in the paleouplift region was overlayed with thin thickness, including shore facies, mixed continental shelf facies and atypical carbonate platform facies. The marginal sag had complete strata and large thickness, and developed deep water shelf facies and restricted basin facies.(2) The Doushantuo Formation is divided into four members from bottom to top, and the sedimentary sequence is a complete sedimentary cycle of transgression–high position–regression. The first member is atypical carbonate gentle slope deposit in the early stage of the transgression, the second member is shore-mixed shelf deposit in the extensive transgression period, and the third member is atypical restricted–open sea platform deposit of the high position of the transgression.(3) The second member has organic-rich black shale developed with stable distribution and large thickness, which is an important source rock interval and major shale gas interval. The third member is characterized by microbial carbonate rock and has good storage conditions which is conducive to the accumulation of natural gas, phosphate and other mineral resources, so it is a new area worthy of attention. The Qinling trough and western Hubei trough are favorable areas for exploration of natural gas(including shale gas) and mineral resources such as phosphate and manganese ore.
基金supported by the National Key R&D Plan of China(Grant No.2018YFE0204204)the National Natural Science Foundation of China(Grant Nos.42050104,41790455,and 42072116).
文摘The climate paleogeography,especially the climate classifications,helps to interpret the global and regional climate changes and intuitively compare the climate conditions in different regions.However,the application of climate classification in deep time(i.e.,climate paleogeography)is prohibited due to the usually qualitatively constrained paleoclimate and the inconsistent descriptions and semantic heterogeneity of the climate types.In this study,a climate paleogeography knowledge graph is established under the framework of the Deep-Time Digital Earth program(DDE).The hierarchical knowledge graph consists of five paleoclimate classifications based on various strategies.The classifications are described and their strengths and weaknesses are fully evaluated in four aspects:“simplicity,applicability,quantifiability,and comparability”.We also reconstruct the global climate distributions in the Late Cretaceous according to these classifications.The results are compared and the relationships among these climate types in different classifications are evaluated.Our study unifies scientific concepts from different paleoclimate classifications,which provides an important theoretical basis for the application of paleoclimate classifications in deep time.
文摘The Weihe Basin,which is known as a Cenozoic rift Basin,is special for its location where not only enrich oil,gas and water,but also is a"sweet"for environment evolution research.It sits in the transition area between the ordos basin with full of oil and gas resources in the north and the Qinling Orogenic Belt with rich mineral
基金Supported by the National Natural Science Foundation of China (41802147)China Postdoctoral Science(2019M651785)。
文摘Based on analysis of outcrop,drilling,logging and seismic data,and geotectonic background,the lithofacies paleogeography and paleokarst geomorphology of the Middle Permian Maokou Formation in the northwestern Sichuan Basin were reconstructed,and the petroleum geological significance of the lithofacies paleogeography and paleokarst geomorphology were discussed.The Maokou Formation is divided into 3 long-term cycles,namely LSCl,LSC2 and LSC3,which correspond to the Member 1,Member 2 and Member 3 of the Maokou Formation,respectively.Controlled by the extensional structure caused by opening of the Mianlue Ocean in the north margin of the upper Yangtze blocks and basement faults produced by mantle plume uplifting,the area had tectonic differentiation in NWW and NE,and sedimentary basement took on episodic settlement from north to south,as a result,the sedimentary systems of Member 1 to Member 3 gradually evolved from carbonate platform to platform-slope-continental shelf.According to the residual thickness,paleokarst geomorphologic units such as karst highland,karst slope and karst depression at different stages were reconstructed.The karst geomorphological units were developed successively on the basis of sedimentary geomorphology.Sedimentary facies and paleokarst geomorphology are of great significance for oil and gas accumulation.The Maokou Formation in northwestern Sichuan has two kinds of most favorable reservoir zone combinations:high energy grain shoal and karst monadnock,platform margin slope and karst slope.Based on this understanding,the planar distribution of the two kinds of reservoir zones were predicted by overlapping the favorable reservoir facies belt with paleokarst geomorphology.The study results provide a new idea and reference for the exploration deployment of the Middle Permian Maokou Formation in the Sichuan Basin.
基金Supported by the China National Science and Technology Major Project(2011ZX05028-003,2016ZX05029-001)
文摘By using a large amount of geological and geophysical data, the geological characteristics such as lithofacies and paleogeography of 4981 geological units at thirteen key geological periods or epoches since the Precambrian in the world have been figured out. The global lithofacies and paleogeography charts have been compiled by ArcGis mapping technology. Combined with the results of plate-paleogeography reconstruction, the lithofacies and paleogeography as well as the prototype basins of these global paleoplates have been restored with the Gplate software. Results show that there are 22 kinds of lithofacies combinations and 10 types of paleogeography units developed since Precambrian. These features of lithofacies and paleogeography as well as their evolution were mainly controlled by the divergent and convergent movements of those plates. Taking the results of the lithofacis and paleogeography at the present and paleoplate location during the seven key geological periods from the Precambrian to Paleozoic for example, during the Late Precambrian and Cambrian, the large-scale disintegration of the Rodinia supercontinent resulted in reduction of uplift denudation area and clastic terrestrial facies area, the expansion of coastal-shallow marine facies and shallow-water carbonate platform. In Devonian, uplift denudation area and clastic terrestrial facies area began to increase and littoral-shallow marine facies area and shallow-water carbonate platform shrank as a result of the formation of Larussia supercontinent. In the Permian, with the formation of the Pangea continent, the development of the global uplift denudation area and clastic terrestrial facies reached its peak, while the littoral and shallow marine facies were very limited in distribution. The lithofacies and paleogeography features and evolution patterns of different stages lay a solid foundation for analyzing the formation conditions of geological elements, such as source rocks, reservoirs and cap rocks for oil and gas accumulation, and revealing the distribution regularity of oil and gas around the world.
基金Supported by China National Science and Technology Major Project (2016ZX05003-001)PetroChina Science and Technology Project (2019B-0505,2021DJ0202,2021DJ0302)。
文摘In view of the difficulties in the study of lithofacies paleogeography and the low reliability of the distribution range of sedimentary sand bodies in the prototype basin caused by less deep drilling, complex seismic imaging and low degree of exploration in the southern margin of Junggar Basin, NW China. A new method based on the source to sink idea was used to restore lithofacies paleogeography and predict glutenite distribution. In the restoration, apatite fission track age was used to define range and uplift time of macro-provenance;the range of provenance area and the migration process of lake shoreline were restored based on the quantitative relationship between gravel diameter and transportation distance, tectonic shortening and other geological parameters;drilling cores and field outcrop sedimentary structures were analyzed, and a series of maps of lithofacies paleogeographic evolution and distribution range of glutenite bodies were compiled. It is concluded that from Early Jurassic to Early Cretaceous, in the southern margin of Junggar Basin, the provenance area gradually expanded from south to north, the lake basin expanded, shrunk and expanded, and the paleoclimate changed from humid to drought to humid. The western section always had proximal fan delta deposits from the southern ancient Tianshan provenance developed, and in the middle and eastern sections, the provenance areas evolved from far source to near source, mainly river-delta, braided delta, fan delta and other sediments developed. The boundary between provenance areas of the western and middle sections is speculated to be Hongche fault zone. In an angle open to the northwest with the current basin edge line, the restored ancient lake shoreline controlled the heterogeneity of reservoirs in the delta plain belt and delta front belt on its both sides. The ancient lake shoreline, current stratigraphic denudation line and current basin margin line limit the types and scope of favorable reservoirs.This understanding provides an important geological basis for oil and gas exploration in the deep lower source-reservoir assemblage at the southern margin of Junggar Basin.
基金Supported by the China National Science and Technology Major Project(2016ZX05004-001)
文摘The paleotectonic pattern,lithofacies paleogeographic features,sedimentary evolution and its controlling effects on hydrocarbon accumulation assemblages during the depositional period of the Sinian Dengying Formation in middle-upper Yangtze region were investigated based on outcrops,drilling,log and seismic data.The study shows that,(1)Affected by the breakup of the Rodinia supercontinent,the middle and upper Yangtze areas were in extensional tectonic environment during the depositional period of Dengying Formation.The carbonate platform was structurally differentiated.Intra-platform depressions controlled by syndepositional faults developed,forming a tectonic-paleogeographic pattern of"three platforms with two depressions".(2)During the depositional period of the first and second members of the Dengying Formation,rimmed platforms and intra-platform fault depressions developed in upper Yangtze area and isolated platform developed in middle Yangtze area,and there was the Xuanhan-Kaijiang ancient land block in eastern Sichuan.The depositional period of the third member of the Dengying Formation is the transformation period of tectonic-paleogeographic pattern,when a set of shallow water shelf sediment rich in mud was deposited due to transgression on the background of the eroded terrain formed in EpisodeⅠof Tongwan Movement.The sediment of the fourth member of the Dengying Formation inherited the paleogeographic pattern of the first and second members of the Dengying Formation in general,but the Deyang-Anyue intra-platform fault depression further expanded,and the middle Yangtze platform evolved into two separated platforms.(3)Tectonic-sedimentary differentiation and evolution of carbonate platform in the Sinian gave rise to two types of accumulation assemblages with wide distribution and great exploration potential,which are platform margin and intra-platform.
基金Supported by the PetroChina Science and Technology Major Project(2016E-0601)
文摘Based on isotopic, lithologic and electrical data and logging cycle analysis technique, stratigraphic sequences in the Middle-Upper Cambrian Xixiangchi Group in the Sichuan Basin and its adjacent area are divided, and its sedimentary characteristics and evolution are analyzed. The Xixiangchi Group can be divided into 5 third-order sequences(Sql-Sq5), of which sequences Ⅰ to Ⅲ(Sql-Sq3) are relatively complete, sequences Ⅳ and Ⅴ are denuded in the Late Cambrian because of the Dian-Chuan paleo-uplifts.Third-order sequences of the Xixiangchi Group in this area have the characteristics of thin in the west and thick in the east, showing that the Caledonian paleo-uplift is a synsedimentary paleo-uplift and the paleogeomorphology in the platform is a gentle slope. Sequence Ⅰdevelops high stand systems tract and transgressive systems tract. The other third-order sequences are dominated by highstand systems tracts, and the transgressive systems tracts last shortly in time and are limited in area. The basic features of evaporative-restricted platform of gentle slope type developed continuously in the sedimentary period of the Xixiangchi Group, its sedimentary environment of "high in west and low in east" and the change of micro paleogeomorphology in the platform control the continuous development of sedimentary facies. Open platform is developed only in sequence Ⅰ and sequence Ⅱ, and the inner beach of the platform and the edge beach of the platform are mostly developed in sequence Ⅱ and sequence Ⅲ. It indicates that there are two platform margin zones in the study area,a relatively stable, large-scale platform marginal zone in NE Guizhou-Western Hunan and Hubei, and a moving and small-scale platform marginal zone in North Chongqing-Western Hubei.
基金Supported by the China National Science and Technology Major Project(2011ZX05028-003,2016ZX05029-001).
文摘Based on the compilation and analysis of the lithofacies and paleogeography distribution maps at present and paleoplate locations during six key geological periods of the Mesozoic and Cenozoic,the lithofacies and paleogeography features and their development laws were expounded.Based on our previous research results on lithofacies and paleogeography from Precambrian to Paleozoic,we systematically studied the features and evolution laws of global lithofacies and paleogeography from the Precambrian and their effects on the formation of source rocks,reservoirs,cap rocks and the distribution of oil and gas worldwide.The results show that since Precambrian,the distribution areas of uplift erosion and terrestrial clastic deposition tended to increase gradually,and increased significantly during the period of continental growth.The scale of coastal and shallow marine facies area had three distinct cycles,namely,from Precambrian to Devonian,from Carboniferous to Triassic,and from Jurassic to Neogene.Correspondingly,the development of shallow carbonate platform also showed three cycles;the lacustrine facies onshore was relatively developed in Mesozoic and Cenozoic;the sabkha was mainly developed in the Devonian,Permian and Triassic.The Cretaceous is the most important source rock layers in the world,followed by the Jurassic and Paleogene source rocks;the clastic reservoirs have more oil and gas than the carbonate reservoirs;the basins with shale caprocks have the widest distribution,the most abundant reserves of oil and gas,and the evaporite caprocks have the strongest sealing capacity,which can seal some huge oil and gas fields.
文摘For predicting the distribution of favorable reservoir facies belts of the super-large ancient Anyue carbonate gas field in the Sichuan Basin,through an analysis of structure and lithofacies paleogeography,the lithofacies paleogeography and sedimentary model of the Sinian Dengying Fm was reconstructed based on the field outcrop,drilling and seismic data.As a result,achievements are made in four aspects.First,the basin and its periphery resided in an extensional tectonic setting in the Sinian.Intense extension led to the formation of the Deyang-Anyue intraplatform rift.The Sichuan Basin was divided into the palaeo-geographic pattern of“two uplifts and four sags”.The“two uplifts”evolved into the platform,and the“four sags”evolved into the slope-basin environment.Second,in the depositional stage of the Deng 2 Member,some favorable reservoir belts developed,such as bioherm-shoal at the continental margin,bioherm-shoal at the rift margin,and bioherm-shoal in the platform.The bioherm-shoal at rift margin developed along both sides of the DeyangeAnyue rift,in a U-shape,with a width of about 5-40 km and a length of about 500 km.It connected with the platform margin belt at the continental margin to the west in the Shifang area,and to the north near Guangyuan area.Third,in the depositional stage of the Deng 4 Member,when the lithofacies paleogeographic features in the Deng 2 Member remained,the platform margin belt at the rift margin evolved into two parts in the east and the west as a result of the continuous southward extensional faulting of the Deyang-eAnyue rift until it finally crossed the basin from north to south.The eastern platform margin belt was located in the Guangyuan-Yanting-Anyue-Luzhou area,showing NS distribution with a length of about 450 km and a width of about 4-50 km.The western platform margin belt mainly developed in the Dujiangyan-Chengdu-Weiyuan-Yibin-Mabian area,showing an eastward arc distribution with a length of about 300 km and a width of 4-30 km.And fourth,the sedimentary model of rimmed platform with double platform margins in the Dengying Fm was established,providing a guidance for predicting the distribution of favorable reservoir facies belts.
