Qinling orogen is one of the five main repository distribution provinces of large scale graphite resources. Graphite occurrence strata are multitudinous including NeoArchaean group to Neopaleozoic. Mineral deposit typ...Qinling orogen is one of the five main repository distribution provinces of large scale graphite resources. Graphite occurrence strata are multitudinous including NeoArchaean group to Neopaleozoic. Mineral deposit types are complete consisting of crystal flaky graphite deposit and aphanitic graphite deposit, ore types of the former are main graphite gneiss, graphite schist and graphitized marble, and ore types of the latter are main graphite layer metamorphosised from coal bed and graphitic carbargilite. At present, most graphite deposits with low research degree only implement preliminary investigations of the graphite resource, which has a good prospect. Based on the basic material of dozens of graphite deposits, spots and plays discovered in the Qinling orogen, this paper applied geologic multidisciplinary analysis method to disclose the graphite deposit types of the Qinling orogen, mainly through outdoors geologic survey and specimen examination with analysis of some typical deposits： regional metamorphism crystal graphite deposits and thermo-contact metamorphic aphanitic graphite deposits, with the control of latitudinally trending regional tectonic, graphite deposits of the Qinling orogen distribute sublatitudinally trending three large ore belts： I the Neoarchean-Proterozoic basement crystal graphite enrichment deposits zone along the south margin of North China plate; II the Carboniferous intermountain basin group aphanitic graphite enrichment deposits zone near the Shangdan suture of the West Qinling; III Paleozoic crystal graphite enrichment deposits zone in the Qinling paleomicroplate of the west part of the East Qinling.Conclusions are reached from multiple inquiries： Qinling multi-cycle complex continental collision orogen zone has experienced multiple tectonic framework transformation and polyphase tectonic thermal event from NeoArchean Erathem adjointing multiple graphite tectonic mineralization cycle. In the light of chief control of mineralization and ore types, each of the three large graphite deposits belts of the Qinling orogen has its own genesis： I graphite deposits enriched metallogenetic zone is that regional tectogenetic movement from NeoArchaean caused polyphase metapepsis, which superimposed up and reconstructed NeoArchean Erathem to Proterozoic basement, forming regional metamorphic big flake crystal graphite deposits; I! graphite deposits enriched metallogenetic zone is that polyphase regional tectogenetic movement associated with multiple heating caused by multiphase igneous intrusion, which resulted in original coal layers emerging multiple thermo-contact metamorphisms and formed thermo-contact metamorphic aphanitic graphite deposits. III graphite deposits enriched metallogenetic zone is that Palaeozoic cap- rock experienced polyphase metapepsis, forming regional metamorphic finely flake crystal graphite deposits. Cemprehensive research of metallogenetic mechanism in graphite deposits and its associated profitable deposits of the Qinling orogen is importance for future exploration.展开更多
Research into the contourite deposits in the Upper Meishan Formation of the southern Qiongdongnan Basin in South China Sea is weak;their characteristics,distribution and original geological conditions are not clear.Us...Research into the contourite deposits in the Upper Meishan Formation of the southern Qiongdongnan Basin in South China Sea is weak;their characteristics,distribution and original geological conditions are not clear.Using geologic al and geophysical methods including seismic and drilling data,based on seismic reflection characteristics,geometrical configuration description,and wave impedance inversion,two types of contourite deposits are recognized.Contourite deposits have blurred boundaries between each deposit and disordered internal seismic reflections;They are mound-shaped only in transverse section,and banded in the longitudinal direction.TypeⅠcontourite deposits are conical,with mediumhigh amplitude,low-continuity,low-frequency mound-shaped seismic facies,and subparallel-chaotic reflections internally.These deposits are conical with sharp tops,the canal between mounds is V-shaped and deep.The western wing is gentle and the eastern wing is steep,with the slope toe mostly between 10°and 20°,and width height ratio about 1-2.TypeⅡcontourite deposits are flat,exhibiting medium-amplitude,medium-continuity,low-frequency mound-shaped seismic facies,with subparallel weak reflections internally.Their mounds are flat with gently arced tops,with shallow canals between.The slope toe is between 5°and 10°,with a width height ratio of about 2-5.The wave impedance value of these contourite deposits is 4.6 kg/m^(3)×m/s to 6.8 kg/m^(3)×m/s,about 5.8 kg/m^(3)×m/s on average,which is presumed to represent marlycalcareous clastic sediments.The contourite deposits mainly develop beneath the slope break at the margin of the faultcontrolled platform in the Southern Uplift zone of the basin.In plane view,they are distributed approaching a west-to-east direction,and in section,lie in low-lying areas near the faults at fault-controlled terraces of the Southern Uplift zone,with a paleo-current direction nearly west-to-east.The paleotectonic setting of the gentle monoclinic platform was favorable for the development of such contourite deposits.The intensification of the Mid-Miocene deepest bottom current gave rise to the contourite-forming currents around the Southern Uplift zone in the northern South China Sea,which flow from Hainan Island to the Xisha Trough in a nearly west-to-east direction leading to the contourite deposits developing in the late MidMiocene transgressive environment,with multiple slow sea-level fall cycles.展开更多
Many mound-shaped reflectors with different features and shapes are evident in the Upper Member of the Meishan Formation from seismic profiles taken in the deep-water area of the Southern Qiongdongnan Basin.Based on t...Many mound-shaped reflectors with different features and shapes are evident in the Upper Member of the Meishan Formation from seismic profiles taken in the deep-water area of the Southern Qiongdongnan Basin.Based on the drilling,2 D and 3 D seismic data from the study area,descriptions of the seismic reflection characteristics as well as the geometric shape,wave impedance inversion,analogy and comparative analyses are carried out.Taken in conjunction with research on the paleo structure and paleo sedimentary background,we consider that the mound-shaped seismic reflectors are distributed in the Southern Slop belt and the Southern High-rise of the Qiongdongnan Basin,which can be subdivided into three types:reefs,contourite mounds and magmatic diapirs.The first type,reefs,includes patch reefs,platform marginal reefs and pinnacle reefs.Patch reefs present mound-shaped seismic facies with medium frequency and a moderately strong amplitude,being distributed at the uplift of the fault control platform on the Southern Slop belt.The platform marginal reefs have flat mound-shaped seismic facies with strong amplitude and medium frequency,developing at the margin of the carbonate platform in the Southern High-rise.The pinnacle reefs have mound-shaped seismic facies with strong amplitude and medium frequency and are developed on an isolated volcanic cone.The boundaries between individual reefs are clear on the seismic section,with reef ridge and reef ditch developed,the phenomenon of’front product’being visible within,two-way superelevation between wings is developed and they exist visibly as mounds in any viewed direction of the crosssection.They are slightly asymmetrical in the direction perpendicular to the paleodepth the reef body being steep near the deep-water side,while being gentle near the shallow water side.The wave impedance of a patch reef is about 7 kg/m^(3)×m/s,while the wave impedance of a platform marginal reef is about 7.5 kg/m^(3)×m/s.The second type-contourite moundsare mainly developed under the slope break of the southern slope fault control platform’s edge.They are subdivided into two types:conical and flat.The former has mound-shaped seismic facies with medium-strong amplitude and low frequency,the latter having mound-shaped seismic facies with medium amplitude and low frequency.The internal texture of the mounds is not clear on the seismic section,with the boundaries between contourite mounds being blurred.They are mound-shaped only in cross-section,being banded in the extending direction.The upper surface of a single contourite mound is relatively gentle near the deep-water side,while being steep near the shallow water area.The wave impedance of contourite mounds is about 5.8 kg/m^(3)×m/s,which is speculated to represent a marly to calcareous clastic deposit.The third type is the magmatic diapir,which has’roots’.They have a dome-shaped upper boundary,are bottomless,with a chaotic interior.They penetrated multiple formations,opening towards the base.There are two major accumulation assemblages of reefs,one is the platform margin reef accumulation assemblage with distant source rocks and long-distance migration through an unconformity surface in the Southern High-rise,the other is the patch reef accumulation assemblage with twin sources and short distance migration through faults in the Southern Slop belt near the Central Depression zone.The latter is the main exploration targets at present.There are contourite mound accumulation assemblages with nearby source rocks and short distance vertical migration through faults,which are potentially important targets.The magmatic diapirs pierce the overlying strata and form good hydrocarbon traps and migration pathways,thus representing potential prospecting targets.展开更多
1 Introduction Yining basin, an independent unit of the Yili- Zhongtianshan micro plate （Wang et al., 2007; Han et al., 2011）, is an intermontane superimposed basin （Dai et al., 2015）. Yining basin has well-develo...1 Introduction Yining basin, an independent unit of the Yili- Zhongtianshan micro plate （Wang et al., 2007; Han et al., 2011）, is an intermontane superimposed basin （Dai et al., 2015）. Yining basin has well-developed Tiemulike dark shale with normal lake facies formed in late period of middle Permian, which has good foreground material conditions of shale gas reservoirs from the study of predecessors.展开更多
1 Deepwater Settings of Marginal Seas一the Frontier of Oil and Gas Exploration From the perspective of geographical environment,the areas of global oil and gas exploration can be divided into land,shallow water and de...1 Deepwater Settings of Marginal Seas一the Frontier of Oil and Gas Exploration From the perspective of geographical environment,the areas of global oil and gas exploration can be divided into land,shallow water and deep water areas.The timespan of oil and gas discovery in each field is different.Oil and gas have been discovered on land since ancient tinies,but the application of modern technology to discover oil and gas began in 1859 in Pennsylvania,USA(Hua,1984).Largescale oil and gas exploration began in the 1920s,and the reserve discovery reached its peak in the 1960s and 1970s.展开更多
基金financially supported by National Natural Science Foundation of China (NO.41390451 and NO.41172101)Science and technology research projects of China Coal Geological Bureau (2013-I-03)basic geological survey project of China Geological Survey (12120114083001)
文摘Qinling orogen is one of the five main repository distribution provinces of large scale graphite resources. Graphite occurrence strata are multitudinous including NeoArchaean group to Neopaleozoic. Mineral deposit types are complete consisting of crystal flaky graphite deposit and aphanitic graphite deposit, ore types of the former are main graphite gneiss, graphite schist and graphitized marble, and ore types of the latter are main graphite layer metamorphosised from coal bed and graphitic carbargilite. At present, most graphite deposits with low research degree only implement preliminary investigations of the graphite resource, which has a good prospect. Based on the basic material of dozens of graphite deposits, spots and plays discovered in the Qinling orogen, this paper applied geologic multidisciplinary analysis method to disclose the graphite deposit types of the Qinling orogen, mainly through outdoors geologic survey and specimen examination with analysis of some typical deposits： regional metamorphism crystal graphite deposits and thermo-contact metamorphic aphanitic graphite deposits, with the control of latitudinally trending regional tectonic, graphite deposits of the Qinling orogen distribute sublatitudinally trending three large ore belts： I the Neoarchean-Proterozoic basement crystal graphite enrichment deposits zone along the south margin of North China plate; II the Carboniferous intermountain basin group aphanitic graphite enrichment deposits zone near the Shangdan suture of the West Qinling; III Paleozoic crystal graphite enrichment deposits zone in the Qinling paleomicroplate of the west part of the East Qinling.Conclusions are reached from multiple inquiries： Qinling multi-cycle complex continental collision orogen zone has experienced multiple tectonic framework transformation and polyphase tectonic thermal event from NeoArchean Erathem adjointing multiple graphite tectonic mineralization cycle. In the light of chief control of mineralization and ore types, each of the three large graphite deposits belts of the Qinling orogen has its own genesis： I graphite deposits enriched metallogenetic zone is that regional tectogenetic movement from NeoArchaean caused polyphase metapepsis, which superimposed up and reconstructed NeoArchean Erathem to Proterozoic basement, forming regional metamorphic big flake crystal graphite deposits; I! graphite deposits enriched metallogenetic zone is that polyphase regional tectogenetic movement associated with multiple heating caused by multiphase igneous intrusion, which resulted in original coal layers emerging multiple thermo-contact metamorphisms and formed thermo-contact metamorphic aphanitic graphite deposits. III graphite deposits enriched metallogenetic zone is that Palaeozoic cap- rock experienced polyphase metapepsis, forming regional metamorphic finely flake crystal graphite deposits. Cemprehensive research of metallogenetic mechanism in graphite deposits and its associated profitable deposits of the Qinling orogen is importance for future exploration.
基金supported by the National Natural Science Foundation of China(grant no.41972155)the Jiangxi Provincial Natural Science Foundtion(grant no.2020BABL211019)the National Science and Technology Major Profect(grant no.2016ZX05026007)。
文摘Research into the contourite deposits in the Upper Meishan Formation of the southern Qiongdongnan Basin in South China Sea is weak;their characteristics,distribution and original geological conditions are not clear.Using geologic al and geophysical methods including seismic and drilling data,based on seismic reflection characteristics,geometrical configuration description,and wave impedance inversion,two types of contourite deposits are recognized.Contourite deposits have blurred boundaries between each deposit and disordered internal seismic reflections;They are mound-shaped only in transverse section,and banded in the longitudinal direction.TypeⅠcontourite deposits are conical,with mediumhigh amplitude,low-continuity,low-frequency mound-shaped seismic facies,and subparallel-chaotic reflections internally.These deposits are conical with sharp tops,the canal between mounds is V-shaped and deep.The western wing is gentle and the eastern wing is steep,with the slope toe mostly between 10°and 20°,and width height ratio about 1-2.TypeⅡcontourite deposits are flat,exhibiting medium-amplitude,medium-continuity,low-frequency mound-shaped seismic facies,with subparallel weak reflections internally.Their mounds are flat with gently arced tops,with shallow canals between.The slope toe is between 5°and 10°,with a width height ratio of about 2-5.The wave impedance value of these contourite deposits is 4.6 kg/m^(3)×m/s to 6.8 kg/m^(3)×m/s,about 5.8 kg/m^(3)×m/s on average,which is presumed to represent marlycalcareous clastic sediments.The contourite deposits mainly develop beneath the slope break at the margin of the faultcontrolled platform in the Southern Uplift zone of the basin.In plane view,they are distributed approaching a west-to-east direction,and in section,lie in low-lying areas near the faults at fault-controlled terraces of the Southern Uplift zone,with a paleo-current direction nearly west-to-east.The paleotectonic setting of the gentle monoclinic platform was favorable for the development of such contourite deposits.The intensification of the Mid-Miocene deepest bottom current gave rise to the contourite-forming currents around the Southern Uplift zone in the northern South China Sea,which flow from Hainan Island to the Xisha Trough in a nearly west-to-east direction leading to the contourite deposits developing in the late MidMiocene transgressive environment,with multiple slow sea-level fall cycles.
基金funded by the National Natural Science Foundation of China(41872172,42072188)Jiangxi Provincial Natural Science Foundation(20202BABL211019)Open Fund Project of the Key Laboratory of Sedimentary Mineralization and Sedimentary Mineral Resources in Shandong Province(DMSM 2019008)。
文摘Many mound-shaped reflectors with different features and shapes are evident in the Upper Member of the Meishan Formation from seismic profiles taken in the deep-water area of the Southern Qiongdongnan Basin.Based on the drilling,2 D and 3 D seismic data from the study area,descriptions of the seismic reflection characteristics as well as the geometric shape,wave impedance inversion,analogy and comparative analyses are carried out.Taken in conjunction with research on the paleo structure and paleo sedimentary background,we consider that the mound-shaped seismic reflectors are distributed in the Southern Slop belt and the Southern High-rise of the Qiongdongnan Basin,which can be subdivided into three types:reefs,contourite mounds and magmatic diapirs.The first type,reefs,includes patch reefs,platform marginal reefs and pinnacle reefs.Patch reefs present mound-shaped seismic facies with medium frequency and a moderately strong amplitude,being distributed at the uplift of the fault control platform on the Southern Slop belt.The platform marginal reefs have flat mound-shaped seismic facies with strong amplitude and medium frequency,developing at the margin of the carbonate platform in the Southern High-rise.The pinnacle reefs have mound-shaped seismic facies with strong amplitude and medium frequency and are developed on an isolated volcanic cone.The boundaries between individual reefs are clear on the seismic section,with reef ridge and reef ditch developed,the phenomenon of’front product’being visible within,two-way superelevation between wings is developed and they exist visibly as mounds in any viewed direction of the crosssection.They are slightly asymmetrical in the direction perpendicular to the paleodepth the reef body being steep near the deep-water side,while being gentle near the shallow water side.The wave impedance of a patch reef is about 7 kg/m^(3)×m/s,while the wave impedance of a platform marginal reef is about 7.5 kg/m^(3)×m/s.The second type-contourite moundsare mainly developed under the slope break of the southern slope fault control platform’s edge.They are subdivided into two types:conical and flat.The former has mound-shaped seismic facies with medium-strong amplitude and low frequency,the latter having mound-shaped seismic facies with medium amplitude and low frequency.The internal texture of the mounds is not clear on the seismic section,with the boundaries between contourite mounds being blurred.They are mound-shaped only in cross-section,being banded in the extending direction.The upper surface of a single contourite mound is relatively gentle near the deep-water side,while being steep near the shallow water area.The wave impedance of contourite mounds is about 5.8 kg/m^(3)×m/s,which is speculated to represent a marly to calcareous clastic deposit.The third type is the magmatic diapir,which has’roots’.They have a dome-shaped upper boundary,are bottomless,with a chaotic interior.They penetrated multiple formations,opening towards the base.There are two major accumulation assemblages of reefs,one is the platform margin reef accumulation assemblage with distant source rocks and long-distance migration through an unconformity surface in the Southern High-rise,the other is the patch reef accumulation assemblage with twin sources and short distance migration through faults in the Southern Slop belt near the Central Depression zone.The latter is the main exploration targets at present.There are contourite mound accumulation assemblages with nearby source rocks and short distance vertical migration through faults,which are potentially important targets.The magmatic diapirs pierce the overlying strata and form good hydrocarbon traps and migration pathways,thus representing potential prospecting targets.
基金financially supported by Shale Gas Resources Survey Project in Northwest of China(NO.[2014]03-020-004)
文摘1 Introduction Yining basin, an independent unit of the Yili- Zhongtianshan micro plate （Wang et al., 2007; Han et al., 2011）, is an intermontane superimposed basin （Dai et al., 2015）. Yining basin has well-developed Tiemulike dark shale with normal lake facies formed in late period of middle Permian, which has good foreground material conditions of shale gas reservoirs from the study of predecessors.
基金funded by the National Science and Technology Major Project(grant nos.2016ZX05026,20HZX05025,2008ZX05025)the Jiangxi Provincial Natural Science Foundation(grant no.20202BABL211019)the major research projects of NSFC(grant no.2009CB219400).In particular,we would like to thank associate E1C Zhang Gongcheng for his attention to the scientific research achievements of our team.We thank the team members for their sincere and united work as always.Thanks to all the leaders,colleagues and graduate students who have supported and cared about the team's research work for many years.Many thanks for the constructive opinions and suggestions from the peer reviewers.Thanks to the hard work of the chief editor and all the editors of Acta Geologica Sinica(English Edition)including Susan Turner(Brisbane)who assisted with English language。
文摘1 Deepwater Settings of Marginal Seas一the Frontier of Oil and Gas Exploration From the perspective of geographical environment,the areas of global oil and gas exploration can be divided into land,shallow water and deep water areas.The timespan of oil and gas discovery in each field is different.Oil and gas have been discovered on land since ancient tinies,but the application of modern technology to discover oil and gas began in 1859 in Pennsylvania,USA(Hua,1984).Largescale oil and gas exploration began in the 1920s,and the reserve discovery reached its peak in the 1960s and 1970s.
