The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of tran...The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.展开更多
1 Introduction The eastern Tianshan region covers around 60000 km2in area and is located in the eastern part of Xinjiang.The district contains various types mineral commodities including Cu,Ni,Au,Fe,Pb and Zn(Wang et ...1 Introduction The eastern Tianshan region covers around 60000 km2in area and is located in the eastern part of Xinjiang.The district contains various types mineral commodities including Cu,Ni,Au,Fe,Pb and Zn(Wang et al.,2006).The Dannanhu belt in eastern part of the area is interpreted as a volcanic arc and forms an important mineralized zone bordered by the Turpan-Hami Basin to the north and Kanggur back-arc basin to the south.展开更多
Electron paramagnetic resonance spectra, absorption spectra, cathodoluminescence spectra and infrared spectra of sphalerite from the Lechang remoulded sedimentary lead-zinc deposit have been studied so as to provide m...Electron paramagnetic resonance spectra, absorption spectra, cathodoluminescence spectra and infrared spectra of sphalerite from the Lechang remoulded sedimentary lead-zinc deposit have been studied so as to provide microscopic evidence for the formation conditions and mineralization stages of the deposit as well as the geochemical processes of mineralization. On the basis of thermodynamic calculations, the stable fields of sphalerite from different mineralization stages were determined and are shown in logfs_2-logfo_2 diagrams; furthermore. the physico-chemical conditions of mineralization and the properties of mineralization solutions are discussed so that reliability of the genetic information provided by the spectroscopy of sphalerite may also be verified. It is suggested that the temperature and pH value of the mineralization system decrease, and so do the fugacities of O_2, S_2, H_2. and H_2S and the activities of HS^- and SO_4^(2-) from the early to late stages of minerahzation.展开更多
The recently confirmed Hapcheon impact crater in Korea is a complex impact structure 7 km in diameter,with clear rims and impact-driven underground lacustrine sedimentary features.We investigated the lithological feat...The recently confirmed Hapcheon impact crater in Korea is a complex impact structure 7 km in diameter,with clear rims and impact-driven underground lacustrine sedimentary features.We investigated the lithological features of deposits within the impact crater using drilled sedimentary cores(23HIC01,20CR05,20CR09,and 20CR10),which consisted of an ascending order of impact breccias,lake sediments,and subaerial(e.g.,wetland)sediments.The impact breccia deposits in the 20CR05 and 23HIC01 cores contain shatter cones,which are a macroscopic indication of a meteorite impact.The overlying lake sediments were divided into three stages.The early stage of the post-impact lake environment corresponded to the lowermost lake sediments with frequent microfaults and slump-turbidite events.This stage is characterized by high calcite content of up to 13%.The middle stage showed a stable depositional environment,with silty to sandy lamination and bedding,and fewer microfaults.The final stage of the post-impact lake environment appears to have been very short and dramatic.This ended with the final slumping event,which appears to have been triggered by an abrupt outburst of lake water.This study demonstrates early post-impact lake sedimentation processes and crater instability in terms of soft-sediment deformation structures(e.g.,microfaults and slumps).展开更多
The upper Dalan and Kangan or Permian-Triassic carbonate formations in the central the Persian Gulf are considered as world's giant gas reservoirs.The primary purpose of this research is to model and evaluate the ...The upper Dalan and Kangan or Permian-Triassic carbonate formations in the central the Persian Gulf are considered as world's giant gas reservoirs.The primary purpose of this research is to model and evaluate the relationship between hydraulic flow units(HFUs),electrofacies and microfacies with systems tracts of Permian-Triassic sequences.By integrating the results of core data,petrographic studies,and petrophysical logs of the studied formations,hydraulic flow units and electrofacies were identified.Based on the results of petrographic studies,twelve microfacies were identified in terms of textural and depositional characteristics.Based on depositional setting,sedimentary facies and INPEFA values obtained from gamma ray log and gamma deviation log(GDL)in the context of sequence stratigraphy,zonation of Dalan and Kangan reservoirs is carried out.The zonation boundaries correspond to the key stratal surfaces(sequence boundary and maximum flooding surface).Seven petrographic rock types(PRT)were identified for the upper Dalan-Kangan reservoirs based on sedimentary texture,diagenetic process and dominant pores.Using porosity and permeability data from the core analysis,five hydraulic flow units were identified based on the flow zone indicator(FZI)method.Using multi-resolution graph-based clustering(MRGC)four electrofacies were detected from petrophysical data(gamma,neutron,density and acoustic logs).Subsequently,the INPEFA,GDL and electrofacies were spatially modeled using the sequential indicator simulation(SIS)and sequential Gaussian simulation(SGS)geostatistical methods.Finally,a clear agreement was revealed between the reservoir zones and the stratigraphic sequence framework.It this regard,the microfacies belonging to the high-energy and grain-dominated settings(packstone,grainstone)of leeward shoal,shoal and seaward shoal belts have the best reservoir units due to the influence of dissolution and dolomitization.The best reservoir units in the Permian-Triassic deposits in the middle of the upper Dalan and lower Kangan are developed in UDS4,upper KS2 and middle KS1 units.On the other hand,mud-dominated facies(mudstone,wackestone)and anhydrite textures are mostly associated with the low-energy lagoonal environments,between tidal flat and Sabkha.Non-reservoir units have been formed in the upper Dalan/Kangan and in the transgressive systems tract of UDS3-a,KS2-a and the lower and upper part of KS1 transgressive-highstand systems tract.展开更多
基金Sponsored by National Ninth Five Year Plan Science and Technology Project (970204-01-01).
文摘The largest Mesozoic northward transgression in Qangtang Basin of Qinghai-Xizang (Tibet) Plateau occurred during the Buqu Stage, Middle Jurassic. Mainly filled with carbonate rocks, the whole basin is composed of transgression-regression sedimentary cycle. Field outcrops and indoor analysis revealed 8 types of sedimentary facies markers in this region. 4 types of sedimentary facies have been recognized: platform facies, platform marginal facies, foreslope facies and basin facies. Influenced by the northern Lazhuglung-Jinshajiang suture zone, central uplift region and southern Bangongco-Nujiang suture zone, these facies belts extended east-west. The sedimentary model was established based on observed depositional features. From their biological features and sedimentary characteristics, it is suggested that the paleoclimate was warm and humid at that time. The Buqu Formation is a promising target for oil and gas exploration in Shuanghu-Duoyong area in future.
基金financially supported by Chinese National Basic Research 973 Program(2014CB440803)the National Natural Science Foundation of China(41572077)China Geological Survey Bureau(12120114065801,121201001000150010 and 121201004000150017-43)
文摘1 Introduction The eastern Tianshan region covers around 60000 km2in area and is located in the eastern part of Xinjiang.The district contains various types mineral commodities including Cu,Ni,Au,Fe,Pb and Zn(Wang et al.,2006).The Dannanhu belt in eastern part of the area is interpreted as a volcanic arc and forms an important mineralized zone bordered by the Turpan-Hami Basin to the north and Kanggur back-arc basin to the south.
文摘Electron paramagnetic resonance spectra, absorption spectra, cathodoluminescence spectra and infrared spectra of sphalerite from the Lechang remoulded sedimentary lead-zinc deposit have been studied so as to provide microscopic evidence for the formation conditions and mineralization stages of the deposit as well as the geochemical processes of mineralization. On the basis of thermodynamic calculations, the stable fields of sphalerite from different mineralization stages were determined and are shown in logfs_2-logfo_2 diagrams; furthermore. the physico-chemical conditions of mineralization and the properties of mineralization solutions are discussed so that reliability of the genetic information provided by the spectroscopy of sphalerite may also be verified. It is suggested that the temperature and pH value of the mineralization system decrease, and so do the fugacities of O_2, S_2, H_2. and H_2S and the activities of HS^- and SO_4^(2-) from the early to late stages of minerahzation.
基金supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources(GP2022-006[24-3111-3]and GP2022-005[24-3807])。
文摘The recently confirmed Hapcheon impact crater in Korea is a complex impact structure 7 km in diameter,with clear rims and impact-driven underground lacustrine sedimentary features.We investigated the lithological features of deposits within the impact crater using drilled sedimentary cores(23HIC01,20CR05,20CR09,and 20CR10),which consisted of an ascending order of impact breccias,lake sediments,and subaerial(e.g.,wetland)sediments.The impact breccia deposits in the 20CR05 and 23HIC01 cores contain shatter cones,which are a macroscopic indication of a meteorite impact.The overlying lake sediments were divided into three stages.The early stage of the post-impact lake environment corresponded to the lowermost lake sediments with frequent microfaults and slump-turbidite events.This stage is characterized by high calcite content of up to 13%.The middle stage showed a stable depositional environment,with silty to sandy lamination and bedding,and fewer microfaults.The final stage of the post-impact lake environment appears to have been very short and dramatic.This ended with the final slumping event,which appears to have been triggered by an abrupt outburst of lake water.This study demonstrates early post-impact lake sedimentation processes and crater instability in terms of soft-sediment deformation structures(e.g.,microfaults and slumps).
文摘The upper Dalan and Kangan or Permian-Triassic carbonate formations in the central the Persian Gulf are considered as world's giant gas reservoirs.The primary purpose of this research is to model and evaluate the relationship between hydraulic flow units(HFUs),electrofacies and microfacies with systems tracts of Permian-Triassic sequences.By integrating the results of core data,petrographic studies,and petrophysical logs of the studied formations,hydraulic flow units and electrofacies were identified.Based on the results of petrographic studies,twelve microfacies were identified in terms of textural and depositional characteristics.Based on depositional setting,sedimentary facies and INPEFA values obtained from gamma ray log and gamma deviation log(GDL)in the context of sequence stratigraphy,zonation of Dalan and Kangan reservoirs is carried out.The zonation boundaries correspond to the key stratal surfaces(sequence boundary and maximum flooding surface).Seven petrographic rock types(PRT)were identified for the upper Dalan-Kangan reservoirs based on sedimentary texture,diagenetic process and dominant pores.Using porosity and permeability data from the core analysis,five hydraulic flow units were identified based on the flow zone indicator(FZI)method.Using multi-resolution graph-based clustering(MRGC)four electrofacies were detected from petrophysical data(gamma,neutron,density and acoustic logs).Subsequently,the INPEFA,GDL and electrofacies were spatially modeled using the sequential indicator simulation(SIS)and sequential Gaussian simulation(SGS)geostatistical methods.Finally,a clear agreement was revealed between the reservoir zones and the stratigraphic sequence framework.It this regard,the microfacies belonging to the high-energy and grain-dominated settings(packstone,grainstone)of leeward shoal,shoal and seaward shoal belts have the best reservoir units due to the influence of dissolution and dolomitization.The best reservoir units in the Permian-Triassic deposits in the middle of the upper Dalan and lower Kangan are developed in UDS4,upper KS2 and middle KS1 units.On the other hand,mud-dominated facies(mudstone,wackestone)and anhydrite textures are mostly associated with the low-energy lagoonal environments,between tidal flat and Sabkha.Non-reservoir units have been formed in the upper Dalan/Kangan and in the transgressive systems tract of UDS3-a,KS2-a and the lower and upper part of KS1 transgressive-highstand systems tract.
