The change of the primary productivity across the Permian-Triassic boundary （PTB） remains controversial. In this study, records from two deep-water sections in South China （Xiakou and Xinmin sections） show the pri...The change of the primary productivity across the Permian-Triassic boundary （PTB） remains controversial. In this study, records from two deep-water sections in South China （Xiakou and Xinmin sections） show the primary productivity decreased gradually from the latest Permian to the earliest Triassic, and five evolutionary stages Increase-Decrease-Recovery-Recession- Stagnation） can be observed from Clarkina changxingensis-C, deflecta to Hindeodus parvus-lsarcicella isarcica zones. Pri- mary productivity decreased abruptly from the base of C. meishanensis zone. Besides, for adjusting to the deterioration of the oceanic environment, the primary producers in the oceanic surface had changed to acritarch and cyanobacteria, which were more tolerant of stressful environment. Then the producers were under huge stagnation in the H. parvus-L isarcica zone. The values of quantitative calculation of the primary productivity from the black rock series in the Dalong Formation were very high, corresponding to that of an upwelling area in modern ocean, which shows that the strata of the Dalong Formation in the study region are potential hydrocarbon source-rocks. This result may come from the fact that South China craton was located at the equatorial upwelling area during the Permian-Triassic transitions. But organic matter contents were different in various sections because they could be affected by redox conditions and diagenesis process after burial.展开更多
Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The ...Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The radiolarian fauna consists of all spherical radiolarians,without any species of Albaillellaria and Latentifistularia,indicating a relative shallow water sedimentary environment.The high relative co-efficient between the radiolarian abundance and total organic carbon(TOC)shows that the radiolarian assemblage represented by Copicyntra and Paracopicyntra can be used as a proxy to the paleo-productivity.However,the relative co-efficient between biogenic silica and the radiolarian and sponge spicule abundances is low.A possible explanation is that an oceanic circulation has changed the biogenic silica content after radiolarian test and siliceous spongy spicule were dissolved.展开更多
为研究川西坳陷中段雷口坡组碳酸盐岩作为有效烃源岩是否具有可行性,通过川西坳陷中段三口钻井岩心样品的有机碳含量、有机显微组分以及沥青反射率的测定,分析样品的有机地球化学特征;结合主、微量元素特征以及Sr、Ba、Cu、Al、V、Cr、N...为研究川西坳陷中段雷口坡组碳酸盐岩作为有效烃源岩是否具有可行性,通过川西坳陷中段三口钻井岩心样品的有机碳含量、有机显微组分以及沥青反射率的测定,分析样品的有机地球化学特征;结合主、微量元素特征以及Sr、Ba、Cu、Al、V、Cr、Ni等元素指标,探讨研究区当时所处的沉积环境。结果表明:研究区雷口坡组碳酸盐岩有机质丰度整体偏低,传统方法测得样品有机碳含量普遍低于0.2%,有机质类型为Ⅰ-Ⅱ1型,有机质成熟度大于2.0%,处于过成熟阶段;生源Ba含量表明研究区雷口坡组具有中-低等古生产力水平;依据Sr/Ba、Sr/Cu、CaO/(MgO×Al 2 O 3)、V/Cr与V/(V+Ni)的比值特征推断雷口坡组当时处于炎热干旱、高盐度、低能、弱氧化-还原的环境。展开更多
天然气水合物作为一种新型的清洁能源,其形成需要稳定的有机质供应。南海北部神狐海域为天然气水合物成藏的有利区域,2017年中国地质调查局在神狐海域水合物试采获得突破性成功。为了进一步了解古环境和古生产率对形成水合物有机质供应...天然气水合物作为一种新型的清洁能源,其形成需要稳定的有机质供应。南海北部神狐海域为天然气水合物成藏的有利区域,2017年中国地质调查局在神狐海域水合物试采获得突破性成功。为了进一步了解古环境和古生产率对形成水合物有机质供应的影响,对南海北部神狐海域水合物钻探区SH3站位180～215mbsf(meters below the sea floor)层位,尤其是水合物主要赋存层位190～200mbsf的古环境、古生产率以及陆源碎屑物质的地球化学指标进行分析研究。研究表明水合物主要赋存层位陆源碎屑物质(TDM)输入增加,较高的陆源碎屑物质输入和次氧化的沉积环境共同造就了比较好的有机质的外部保存条件;同时较强的水动力条件,有利于藻类生物的繁殖,因此,生物成因有机质比较丰富,再加上神狐海域有比较良好的热解气的形成条件,这3个层面共同保证了神狐海域具有比较充足的有机质供应。展开更多
The main oil source in western Qaidam Basin is the Paleogene saline lacustrine source rocks.Traditionally,it was considered that these source rocks were characterized by low abundance and poor type of organic matter a...The main oil source in western Qaidam Basin is the Paleogene saline lacustrine source rocks.Traditionally,it was considered that these source rocks were characterized by low abundance and poor type of organic matter as well as limited oil generation potential,but this poor source rock condition was very inconsistent with good hydrocarbon exploration results.A previous study has just confirmed that this area develops high-quality source rocks,which is of great significance for recognizing potential of hydrocarbon resource and consolidating confidence to search large and medium-sized oil and gas fields in western Qaidam Basin.Based on fine geochemical analysis of source rocks,petrology,element geochemistry and organic geochemistry are applied to discuss development conditions of high-quality source rocks in this area.The results showed that the saline lacustrine sediments in western Qaidam Basin were deposited in relatively shallow and quiet water with relatively high salinity and low nutrient content;influenced by the drought and cold climate,the terrigenous supply of fresh water was limited,and few aquatic organisms were developed.Good preservation condition is favorable for rapid preservation of oil generating biomass(such as aquatic organisms),to form source rocks rich in hydrogen element with high soluble organic matter content;but relatively lower paleo-productivity makes organic matter abundance lower than that in the eastern saline lacustrine basins.The semi-deep lake,with relatively low salinity and abundant nutrients,is the most favorable are for development of high-quality source rocks;the source rocks have large thickness in the sedimentary depression areas,but due to high water salinity and far away from the provenance area,the water stratification was obvious,so it have moderate to high organic matter abundance.展开更多
基金was supported by National Natural Science Foundation of China (Grant Nos. 41073007 and 41273005)National Basic Research Program of China (Grant No. 2011CB808800)+3 种基金the 111 Project (Grant No. B08030)Research Fund for the Doctoral Program of Higher Education (Grant No. 20110145130001)special funding from the State Key Laboratory of Geological Processes and Mineral Resourcesa contribution to IGCP Project 572 (Grant No. GPMR201301)
文摘The change of the primary productivity across the Permian-Triassic boundary （PTB） remains controversial. In this study, records from two deep-water sections in South China （Xiakou and Xinmin sections） show the primary productivity decreased gradually from the latest Permian to the earliest Triassic, and five evolutionary stages Increase-Decrease-Recovery-Recession- Stagnation） can be observed from Clarkina changxingensis-C, deflecta to Hindeodus parvus-lsarcicella isarcica zones. Pri- mary productivity decreased abruptly from the base of C. meishanensis zone. Besides, for adjusting to the deterioration of the oceanic environment, the primary producers in the oceanic surface had changed to acritarch and cyanobacteria, which were more tolerant of stressful environment. Then the producers were under huge stagnation in the H. parvus-L isarcica zone. The values of quantitative calculation of the primary productivity from the black rock series in the Dalong Formation were very high, corresponding to that of an upwelling area in modern ocean, which shows that the strata of the Dalong Formation in the study region are potential hydrocarbon source-rocks. This result may come from the fact that South China craton was located at the equatorial upwelling area during the Permian-Triassic transitions. But organic matter contents were different in various sections because they could be affected by redox conditions and diagenesis process after burial.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40839903,40921062)special funding from the GPMR
文摘Abundant siliceous micro-fossils were found from the Dalong Formation,Xinmin section,Guizhou,which include nine species of radiolarians belonging to seven genera as well as nine types of siliceous spongy spicules.The radiolarian fauna consists of all spherical radiolarians,without any species of Albaillellaria and Latentifistularia,indicating a relative shallow water sedimentary environment.The high relative co-efficient between the radiolarian abundance and total organic carbon(TOC)shows that the radiolarian assemblage represented by Copicyntra and Paracopicyntra can be used as a proxy to the paleo-productivity.However,the relative co-efficient between biogenic silica and the radiolarian and sponge spicule abundances is low.A possible explanation is that an oceanic circulation has changed the biogenic silica content after radiolarian test and siliceous spongy spicule were dissolved.
文摘为研究川西坳陷中段雷口坡组碳酸盐岩作为有效烃源岩是否具有可行性,通过川西坳陷中段三口钻井岩心样品的有机碳含量、有机显微组分以及沥青反射率的测定,分析样品的有机地球化学特征;结合主、微量元素特征以及Sr、Ba、Cu、Al、V、Cr、Ni等元素指标,探讨研究区当时所处的沉积环境。结果表明:研究区雷口坡组碳酸盐岩有机质丰度整体偏低,传统方法测得样品有机碳含量普遍低于0.2%,有机质类型为Ⅰ-Ⅱ1型,有机质成熟度大于2.0%,处于过成熟阶段;生源Ba含量表明研究区雷口坡组具有中-低等古生产力水平;依据Sr/Ba、Sr/Cu、CaO/(MgO×Al 2 O 3)、V/Cr与V/(V+Ni)的比值特征推断雷口坡组当时处于炎热干旱、高盐度、低能、弱氧化-还原的环境。
文摘天然气水合物作为一种新型的清洁能源,其形成需要稳定的有机质供应。南海北部神狐海域为天然气水合物成藏的有利区域,2017年中国地质调查局在神狐海域水合物试采获得突破性成功。为了进一步了解古环境和古生产率对形成水合物有机质供应的影响,对南海北部神狐海域水合物钻探区SH3站位180～215mbsf(meters below the sea floor)层位,尤其是水合物主要赋存层位190～200mbsf的古环境、古生产率以及陆源碎屑物质的地球化学指标进行分析研究。研究表明水合物主要赋存层位陆源碎屑物质(TDM)输入增加,较高的陆源碎屑物质输入和次氧化的沉积环境共同造就了比较好的有机质的外部保存条件;同时较强的水动力条件,有利于藻类生物的繁殖,因此,生物成因有机质比较丰富,再加上神狐海域有比较良好的热解气的形成条件,这3个层面共同保证了神狐海域具有比较充足的有机质供应。
基金The work was supported by the Petrochina Science and Technology Major Project(2016E-0101).
文摘The main oil source in western Qaidam Basin is the Paleogene saline lacustrine source rocks.Traditionally,it was considered that these source rocks were characterized by low abundance and poor type of organic matter as well as limited oil generation potential,but this poor source rock condition was very inconsistent with good hydrocarbon exploration results.A previous study has just confirmed that this area develops high-quality source rocks,which is of great significance for recognizing potential of hydrocarbon resource and consolidating confidence to search large and medium-sized oil and gas fields in western Qaidam Basin.Based on fine geochemical analysis of source rocks,petrology,element geochemistry and organic geochemistry are applied to discuss development conditions of high-quality source rocks in this area.The results showed that the saline lacustrine sediments in western Qaidam Basin were deposited in relatively shallow and quiet water with relatively high salinity and low nutrient content;influenced by the drought and cold climate,the terrigenous supply of fresh water was limited,and few aquatic organisms were developed.Good preservation condition is favorable for rapid preservation of oil generating biomass(such as aquatic organisms),to form source rocks rich in hydrogen element with high soluble organic matter content;but relatively lower paleo-productivity makes organic matter abundance lower than that in the eastern saline lacustrine basins.The semi-deep lake,with relatively low salinity and abundant nutrients,is the most favorable are for development of high-quality source rocks;the source rocks have large thickness in the sedimentary depression areas,but due to high water salinity and far away from the provenance area,the water stratification was obvious,so it have moderate to high organic matter abundance.
