The Eocene Niubao Formation is the primary research target of oil exploration in the Lunpola Basin.Crude oil was extracted from Well Z1 on the northern margin of the basin in 1993.In this study,an integrated evaluatio...The Eocene Niubao Formation is the primary research target of oil exploration in the Lunpola Basin.Crude oil was extracted from Well Z1 on the northern margin of the basin in 1993.In this study,an integrated evaluation of the source rock geothermal,and maturity histories and the fluid inclusion and fluid potential distributions was performed to aid in predicting areas of hydrocarbon accumulation.Due to the abundance of organic matter,the kerogen types,maturity,and oil-sources correlate with the geochemical data.The middle submember of the second member of the Niubao Formation(E2n^2-2)is the most favorable source rock based on the amount of oil produced from the E2n^2-3and E2n^3-1reservoirs.One-and twodimensional basin modeling,using BasinMod software,shows that the E2n^2-2source rock started to generate hydrocarbon at 35-30 Ma,reached a maturity of Ro=0.7%at 25-20 Ma,and at present,it has reached the peak oil generation stage with a thermal maturity of Ro=0.8%to less than Ro=1.0%.By using fluid inclusion petrography,fluorescence spectroscopy,and microthermometry,two major periods of oil charging have been revealed at 26.1-17.5 and 32.4-24.6 Ma.The oil accumulation modeling results,conducted by using the Trinity software,show a good fit of the oil shows in the wells and predict that the structural highs and lithologic transitions within the Jiangriaco and Paco sags are potential oil traps.展开更多
The evolution of the Asian monsoon from the Late Oligocene to the Early Miocene is poorly understood.Here,we first reconstruct the precipitation data of central Tibet during 26–16 million years ago(Ma),applying the c...The evolution of the Asian monsoon from the Late Oligocene to the Early Miocene is poorly understood.Here,we first reconstruct the precipitation data of central Tibet during 26–16 million years ago(Ma),applying the coexistence approach to sedimentary pollen data,and detect an intensified Asian monsoon with1.35 Ma and0.33 Ma cycles.Paleoclimate modeling is used to show the importance of paleogeographic location in the development of the paleomonsoon.In addition,the results of spectral analysis suggest that the fluctuations in the Asian monsoon during 26–16 Ma can be attributed to the long-period cyclicities in obliquity(1.2 Ma).These findings provide climate data that can be used to understand the Asian monsoon evolution during the Late Oligocene to Early Miocene and highlight the effects of paleogeographic patterns and long-period orbital forcings on the tectonic-scale evolution of the Asian monsoon.展开更多
The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lu...The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.展开更多
基金financially supported by the National Science and the Technology Major Project(Nos.2016ZX05024002-003,2017ZX05032-001-004,2016ZX05027-001-005)the National Science Foundation of China(No.41672136)the Branch of Exploration Project,SINOPEC(No.G0800-14-KK-169)
文摘The Eocene Niubao Formation is the primary research target of oil exploration in the Lunpola Basin.Crude oil was extracted from Well Z1 on the northern margin of the basin in 1993.In this study,an integrated evaluation of the source rock geothermal,and maturity histories and the fluid inclusion and fluid potential distributions was performed to aid in predicting areas of hydrocarbon accumulation.Due to the abundance of organic matter,the kerogen types,maturity,and oil-sources correlate with the geochemical data.The middle submember of the second member of the Niubao Formation(E2n^2-2)is the most favorable source rock based on the amount of oil produced from the E2n^2-3and E2n^3-1reservoirs.One-and twodimensional basin modeling,using BasinMod software,shows that the E2n^2-2source rock started to generate hydrocarbon at 35-30 Ma,reached a maturity of Ro=0.7%at 25-20 Ma,and at present,it has reached the peak oil generation stage with a thermal maturity of Ro=0.8%to less than Ro=1.0%.By using fluid inclusion petrography,fluorescence spectroscopy,and microthermometry,two major periods of oil charging have been revealed at 26.1-17.5 and 32.4-24.6 Ma.The oil accumulation modeling results,conducted by using the Trinity software,show a good fit of the oil shows in the wells and predict that the structural highs and lithologic transitions within the Jiangriaco and Paco sags are potential oil traps.
基金The authors thank Prof.Chun-Ju Huang from the China University of Geosciences(Wuhan)for a useful discussion.This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(no.XDB26000000)the China National Key Basic Research Program(2014CB954201)+2 种基金the National Natural Science Foundation of China(nos.31570223,41690115,and 32000174)the State Key Laboratory of Systematic and Evolutionary Botany(nos.LSEB2019-1 and LSEB2019-4)and the Chinese Academy of Sciences President’s International Fellowship Initiative(2018VBA0016).
文摘The evolution of the Asian monsoon from the Late Oligocene to the Early Miocene is poorly understood.Here,we first reconstruct the precipitation data of central Tibet during 26–16 million years ago(Ma),applying the coexistence approach to sedimentary pollen data,and detect an intensified Asian monsoon with1.35 Ma and0.33 Ma cycles.Paleoclimate modeling is used to show the importance of paleogeographic location in the development of the paleomonsoon.In addition,the results of spectral analysis suggest that the fluctuations in the Asian monsoon during 26–16 Ma can be attributed to the long-period cyclicities in obliquity(1.2 Ma).These findings provide climate data that can be used to understand the Asian monsoon evolution during the Late Oligocene to Early Miocene and highlight the effects of paleogeographic patterns and long-period orbital forcings on the tectonic-scale evolution of the Asian monsoon.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (KZCX2-YW-Q09)the National Basic Research Program of China (2012CB821906)the National Natural Science Foundation of China (40730210)
文摘The distal extremity of a rhinocerotid humerus from the upper part of the Dingqing Formation at the Lunbori locality in Baingoin County,northern Tibet,is the first mammalian fossil found in Cenozoic deposits of the Lunpola Basin.The medial condyle of the distal trochlea of the humerus specimen from Lunbori gradually contracts from medially to laterally.The margin of the medial surface of the medial condyle is not prominent,the well-developed medial epicondyle strongly extends posteriorly,and is divided from the articular facet of the medial condyle by a groove;all of which are characteristic for the Rhinocerotidae.The medial condyle is wide at the bottom and narrow at the top.The medial collateral ligament fossa is relatively shallow,and the medial collateral ligament tubercle is very weak.The medial part of the upper margin of the medial condyle smoothly connects to the bony surface above,but there is no clear boundary between them.All of these characteristics are identical with those of Plesiaceratherium.These comparisons imply that the Lunbori specimen is closest to Plesiaceratherium gracile in the Shanwang Fauna from Linqu,Shandong Province,in size and morphology.Thus,its age is suggested to be the late Early Miocene(Shanwangian Age),about 18-16 Ma.Discovery of the rhinocerotid fossil suggests that the upper part of the Dingqing Formation deposited in the Neogene.While adjusting to paleo-temperatures of the Early Miocene,a paleo-ecosystem reconstruction indicates that the paleo-elevation was close to 3000 m in the Lunpola Basin during this time.
