Following the orogeny in the Early Palaeozoic, the tectonic evolution of the Nanpanjiang basin in the Hercynian-Indosinian stage constituted a complete Wilson Cycle, made up of the stages of early rifting (D-P1), late...Following the orogeny in the Early Palaeozoic, the tectonic evolution of the Nanpanjiang basin in the Hercynian-Indosinian stage constituted a complete Wilson Cycle, made up of the stages of early rifting (D-P1), late rifting and passive margin developement (P2-T1), and peripheral foreland basin developement (T2-T3). The REE data of the initial Early Triassic basalts from the southern part of the basin has verified the existence of the oceanic crust once in the basinal evolution. The basin developed into a foreland one in the Middle-Late Triassic, indicating that the Yangtze plate once collided with the Indo-Sinian plate along the Black River fracture zone.展开更多
There are complex and regular changes on sedimentary facies from the Early to the Middle Triassic in the Nanpanjiang basin. After the obvious drowned event of carbonate platforms in the transitional period between Per...There are complex and regular changes on sedimentary facies from the Early to the Middle Triassic in the Nanpanjiang basin. After the obvious drowned event of carbonate platforms in the transitional period between Permian and Triassic, carbonate platforms have evolved into the ramp type from the rimmed shelf type. The differentiation of sedimentary facies becomes clearer in space, which are marked by the changes from an attached platform to a turbidity basin and several isolated platforms in the basin. The striking characteristics are the development of oolitic banks on isolated platforms in Nanning and Jingxi and the reef and bank limestones in the margin of the attached platform in the Early Triassic. Despite the difference of the time span and the architecture of facies succession of third order sedimentary sequences, the process of the third order relative sea level changes reflected by the sedimentary facies succession of the third order sequences is generally synchronous. Therefore, six third order sequences could be discerned in the strata from the Early to the Middle Triassic in the Nanpanjiang basin. Using two types of facies changing surfaces and two types of diachronisms in stratigraphic records as the key elements, the sedimentary facies architectures of the third order sequences that represent sequence stratigraphic frameworks from the Early to the Middle Triassic in the Nanpanjiang basin could be constructed.展开更多
The Triassic ＂Green-bean Rock＂ （GBR） layers were widely recognized around the Early-Middle Triassic boundary interval in the Nanpanjiang Basin, South China. To determine the precise relationship between the GBR la...The Triassic ＂Green-bean Rock＂ （GBR） layers were widely recognized around the Early-Middle Triassic boundary interval in the Nanpanjiang Basin, South China. To determine the precise relationship between the GBR layers and the first appearance datum （FAD） of the conodont Chiosella timorensis, four Lower-Middle Triassic sections from the Nanpanjiang Basin, including the Gaimao, Bianyang lI, Zuodeng and Wantou sections have been studied in detail. Detailed conodont biostratigraphy convinces us that there is no exact temporal relationship between the GBR layers and first occurrence of Ch. timorensis. Moreover, the numbers of the GBR layers are different from the place to place within the Nanpanjiang Basin, and the time span of the GBR layers was much longer than previously estimated. Global correlations show that the FAD of Ch. timorensis is contemporaneous basinwide and worldwide and more suitable marker defining the Olenekian-Anisian boundary （Early-Middle Triassic boundary） than any other proxies.展开更多
Bitumen from the Nanpanjiang Basin occurs mainly in the Middle Devonian and Upper Permian reef limestone paleo-oil reservoirs and reserves primarily in holes and fractures and secondarily in minor matrix pores and bio...Bitumen from the Nanpanjiang Basin occurs mainly in the Middle Devonian and Upper Permian reef limestone paleo-oil reservoirs and reserves primarily in holes and fractures and secondarily in minor matrix pores and bio-cavities. N2 is the main component of the natural gas and is often associated with pyrobitumen in paleo-oil reservoirs. The present study shows that the bitumen in paleo-oil reservoirs was sourced from the Middle Devonian argillaceous source rock and belongs to pyrobitumen by crude oil cracking under high temperature and pressure. But the natural gas with high content of N2 is neither an oil-cracked gas nor a coal-formed gas generated from the Upper Permian Longtan Formation source rock, instead it is a kerogen-cracked gas generated at the late stage from the Middle Devonian argilla- ceous source rock. The crude oil in paleo-oil reservoirs completely cracked into pyrobitumen and methane gas by the agency of hugely thick Triassic deposits. After that, the abnormal high pressure of methane gas reservoirs was completely destroyed due to the erosion of 2000--4500-m-thick Triassic strata. But the kerogen-cracked gas with normal pressure was preserved under the relatively sealed condition and became the main body of the gas shows.展开更多
文摘Following the orogeny in the Early Palaeozoic, the tectonic evolution of the Nanpanjiang basin in the Hercynian-Indosinian stage constituted a complete Wilson Cycle, made up of the stages of early rifting (D-P1), late rifting and passive margin developement (P2-T1), and peripheral foreland basin developement (T2-T3). The REE data of the initial Early Triassic basalts from the southern part of the basin has verified the existence of the oceanic crust once in the basinal evolution. The basin developed into a foreland one in the Middle-Late Triassic, indicating that the Yangtze plate once collided with the Indo-Sinian plate along the Black River fracture zone.
基金ThestudyisjointlysupportedbytheChinaPetroleumCorporation (No .NPJ- 10 0 19)andalsobytheMinistryofScienceandTechnology (SSER)
文摘There are complex and regular changes on sedimentary facies from the Early to the Middle Triassic in the Nanpanjiang basin. After the obvious drowned event of carbonate platforms in the transitional period between Permian and Triassic, carbonate platforms have evolved into the ramp type from the rimmed shelf type. The differentiation of sedimentary facies becomes clearer in space, which are marked by the changes from an attached platform to a turbidity basin and several isolated platforms in the basin. The striking characteristics are the development of oolitic banks on isolated platforms in Nanning and Jingxi and the reef and bank limestones in the margin of the attached platform in the Early Triassic. Despite the difference of the time span and the architecture of facies succession of third order sedimentary sequences, the process of the third order relative sea level changes reflected by the sedimentary facies succession of the third order sequences is generally synchronous. Therefore, six third order sequences could be discerned in the strata from the Early to the Middle Triassic in the Nanpanjiang basin. Using two types of facies changing surfaces and two types of diachronisms in stratigraphic records as the key elements, the sedimentary facies architectures of the third order sequences that represent sequence stratigraphic frameworks from the Early to the Middle Triassic in the Nanpanjiang basin could be constructed.
基金supported by 973 Program (No. 2011CB808800)the Natural Science Foundation of China (Nos. 41172024, 41272044, 41402005)+2 种基金the "111" project (No. B08030)the ‘Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan)the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (No. GBL11202)
文摘The Triassic ＂Green-bean Rock＂ （GBR） layers were widely recognized around the Early-Middle Triassic boundary interval in the Nanpanjiang Basin, South China. To determine the precise relationship between the GBR layers and the first appearance datum （FAD） of the conodont Chiosella timorensis, four Lower-Middle Triassic sections from the Nanpanjiang Basin, including the Gaimao, Bianyang lI, Zuodeng and Wantou sections have been studied in detail. Detailed conodont biostratigraphy convinces us that there is no exact temporal relationship between the GBR layers and first occurrence of Ch. timorensis. Moreover, the numbers of the GBR layers are different from the place to place within the Nanpanjiang Basin, and the time span of the GBR layers was much longer than previously estimated. Global correlations show that the FAD of Ch. timorensis is contemporaneous basinwide and worldwide and more suitable marker defining the Olenekian-Anisian boundary （Early-Middle Triassic boundary） than any other proxies.
基金Supported by the Sinopec Project (Grant No: P00045)the National Science & Technology Project for the 10th Five-Year Plan (Grant No. 2001BA605A-06)
文摘Bitumen from the Nanpanjiang Basin occurs mainly in the Middle Devonian and Upper Permian reef limestone paleo-oil reservoirs and reserves primarily in holes and fractures and secondarily in minor matrix pores and bio-cavities. N2 is the main component of the natural gas and is often associated with pyrobitumen in paleo-oil reservoirs. The present study shows that the bitumen in paleo-oil reservoirs was sourced from the Middle Devonian argillaceous source rock and belongs to pyrobitumen by crude oil cracking under high temperature and pressure. But the natural gas with high content of N2 is neither an oil-cracked gas nor a coal-formed gas generated from the Upper Permian Longtan Formation source rock, instead it is a kerogen-cracked gas generated at the late stage from the Middle Devonian argilla- ceous source rock. The crude oil in paleo-oil reservoirs completely cracked into pyrobitumen and methane gas by the agency of hugely thick Triassic deposits. After that, the abnormal high pressure of methane gas reservoirs was completely destroyed due to the erosion of 2000--4500-m-thick Triassic strata. But the kerogen-cracked gas with normal pressure was preserved under the relatively sealed condition and became the main body of the gas shows.
