The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian s...The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian stratigraphers include further subdivision of these standard stages, strictly constrained absolute ages for the boundaries, and precise neritic-pelagic and marine-terrestrial correlations using multidisciplinary stratigraphy methods. Establishment of high-resolution Devonian integrative stratigraphy framework and timescale of China would play an important role in improving regional and international correlation, facilitating the recognition of important stratigraphic levels in different paleogeographic settings, and understanding the evolution pattern of biota, paleoclimate and paleoenvironment during this critical interval. Based on well-studied bio-and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.Up to date, few studies have been conducted on the astronomical cyclostratigraphy and high-resolution radioactive isotope dating in Devonian of China, which should be our main focuses in the near future.展开更多
Carbon isotope （δ13Corg） analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East...Carbon isotope （δ13Corg） analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as -25.2‰ （Xishancun） and -19.9‰（Putonggou） in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti （only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna）. These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary （SDB） at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point （GSSP） in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation （between sample QX-20 and sample QX-21） in the Xishancun Section and the lower part of the Xiaputonggou Formation （between sample ZP-09 and sample ZP-10） in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine展开更多
High resolution carbon isotope analyses of carbonate and organic carbon from Meishan, South China showed that the variation of δ13Ccarb is marked by three large positive excursions during the Changhsingian (end-Permi...High resolution carbon isotope analyses of carbonate and organic carbon from Meishan, South China showed that the variation of δ13Ccarb is marked by three large positive excursions during the Changhsingian (end-Permian). Carbon isotope stratigraphy during this stage shows three cyclic intervals in δ13Ccarb, with two cycles corresponding to the lower (Paleofusulinid minima Zone) and one corresponding to the upper Changhsingian (P. sinensis Zone). The large positive δ13Ccarb excursions indicate episodes of enhanced burial of isotopically light or-ganic carbon, presumably in response to deep-water anoxia episodically extending into shallow water with the rise of sea level. The organic carbon during the Changhsingian is distinguished into two groups, and the δ13Corg of each group parallels (separately) the more detailed profile of δ13Ccarb, strongly showing that the values of fractionation Δ13Ccab-org remain relatively constant, with only two intervals with anomaly. The enhanced fractionation Δ13Ccab-org with large negative δ13Corg excursions apparently indicates significant inputs from sulfide-oxidizing bacteria and green sulfur bacteria, notably at bed 24 just predating mass extinction. Our evidence appears to support that the ex-tended euxinic water is possible for the main pulse of mass extinction at the end-Permian.展开更多
Carbon-isotope stratigraphy launched since the early technological development of carbon- isotope measurement in 1950s, however, the emergence and advance of terrestrial carbon-isotope stratigraphy took quite a long w...Carbon-isotope stratigraphy launched since the early technological development of carbon- isotope measurement in 1950s, however, the emergence and advance of terrestrial carbon-isotope stratigraphy took quite a long way. At early stage the exploration of carbon-isotope stratigraphy based on the marine biological shell carbonates was verified by repeatable carbon-isotope stratigraphic data, laboratory chemical experiments and the later laboratory foraminiferal culture experiments. The breakthrough for testifying the fundamentals of terrestrial carbon-isotope stratigraphy lies on the synchronous fluctuations between the carbon-isotope stratigraphic curves derived from marine biological shell carbonates and those derived from terrestrial C3 plants. The character that carbon-isotope stratigraphic curves can be globally synchronously correlated over the marine and terrestrial/atmospheric reservoir mainly excludes the potential biasing factors, such as diagenetic bias, carbon-isotope variations in intra/inter individual plant in same species or between species, ecological changes, changes in aridity, changes in source input and representative sampling. Therefore, the fundamentals of terrestrial carbon-isotope stratigraphy based on C3 plant successfully established. The terrestrial carbon-isotope stratigraphy can be used for global stratigraphic correlation, reconstructing the evolution of atmospheric CO2 and can further verify the published global carbon-cycle models. The terrestrial carbon-isotope stratigraphy based on the compound specific biomarkers and single-grained pollen may be a promising perspective in future.展开更多
基金supported by the Strategic Priority Research Program (B) of Chinese Academy of Sciences (Grant Nos. XDB26000000, XDB18000000)the National Natural Science Foundation of China (Grant Nos. 41290260, 41772004, 41772012)the Special Program for Basic Research of the Ministry of Science and Techology, China (Grant No. 2013FY111000)
文摘The Global Boundary Stratotype Sections and Points(GSSPs) for the bases of all seven international Devonian stages have been formally defined and ratified by IUGS till 1996, and nowadays, the main tasks for Devonian stratigraphers include further subdivision of these standard stages, strictly constrained absolute ages for the boundaries, and precise neritic-pelagic and marine-terrestrial correlations using multidisciplinary stratigraphy methods. Establishment of high-resolution Devonian integrative stratigraphy framework and timescale of China would play an important role in improving regional and international correlation, facilitating the recognition of important stratigraphic levels in different paleogeographic settings, and understanding the evolution pattern of biota, paleoclimate and paleoenvironment during this critical interval. Based on well-studied bio-and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.Up to date, few studies have been conducted on the astronomical cyclostratigraphy and high-resolution radioactive isotope dating in Devonian of China, which should be our main focuses in the near future.
基金supported by the Basic Research Projects of Science and Technology: Research on standard sections and some GSSPs in China (2006FY120300-6)the Major State Basic Research Projects (2006CB806400) of MST of China+2 种基金the Creative Research Project of CAS (KZCX2-YW-156)the National Natural Science Foundation of China (40930208)the Important National Science and Technology Specific Projects (2008ZX05008-001)
文摘Carbon isotope （δ13Corg） analyses of non-marine clastic rocks and neritic carbonates and black shales spanning the Silurian/Devonian transition are compared from two richly fossiliferous sequences in Qujing of East Yunnan and Zoige of Sichuan, South China. The two sections, Xishancun and Putonggou sections in South China, reveal positive δ13Corg shifts happening in the Upper Pridoli and Lower Devonian and reaching peak values as heavy as -25.2‰ （Xishancun） and -19.9‰（Putonggou） in the lowermost Lochkovian following the first occurrence of the thelodont Parathelodus and the conodont Icriodus woschmidti woschmidti （only in Putonggou Section and together with Protathyris-Lanceomyonia brachiopod fauna）. These results replicate a globally known positive shift in δ13Corg from the uppermost Silurian to the lowermost Devonian. The δ13Corg variations across the Silurian/Devonian Boundary （SDB） at the two sections in South China exhibit a shift in carbon isotopic composition similar to the detailed SDB curves from the borehole Klonk-1 drilled at top of the Klonk Global Standard Stratotype-Section and Point （GSSP） in the Prague Basin, Czech Republic. In addition, four microvertebrate assemblages, including the Liaojiaoshan, Xishancun, Yanglugou and Xiaputonggou assemblages, are recognized from the Silurian/Devonian transition exposed in the Xishancun and Putonggou sections, respectively. The results from both carbon isotope stratigraphy and microvertebrate assemblage sequences suggest that the SDB in South China is located at the base of the Xishancun Formation （between sample QX-20 and sample QX-21） in the Xishancun Section and the lower part of the Xiaputonggou Formation （between sample ZP-09 and sample ZP-10） in the Putonggou Section. The isotopic trend for organic carbon together with the changes of microvertebrate remains across the SDB can offer an approach to a potential correlation of the SDB from different sedimentary facies, which help to correlate the marine with non-marine
基金supported jointly by the National Natural Science Foundation of China (40972092)the Special Program for National Science and Technology (2008ZX05005-01-08)the United Foundation of NSFC and China's Petroleum Chemical Industry (40739902)
文摘High resolution carbon isotope analyses of carbonate and organic carbon from Meishan, South China showed that the variation of δ13Ccarb is marked by three large positive excursions during the Changhsingian (end-Permian). Carbon isotope stratigraphy during this stage shows three cyclic intervals in δ13Ccarb, with two cycles corresponding to the lower (Paleofusulinid minima Zone) and one corresponding to the upper Changhsingian (P. sinensis Zone). The large positive δ13Ccarb excursions indicate episodes of enhanced burial of isotopically light or-ganic carbon, presumably in response to deep-water anoxia episodically extending into shallow water with the rise of sea level. The organic carbon during the Changhsingian is distinguished into two groups, and the δ13Corg of each group parallels (separately) the more detailed profile of δ13Ccarb, strongly showing that the values of fractionation Δ13Ccab-org remain relatively constant, with only two intervals with anomaly. The enhanced fractionation Δ13Ccab-org with large negative δ13Corg excursions apparently indicates significant inputs from sulfide-oxidizing bacteria and green sulfur bacteria, notably at bed 24 just predating mass extinction. Our evidence appears to support that the ex-tended euxinic water is possible for the main pulse of mass extinction at the end-Permian.
基金the China Oxford Scholarship Fund (COSF) from Hong KongBurdett-Coutts Fund from Department of Earth Sciences and Graduate Student Award from St Peter’s College,University of Oxford, Wing Yip Bursary from Wing Yip Fund, LondonSeed Science Fund (No.2462014YJRC027) from China University of Petroleum-Beijing for this research
文摘Carbon-isotope stratigraphy launched since the early technological development of carbon- isotope measurement in 1950s, however, the emergence and advance of terrestrial carbon-isotope stratigraphy took quite a long way. At early stage the exploration of carbon-isotope stratigraphy based on the marine biological shell carbonates was verified by repeatable carbon-isotope stratigraphic data, laboratory chemical experiments and the later laboratory foraminiferal culture experiments. The breakthrough for testifying the fundamentals of terrestrial carbon-isotope stratigraphy lies on the synchronous fluctuations between the carbon-isotope stratigraphic curves derived from marine biological shell carbonates and those derived from terrestrial C3 plants. The character that carbon-isotope stratigraphic curves can be globally synchronously correlated over the marine and terrestrial/atmospheric reservoir mainly excludes the potential biasing factors, such as diagenetic bias, carbon-isotope variations in intra/inter individual plant in same species or between species, ecological changes, changes in aridity, changes in source input and representative sampling. Therefore, the fundamentals of terrestrial carbon-isotope stratigraphy based on C3 plant successfully established. The terrestrial carbon-isotope stratigraphy can be used for global stratigraphic correlation, reconstructing the evolution of atmospheric CO2 and can further verify the published global carbon-cycle models. The terrestrial carbon-isotope stratigraphy based on the compound specific biomarkers and single-grained pollen may be a promising perspective in future.
