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| Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition: Enlightening from carbon isotopes and molecular fossils | |
| 作者姓名： | GONG Yiming XU Ran TANG Zhongdao SI Yuanlan & LI Baohua . Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China . Institute of Resources & Environments Henan Polytechnic University Jiaozuo China . |
| 作者单位： | GONG Yiming1，2，XU Ran1，TANG Zhongdao1，SI Yuanlan3 & LI Baohua4 1. Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources，China University of Geosciences，Wuhan 430074，China; 2. Institute of Resources & Environments，Henan Polytechnic University，Jiaozuo 454003，China; 3. Department of Computer Science，South-Central University for Nationalities，Wuhan 430074，China; 4. Laboratory of Marine Geology，Tongji University，Shanghai 200092，China |
| 基金项目： | 国家自然科学基金，高等学校博士学科点专项科研项目，河南工业大学校科研和教改项目 |
| 摘 要： | The five major mass extinctions which occurred in the transition of the Ordovician-Silurian (440 Ma), Late Devonian Frasnian-Famennian (F-F) (370 Ma), Permian-Triassic (250 Ma), Triassic-Jurassic (205 Ma) and Cretaceous-Paleogene (65 Ma) are significant phenomena in the Phanerozoic global environment and organic evolution. Their corresponding extinction rates of marine invertebrate at the level of genus and family are 60% (genus) and 26% (family), 57% and 22%, 82% and 51%, 53% and 22%, … |
Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition: Enlightening from carbon isotopes and molecular fossils |
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| GONG Yiming,,XU Ran,TANG Zhongdao,SI Yuanlan & LI Baohua . Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan ,China, . Institute of Resources & Environments,Henan Polytechnic University,Jiaozuo ,China, ..Relationships between bacterial-algal proliferating and mass extinction in the Late Devonian Frasnian-Famennian transition: Enlightening from carbon isotopes and molecular fossils[J].Science in China(Earth Sciences),2005,48(10). | |
| Authors: | GONG Yiming XU Ran TANG Zhongdao SI Yuanlan LI Baohua |
| Institution: | 1. Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China;Institute of Resources & Environments, Henan Polytechnic University, Jiaozuo 454003, China 2. Faculty of Earth Science and State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China 3. Department of Computer Science, South-Central University for Nationalities, Wuhan 430074, China 4. Laboratory of Marine Geology, Tongji University, Shanghai 200092, China |
| Abstract: | Studies show positive shifts of inorganic and organic carbon isotope values (δ13Ccarb and δ 13Ckerogen) from +0.43 (‰ V-PDB) to +3.54 (‰ V-PDB) and from -29.38 (‰ V-PDB) to -24.14 (‰ V-PDB), respectively, B* (Ba* = Ba/ (Al2O3 X 15%)) values from 0.015 to 0.144, TOC values from 0.02% to 0.21%, V/Cr values from 0.3 to 2.0, Sr/Ba values from 3.20 to 49.50 in the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone of the Yangdi section deposited in carbonate slope facies of Guilin, Guangxi, South China, which indicates that biomass, productivity, organic carbon burial and salinity increase and that oxygenation near the boundary between sediments and waters decreases from the Late Devonian Frasnian Upper rhenana zone to the top linguiformis zone. Abundance of molecular fossils increases and normal alkanes, isoprenoid hydrocarbon, terpanes and steranes are dominated from the Late Devonian Frasnian to the bottom of Famennian, which shows that the predecessors of molecular fossils of the Frasnian-Famennian (F-F) transition are dominated by marine phytoplankton, zooplankton and benthic bacteria with no photosynthesis. Therefore, it is considered that the F-F transitional mass extinction with a multistage, selection and global synchronizing was caused by bacterial-algal proliferating, continuing deterioration of the shallow marine ecoenvironment of the middle-lower latitudes. A simple cause and effect chain can be expressed as: appearance of seed plants and multi-storied forests → Enhanced chemical and biochemical weathering and pedogenesis→ Wide development of soils → Increasing riverine nutrient fluxes in epicontinental sea → From superoligotrophic to eutrophic in epicontinental sea →Proliferating of marine phytoplankton and zooplankton → Frequent red tide and anoxia → Mass extinction of shallow marine organisms in the middle-lower latitudes. It is worth notice that the factor drawdown of atmospheric Pco2, climatic cooling and sea level falling caused by eutrophication, anoxia and organic carbon burial increasing may be important for the mass extinction. |
| Keywords: | mass extinction bacteria-algae carbon isotopes molecular fossils biodiversity Late Devonian Guangxi South China |
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