The large increase of δ^(13)C_(carb)-depth gradient and the end-Permian mass extinction  

作　　者：SONG HaiJun TONG JinNan XIONG YanLin SUN DongYing TIAN Li SONG HuYue 

机构地区：[1]State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China

出　　处：《Science China Earth Sciences》2012年第7期1101-1109,共9页中国科学（地球科学英文版）

基　　金：supported by "973 Program" (Grant No. 2011CB808800);National Natural Science Foundation of China (Grant Nos. 40830212,40921062,41172312);Doctoral Fund of Ministry of Education of China (Grant No. 200804910503);Fund of State Key Laboratory of Biogeology and Environmental Geology(Grant No. BGEG0802);Scientific and Technological Project of Jiangxi (Grant No. GJJ10623)

摘　　要：Carbonate carbon isotope （δ^13Ccarb） has received considerable attention in the Permian-Triassic transition for its rapid negative shift coinciding with the great end-Permian mass extinction event. The mechanism has long been debated for such a c~ δ^13Ccarb negative excursion through the end-Permian crisis and subsequent large perturbations in the entire Early Triassic. A δ^13Ccarb depth gradient is observed at the Permian-Triassic boundary sections of different water-depths, i.e., the Yangou, Meishan, and Shangsi sections, and such a large δ^13Ccarb-depth gradient near the end-Permian mass extinction horizon is believed to result from a stratified Paleotethys Ocean with widespread anoxic/euxinic deep water. The evolution of δ^13Ccarb-depth gradient com- bined with paleontological and geochemical data suggests that abundant cyanobacteria and vigorous biological pump in the immediate aftermath of the end-Permian extinction would be the main cause of the large δ^13Ccarb-depth gradient, and the enhanced continental weathering with the mass extinction on land provides a mass amount of nutriment for the flourishing cyanobacteria. Photic zone anoxia/euxinia from the onset of chemocline upward excursion might be the direct cause for the mass extinction whereas the instability of chemocline in the stratified Early Triassic ocean would be the reason for the delayed and involuted biotic recovery.Carbonate carbon isotope δ(13Ccarb) has received considerable attention in the Permian-Triassic transition for its rapid negative shift coinciding with the great end-Permian mass extinction event.The mechanism has long been debated for such a δ13Ccarb negative excursion through the end-Permian crisis and subsequent large perturbations in the entire Early Triassic.A δ13Ccarb depth gradient is observed at the Permian-Triassic boundary sections of different water-depths,i.e.,the Yangou,Meishan,and Shangsi sections,and such a large δ13Ccarb-depth gradient near the end-Permian mass extinction horizon is believed to result from a stratified Paleotethys Ocean with widespread anoxic/euxinic deep water.The evolution of δ13Ccarb-depth gradient combined with paleontological and geochemical data suggests that abundant cyanobacteria and vigorous biological pump in the immediate aftermath of the end-Permian extinction would be the main cause of the large δ13Ccarb-depth gradient,and the enhanced continental weathering with the mass extinction on land provides a mass amount of nutriment for the flourishing cyanobacteria.Photic zone anoxia/euxinia from the onset of chemocline upward excursion might be the direct cause for the mass extinction whereas the instability of chemocline in the stratified Early Triassic ocean would be the reason for the delayed and involuted biotic recovery.

关 键 词：Permian-Triassic boundary carbon isotope ocean stratification bioproductivity biological pump mass extinction 

分 类 号：P534.46[天文地球—古生物学与地层学] Q111.7[天文地球—地质学]