文献类型：期刊文献

英文题名：Fluctuation in redox conditions and the evolution of early Cambrian life constrained by nitrogen isotopes in the middle Yangtze Block, South China

作者：Wei, Kai[1,5];Cao, Hansheng[2,3,4];Chen, Fajin[2,3,4];Wang, Zaiyun[2,3,4];An, Zhihui[1,5];Huang, Hanli[2,3,4];Chen, Chunqing[3,4]

机构：[1]China Geol Survey, Wuhan Ctr, Geosci Innovat Ctr Cent South China, Wuhan, Peoples R China;[2]Guangdong Ocean Univ, Coll Ocean & Meterol, Lab Coastal Ocean Variat & Disaster Predict, Zhanjiang, Peoples R China;[3]Guangdong Ocean Univ, Key Lab Climate Resources & Environm Continental, Dept Educ Guangdong Prov, Coll Ocean & Meteorol, Zhanjiang, Peoples R China;[4]Minist Nat Resources, Key Lab Space Ocean Remote Sensing & Applicat, Beijing, Peoples R China;[5]China Geol Survey, Wuhan Ctr, Wuhan, Peoples R China

年份：2023

卷号：160

期号：10

起止页码：1932

外文期刊名：GEOLOGICAL MAGAZINE

收录：SCI-EXPANDED(收录号：WOS:001193799800006)、、EI(收录号：20240415444279)、Scopus(收录号：2-s2.0-85183023198)、WOS

基金：We are grateful for support from the China Geological Survey (DD20230006), the Natural Science Foundation of Hubei Province (2023AFB1103), Guangdong Natural Science Foundation of China (2022A1515012100), the Foreign Aid Project of the Ministry of Commerce of the People's Republic of China ((2021) 28), South China Sea Scholar Project of Guangdong Ocean University (002029002007), Guangdong Provincial College Innovation Team Project (2019KCXTF021) and First-class Discipline Plan of Guangdong Province (080503032101, 231420003).

语种：英文

外文关键词：Carbon isotope anomalies; Cambrian explosion; nitrogen cycling; Paleo-oceanic environment; nitrate pool

外文摘要：The Ediacaran-Cambrian (E-C) transition (similar to 542-517 Ma) witnessed the rapid evolution of Cambrian animals, which was accompanied by carbon cycling anomalies and a significant increase in the concentration of oxygen in Earth's atmosphere. The mechanisms stimulating the evolution of complex eukaryotes, however, remain problematic, especially concerning the link between biological evolution and contemporaneous changes in the oceanic environment. In this study, integrated delta C-13(carb)-delta C-13(org)-delta N-15 compositions were analysed from the YD-4 core samples to understand redox fluctuations and nitrogen cycling of the middle Yangtze Block across the E-C transition. Two negative delta C-13(carb) excursions (N1 and N2) and a positive delta C-13(carb) excursion (P1) are identified from the studied samples and are supposedly of primary origin. Constrained by of the U-Pb age, biolithology and pattern of isotopic variation, N1, P1 and N2 are comparable to the Basal Cambrian Carbon Isotope Excursion (BACE), Zhujiaqing Carbon Isotope Excursion (ZHUCE) and Shiyantou Carbon Isotope Excursion (SHICE). We interpreted the decreased delta N-15 values in this study as resulting from intensified atmospheric nitrogen fixation driven by enhanced denitrification associated with expanded marine anoxia, as well as partial ammonium assimilation, while increased delta N-15 values suggest weakened denitrification associated with an amplified oxic water mass. The temporal coincidence of N1 and N2, with two episodes of negative delta N-15 excursions, and of P1, with a positive delta N-15 excursion, suggests that variable oceanic redox conditions and nitrogen bioavailability may have influenced the evolution of the Cambrian eukaryote-dominated community.