Sulfur Isotopes of Framboidal Pyrite in the Permian-Triassic Boundary Clay at Meishan Section  

作　　者：ZHANG Jun LIANG Handong HE Xiaoqing YANG Ye CHEN Baohua 

机构地区：[1]State Key Laboratory of Coal Resources andSafety Mining, China University of Mining and Technology, Beijing 100083, China [2]Haihe River Water Environmental Monitoring Center, Haihe River Water Conservancy Commission, Ministry of Water Resources, Tianjin 300170, China

出　　处：《Acta Geologica Sinica(English Edition)》2011年第3期694-701,共8页地质学报（英文版）

基　　金：supported by China Scholarship Council,National Natural Science Foundation of China(No40572020);Doctoral Program of Higher Education(No20040290005)

摘　　要：Pyrite framboids were found in the Permian-Triassic boundary at Meishan Section,while their sulfur isotopes were determined.The majority of framboids is less than 5μm in diameter,with some large-sized framboids.Also,euhedral gypsums were observed in the boundary clay.The authors suppose that most of the pyrite framboids formed just below the redox boundary and stopped growing after entering the lower water column.The result indicates that it was probably lower dysoxia condition in the temporal ocean.Moreover,the authors also presume that some pyrite was oxidated to sulfates accompanying the fluctuation of redox condition,which would probably be the origin of the negative sulfur isotopes of gypsum and CAS reported before.In addition,sulfur isotope of framboidal pyrite suggests that sulfur is originated from bacterial sulfate reduction in anoxic condition.Therefore, this study confirms that the ocean was widely anoxic during the Permian-Triassic transitional period. However,the redox condition in temporal ocean was probably not stable,with short-term fluctuations.Pyrite framboids were found in the Permian-Triassic boundary at Meishan Section,while their sulfur isotopes were determined.The majority of framboids is less than 5μm in diameter,with some large-sized framboids.Also,euhedral gypsums were observed in the boundary clay.The authors suppose that most of the pyrite framboids formed just below the redox boundary and stopped growing after entering the lower water column.The result indicates that it was probably lower dysoxia condition in the temporal ocean.Moreover,the authors also presume that some pyrite was oxidated to sulfates accompanying the fluctuation of redox condition,which would probably be the origin of the negative sulfur isotopes of gypsum and CAS reported before.In addition,sulfur isotope of framboidal pyrite suggests that sulfur is originated from bacterial sulfate reduction in anoxic condition.Therefore, this study confirms that the ocean was widely anoxic during the Permian-Triassic transitional period. However,the redox condition in temporal ocean was probably not stable,with short-term fluctuations.

关 键 词：PERMIAN-TRIASSIC framboidal pyrite sulfur isotope ANOXIC MEISHAN 

分 类 号：P618.51[天文地球—矿床学] P318.4[天文地球—地质学]