沉积过程对自生黄铁矿硫同位素的约束  

Constraint of Sedimentary Processes on the Sulfur Isotope of Authigenic Pyrite

作　　者：刘喜停 李安春[2] 马志鑫[3] 董江 张凯棣 徐方建[5] 王厚杰[1] LIU XiTing;LI AnChun;MA ZhiXin;DONG Jiang;ZHANG KaiDi;XU FangJian;WANG HouJie(College of Marine Geosciences,Key Laboratory of Submarine Geosciences and Prospecting Technology,Ocean University of China,Qingdao,Shandong 266100,China;Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences,Qingdao,Shandong 266071,China;Chengdu Center,China Geological Survey,Chengdu 610081,China;Key Laboratory of Marine Sedimentology and Environmental Geology,First Institute of Oceanography,Ministry of Natural Resources,Qingdao,Shandong 266061,China;School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China)

机构地区：[1]中国海洋大学海洋地球科学学院,海底科学与探测技术教育部重点实验室,山东青岛266100 [2]中国科学院海洋研究所海洋地质与环境重点实验室,山东青岛266071 [3]中国地质调查局成都地质调查中心,成都610081 [4]自然资源部第一海洋研究所海洋沉积与环境地质重点实验室,山东青岛266061 [5]中国石油大学(华东)地球科学与技术学院,山东青岛266580

出　　处：《沉积学报》2020年第1期124-137,共14页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目（41976053,41430965,41606062）;“科学”高端用户项目（KEXUE2017G15)~~

摘　　要：自生黄铁矿是海洋沉积物中还原态硫的主要赋存形式,其形成过程与有机质矿化相关,影响全球的C⁃S⁃Fe生物地球化学循环。自生黄铁矿硫同位素分馏主要受微生物硫酸盐还原的控制,但近期的研究成果表明局部沉积环境的改变也可以影响黄铁矿硫同位素的组成,特别是在浅海环境。在浅海非稳态沉积环境内,物理再改造和生物扰动作用,导致硫酸盐还原带内生成的硫化物被再氧化,进而影响黄铁矿的硫同位素值。浅海沉积过程容易受到古气候和海平面变化的影响,引起沉积速率的剧烈波动,导致有机质和活性铁输入的不稳定,进而影响成岩系统的开放性和硫酸盐还原速率,最终影响黄铁矿的硫同位素值。另外,沉积速率的改变还影响硫酸盐—甲烷转换带的迁移,造成有机质和甲烷厌氧氧化硫酸盐还原的相互转化,产生不同的硫同位素信号。东海内陆架泥质区为研究沉积过程对自生黄铁矿的形成及其硫同位素组成的约束机制提供了很好的研究材料。该区域有很好的沉积学研究基础,自生黄铁矿丰富、并且个别层位有生物气(甲烷为主)存在,是研究边缘海C⁃S⁃Fe循环的理想场所。Authigenic pyrite is the main mineral specie of reduced sulfur in marine sediments.Its formation process is related to organic mineralization and affects the global C⁃S⁃Fe biogeochemical cycle.Sulfur isotope fractionation of authigenic pyrite is mainly controlled by microbial sulfate reduction,but recent studies have indicated that the local depositional environment also affects the composition of pyrite sulfur isotopes,especially in shallow depositional envi⁃ronments.In an unsteady shallow environment,physical reworking and bioturbation lead to reoxidation of sulfides formed in the sulfate reduction zone,which in turn affects the sulfur isotopes of pyrite.The sedimentation process in a shallow depositional environment is readily affected by paleoclimate and sea⁃level changes,which cause drastic fluc⁃tuations in sedimentation rate as well as instable input of,for instance,organic matter and active iron.This in turn af⁃fects the openness of the diagenetic system and ultimately affects the isotopic value of pyritic sulfur.In addition,any change in sedimentation rate also affects the movement of the sulfate⁃methane transition zone,resulting in the conver⁃sion of organic matter and anaerobic oxidation methane sulfate reduction,producing different sulfur isotope signals.The study of the sulfur isotopes of authigenic pyrite in the mud area of the inner shelf of the East China Sea provides a good example for depositional control on the formation of authigenic pyrite and its sulfur isotope composition.The sed⁃imentary process of this area has been well studied,and its sediments have been shown to be enriched in authigenic pyrite and biogas(CH4).Therefore,it is an ideal site for studying the sulfur cycle in a marginal sea,and is expected to provide a new perspective on the global C⁃S⁃Fe biogeochemical cycle.

关 键 词：黄铁矿 硫同位素 微生物硫酸盐还原 沉积环境 东海 

分 类 号：P736.44[天文地球—海洋地质]