中元古代微生物硅循环促进浅海硅岩沉积  

Microbial Silicon Cycling Promoted Shallow-Sea Chert Deposition in Mesoproterozoic Ocean

作　　者：史青 史晓颖[1,3,4] Jiang Ganqing 汤冬杰[1,2,4] 王新强 Shi Qing;Shi Xiaoying;Jiang Ganqing;Tang Dongjie;Wang Xinqiang(State Key Laboratory of Geomicrobiology and Environmental Changes,China University of Geosciences(Beijing),Beijing 100083,China;Institute of Earth Sciences,China University of Geosciences(Beijing),Beijing 100083,China;School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China;Frontier Science Center for Deep-Time Digital Earth,China University of Geosciences(Beijing),Beijing 100083,China;Department of Geoscience,University of Nevada,Las Vegas,NV 89154-4010,USA)

机构地区：[1]中国地质大学(北京)地质微生物与环境全国重点实验室,北京100083 [2]中国地质大学(北京)科学研究院,北京100083 [3]中国地质大学(北京)地球科学与资源学院,北京100083 [4]中国地质大学(北京)深时数字地球前沿科学中心,北京100083 [5]Department of Geoscience,University of Nevada,Las Vegas,NV 891544010,USA

出　　处：《地球科学》2025年第3期1082-1104,共23页Earth Science

基　　金：国家自然科学基金项目(No.41930320);教育部“111”项目(No.B20011).

摘　　要：为揭示中元古代浅海硅循环和硅岩形成机制,运用沉积学、矿物学、地球生物学和地球化学方法对华北~1.48 Ga雾迷山组硅岩开展了综合研究.结果表明,硅岩以微石英为主(~90%),含少量硅交代碳酸盐颗粒(~5%)和微量黄铁矿(~1%);并具高Ge/Si摩尔比(~8.83μmol/mol)和正Eu异常(~1.41),表明其主要为原生沉淀硅,~94%的硅源自海水.硅岩中保存良好的微生物组构(菌丝、胞外聚合物(extracellular polymeric substances,简称EPS)、席碎片)和微小蓝细菌与有机矿物密切共生,表明微生物在诱发硅沉淀中有重要作用.粘硅EPS和有机硅复合体降解释放硅可增加局部溶解硅浓度,改变沉积浅层和孔隙水化学条件,促进硅沉淀.微小蓝细菌和其他可聚硅微生物在浅海的繁盛对中元古代硅循环有重要影响,并促进了浅海环境的硅岩沉积.To reveal the silicon cycling and potential mechanism of chert deposition in Mesoproterozoic shallow seas,an integrated study of sedimentology,mineralogy,geobiology and geochemistry was conducted on the Wumishan cherts(~1.48 Ga)using multiple techniques.The results show that the cherts are predominated by microquartz(~90%)in composition,with some silicareplaced carbonate(~5%)and minor pyrite(~1%)grains,indicating that the cherts largely originated from primary silica precipitation.High Ge/Si molar ratios(~8.83μmol/mol)and positive Eu anomalies(~1.41)in the cherts suggest silica largely deriving from seawater(~94%),with a small contribution of thermally derived Si(~6%).Diverse microbial components(e.g.,microbial filaments,EPS(extracellular polymeric substances)relics,mat fragments)and picocyanobacterian fossils were closely associated with organominerals,suggesting that microbial activities played important roles in silica precipitation.The Si liberated from degraded EPS and organo-Si complexes locally increased the dissolved Si concentrations and changed the chemical conditions in shallow substrate and pore-waters,promoting silica precipitation.The flourishing picocyanobacteria and certain prokaryotes that can accumulate silica in their cells or EPS may have changed the Si-cycling in Mesoproterozoic ocean,and the biogenic silica released from the microbial biomass may have promoted the silica precipitation in the Mesoproterozoic shallow-sea environments.

关 键 词：中元古代浅海硅循环 生物成因硅 微生物硅化 海水溶解硅浓度 华北地台 沉积学 矿物学 

分 类 号：P534.3[天文地球—古生物学与地层学]