Mesoproterozoic biomineralization:Cyanobacterium-like filamentous siderite sheaths~1.4 Ga  

作　　者：Dong-Jie Tang Xiao-Ying Shi Xi-Qiang Zhou Robert Riding 

机构地区：[1]State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences(Beijing),Beijing 100083,China [2]Institute of Earth Sciences,China University of Geosciences(Beijing),Beijing 100083,China [3]School of Earth Sciences and Resources,China University of Geosciences(Beijing),Beijing 100083,China [4]Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [5]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [6]Department of Earth and Planetary Sciences,University of Tennessee,Knoxville,TN 37996-1526,USA

出　　处：《Journal of Palaeogeography》2023年第3期384-400,共17页古地理学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41930320,41972028);the National Key Research and Development Project of China(Grant No.2020YFA0714803);the Chinese"111"Project(Grant No.B20011)。

摘　　要：Biomineralization was a key development in a wide variety of organisms,yet its history prior to the Ediacaran remains poorly understood.In this paper,we describe~1420-1330 million year old microscopic tubes preserved as siderite(FeCO_(3)).In size and shape these tubes closely resemble cyanobacterial sheaths forming mineralized mats.We consider two competing explanations for their formation.First,the tubes and associated sediment were originally composed of Ca-carbonate that was subsequently replaced by siderite.In this case,siderite mineralization was early,but post-mortem,as in early silicification,and preferentially preserved the more resilient sheath.However,no relict calcite is observed.Second,the Fe-carbonate mineralogy of the tubes and sediment is synsedimentary.In this case,photosynthetic oxygen may have precipitated Fe-oxyhydroxide that was promptly converted to siderite by dissimilatory iron reduction(DIR).Primary siderite mineralization of cyanobacteria has not been described before.Both explanations link photosynthetic processes to preferential sheath mineralization during the life of the cyanobacteria,as observed in present-day calcified cyanobacteria.This process might include CO_(2)-concentrating mechanisms(CCMs)linked to relatively low levels of atmospheric CO_(2),consistent with empirical estimates of mid-Proterozoic CO_(2)levels based on paleosols and weathering rinds.In either case,these cyanobacterium-like fossils preserved in siderite provide an early example of biomineralization and suggest the interactive in-fluences of both metabolic processes and ambient seawater chemistry.

关 键 词：Xiamaling Formation SIDERITE Ferruginous Dissimilatory iron reduction(DIR) Iron formation(IF) CO_(2)-concentrating mechanism(CCM) 

分 类 号：P57[天文地球—矿物学] P534.3[天文地球—地质学] Q91[生物学—古生物学]