Microbially-mediated formation of Ca-Fe carbonates during dissimilatory ferrihydrite reduction:Implications for the origin of sedimentary ankerite  

作　　者：Deng LIU Jinpeng CAO Shanshan YANG Yating YIN Pengcong WANG Dominic PAPINEAU Hongmei WANG Xuan QIU Genming LUO Zongmin ZHU Fengping WANG 

机构地区：[1]State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences,Wuhan 430074,China [2]School of Environmental Studies,China University of Geosciences,Wuhan 430074,China [3]London Centre for Nanotechnology,University College London,London WC1H 0AH,UK [4]Department of Earth Sciences,University College London,London WC1E 6BT,UK [5]Center for Planetary Sciences,University College London and Birkbeck College London,London WC1E 6BT,UK [6]State Key Laboratory of Microbial Metabolism,State Key Laboratory of Ocean Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Science China Earth Sciences》2024年第1期208-221,共14页中国科学（地球科学英文版）

基　　金：This research was jointly supported by the National Natural Science Foundation of China(Grant Nos.42272046,42293292 and 42072336);the National Key R&D Program of China(Grant No.2022YFF0800304);the 111 Project(Grant No.BP0820004).

摘　　要：The origin of sedimentary dolomite has become a long-standing problem in the Earth Sciences.Some carbonate minerals like ankerite have the same crystal structure as dolomite,hence their genesis may provide clues to help solving the dolomite problem.The purpose of this study was to probe whether microbial activity can be involved in the formation of ankerite.Bio-carbonation experiments associated with microbial iron reduction were performed in batch systems with various concentrations of Ca^(2+)(0–20 mmol/L),with a marine iron-reducing bacterium Shewanella piezotolerans WP3 as the reaction mediator,and with lactate and ferrihydrite as the respective electron donor and acceptor.Our biomineralization data showed that Ca-amendments expedited microbially-mediated ferrihydrite reduction by enhancing the adhesion between WP3 cells and ferrihydrite particles.After bioreduction,siderite occurred as the principal secondary mineral in the Ca-free systems.Instead,Ca-Fe carbonates were formed when Ca^(2+)ions were present.The CaCO_(3) content of microbially-induced Ca-Fe carbonates was positively correlated with the initial Ca2+concentration.The Ca-Fe carbonate phase produced in the 20 mmol/L Ca-amended biosystems had a chemical formula of Ca_(0.8)Fe_(1.2)(CO_(3))_(2),which is close to the theoretical composition of ankerite.This ankeritelike phase was nanometric in size and spherical,Ca-Fe disordered,and structurally defective.Our simulated diagenesis experiments further demonstrated that the resulting ankerite-like phase could be converted into ordered ankerite under hydrothermal conditions.We introduced the term“proto-ankerite”to define the Ca-Fe phases that possess near-ankerite stoichiometry but disordered cation arrangement.On the basis of the present study,we proposed herein that microbial activity is an important contributor to the genesis of sedimentary ankerite by providing the metastable Ca-Fe carbonate precursors.

关 键 词：ANKERITE Proto-ankerite Microbial iron reduction Dolomite problem Mineral transformation 

分 类 号：P578.61[天文地球—矿物学]