Neoarchean atmospheric chemistry and the preservation of S-MIF in sediments from the São Francisco Craton  

作　　者：Alice Bosco-Santos William Patrick Gilhooly Ⅲ Paola de Melo-Silva Fotios Fouskas Amaury Bouyon João Gabriel Motta Mauricio Rigoni Baldim Wendell Fabricio-Silva Pascal Philippot Elson Paiva Oliveira 

机构地区：[1]Department of Geology and Natural Resources,University of Campinas,Campinas,SP 13083855,Brazil [2]Department of Earth Sciences,Indiana University-Purdue University Indianapolis,Indianapolis,IN,USA [3]Institut de Physique du Globe de Paris,Universitéde Paris,CNRS-UMR 7154,75005 Paris Cedex 05,France [4]Vizlab-X-Reality and GeoInformatics Lab,UNISINOS,São Leopoldo,RS 93022-750,Brazil [5]Geosciences Department,Federal University of Mato Grosso,Cuiabá,MT,Brazil [6]Geosciences Institute,University of Brasilia,Brasília,Distrito Federal 70910-900,Brazil [7]Institute of Geography and Geology,University of Würzburg,97074 Würzburg,Germany [8]Géosciences Montpellier,Universitéde Montpellier,CNRS,Universitédes Antilles,Montpellier,France [9]Institute of Astronomy,Geophysics,and Atmospheric Sciences,University of São Paulo,Rua do Matão 1226,São Paulo,Brazil

出　　处：《Geoscience Frontiers》2022年第5期207-226,共20页地学前缘（英文版）

基　　金：São Paulo Research Foundation(FAPESP grants2016/02933-2 to ABS,12/15824-6 to EPO and 2015/16235-2 to PP);the Agouron Institute(to WPG)for financial support。

摘　　要：Sulfur mass-independent fractionation(S-MIF)preserved in Archean sedimentary pyrite is interpreted to reflect atmospheric chemistry.Small ranges in Δ^(33)S that expanded into larger fractionations leading up to the Great Oxygenation Event(GOE;2.45–2.2 Ga)are disproportionately represented by sequences from the Kaapvaal and Pilbara Cratons.These patterns of S-MIF attenuation and enhancement may differ from the timing and magnitude of minor sulfur isotope fractionations reported from other cratons,thus obscuring local for global sulfur cycling dynamics.By expanding the Δ^(33)S record to include the relatively underrepresented São Francisco Craton in Brazil,we suggest that marine biogeochemistry affected S-MIF preservation prior to the GOE.In an early Neoarchean sequence(2763–2730 Ma)from the Rio das Velhas Greenstone Belt,we propose that low δ^(13)Corg(<-30‰)and dampened Δ^(33)S(-0.4‰to-0.7‰)in banded iron formation reflect the marine diagenetic process of anaerobic methane oxidation.The overlying black shale(TOC up to 7.8%)with higher δ^(13)Corg(-33.4‰to-19.2‰)and expanded Δ^(33)S(2.3‰±0.8‰),recorded oxidative sulfur cycling that resulted in enhance preservation of S-MIF input from atmospheric sources of elemental sulfur.The sequence culminates in a metasandstone,where concomitant changes to more uniform δCorg(-30‰to--25‰),potentially associated with the RuBisCO I enzyme,and near-zero Δ^(33)S(-0.04‰to 0.38‰)is mainly interpreted as evidence for local oxygen production.When placed in the context of other sequences worldwide,the Rio das Velhas helps differentiate the influences of global atmospheric chemistry and local marine diagenesis in Archean biogeochemical processes.Our data suggest that prokaryotic sulfur,iron,and methane cycles might have an underestimated role in pre-GOE sulfur minor isotope records.

关 键 词：S-MIF preservation Archean atmospheric chemistry GOE São Francisco Craton 

分 类 号：P402[天文地球—大气物理学与大气环境] P534.2[天文地球—大气科学及气象学]