The Paleoarchean Northern Mundo Novo Greenstone Belt,São Francisco Craton:Geochemistry,U-Pb-Hf-O in zircon and pyriteδ^(34)S-Δ^(33)S-Δ^(36)S signatures  

作　　者：Guilherme S.Teles Farid Chemale Jr. Janaína N.Ávila Trevor R.Ireland 

机构地区：[1]Unidade Acadêmica de Mineração e Geologia,Universidade Federal de Campina Grande,Campina Grande,Brazil [2]Programa de Pós-Graduação em Geologia,Universidade de Brasília,Brasília,Brazil [3]Programa de Pós-Graduação em Geologia,Universidade do Vale do Rio dos Sinos,São Leopoldo,Brazil [4]Research School of Earth Sciences,The Australian National University,Canberra,ACT 2601,Australia [5]Griffith Centre for Social and Cultural Research,Griffith University,Nathan,Queensland 4111,Australia

出　　处：《Geoscience Frontiers》2022年第5期190-206,共17页地学前缘（英文版）

基　　金：the Brazilian National Council for Scientific and Technological Development(CNPq)for financial support(grants 163459/2013-4 and 202267/2014-8 for G.S Teles and 305053/2014-0 for F.Chemale Jr.);the Australian Research Council(ARC)(grant DP140103393 for T.R.Ireland)。

摘　　要：Greenstone belts contain several clues about the evolutionary history of primitive Earth.Here,we describe the volcano-sedimentary rock association exposed along the eastern margin of the Gavião Block,named the Northern Mundo Novo Greenstone Belt(N-MNGB),and present data collected with different techniques,including U–Pb–Hf–O isotopes of zircon and multiple sulfur isotopes(^(32)S,^(33)S,^(34)S,and ^(36)S)of pyrite from this supracrustal sequence.A pillowed metabasalt situated in the upper section of the N-MNGB is 3337±25 Ma old and has zircon with ε_(Hf)(t)=2.47 to1.40,Hf model ages between 3.75 Ga and 3.82 Ga,and δ^(18)O=+3.6‰to+7.3‰.These isotopic data,together with compiled whole-rock trace element data,suggest that the mafic metavolcanic rocks formed in a subduction-related setting,likely a back-arc basin juxtaposed to a continental arc.In this context,the magma interacted with older Eoarchean crustal components from the Gavião Block.Detrital zircons from the overlying quartzites of the Jacobina Group are sourced from Paleoarchean rocks,in accordance with previous studies,yielding a maximum depositional age of 3353±22 Ma.These detrital zircons have ε_(Hf)(t)=5.40 to0.84,Hf model ages between 3.66 Ga and 4.30 Ga,and δ^(18)O=+4.8‰to+6.4‰.The pyrite multiple sulfur isotope investigation of the 3.3 Ga supracrustal rocks from the N-MNGB enabled a further understanding of Paleoarchean sulfur cycling.The samples have diverse isotopic compositions that indicate sulfur sourced from distinct reservoirs.Significantly,they preserve the signal of the anoxic Archean atmosphere,expressed by MIF-S signatures(Δ^(33)S between1.3‰to+1.4‰)and a Δ^(36)S/Δ^(33)S slope of0.81 that is indistinguishable from the so-called Archean array.A BIF sample has a magmatic origin of sulfur,as indicated by the limited Δ^(34)S range(0 to+2‰),Δ^(33)S~0‰,and Δ^(36)S~0‰.A carbonaceous schist shows positive Δ^(34)S(2.1‰–3.5‰)and elevated Δ^(33)S(1.2‰–1.4‰)values,with corresponding negative Δ^(36)S

关 键 词：Northern Mundo Novo Greenstone Belt Multiple sulfur isotopes GEOCHRONOLOGY Paleoarchean Gavião Block São Francisco Craton 

分 类 号：P542[天文地球—构造地质学] P597[天文地球—地质学]