Paleo-and Mesoarchean TTG-sanukitoid to high-K granite cycles in the southern São Francisco craton,SE Brazil  

作　　者：Claudio de Morisson Valeriano Caio Vinicius Gabrig Turbay Henrique Bruno Antonio Simonetti Monica Heilbron Samuel Moreira Bersan Rob Strachan 

机构地区：[1]Universidade do Estado do Rio de Janeiro,Faculdade de Geologia,Rua São Francisco Xavier 524/4006-B,Maracanã,Rio de Janeiro,Brazil [2]Universidade Federal do Sul da Bahia,Centro de Formação em Ciências Ambientais,Porto Seguro,Bahia,Brazil [3]University of Portsmouth,School of Environment,Geography and Geosciences,Burnaby Building,Burnaby Road,Portsmouth PO13QL,United Kingdom [4]University of Notre Dame,Department of Civil and Environmental Engineering and Earth Sciences,46556,United States

出　　处：《Geoscience Frontiers》2022年第5期153-168,共16页地学前缘（英文版）

基　　金：support from the PRONAGEO mapping program of the CPRM(Brazilian Geological Service);funding to CMV and MH respectively。

摘　　要：The generation of the continental crust is widely accepted to have taken place predominantly in the Archean,when TTG magmatism associated with greenstone-belt supracrustal succession development was typically followed by emplacement of high-K granites before crustal stabilization.This study focuses on the Campos Gerais complex(CGC),which is an Archean granite-greenstone belt lithological association in a tectonic window located in the southwesternmost portion of the São Francisco craton(SFC).The CGC is an important segment of Paleo-to Mesoarchean continental crust to be integrated into paleogeographic reconstructions prior to the transition into the Paleoproterozoic.This investigation reports field relationships,28 major and trace element compositions,U–Pb(zircon)geochronological results,and Hf and Sm–Nd isotope data for orthogneiss and amphibolite samples.The results indicate that the CGC records a complex Archean crustal evolution,where voluminous 2.97 Ga TTG tonalites and trondhjemites(ε_(Nd)(t)=-4.7;T_(DM)=3.24 Ga)were followed by 2.89 Ga sanukitoid tonalite production(ε_(Nd)(t)=-1.9;T_(DM)=3.02 Ga),broadly coeval with the development of the Fortaleza de Minas and Pitangui greenstone-belts.These events are interpreted to represent the initial stage of an important subduction-accretion tectonic cycle,which ended with the emplacement of 2.82–2.81 Ga high-K leucogranites and migmatization of the TTG-sanukitoid crust,with hybrid and two-mica,peraluminous compositions(ε_(Nd)(t)=-8.0 to-8.6;T_(DM)=3.57–3.34 Ga).The presence of inherited zircons with207Pb/206Pb ages of 3.08 Ga,3.29 Ga,3.55 Ga and 3.62 Ga indicates that the Mesoarchean tectonic processes involved reworking of Meso-to Eo-archean crust.Renewed TTG magmatism took place at ca.2.77 Ga represented by juvenile tonalite stocks(ε_(Nd)(t)=+1.0 to-1.5;T_(DM)=2.80–2.88 Ga)which intrude the TTG-greenstone belt association.Crustal stabilization was attained by 2.67 Ga,allowing for the emplacement of within-plate tholeiitic amphibolites(ε_(Nd)(t)=-3

关 键 词：Crustal evolution Sm–Nd Lu–Hf LA-ICPMS zircon U–Pb 

分 类 号：P548[天文地球—构造地质学]