Isotopic and geochemical constraints for a Paleoproterozoic accretionary orogen in the Borborema Province,NE Brazil:Implications for reconstructing Nuna/Columbia  

作　　者：Lauro Cézar M.de Lira Santos Geysson A.Lages Fabrício A.Caxito Elton L.Dantas Peter A.Cawood Haroldo M.Lima Felipe Jda Cruz Lima 

机构地区：[1]Departamento de Geologia,Universidade Federal de Pernambuco,Av.da Arquitetura,Cidade Universitária,Recife,PE,Brazil [2]Serviço Geológico do Brasil-CPRM,Av.Sul,Afogados,Recife,PE,Brazil [3]CPMTC,Instituto de Geociências,Universidade Federal de Minas Gerais,Av.Pres.Antônio Carlos,Pampulha,Belo Horizonte,MG,Brazil [4]Instituto de Geociências,Universidade de Brasília,Campus Universitário Darcy Ribeiro,Asa Norte,Brasília,DF,Brazil [5]School of Earth,Atmosphere and Environment,Monash University,Wellington Rd,Clayton,VIC 3800,Australia [6]Departamento de Geologia,Universidade Federal do Ceará,Campus do Pici,Parquelândia,Fortaleza,CE,Brazil

出　　处：《Geoscience Frontiers》2022年第5期267-285,共19页地学前缘（英文版）

基　　金：support from Australian Research Council grant FL160100168;supported by the National Institute of Science and Technology for Tectonic Studies(INCT)of Brazil。

摘　　要：The Alto MoxotóTerrane of the Borborema Province presents a wide exposure of Paleoproterozoic crust,but unlike other continental blocks of South America,its orogenic history is strongly obliterated by late Neoproterozoic deformation.New isotopic and geochemical studies were conducted in mafic-ultramafic(Fazenda Carmo Suite)and granitic-gneissic rocks(Riacho do Navio Suite)within the terrane.The former present zircon U-Pb crystallization ages at ca.2.13 Ga,whereas Sm-Nd data suggests a juvenile origin via melting of early Paleoproterozoic to Archean peridotitic sources.Geochemical data for these rocks are compatible with tholeiitic magmas with some degree of crustal contamination and trace element distribution points to a continental-arc related setting interpreted as remnants of the early stages of subduction.In contrast,the Riacho do Navio Suite was emplaced at ca.2.08 Ga and has highly negativeεNd(t)values indicating crustal reworking.The suite displays calc-alkali to alkali-calcic and ferroan geochemical signatures compatible with Cordilleran magmas.In addition,trace-element distribution as well as discriminant diagrams suggest that the precursor magmas were generated during the later stages of a continental arc or in a syn-collisional setting.Based on our results,we suggest that the studied units might represent missing pieces of a Paleoproterozoic accretionary orogen that formed the crustal framework of the Alto MoxotóTerrane,and that this represents a block associated with assembly of the Nuna/Columbia supercontinent,which is now largely hidden within the Neoproterozoic orogenic belts of West Gondwana.

关 键 词：Paleoproterozoic accretionary-collisional event Early orogenic and syn-collisional magmatism Paleoproterozoic inlier within West GONDWANA Nuna/Columbia Supercontinent 

分 类 号：P597[天文地球—地球化学] P542.2[天文地球—地质学]