The Alto Moxotó Terrane 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 distri-bution points to a continental-arc related setting interpreted as remnants of the early stages of subduc-tion.In contrast,the Riacho do Navio Suite was emplaced at ca.2.08 Ga and has highly negative εNd(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 dis-criminant diagrams suggest that the precursor magmas were generated during the later stages of a con-tinental 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 Moxotó Terrane,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.

Lauro Cézar M.de Lira Santos;Geysson A.Lages;Fabrício A.Caxito;Elton L.Dantas;Peter A.Cawood;Haroldo M.Lima;Felipe J.da Cruz Lima

Departamento de Geologia,Universidade Federal de Pernambuco,Av.da Arquitetura,Cidade Universitária,Recife,PE,Brazil;Servi?o Geológico do Brasil-CPRM,Av.Sul,Afogados,Recife,PE,Brazil;CPMTC,Instituto de Geociências,Universidade Federal de Minas Gerais,Av.Pres.Ant?nio Carlos,Pampulha,Belo Horizonte,MG,Brazil;Instituto de Geociências,Universidade de Brasília,Campus Universitário Darcy Ribeiro,Asa Norte,Brasília,DF,Brazil;School of Earth,Atmosphere and Environment,Monash University,Wellington Rd,Clayton,VIC 3800,Australia;Departamento de Geologia,Universidade Federal do Ceará,Campus do Pici,Parquelandia,Fortaleza,CE,Brazil

地学前缘（英文版）

[1]Lauro Cézar M.de Lira Santos;Geysson A.Lages;Fabrício A.Caxito;Elton L.Dantas;Peter A.Cawood;Haroldo M.Lima;Felipe J.da Cruz Lima-.Isotopic and geochemical constraints for a Paleoproterozoic accretionary orogen in the Borborema Province,NE Brazil:Implications for reconstructing Nuna/Columbia)[J].地学前缘（英文版）,2022(05):267-285

Borborema,Moxot,obliterated,Fazenda,Carmo,Riacho,Navio,peridotitic,tholeiitic,subduc,ferroan,Cordilleran,tinental

Isotopic,geochemical,constraints,Paleoproterozoic,accretionary,Province,NE,Brazil,Implications,reconstructing,Nuna,Columbia,Alto,Terrane,wide,exposure,unlike,other,continental,blocks,South,America,orogenic,history,strongly,by,Neoproterozoic,deformation,New,isotopic,studies,were,conducted,ultramafic,Suite,granitic,gneissic,rocks,within,terrane,former,zircon,Pb,crystallization,Ga,whereas,Sm,Nd,data,suggests,juvenile,origin,via,melting,early,Archean,sources,Geochemical,these,are,compatible,magmas,some,degree,crustal,contamination,trace,element,points,arc,related,setting,interpreted,remnants,stages,In,contrast,was,emplaced,has,highly,negative,values,indicating,reworking,suite,displays,alkali,calcic,signatures,addition,distribution,well,criminant,diagrams,that,precursor,generated,during,later,syn,collisional,Based,results,studied,units,might,missing,pieces,formed,framework,this,represents,associated,assembly,supercontinent,which,now,largely,hidden,belts,West,Gondwana

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