Late Cryogenian-Ediacaran magmatism in southern Borborema Province,NE Brazil:Ages,sources,petrogenesis,and tectonic setting  

作　　者：Fábio Santos Pereira Herbet Conceição Maria de Lourdes Silva Rosa Moacyr Moura Marinho Colombo Celso Gaeta Tassinari João Marinho Milhomem Neto Jean-Michel Lafon 

机构地区：[1]Programa de Pós-Graduação em Geologia e Geoquímica(PPGG),Instituto de Geociências,Universidade Federal do Pará(UFPA),66075-110 Belém,Pará,Brazil [2]Programa de Pós-Graduação em Geociências e Análise de Bacias(PGAB),Universidade Federal de Sergipe(UFS),49100-000 São Cristóvão,Sergipe,Brazil [3]Instituto de Geociências,Universidade Federal da Bahia(UFBA),40170-290 Salvador,Bahia,Brazil [4]Instituto de Geociências,Universidade de São Paulo(USP),05508-900 São Paulo,Brazil [5]Laboratório de Geologia Isotópica(Pará-Iso),IG-UFPA,66075-110 Belém,Pará,Brazil

出　　处：《Geoscience Frontiers》2023年第6期70-101,共32页地学前缘(英文版)

基　　金：This study was financed in part by the Coordenação de Aper-feiçoamento de Pessoal de Nível Superior-Brazil(CAPES)-Finance Code 001;The research was supported with funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq,Jean-Michel Lafon-grants 312393/2020-2 and 42625/2018-7;Maria de Lourdes Silva Rosa-grant 311023/2021-5;and Herbet Conceição-grant 310740/2021-5).

摘　　要：The Sergipano Orogenic System(SOS)in southern Borborema Province(NE Brazil)hosts voluminous Neoproterozoic plutonism related to the Brasiliano/Pan-African Orogeny.This paper presents comprehensive whole-rock geochemical data,titanite U-Pb ages,and the first combined zircon U-Pb and Lu-Hf isotope results for plutonic rocks from the MacururéDomain to constrain their sources,petrogenesis,and tectonic setting.Three magmatic episodes are recognized and record the evolutionary stages of the orogen.(i)Early-collisional magmatism(643–628 Ma)comprises gabbros and diorites with minor tonalites characterized by well-developed tectonic foliation and evidence of solid-state deformation.These rocks are magnesian,high-K calc-alkaline,LILE-and LREE-enriched and provide subchondriticε_(Hf)(t)values(6.5 to4.7)and Orosirian Hf-T^(C)_(DM)model ages(1.83–1.94 Ga).Such features indicate derivation from a lithospheric mantle source metasomatized by incorporating crustal components through subduction processes prior to magma generation,possibly related to the Rhyacian Orogeny(2.20–1.96 Ga).Extensive mixing/mingling between basaltic and crust-derived magmas took place at lower crustal depths,producing coeval hybrid diorites and quartz-diorites.(ii)Syn-collisional magmatism(630–624 Ma)encompasses biotite-and muscovite-bearing granodiorites and monzogranites,preserving their structures parallel to the schistosity of the country rocks.These rocks are leucocratic,weakly metaluminous to peraluminous,and contain abundant surmicaceous enclaves.Petrographic features and geochemical composition suggest an origin related to the partial melting of graywacke protoliths with a subordinate igneous component.(iii)Late-collisional magmatism(625–600 Ma)includes undeformed and isotropic monzonites and granodiorites,which truncate the regional foliation.These rocks are consistently metaluminous and magnesian,showing affinities with the high-K calc-alkaline to shoshonite series.Trace element modeling with subchondriticε_(Hf)(t)values(8.3 to4.1)

关 键 词：Brasiliano/Pan-African Orogeny Western Gondwana Zircon and titanite U-Pb dating Hf isotope data Magma source 

分 类 号：P588.1[天文地球—岩石学] P597[天文地球—地质学] P534.4