Proto-Adamastor ocean crust(920 Ma)described in Brasiliano Orogen from coetaneous zircon and tourmaline

作     者：Léo A.Hartmann Mariana Werle Cassiana R.L. Michelin Cristiano Lana Gláucia N. Queiroga Marco P. Castro Karine R. Arena 

作者机构：Instituto de GeociênciasUniversidade Federal do Rio Grande do SulAvenida Bento Goncalves950091501-970Porto AlegreRio Grande do SulBrazil Departamento de GeologiaEscola de MinasUniversidade Federal de Ouro PretoMorro do Cruzeiro35400-000Ouro PretoMinas GeraisBrazil 

出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)

年 卷 期：2019年第10卷第4期

页      面：1623-1633页

核心收录：

学科分类：07[理学] 0708[理学-地球物理学] 0704[理学-天文学] 

基　　金：field support from José Alirio Lenzi at Mina da Bossoroca Conselho Nacional do Desenvolvimento Científico e Tecnológico (Government of Brazil) supported systematically investigations by the authors  including undergraduate scholarship to Mariana Werle 

主　　题：Coeval zircon and tourmaline Bossoroca ophiolite Early Brasiliano Orogen Zircon U-Pb-Hf isotopes Zircon trace elements Tourmaline boron isotopes 

摘      要：Proto-Adamastor ocean bathed Rodinia and successor continental fragments from 1.0-0.9 Ga up to0.75 Ga,and evolved into world Adamastor Ocean at 0.75-0.60 Ga.Mesoproterozoic oceanic crust is poorly preserved on continents,only indirect evidence registered in Brasiliano Orogen.We report first evidence of ophiolite originated in proto-Adamastor.We use multi-technique U-Pb-Hf zircon andδ^11B tourmaline isotopic and elemental compositions.The host tourmalinite is enclosed in metaserpentinite,both belonging to the Bossoroca ophiolite.Zircon is 920 Ma-old,εHf(920 Ma)=+12,HfTDM=1.0 Ga and has’oceanic’composition(e.g.,U/Yb0.1).Tourmaline is dravite withδ^11B=+1.8‰(Tur 1),0‰(Tur 2),-8.5‰(Tur 3).These characteristics are a novel contribution to Rodinia and associated world ocean,because a fragment of proto-Adamastor oceanic crust and mantle evolved at the beginning of the Brasiliano Orogen.