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首页> 外文期刊>Brazilian Journal of Geology >Geochemistry, metamorphic evolution and tectonic significance of metabasites from Ca?apava do Sul, southern Brazil
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Geochemistry, metamorphic evolution and tectonic significance of metabasites from Ca?apava do Sul, southern Brazil

机译：巴西南部卡帕帕瓦杜苏尔的变质岩的地球化学，变质演化和构造意义

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This paper proposes the generation and closure of a proto-ocean and formation of an island arc in the Neoproterozoic Passo Feio Metamorphic Complex (PFMC), Ca?apava do Sul region, southern Brazil. The PFMC, S?o Gabriel Terrane, consists of a Neoproterozoic supracrustal metavolcano-sedimentary sequence intruded by the Ca?apava Granite. The study uses petrography, whole-rock geochemistry and mineral chemistry to identify the geochemical affinity and tectonic environment of the amphibolites contained in PFMC, the basalts and pillow lavas of Arroio Mudador Formation and dikes intruded in nearby volcanogenic rocks of Hilário Formation. The applied methods allow the metamorphic facies classification of -prehnite-pumpellyite for the basalts and pillow lavas, greenschist for the dikes and lower amphibolite for the amphibolites. The discriminant diagrams indicate from tholeiitic to alkaline affinities for the Hilário Formation dikes. The basalts, pillow lavas and amphibolites have basaltic to basaltic-andesite composition and predominant tholeiitic affinity, interpreted as derived of the same protolith. The geotectonic diagrams mostly indicate volcanic arc basalts. The proposed evolution model starts with a proto-ocean opening through the Bossoroca Arc rifting around 760Ma, where an island arc is formed (PFMC rocks), precipitation of carbonates and marls, subsequent closure, two metamorphism events and the Ca?apava Granite intrusion around 562 Ma.
机译：本文提出了巴西南部南卡帕帕瓦多地区的新元古代Passo Feio变质复合体（PFMC）的原始海洋的形成和封闭以及岛屿弧的形成。 PFMC，S？o Gabriel Terrane，由Ca？apava花岗岩侵入的新元古代超壳火山沉积沉积序列组成。该研究利用岩相学，全岩石地球化学和矿物化学来确定PFMC中所含闪石的地球化学亲和力和构造环境，Arroio Mudador组的玄武岩和枕状熔岩以及侵入希拉里奥组附近火山岩的堤坝。所应用的方法允许对玄武岩和枕形熔岩进行-亚闪石-斜辉岩的变质相分类，对堤防进行Greenschist的变质分类，对角闪石的低变角质进行变质相分类。判别图表明希拉里奥组堤防从亲和力到碱性。玄武岩，枕状熔岩和闪石具有玄武岩到玄武岩-安山岩的成分，并具有主要的亲脂性，被解释为源自相同的原石。大地构造图主要显示火山弧玄武岩。拟议的演化模型始于760Ma附近的Bossoroca弧裂谷的原始海洋开口，其中形成了岛弧（PFMC岩石），碳酸盐和泥灰的沉淀，随后的封闭，两次变质事件以及Ca？apava花岗岩侵入周围562毫安。

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