非洲西北部的In Ouzzal麻粒岩带  

IN OUZZAL GRANULTIC TERRANE IN NORTH -WEST AFRICA

作　　者：刘新秒[1] 

机构地区：[1]中国地质科学院天津地质矿产研究所,天津300170

出　　处：《前寒武纪研究进展》1998年第2期54-60,共7页Progress in Precambrian Research

摘　　要：非洲西北部的InOuzzal麻粒岩带是太古宙地体，以构造窗形式出现在新元古代的泛非造山带中。基底岩石主要是2．7Ga前的TTG岩套以及后来的侵入体，表壳岩有绿岩带和变质沉积岩，在20Ga的比里姆（Biriman）期发生了极高温的变质作用（P≈12×108Pa，T≈1100℃），具有顺时针的PTt轨迹。在后来的泛非期，该带两侧叠加了糜棱岩化作用，形成了热液型的世界级金矿床。大部分研究者认为该地体是地壳深处岩石的地表露头，对研究地壳的形成、演化及相应的大陆裂解和碰撞有非常重要的意义。In Ouzzal granulite unit is an mainly Archaean block within the NeoproterozoicPan- African belt of north - west Africa. The granulites derive from Archaean Protoliths thatinclude me of metasediments which deposited on a 3. 2 Ga genessic basement. The meta -igneous rocks can be dated and generally classified according to their chemical comopitions asbassic- ultrabasic granulites and acid orthogneisses. The former is like to be the suites found inArchaean greenstone belts and the latter is similar to the TTG suits. The very high - temperaturemetamorphism occured at 2007 ± 7 Ma from the age of synfoliation intrusions and theretrogressive metamorphism is dated at 1. 95 Ga from garnet - Nd ages. Seveal strike- slip faultswith mylonite belts were formed during Pan - African, and the N - S East Ouzzal shear conehosts several wold - class gold deposits over a 100 km length.

关 键 词：太古宙 麻粒岩带 高温变质作用 热液型 金矿床 

分 类 号：P618.510.2[天文地球—矿床学] P588.346[天文地球—地质学]