柴北缘前震旦纪地层系统的新认识

New Idea on Presinian Strata in the Northern Margin of Qaidam Massif

柴北缘的变质基底具有复杂的岩石组成,除成因迥异的多期变质深成侵入体外,还包括变质程度不同的表壳岩。南带的沙柳河、鱼卡河等地出露大理岩、石英岩、含石榴石片岩和条带状斜长角闪岩等以副变质岩为主的表壳岩系,共同构成了中元古界沙柳河岩群;而出露在北带全吉山、德令哈等地的中高级变质表壳岩系,则为形成于古元古代并具有较强的钾质混合岩化的达肯大坂岩群。柴北缘的榴辉岩分布在南带,除以规模较小的透镜体状赋存于新元古代花岗片麻岩中外,还和沙柳河岩群共生,但在北带的达肯大坂岩群中没有出现。全吉群的时代为南华纪至震旦纪。

There is very complicated composition in the metamorphic basement of the Northern Margin of Qaidam Massif. It includes multi-metamophic plutons and metamorphic crust. In the south part of the area appear marble, quartzite garnet-bearing schist, banded-plagioamphibolite and other paragneiss system and they are named ShaLiuhe Grupe. ln Quanjishan and Delingha area appear mid-high-metamophic crust system with extensive potassic migmatization, which formed in paleo-proterozoic and named DaKendaban Grorp.The eclogite in Qaidam is distributed only in the south part as small lens rounded by granite-gneiss, and some of them are in Shaliuhe Group. The age of Quanji Group is about from Nanhua to Sinian period.