北羌塘地区冬布勒山基性、超基性岩特征及构造意义

冬布勒山基性、超基性岩产于若拉岗日逆冲断裂带北侧,近东西向展布,岩石组合为超镁铁岩及变质玄武岩,与千枚岩、硅质岩、碳酸盐岩共生,呈岩块状镶嵌于上三叠统若拉岗日岩群砂泥质复理石、中基性火山岩及灰岩中。超镁铁岩浆来自亏损的地幔,并受壳源物质混染;玄武岩贫钾富钠,属钙碱性、碱性系列,为过渡型洋脊玄武岩,它们为蛇绿岩残片,与西侧大横山、弯岛湖蛇绿混杂岩带、东部康特金—岗齐曲蛇绿混杂岩带处于同一构造带,东连金沙江蛇绿岩带,是古特提斯洋壳向北俯冲消减过程中形成的增生楔。

Characteristics and tectonic significance of Dongbuleshan basic-ultrabasic rocks in Northern Qiangtang Region

Dongbuleshan basic-ultrabasic rocks,located at the northern of Ruolagongri thrust fault zone,occurred along the east-west direction together with the phyllite,siliceous,and carbonate rocks.They were mosaic in a massive rock early Triassic Ruolagangri Rock Group flysch sand-mud rocks,intermediate-mafic volcanic rocks and limestone rocks.Ultramafic rocks,derived from depleted mantle,are subjected to the contamination by crustal material;the basalt rocks are poor-K and Na-rich,and belong to calc-alkaline-alkal...