大别山北大别杂岩的大地构造属性

摘要

北大别杂岩主要由花岗质片麻岩及斜长角闪岩组成，含有 不同类型、大小不等的麻粒岩岩块和变质超镁铁质岩块，侵入有大量白垩纪花岗岩和辉石- 辉长岩类。其中的花岗质片麻岩、斜长角闪岩具有岛弧环境的岩石地球化学特征，代表拼贴 于扬子陆块北缘的新元古代古岛弧。北大别杂岩北可与庐镇关群相连，南俯于超高压变质岩 之下，在三叠纪扬子陆块与华北陆块的碰撞过程中，曾与超高压变质岩一起俯冲到地幔深度 并经受榴辉岩相变质作用，然后在折返过程中叠加了麻粒岩相及角闪岩相变质作用，是扬子 陆块北缘陆壳俯冲基底的一部分。%The North Dabie Complex is mainly composed of granitic gneiss,amphibolite with l ots of different kinds and different sizes of granulite blocks and mate-ultrama fic blocks,which were intruded by massive Cretaceous granite and gabbro-pyroxin ite.The granitic gneiss and amphibolite formed at new Proterozoic with island-a rc geochemical features,represent a Late Proterozoic island arc.The North Dabie Complex can extend to the Luzhenguan Formation in the North Huaiyang belt to nor th and underlay the UHP metamorphic rocks to south.The North Dabie Complex subdu ct to the mantle depth and suffered the eclogite facies metamorphism together wi th the UHP metamorphic rocks in the Early Triassic collision between the Yangtze and North China continental blocks,and then overprinted by granulite facies and amphibolite facies retrogression during their exhumation,therefore the North Da bie Complex is a part of the subduct continental crust basement on the north mar gin of the Yangtze continental blocks.