论文部分内容阅读
位于巴基斯坦北部西喜马拉雅的科希斯坦地体为夹持于亚洲板块与印度板块之间的倾斜的岛弧型壳体.科希斯坦岛弧北界为主地幔逆冲断层(MMT),北界为北部缝合带(或喀啦昆仑主逆冲断层,MKT),可将其划分为几个地质单元.奇拉斯(Chilas)杂岩体为一长约300 km、宽50 km的巨型基性侵入岩体与MMT和MKT近平行展布.它被认为是科希斯坦岛弧的岩浆房根区.奇拉斯杂岩体主要由辉长苏长岩和几个超镁铁质岩.镁铁质岩(简称UMA)岩体组成.前者侵入后者之中.奇拉斯杂岩体 岩石普遍发生轻微变形,出现叶理化和韧性剪切带.UMA主要由橄榄石(含或不含单斜辉石)堆积岩 (纯橄岩,异剥橄岩)和斜长石.单斜辉石-斜方辉石堆积岩(二辉辉长岩)组成,含有少量单斜辉石-斜方 辉石堆积岩(辉石岩)。辉长苏长岩的地球化学特征表明其为岛弧环境下形成的非堆积岩,而UMA的 地球化学特征表明其为岛弧环境下的堆积岩.辉长苏长岩和UMA的主元素地球化学特征在AFM图 解上可用堆积和非堆积的模式来解释.辉长苏长岩的稀土和微量元素地球化学特征在100 MgO/(MgO+TFeO)图解上显示岛弧型特点,且UMA表明其堆积特性.
The Koštistan terrane in western Himalayas in northern Pakistan is a sloped island-shaped shell sandwiched between the Asian and Indian plates. The northern boundary of the arc in Kohistanistan is dominated by the mantle thrust fault (MMT) For the northern suture (or Kalachakram main thrust, MKT), it can be divided into several geological units.The Chilas complex is a massive mantle with a length of about 300 km and a width of 50 km The intruded rock mass is nearly parallel to MMT and MKT and is considered as the magmatic root zone of the Kohishitan arc. The Chrysler complex consists mainly of gabbroic facies and several ultramafic rocks. (UMA), the former invades the latter.The rock of the Chilas complex generally undergo slight deformation and appear leaf physicochemical and ductile shear zones.UMA mainly consists of olivine (with or without monoclinic (Pegmatite, exodont), plagioclase, clinopyroxene-orthopyroxene (dacite gabbro), with a small amount of clinopyroxene-orthopyroxene Accumulation rock (pyroxene). The geochemical characteristics of the Hui-long magmatic rocks indicate that it is a non-accumulative rock formed in the island arc environment, while the geochemical characteristics of the UMA indicate that it is a sedimentary rock in an island arc environment. The main elemental geochemical characteristics of the Hui-long magmatic rocks and UMA are described in AFM The patterns can be explained by the patterns of accumulation and non-accumulation.The REE and trace element geochemical characteristics of the Hui-Chang syenite show island-arc characteristics on the graph of 100 MgO / (MgO + TFeO), and the UMA shows its accumulation characteristics.