新疆北山盐滩断裂南一带高级变质岩系的发现、地质热力学特征及其大地构造意义

发布时间：2018-05-25 16:37

  本文选题：新疆北山 + 高级变质岩系　； 参考：《岩石学报》2016年06期

【摘要】：新疆北山盐滩断裂南一带从原划奥陶-志留系地层中解体出古老的角闪岩相-麻粒岩相变质岩和变质侵入岩体,主要岩性为黑云母斜长片麻岩、条带状混合岩、斜长角闪岩、及少量变粒岩、麻粒岩等。其中首次发现了代表中、下地壳深变质作用的中-高压基性麻粒岩。详细的野外调查、岩相学及矿物学研究表明,该基性麻粒岩主要由透辉石、紫苏辉石、褐色普通角闪石及拉长石组成。其演化经历了由麻粒岩相岩石经退变质反应而成为角闪岩相变质岩的过程。研究表明,该区麻粒岩中的单斜辉石及角闪石矿物学成因均属于变质成因,其中单斜辉石形成环境为高压型,而角闪石形成环境为中低压环境。麻粒岩相变质岩形成于约1.25GPa(42km埋深)以下的中高压-高压环境,其形成温度约841℃;而退变质作用下的角闪岩相变质岩应形成于650~657℃的温度范围之内,压力为0.460~0.495GPa之间,相应的代表埋深约为16.5km的中低压型环境。该区高级变质岩及其基性麻粒岩的发现,将对该区地壳成分、麻粒岩的成因与变质作用以及所处的大地构造背景演化等研究无疑将起到非常重要的作用。
[Abstract]:The ancient amphibolite-granulite facies metamorphic rock and metamorphic intrusive rock bodies have been disintegrated from the Ordovician strata in the southern area of Beishan Yantan fault in Xinjiang. The main lithology is biotite plagiocline gneiss, banded migmatite, and amphibolite. And a small amount of granulite, etc. The intermediate-high pressure basic granulites representing the deep metamorphism of the middle and lower crust were first found. Detailed field investigation, petrographic and mineralogical studies show that the basic granulite is mainly composed of diopside, perilla pyroxene, brown common hornblende and elongate. The evolution of amphibolite metamorphic rocks from granulite facies rocks to amphibolite facies metamorphic rocks by retrograde metamorphism. The results show that both clinopyroxene and hornblende mineralogy in granulite belong to metamorphic origin. The formation environment of clinopyroxene is high pressure and that of hornblende is middle and low pressure. The granulite facies metamorphic rocks were formed in the medium and high pressure environment (about 1.25GPa(42km buried depth) and the formation temperature was about 841 鈩，

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