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东南极格罗夫山泛非期变质演化及东冈瓦纳形成历史研究

项目名称: 东南极格罗夫山泛非期变质演化及东冈瓦纳形成历史研究
项目类型: 国家自然科学基金委员会(自由申请)
项目负责人: 刘晓春
项目成员: 赵越; 赵子然; 曲玮
项目编号: 40072028
父项目编号:
规划期:
立项时间: 2001-01-01
预期结束: 2001-12-31
实际结束:
金额(万元): 29
目录

详细描述

项目简介

   东南极地盾内部泛非构造热事件的规模、性质及其大地构造意义是国际地质学界研究的前沿课题。本项目通过格罗夫山地区高级变质杂岩的变质岩石学和同位素年代学研究,获得如下重要认识:(1)发现辉石出溶结构,由此获得峰期变质温度为850 C,并根据火成普通辉石的识别确定该区只存在单相麻粒岩相变质;(2)通过伟晶岩中石榴石斑晶与围岩中石榴石的对比研究提出了石榴石的捕虏晶成因,进而确定该区不存在晚期角闪岩相变质作用;(3)在东南极首次识别出泛非期紫苏花岗岩和后构造层状花岗岩,为泛非构造热事件的碰撞造山成因提供了重要佐证;(4)对不同岩石类型的锆石SHRIMP定年精确地限定了格罗夫山地区主期变质作用发生于泛非期,~550 Ma,热事件结束于~500 Ma,年代学数据没有揭示在该区存在格林威尔期麻粒岩相变质作用的迹象;(5)进一步确认了东南极内部普里兹带的存在,它属于冈瓦纳超大陆内部的第二条泛非期缝合带,据此认为冈瓦纳超大陆并不是由东、西冈瓦纳陆块的简单拼合而成,而是多个不同块体拼合的结果。该项研究对新元古代-早古生代全球构造演化的研究具有重要的科学意义。

introduction

   The extent, nature and significance of the Pan-African tectonothermal event in the East Antarctic Shield are the current discussed issue. Based on the petrological and geochronological study of metamorphic complexes from the Grove Mountains, the following conclusions are reached. (1)Exsolution texture is widely found in clinopyroxene in mafic granulites. A peak metamorphic temperature of 850 C was obtained from the reintegrated compositions of exsolved clinopyroxene. The preservation of augite megacrysts suggests a single episode of high-grade metamorphism for the Grove Mountains. (2)The compositional comparison of garnet from pegmatites with that from country rocks demonstrates that garnet in pegmatites is of xenocryst origin, and late amphibolite facies metamorphism does not occur in this area. (3)The Pan-African charnockite and post-tectonic sheet-like granite were first recognized in East Antarctica. Their occurrences suggest a collisional orogeny during the Pan-African time. (4)The SHRIMP U-Pb zircon dating on various rock types indicates that the major metamorphism in the Grove Mountains occurs at c. 550 Ma, and the tectonothermal evolution terminated at c. 500 Ma. The Grenvillian granulite facies metamorphism did not develop in the studied area. (5)The Prydz belt, the second Pan-African suture within the Gondwana suppercontinent, was further comfirmed based on this study. The Gondwana suppercontinent was not formed by the simply juxtaposition of East and West Gondwana, but by the collision of several blocks during the Pan-African time. These conclusions are very important for understanding the tectonic evolution of the earth during the Neoproterozoic to early Palaeozoic.


相关论文

期刊 标题 作者
Precambrian Research 2006 145 Late Pan-African granitoids from the Grove Mountains, East Antarctica: Age, origin and tectonic implications Bor-ming Jahn; Yue Zhao; Miao Li; Huimin Li; 刘晓春; 李淼; 刘小汉
Precambrian Research 2006 145 Late Pan-African granitoids from the Grove Mountains, East Antarctica: Age, origin and tectonic implications Bor-ming Jahn; Yue Zhao; Miao Li; Huimin Li; 刘晓春; 李淼; 刘小汉
极地研究 2013 25 东南极格罗夫山:普里兹造山带中一个典型的泛非期变质地体 赵越; 胡健民; 刘小汉; 曲玮; 刘晓春