东喜马拉雅构造结高压基性麻粒岩成因与构造意义
作者:
作者单位:

作者简介:

通讯作者:

中图分类号:

基金项目:

本文为中国地质调查项目(编号DD20221630)和国家自然科学基金项目(编号41941016- 2,U2244203,91855210)联合资助的成果


Petrogenesis of the high- pressure mafic granulite in the Eastern Himalayan Syntaxis and its tectonic implications
Author:
Affiliation:

Fund Project:

  • 摘要
  • |
  • 图/表
  • |
  • 访问统计
  • |
  • 参考文献
  • |
  • 相似文献
  • |
  • 引证文献
  • |
  • 资源附件
  • |
  • 文章评论
    摘要:

    东喜马拉雅构造结南迦巴瓦杂岩中存在典型的泥质、长英质和基性高压麻粒岩。但是,高压麻粒岩在南迦巴瓦杂岩中的分布范围、变质条件和变质时间是否存在空间上的变化并不明确。本文对南迦巴瓦杂岩西南部巴嘎地区的高压基性麻粒岩进行了岩石学和年代学研究。研究表明,巴嘎高压基性麻粒岩由石榴子石、单斜辉石、角闪石、斜长石、黑云母和石英组成,石榴子石变斑晶发育生长成分环带。识别出三期矿物组合:进变质矿物组合M1为石榴子石变斑晶核部及其矿物包裹体,包括石榴子石、石英、榍石和磷灰石;峰期矿物组合M2为变斑晶石榴子石边部和基质矿物,即石榴子石+单斜辉石+斜长石+角闪石+石英+金红石+熔体;退变质矿物组合M3呈冠状体或基质产出,其组合为角闪石+斜长石+单斜辉石+黑云母+石英+榍石。高压基性麻粒岩的峰期变质条件约为1. 5 GPa和915 ℃,具有顺时针P- T轨迹,退变质的早期和晚期分别为近等温降压和降温降压过程。高压基性麻粒岩在峰期条件下发生了明显的部分熔融,含~26%(体积)的熔体,其退变质和熔体结晶作用很可能发生在26~14 Ma。本文和研究区现有研究成果表明,东喜马拉雅构造结南迦巴瓦杂岩中的高压麻粒岩广泛分布,从东北部的加拉、直白和派乡延伸到西南部的巴嘎沟,形成了一条长度超过80 km的高压麻粒岩带。整个带中的高压麻粒岩具有类似的变质条件和持续时间,是印度大陆地壳平缓俯冲并经历了高温和高压变质与部分熔融的产物,构成了喜马拉雅造山带的加厚下地壳。大量高压麻粒岩强烈部分熔融产生的熔体可能为喜马拉雅淡色花岗岩提供了源区。

    Abstract:

    There are typical high- pressure pelitic, felsic, and mafic granulites in the Namche Barwa Complex in the Eastern Himalayan Syntaxis. However, the distribution and spatial variation of metamorphic conditions and timing of the high- pressure granulites in the Namche Barwa complex needs to be further studied. In this paper, we conducted a petrological and geochronological study for high- pressure mafic granulite from the Baga area in the southwest segment of the Namche Barwa Complex. The high- pressure mafic granulite consists of garnet, amphibole, clinopyroxene, plagioclase, biotite, and quartz, and the porphyroblastic garnets show growth compositional zoning. The granulite contains three stages of mineral assemblage: the prograde one is the core of porphyroblastic garnet and hosting mineral inclusions, including garnet, quartz, titanite, and apatite; the peak metamorphic assemblage is the rim of porphyroblastic garnet and matrix minerals of clinopyroxene, plagioclase, amphibole, quartz, rutile, and melt; the retrograde assemblage is symplectitic and matrix minerals, including clinopyroxene, amphibole, plagioclase, biotite, quartz, and titanite. The high- pressure granulite has a clockwise P- T path, with peak metamorphic conditions of 1.5 GPa and 915 ℃ and ~26% (volume) partial melt under the peak condition. The retrograde metamorphism and melt crystallization of the granulite is likely to have occurred at ~26 Ma, and last until ~14 Ma. Combined with previous studies, we suggest that the high- pressure granulites in the Namche Barwa Complex have a wide spatial distribution, extending at least more than 80 km from the northeast Gala, Zhibai, Pai to the southwest Baga area, and that these granulites have similar metamorphic conditions and metamorphic time scale. This study indicates that a large number of high- pressure granulites in the Namche Barwa Complex were derived from high- temperature and high- pressure metamorphism and partial melting of the underthrusted Indian continental crust, representing the thickened lower crust of Himalayan orogen. The voluminous melts produced by intensive partial melting of the high- pressure granulites provide the sources for Himalayan granites.

    参考文献
    相似文献
    引证文献
引用本文

吴双鹏,张泽明,田作林,芦维瑞,郭明明,张成圆.2024.东喜马拉雅构造结高压基性麻粒岩成因与构造意义[J].地质学报,98(1):96-115.
WU Shuangpeng, ZHANG Zeming, TIAN Zuolin, LU Weirui, GUO Mingming, ZHANG Chengyuan.2024. Petrogenesis of the high- pressure mafic granulite in the Eastern Himalayan Syntaxis and its tectonic implications[J]. Acta Geologica Sinica,98(1):96-115.

复制
分享
文章指标
  • 点击次数:
  • 下载次数:
  • HTML阅读次数:
  • 引用次数:
历史
  • 收稿日期:2023-02-16
  • 最后修改日期:2023-03-12
  • 录用日期:2023-03-13
  • 在线发布日期: 2024-01-22
  • 出版日期: