西昆仑麻扎构造混杂岩带中－下侏罗统叶尔羌群源区构造背景分析

Provenance analysis of the Middle-Lower Jurassic Yarkant Group in the Mazar tectonic mélange zone in western Kunlun Mountains

摘要: 本文在收集和总结前人研究成果的基础上,通过对西昆仑麻扎地区中-下侏罗统叶尔羌群碎屑组分和砂岩地球化学特征分析,讨论了叶尔羌群沉积源区大地构造背景。在莎里塔什组沉积时期,物源区的构造背景主要为大陆岛弧、大洋岛弧的性质;杨叶组沉积时期,源区的大地构造背景为大陆岛弧,兼有活动大陆边缘性质;塔尔尕组沉积时期,源区构造背景复杂:既显示活动大陆边缘和岛弧(大洋岛弧、大陆岛弧)的性质,同时还显示出被动陆缘环境,其可能与晚三叠世造山开始时克拉通地块边缘的卷入有关。

Abstract: The provenance analysis is conducted on the basis of the compositions and geochemical signatures of the sandstones from the Middle-Lower Jurassic Yarkant Group in the Mazar tectonic mélange zone in western Kunlun Mountains. The tectonic settings of the provenances consist of continental island arcs and oceanic island arcs during the deposition of the Shalitashi Formation; continental island arcs associated with active continental margins during the deposition of the Yangye Formation, and active continental margins, magmatic island arcs(oceanic island arcs and continental island arcs) and passive continental margins during the deposition of the Targa Formation. The results of research in this study may provide helpful information for the approaches to the tectonic evolution of western Qinghai-Xizang Plateau.