阿拉善朱拉扎嘎地区构造的样式、演化及其指示意义

Style and formatiom of structures in the periphery of Zhulazaga area, Alxa Block and their implication

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DOI 10.20086/j.cnki.yskw.2025.4134
刊名
Acta Petrologica et Mineralogica
年,卷(期) 2025, 44(4)
作者
作者单位

自然资源部成矿作用与资源评价重点实验室, 中国地质科学院矿产资源研究所, 北京 100037

摘要
地块边缘构造的研究是探索地块间相互作用的关键。阿拉善地块东缘朱拉扎嘎矿区附近岩石构造样式的解析不仅有助于理解构造控矿的过程,而且可揭示阿拉善地块及华北板块的相互作用,为探讨二者关系提供构造证据。朱拉扎嘎地区主要分布中元古代地层增隆昌组及上覆的阿古鲁沟组,野外地质调查结果显示两者为平行不整合接触。中元古代地层具体的构造样式为: ① 主体地层构成开阔的复式背斜,轴面倾向东,枢纽向南南西或南南东缓倾伏,褶皱过程中由于层间的剪切滑动,形成了一系列次级褶皱及广泛的层-劈构造。② 褶皱西翼增隆昌组推覆于阿古鲁沟组上,造成了增隆昌组推覆体内褶皱轴面倾向南西,产状与主体褶皱内增隆昌组不同,这与晚期南西向北东的逆冲推覆构造有关。褶皱内部未变形花岗斑岩形成时代为274±3 Ma,限定了区域缩短过程结束的时代,这与成矿时代大体一致。参考矿区平面图及勘探线剖面图,认为复式褶皱及核部断裂带控制了成矿过程,矿体形成于背斜南东翼向转折端过渡部位。结合区域地质资料,认为褶皱形成于晚古生代古亚洲洋南向俯冲伴生的挤压作用下,随后沿巴彦乌拉山的左行剪切下枢纽发生倾伏,而南西向北东的逆冲推覆则源于白垩纪青藏高原地区挤压的远程效应。朱拉扎嘎地区岩石的构造样式反映了造山过程中地壳的缩短及伴随的剪切过程,是研究地块间相互作用的重要例证。
Abstract
The study of structures along the margins of tectonic units is crucial for exploring the interactions between blocks or plates. The analysis of structural styles near the Zhulazaga ore district on the eastern margin of the Alxa Block not only helps to understand the process of structurally controlled ores, but also can reveal the interaction between the Alxa Block and the North China Plate. The strata in Zhulazaga area is mainly composed of the Mesoproterozoic Zenglongchang Formation and the overlying Agulugou Formation. Results of geological survey show that they are in parallel unconformity contacts. The specific structural styles are: ① the strata form an open anticlinorium, with the axis plunges towards the east and the hinge gently dipping towards the SSE or SSW. During the folding, a series of secondary folds and bedding-cleavage structures are widely developed due to interlayer shearing; ② In the western limb of the fold, the Zenglongchang Formation is thrust over the Agulugou Formation, causing the northeast-verging of folds within the Zenglongchang Formation, which is different from the occurrence of Zenglongchang Formation within the main fold. This is resulted from the top-to-the northeast thrust in the late stage. The formation age of undeformed granite within the folds is 274±3 Ma, which constrains the end time of the regional deformation and is consistent with the mineralization age. Referring to the planar graph and exploration profiles, it is believed that the anticlinorium and fault in the core controlled the mineralization, and the ore bodies were distributed in the transition area from the eastern limb of the anticline to the hinge zone. Based on regional geological data, it is suggested that the anticlinorium formed under the compression associated with the southward subduction of the Paleo-Asian Ocean in the late Paleozoic, followed by the plunging of the hinge related to the sinistral shearing of the Bayan Ul Mountains. The northeastward thrusting is due to the remote effect of the compression in the Tibetan plateau during the Cretaceous. The structural style of rocks near the Zhulazaga area reflects the shortening of the crust and the accompanying shearing during the orogenic process, which is an important example for studying the interaction between blocks or plates.
关键词
构造样式;控矿构造;晚古生代;朱拉扎嘎金矿床;阿拉善
KeyWord
structural style; ore-controlling structure; Late Paleozoic; Zhulazaga gold deposit; Alxa Block
基金项目
页码 767-787
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王东升*,江思宏,陈雷,刘翼飞,宫江华,季根源,闫鹏程,张博辉. 阿拉善朱拉扎嘎地区构造的样式、演化及其指示意义 [J]. 岩石矿物学杂志. 2025; 44; (4). 767 - 787.

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