西准噶尔走滑断裂系元素分布特征及其成矿意义

The relationship between strike-slip tectonic system and geochemical anomalies in the West Junggar,northwestern China and its implication for mineral exploration

我国新疆西北部西准噶尔走滑断裂构造体系(简称"西准系")是中亚造山带巴尔喀什马蹄形构造的向东延伸部分,由于中生代成吉思-准噶尔断裂的右行走滑断裂作用而被分成了两个部分。西准系是一个多米诺式的走滑断裂构造体系,主要由达拉布特断裂、玛依勒断裂、巴尔鲁克断裂等三条NE走向的左行走滑断裂及其夹在它们之间的地块所组成,可能是晚古生代与走滑断裂相关的陆条弯曲(褶皱)作用的产物。同时,西准噶尔地区也是重要的晚古生代成矿带,产出有一些大型和超大型的金属矿床,包括包古图斑岩铜矿、哈图金矿、萨尔托海铬铁矿和杨庄铍矿床等。本文分析了西准系走滑断裂构造与元素分布之间的关系。结果显示,西准噶尔成矿带元素与地球化学块体以及铜、金、钼、铬铁矿等矿床的分布,均受晚古生代西准系的形成与演化过程的控制。其中,庙尔沟、红山岩体与金地球化学块体之间的反对称分布特征,说明了花岗岩类侵入体和金元素在达拉布特断裂左行走滑过程中发生了重要的物质调整与迁移作用。庙尔沟岩体的逆时针旋转运动,造成了环状断裂与裂隙系统,以及与之相对应的Cu、Pb等元素风火轮式的分布形式。走滑断裂作用与岩体旋转运动的共同结果,导致了金元素沿断裂和裂隙的迁移与成矿,使得西准地区金矿床在断裂和裂隙中的发育。断裂构造体系与元素地球化学异常之间的关系,可以用来有效指导西准地区未来矿产资源的勘查。

The West Junggar strike-slip faulting tectonic system （WJTS） in northwestern China, is an eastward extending of the Balkhash orocline in the Central Asian Orogenic Belt （CAOB）, truncated by the right-lateral strike-slip Chingiz-Junggar fault during the Mesozoic. It is a domino-type tectonic system composed of the NE-extending left-lateral strike-slip Darabut, Mayile, and Baerluke faults and tectonic blocks among them, due to strike-slip fault-related folding of continental ribbons in the Late Paleozoic. The West Junggar metallogenic belt （ WJMB）, with the occurrence of some large and super-large deposits such as the Baogutu porphyry Cu, Hatu Au, Saertuohai Cr, and Yangzhuang Be deposits, is also an important metallogenic belt formed in the Late Paleozoic. In this paper, the characteristics of the WJTS and its relationship to the geochemical anomalies are analyzed. The results show that, the distribution of geochemical blocks, element anomalies, and the formation and distribution of the NE-extending WJMB and sub-belts, and Cu, Au, Mo, and Cr deposits, is controlled by the formation and evolution of the WJTS in the Late Paleozoic. Antisymmetric distribution of the Miaoergou-Hongshan plutons and the geochemical Au blocks, indicates the important modification and migration of the granitic plutons and element Au during the left-lateral strike-slip faulting along the Darabut fault. The circular rotational fault system surrounding the Miaoergou pluton, results in hotwheel-like distributions of the element anomalies of Cu, Pb, etc. Meanwhile, the distribution of Au deposits in the WJMB is controlled by the fracture zones in the fault system of the WJTS. The understanding of the relationship between tectonic system and geochemical anomalies will benefit the future exploration for mineral deposits in the WJMB.