新疆巴里坤小加山钨成矿岩体地球化学特征及找矿前景

    Geochemistry and ore-search prospect analysis of the Xiaojiashan tungsten metallogenic rock mass in Barkol area, Xinjiang

    • 摘要: 小加山钨矿床位于新疆东准噶尔成矿区,侵入岩主要岩石类型为黑云母花岗岩,赋矿围岩主要为蚀变闪长岩和变晶屑凝灰岩。对侵入岩及其围岩主量、微量和稀土元素的地球化学特征进行分析,充分认识侵入岩浆的性质、成矿物质来源及构造背景。花岗岩蚀变过程中钾长石大量分解,W元素在热液作用下由花岗岩进入矿脉,使蚀变围岩中W含量降低。黑云母花岗岩是晚古生代海西期岩浆活动的产物。该矿床构造背景是后碰撞伸展花岗岩,岩体形成于伸展构造环境。在海西期构造活动影响下含钨花岗质岩浆侵入地层,富含W元素岩浆过渡性流体沿裂隙向上流动,在上部地层中引发硅化和绢云母化。随着大气降水的加入,成矿流体温度降低,成矿物质与石英沉淀形成石英脉型钨矿床。结合矿化富集规律、控矿断裂构造,以及异常带区域W含量等值线,分析认为矿区西部外围、深部的成矿潜力大。

       

      Abstract: Xiaojiashan tungsten deposit is located in East Junggar metallogenic area of Xinjiang and biotite granite is the most widely distributed intrusive rock mass, with alteration diorite and metamorphic crystal tuff being the mainly surrounding rocks.Systematic analyses on geochemical features from major elements, trace elements and rare earth of intrusive rocks and surrounding rock mass in Xiaojiashan reveal nature of faults, sources of ore-forming materials and tectonic settings of intrusive rocks.In the course of alteration, potassium feldspar was decomposed and elements such as W migrated into the vein through granite under the hydrothermal process, making the content of tungsten lower gradually in the alteration of surrounding rocks.The biotite granite is the product of magmatic activities in Hercynian period of Late Paleozoic.Tectonic settings of the deposit are post-collisional extensional granite, and the rocks were formed in an extensional tectonic environment.Under the influence of Hercynian tectonic activities, tungsten-containing granitic magma invaded strata, and magmatic hydrothermal transitional fluid, which was rich in tungsten and flowed upward along the fissure, causing silicification and sericitization in the upper strata.With the increase of atmospheric precipitation, ore-forming fluid temperature was reduced and the ore-forming materials and quartz precipitation formed the quartz vein type tungsten deposit.Combined with the law of mineralization enrichment, ore-controlling fault structures and W content contour lines in anomalous zone, the metallogenic potential in the western periphery and deep part of the mining area was analyzed.

       

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