新疆阿尔泰萨尔朔克铜多金属矿成矿作用研究

The Cu deposits in the Ashele basin are related to Middle Devonian volcanic activities, which have the characteristics of VHMS type of deposit but without "double layer" structure. The Ashele Cu-Zn deposit mainly occurs as beds orebodies while Kayingde Cu deposit occurs as veins orebodies. The Saershuoke Cu polymetallic deposit, a newly discovered medium-sized deposit, which has bed mineralization, vein mineralization and mineralization in diabase dykes, is the best place for studying the metallogeny of VHMS deposit. On the basis of a systematic study of deposit geology and an anatomy of the Saershuoke Cu polymetallic deposit, the author focuses on the vocanic rocks, rhyolite porphyry, diabase, mineralization distribution, mineral assemblage, wall rock alteration and enrichment process of ore-forming elements. The research on geochemistry, fluid inclusions, isotop geoemistry and geochronology is to discuss the metallogenic materials, origin and evolution of ore-forming fluids, magmatism, metallogenic epoch, the enrichment process of Cu polymetal and the relationship between the Cu polymetal and rhyolite porphyry as well as diabase vein, volcanic eruption, hydrothermal sedimentation. The purpose of the study is to redefine the genetic type of the deposit, explore the metallogeny and establish a metallogenic model. This study is conducive to reunderstanding the metallogeny of Cu polymetallic deposits in the Ashele basin, enriching the metallogenic theory of Cu deposits in the Central Asian metallogenic megaprovince and summing up the metallogenic regularity and prospecting criteria, and thus it can provide a theoretical basis for mineral exploration of Cu deposits in northern Xinjiang.

阿舍勒盆地铜矿与中泥盆世火山活动有关，具有VHMS型矿床特征，但又缺乏"双层"结构，阿舍勒铜锌矿以层状矿化为主，喀英德铜矿以脉状为主。萨尔朔克是近年来发现的中型铜多金属矿，既有层状矿化、脉状-网脉状矿化还有与辉绿岩有关的矿化，是研究VHMS型矿床成矿作用的最佳场所。本项目以萨尔朔克铜多金属矿为重点解剖对象，以系统的矿床学研究为基础，重点对火山岩、潜流纹斑岩及辉绿岩，矿化分布、矿物组合、围岩蚀变，成矿元素富集过程进行研究，通过岩石地球化学、流体包裹体、同位素和年代学研究，查明火山喷发、热水沉积、流纹斑岩和辉绿岩脉与铜多金属关系，成矿物质、成矿流体来源及演化，岩浆活动和成矿时代，解析Cu多金属的聚集过程。目的在于厘定成因类型，探讨成矿作用，建立成矿模型。本项目有助于认识阿舍勒盆地铜多金属矿成矿作用，丰富中亚成矿域铜矿成矿理论；总结成矿规律和找矿标志，为新疆北部铜矿的找矿勘查提供理论基础。

萨尔朔克是近年来发现的中型多金属矿，火山岩系中发现了层状矿化、流纹斑岩中有脉状-网脉状矿化，辉绿岩也有少量矿化，是研究VMS型矿床成矿作用的最佳场所。本项目以萨尔朔克为重点解剖对象，开展了含矿火山岩系、次火山岩、韧性剪切带、矿物学、成矿物质来源、成矿流体、成矿时代及成矿机制研究。火山岩锆石LA-ICP-MS U-Pb年龄限定阿舍勒组时代为371～402 Ma，属早-中泥盆世，形成于大洋岛弧环境。矿体主要赋存于流纹斑岩中，少量在阿舍勒组火山岩中。矿石呈致密块状、块状、条纹状、浸染状、细脉、网脉状和脉状构造，围岩蚀变主要是硅化、绢云母化和黄铁矿化，矿床形成经历了喷流沉积期和次火山热液期，金铜铅锌矿化形成于次火山热液期的早成矿阶段。主成矿阶段成矿温度集中于130～390℃，流体盐度集中于3.0～10.0 wt% NaCleq，密度0.56～1.03 g/cm3。硫化物δ34S集中于-1.52‰～6.18‰，峰值为2.5‰，表明硫来自深源岩浆。石英δD介于-140‰～-103‰，δ18OSMOW值6.9‰～8.5‰，δ18OH2O值为-4.03～0.94‰，结合黄铁矿He-Ar同位素，认为成矿流体是岩浆水混合深循环的海水。温度和压力降低导致流体沸腾，同时流体成分改变等在成矿过程中起着主导作用。矿床成因类型为VMS型。阿舍勒矿集区402 Ma形成英安岩，394 Ma在阿舍勒矿区II带形成“双层”结构矿化，387 Ma左右喷流沉积作用形成阿舍勒1号主矿体，383Ma 之前萨尔朔克喷流沉积作用形成少量层状矿化，382～383Ma 在流纹斑岩中形成铜铅锌金矿化，随后辉绿岩脉侵入（381.7Ma），形成少量铜矿化，378 Ma阿舍勒 IV号带在次英安岩中形成铜矿化。251～254 Ma经历了韧性剪切变形，对矿体进行改造。萨尔朔克多金属矿成矿机制研究，有助于认识阿舍勒矿集区铜多金属矿成矿作用，丰富中亚成矿域成矿理论；总结成矿规律，建立矿集区矿床模型为新疆VMS型的找矿勘查提供理论基础。