ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    新疆西天山北缘浅成低温热液金成矿作用

    Epithermal Gold Mineralization in the Northern Margin of the West Tianshan, Xinjiang

    • 摘要: 新疆西天山北缘是浅成低温热液金矿床的重要产区,矿床主要赋存于晚泥盆世—早石炭世大哈拉军山组陆相火山岩中,集中分布于吐拉苏、也里莫顿火山断陷盆地及乌孙山地区。笔者在系统梳理区内阿希、京希–伊尔曼得、塔吾尔别克等典型金矿床地质与地球化学特征基础上,分析了金成矿作用与区域构造–岩浆演化的关系,探讨了成矿后的变化与保存过程及其对找矿勘查的启示。西天山北缘的浅成低温热液金矿床包括低硫型、高硫型及斑岩–浅成低温热液过渡型等多种类型。这些矿床在矿体产状、矿石组构、矿物组合及蚀变特征上具有明显差异。矿床的成矿物质主要来自赋矿的火山–次火山岩,成矿流体主要为岩浆热液(高硫型)、大气降水(低硫型)或二者的混合流体(斑岩–浅成低温热液过渡型),金沉淀机制包括流体沸腾、水–岩反应及流体混合等。成矿时代主要集中于晚泥盆世—早石炭世,形成于北天山洋与南天山洋俯冲高峰期的弧后伸展环境。矿床形成后经历了复杂的变化保存历史,吐拉苏、也里莫顿盆地内的浅成低温热液金矿床因剥蚀较弱而得以保存,其深部具有寻找斑岩–矽卡岩型Cu-Au多金属矿床的潜力;而盆地周缘因剥蚀程度较高,浅成低温热液型矿床多已遭剥蚀破坏,但斑岩–矽卡岩型矿床的找矿前景依然良好。

       

      Abstract: The northern margin of the West Tianshan in Xinjiang is well endowed with epithermal gold deposits. These deposits are primarily hosted in the continental volcanic rocks of the Late Devonian-Early Carboniferous Dahalajunshan Formation and are concentrated in the Tulasu and Yelimodun volcanic fault-depression basins and the Wusunshan area. Based on a systematic review of the geological and geochemical characteristics of typical gold deposits such as Axi, Jingxi-Yermand, and Tawuerbieke in the region, this paper analyzes the relationship between gold mineralization and regional tectonic-magmatic evolution, and discusses the post-mineralization modification and preservation processes as well as their implications for mineral exploration. The epithermal gold deposits in the northern margin of the West Tianshan include various types such as low-sulfidation, high-sulfidation, and porphyry-epithermal transitional types, which exhibit significant differences in ore body occurrence, ore texture, mineral assemblages, and alteration characteristics. The ore-forming materials are mainly derived from the host volcanic-subvolcanic rocks, and the ore-forming fluids consist primarily of magmatic hydrothermal fluids (high-sulfidation type), meteoric water (low-sulfidation type), or a mixture of these two fluids (porphyry-epithermal transitional type). Gold precipitation mechanisms include fluid boiling, water-rock interaction, and fluid mixing. The mineralization age is mainly concentrated in the Late Devonian-Early Carboniferous, formed in a back-arc extensional environment during the peak subduction of the North Tianshan and South Tianshan oceans. After their formation, the deposits underwent a complex modification and preservation history. The epithermal gold deposits in the Tulasu and Yelimodun basins have been preserved due to relatively weak erosion, and their deep sections hold potential for the discovery of porphyry-skarn-type Cu-Au polymetallic deposits. In contrast, the peripheral areas of the basins have experienced higher degrees of erosion, leading to the destruction of most epithermal deposits, but the prospects for porphyry- and skarn-type deposits remain favorable.

       

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