Epithermal deposits in North Xinjiang, NW China
Epithermal deposits in North Xinjiang, NW China
复制标题
DOI：
10.1007/s00531-011-0689-4
复制
发表时间：
2012-06
影响因子：
2.3
通讯作者：
Y. Chen;F. Pirajno;G. Wu;J. Qi;X. Xiong
中科院分区：
文献类型：
--
作者：
Y. Chen;F. Pirajno;G. Wu;J. Qi;X. Xiong
新疆北部地区位于西伯利亚板块、塔里木板块和哈萨克斯坦板块的结合部，是中亚造山带的重要组成部分。该地区是一个具有多阶段大陆生长特征的地区，在此期间形成了多个斑岩和低温热液系统。这些矿物系统与该区域地球动力学演变的关系尚未得到很好的理解。本文列举了新疆北部21个重要的浅成低温热液贵金属及贱金属矿床的主要地质特征，并将其分为高硫化型和低硫化型两类，以低硫化型为主。本文选取了七个在不同构造体制下形成的具有不同类型的浅成低温热液矿床，对其地质和地球化学特征进行了较为详细的讨论。新疆北部浅成低温热液系统的矿床规模地质和地球化学特征与世界其他地区基本相似。新疆北部浅成低温热液矿床均产于火山岩中，时代为泥盆纪至三叠纪，其中以早石炭世火山岩序列最重要，其次为二叠纪和三叠纪。泥盆纪-早石炭世容矿岩属钙碱性系列，形成于前碰撞弧-弧后盆地体系;而二叠纪-三叠纪容矿火山岩属橄榄玄岩系列，形成于俯冲后体系。这些浅成低温热液体系的有效同位素年龄可分为早石炭世（>320 Ma）和晚石炭世-三叠纪（320-220 Ma）两个时期，分别反映了与俯冲有关的增生和俯冲后碰撞体制下的两个成矿幕。据此，新疆北部浅成低温热液矿床可分为三组：（1）碰撞前矿床，碰撞体系矿床;（2）俯冲碰撞体系矿床;（3）俯冲碰撞体系矿床。
The North Xinjiang region (NW China) is an important part of the Central Asia Orogenic Belt, situated at the junction of Siberia, Tarim and Kazakhstan plates. It is an area characterized by multiple stages of Phanerozoic continental growth, during which several porphyry and epithermal systems were formed. The relationship of these mineral systems to the geodynamic evolution of the region has not yet been well understood. In this paper, we list the main geological characteristics of 21 significant epithermal precious and base metal deposits in North Xinjiang, and classify them into high-sulfidation and low-sulfidation styles, with the latter being predominant. We have selected seven epithermal deposits representing different styles formed under different tectonic regimes and discuss their geology and geochemistry in some detail. The deposit-scale geology and geochemistry of epithermal systems in North Xinjiang are essentially similar to those in other parts of the world. All epithermal deposits in North Xinjiang are hosted in volcanic rocks with ages ranging from Devonian to Triassic, with the Early Carboniferous volcanic sequences being the most important, followed by the Permian and Triassic. The Devonian–Early Carboniferous host rocks belong to the calc-alkaline series that developed in pre-collisional arc-back-arc basin systems; whereas the Permian–Triassic host volcanic rocks of shoshonite series formed in post-subduction regimes. Available isotopic ages of these epithermal systems cluster in two periods: Early Carboniferous (>320 Ma) and Late Carboniferous–Triassic (320–220 Ma), reflecting two metallogenic episodes that occurred during subduction-related accretion and post-subduction collision regimes, respectively. Accordingly, three groups of epithermal deposits in North Xinjiang can be recognized as (1) pre-collisional deposits without or with negligible collisional-related modification, (2) deposits formed in collision regime and (3) ore systems strongly overprinted by fluid flow in post-subduction collision regime.