中亚天山—帕米尔地区成矿地质背景

Ore-forming geological background of the Tianshan MountainsPamir region in Central Asia

中亚天山—帕米尔地区地处亚欧大陆腹地,跨古亚洲、特提斯两大全球性构造域,是哈萨克斯坦—准噶尔、卡拉库姆—塔里木、中伊朗—冈底斯、印度四大古板块的结合部位,地质构造复杂,矿产资源丰富。自中新太古代(或古元古代)以来分为5大演化阶段:1太古宙—古元古代演化阶段,本区古陆可能是组成Pangea-Ⅳ泛大陆的一部分;2长城纪—青白口纪泛大陆裂解事件导致了西昆仑地区第一次大规模的成矿作用,新元古代超大陆汇聚形成阶段,中天山地区广泛沉积了一套文德系含炭质岩系,形成金的矿源层,为后期大规模金的成矿作用提供了物质基础;3新元古代超大陆裂解及古亚洲洋—原特提斯洋演化阶段,岩浆活动强烈深部壳幔物质交换频繁,尤其是晚泥盆世—早中二叠世碰撞后伸展期,是区内最重要的成矿期;4研究区工作程度低(部分地区为空白区),特提斯洋演化阶段矿床发现较少,但找矿潜力巨大;5欧亚大陆形成后的后造山阶段,伴随着造山带强烈的挤压、褶皱、抬升、走滑、推覆等构造活动,岩浆作用十分发育,形成了一系列与韧性剪切构造有关的金矿化,以及与中酸性岩浆热液活动有关的铁、铜、多金属、锂铍(铌钽)、钨、锡、钼等矿产。

The Tianshan Mountains-Pamir region is located in the hinterland of Eurasian continent and in the junction of Kazakhstan-junggar, Karakum-Tarim, Central Iran-Gandise and Indian plate. It extends across two global tectonic domains, Tethys and Paleo-Asian Oceans, thus possessing complicated tectonic phenomena and rich mineral resources. Since Middle Neoarchean （or Proterozoic）the study area has experienced five main evolutionary phases. The continental nucleus in this area might have served as a part of“Pangea-Ⅳ”during Archean-Paleoproterozoic evolutionary phase. The first large-scale mineralization in Western Kunlun area was caused by continental breakup in the Changcheng-Qingbaikou period. At the Neoproterozoic supercontinental convergence stage, Vendian carbonaceous rock series was extensively deposited in Middle Tianshan Mountains, which served as the source bed of gold and provided a material basis for large-scale gold mineralization in the following evolutionary phase. Magmatic activities occurred intensely during the Neoproterozoic supercontinental breakup period as well as the evolutionary stage of Paleo-Asian Ocean and Tethys, with frequent exchange of deep crust-mantle material, especially in Late Devonian-Early-Midle Permian post-collisional intraplate extension phase, which seems to have been the most important ore-forming stage in the study area. As the study of this area remains at a very low level （some part in the study area even has no geological work）, few mineral deposits of the Tethys evolutionary stage have been discovered in spite of the fact that this area owns considerable prospecting potential. Following the strong tectonic activities in this area, such as crumpling, folding, lifting, striking-slipping and thrusting, magmatic activities occurred widely at the post-orogenic stage after the formation of Eurasian continent. As a result, there occurred a series of gold mineralization related to ductile shear structures, as well as iron, copper, multi-metal, lithium, beryllium （niobium, tantalum）, tungsten, tin, molybdenum and other minerals related to acidic magmatic hydrothermal activities.