西天山构造演化与优势矿产成矿规律

Tectonic Evolution and Metallogenic Regularity of Dominant Deposits in the Western Tianshan

西天山位于中亚增生型造山带的西南缘,夹于准噶尔地块和塔里木克拉通之间.西天山造山带的构造演化与天山洋的俯冲‒关闭过程密切相关.西天山地质构造复杂,成矿作用独特,既可形成与活动陆缘有关的斑岩铜金矿和火山‒沉积岩型铁锰矿,也可发育与伸展构造有关的海底热水沉积型铅锌矿和浅成低温热液型金矿等多个集中区.西天山地质构造演化和成矿作用一直是地质学家关注和研究的热点,近年来的地质找矿和基础研究工作也取得一系列重大进展,但同时也存在一些急待解决的问题.本文通过对区域地质背景、沉积建造、岩浆演化、成矿地质特征与物质来源、控矿因素等方面资料的综合研究,认为西天山造山带从前寒武纪到晚古生代经历了古陆边缘裂解、洋‒陆俯冲增生、陆‒陆碰撞及后造山伸展等地质过程;与此相应形成了多个成矿区带,主要包括:(1)哈尔达坂前寒武纪古陆边缘裂陷盆地环境的铅锌成矿带,(2)与博罗科努古生代洋‒陆俯冲、碰撞‒碰撞后伸展环境有关的金铜铅锌多金属成矿带,(3)与阿吾拉勒晚古生代岛弧‒弧后盆地有关的铁多金属成矿带,(4)那拉提古生代岛弧金铜多金属成矿带.在此基础上建立了西天山主要成矿区带的成矿模式,厘定了与西天山沉积建造‒构造活动‒岩浆活动有关的成矿序列,总结了西天山铁铜铅锌金等优势矿产时空结构模型.

The West Tianshan is located in the southwest margin of the Central Asian accretionary orogenic belt.It is sandwiched between Junggar Block and Tarim Craton.Its tectonic evolution is closely related to subduction-closed processes of Tianshan ocean.The geological structure of the West Tianshan is complex and its mineralization is unique.Some ore concentration areas were developed in West Tianshan orogen,such as porphyry gold-copper deposit and volcanic-sedimentary type ferromanganese deposit related to active continental margin,and submarine hydrothermal sedimentary lead-zinc deposit and epithermal hydrothermal gold deposit related to extensional tectonics setting.The tectonic evolution and mineralization of the West Tianshan have always been the focus of geological research.In recent years,significant progress has been made in geological prospecting and basic research.However,there are still some major geological and ore-forming problems to be solved urgently.Based on comprehensive study of the regional geological background,sedimentary formation,magmatic evolution,metallogenic geological characteristics,oreforming material sources and ore-controlling factors,it is shown that West Tianshan orogen has experienced some geodynamic processes,namely the formation of Precambrian continent,ocean-continent subduction accretion,continent-continent collision orogen.Some main metallogenic belts were formed in the West Tianshan from Precambrian to Late Paleozoic,such as(1)Haldaban Precambrian Pb-Zn metallogenic belt,(2)Borokonu Paleozoic gold‐copper‐lead-zinc polymetallic metallogenic belt,(3)Awulale Late Paleozoic iron manganese polymetallic metallogenic belt,(4)Nalati Paleozoic gold-copper polymetallic metallogenic belt.And on that basis,some the ore-forming models of the main metallogenic belts were established,the metallogenic sequences related to sedimentary formation-tectonic-magmatic activity were determined,the spatiotemporal structural models of the regional dominant resources such as iron,copper,lead,zinc and gold were summarized.