新疆中亚造山带三叠纪矿床地质特征、时空分布及找矿方向

A review of geological characteristics and time-space distribution as well as prospecting direction of Triassic deposits in Central Asian Orogenic Belt,Xinjiang

中亚造山带以晚古生代成矿为特色,但最近十几年来在新疆阿尔泰、东天山等发现越来越多的三叠纪矿床,包括3个超大型矿床。在古生代造山带中为什么三叠纪能够成矿和成大矿,不同类型矿产特征和分布规律是值得关注的重要科学问题。目前确定新疆中亚造山带19个三叠纪矿床主要为花岗伟晶岩型稀有金属矿床、斑岩型钼矿床和矽卡岩型钨矿床。花岗伟晶岩型稀有金属矿床分布于阿尔泰,斑岩型钼矿床、矽卡岩型钨矿床和钨(钼)矿床分布于东天山。19个矿床的成矿年龄变化于193~248 Ma,峰值为215 Ma。不同矿床类型成矿时代略有差别,形成时间相对较早的有矽卡岩型,其次是斑岩型,伟晶岩型形成时间跨度最大,多数形成于晚三叠世,少数延续到早侏罗世。东天山沙东-小白石头一带钨矿和阿尔泰稀有金属矿最具找矿潜力。

The Central Asian Orogenic Belt is characterized by Late Paleozoic mineralization.However,more and more Triassic deposits,including three superlarge deposits,have been found in Altay and East Tianshan Mountains of Xinjiang in recent years.The mechanisms of mineralization and formation of large deposits in Triassic in the Paleozoic orogenic belt as well as characteristics and distribution regularity of different types of deposits constitute an important scientific problem.Up till now,nineteen Triassic deposits have been discovered in the Central Asian Orogenic Belt of Xinjiang,which are mainly granitic pegmatite rare metal deposits,porphyry Mo deposits,and skarn W deposits.The granitic pegmatite rare metal deposits,porphyry Mo deposits,and skarn W/W-(Mo)deposits are manly distributed in Altay and East Tianshan Mountains.The metallogenic ages of the nineteen deposits range from 248 Ma to 193 Ma with a peak of 215 Ma.In addition,there are slight differences in the metallogenic ages of different deposit types.The formation time of skarn is relatively early,followed by porphyry deposits.The granitic pegmatite deposits have the largest metallogenic age span;they were mostly formed in the Late Triassic with a few formed in the Early Jurassic.The Shadong-Xiaobaishitou tungsten deposits of East Tianshan Mountains and the rare metal deposits of the Alay metallogenic belts have the greatest prospecting potential.