新疆铂族元素成矿地质条件及找矿方向研究

A RESEARCH ABOUT MINERALIZING CONDITIONS AND PROSPECTING TARGET OF PGE IN XINJIANG

在综合分析前人成果基础上,通过大量野外调查和室内综合研究,应用岩浆-沉积建造学观点,从基性、超基性岩与区域大地构造演化,不同类型的火山-沉积作用的成生关系,首次将新疆境内的岩体划分为绿岩、类暗色岩、蛇绿岩三种建造类型,并分别论述了不同类型岩体的形成构造环境、岩石组合和建造持征、区分标志及成矿专属性。绿岩建造型岩体代表早期大陆地壳裂陷作用和一套与绿岩型火山-沉积建造相关的侵入体,以菁布拉克、库鲁克塔格和西昆仑三岩带为代表;蛇绿岩型岩体系哈萨克斯坦板块不同时期和不同发展阶段的大洋化过程产物。计有乌什通沟-卡瓦布拉克、红柳沟-安南坝、阿帕-芒崖、唐巴勒、洪古尔勒楞、达拉布特、阿尔曼泰、克拉麦里、博乐霍洛、库米什及米斯布拉克等共12个岩带;类暗色岩建造型岩体系在西伯利亚、哈萨克斯坦和塔里木三大板块拼合后,成生于一种过渡壳类型的陷裂构造环境,并与一套中酸性火山岩-沉积岩建造有关的侵入体,包括喀拉通克、博格达-巴里坤、黄山、特克斯及穹塔格等五个岩带。依据岩石学、矿物学、地球化学及数学地质等的研究,蛇绿岩型岩体多属镁质系列的超基悱岩类,以铬铁矿化为明显特征,伴生的铂族元素矿化芒要属高温的Os、Ir、Rh、Ru型,且与铬铁矿密切相关。绿岩和类暗色岩建造型由铁质系列的基性一超基性杂岩构成,是区内已知重要的铜、镍、铂成矿类型的岩体。据此,作者从区域成矿地质条件分析入手,对新疆境内的不同类型岩体的含铂性及远景进行了评述,并提出库鲁克塔格、菁布拉克两岩带为成矿远景区带,兴地Ⅱ号和特克斯岩体为成矿靶区岩体。

On the basis of previous achievement, field investigation and indoor comprehensive study, the authors adopted the viewpoint of magma-sedimen- tary formation, first divided the basic-ultrabasic rock bodies distributed in Xingjiang by means of the relationship between these rocks and regional tectonic evolution as well as volcanic-sediment process in to three kinds of formation: greenston, quasi-melanocrate and ophiolite types. The genetic tectonic environment, rock assemblage, formation leature, distinguish mark and metallogenic specialization of different kind of rocks have been discus- sed in this professional paper. It was pointed out that the greenston for- mation type represents intrusive body related to early continental crust rifting and greenston type volcanic-sediment formation, e. g. Jingbulak, Kuruktag and western Kunlun rock belts; ophiolite type belongs to produ- cts of distinct period and developing stage oceanization of Kazakstan pla- te. There were 12 rock belts in the ophiolite, such as Wushitonggou-Karr- wabulak, Hongliugou-Annanba, Arpa-Mangnai, Tangbale Mayil, Hong-go- luneng, Darbut, Armantai, Karamiri, Bolohoro, and Misbulak etc. Quasi-melanocrate formation type, which includes Haratongk, Bogda-Bar- kol, Huangshan, Tekes and Qungtag intrusions, belongs to intrusions rela- ted to mid-acid volcanic-sediment formation, and formed in a rift tectonic environment of transitive crust type after conjuction of Siberia, Hazakstan and Tarim plate. According to petrology, mineralogy, geochemistry and geomathematic study, the authors come to the conclusion that the ophiolite type intrusion belongs to magnesian series ultrabasic rocks, and its significant feature is chromitization. Accompaning PGE mineralization is mainly high-tempera- ture Os, Ir, Rh and Ru type and closely related to chromite. Greenstone and quasimelanocrate formation type is composed of magnesian series basic- ultrabasic complex and is known importan mineralized rock body, especi- ally Cu, Ni and Pt. In this point, the authors evaluated Pt-bearing nature and prospect of distinct rock bodies in Xinjiang by analysing regional me- tallogenic geologic condition, and proposed that Kuruktag and Jingbulak rock belts are prospect area, the target rock bodies are Xingdi No. 2 and Tekes.