东天山天宇镍矿床控矿构造初步研究

A PRELIMINARY STUDY ON THE ORE-CONTROLLING STRUCTURE IN TIANYU NICKEL DEPOSIT,EASTERN TIANSHAN MOUNTAINS,NW CHINA

天宇铜镍矿床位于塔里木板块之中天山地块东南缘,铜镍矿床主要受康古尔断裂和雅满苏断裂控制。矿区及外围主要出露中元古界的一套中、深变质岩系,次为上古生界一套火山熔岩、火山碎屑岩;褶皱构造和断裂构造比较发育,以北东东向为特征,白虎关复背斜是区内一级褶皱构造,砂泉子断裂(雅满苏断裂在区内的部分)是区内一级断裂构造;片麻岩及变形花岗岩中各种片麻状与眼球状构造非常发育,反映遭受了区域性韧性变形。详细的地表地质与坑道调查显示,矿区内以断裂构造为特征,主要有北东向断裂和近南北(北北东)向断裂,其中一部分北东向断裂控制含镍矿超基性岩体的侵位和展布,继而控制镍矿体的分布;近南北(北北东)向断裂主要为成矿后断裂,对含矿超基性岩体及镍矿起左行断错和破坏作用。但是在天宇镍矿区断错有限,主矿体比较完整,没有被明显断错。在1350 m采矿中段镍矿体的突然尖灭不是南北向断裂断错造成的,而是含矿超基性岩体内镍矿化不均匀的自然尖灭结果。此研究成果对于东天山地区乃至国内同类型铜镍矿床的构造控矿作用分析、矿山采矿工程部署等具有重要的启示。

Tianyu nickel deposit is located in southeastern margin of east Tianshan block of the Trim Plate.It is closely related between the ore resource and the tectonics in east Tianshan area,while the Cu-Ni deposits are mainly controlled by regional deep-major fault zone(Kangguer fault and Yamansu Fault et al).The mainly outcropped lithology are medium-hypo metamorphic rocks of middle Proterozoic group and secoundarily are volcanic rocks and pyroclastic rocks of upper Paleozoic group in Tianyu deposit and its vicinity.Folds and faults are well developed with NEE-trending extension in the area,in which,Baihuguan composite anticline is a first-order fold and Shaquanzi fault(as a part of the Yanmansu fault)is a first-order fault.Gneissoid and augen structures of metamorphic rocks or deformed granites are also well developed,which indicates that ductile deformation had occurred.Detailed surface geology and tunnel survey reveal that,there mainly are NE-trending and SN(NNE)-trending faults in ore area.Some of the NE-trending faults control on the Ni ore body by means of controlling the emplacement and distribution of the Ni-bearing ultra-basic rocks.The SN(NNE)-trending faults developed and became active after the forming of the Ni ore body,and often offset ultra-basic rock and Ni ore body with sinistral sense of displacement.Nevertheless,there isn’t an obvious sinistral sense of Ni ore body by SN(NNE)-trending faults in Tianyu ore area,and the main Ni ore body is complete and entire.The lens out of Ni ore body at northeast of CM12 on 1350m level was not caused by F8 fault,but resulting from a nature pinching out because of inhomogeneous nickel mineralization in ore-bearing ultra-basic rocks.The results of this study have important implications for the analysis of ore-controlling structure in eastern Tianshan mountains and all domestic copper-nickel deposits as well as the deployment of mining projects.