东昆仑冰沟南铜镍矿锆石SHRIMP U-Pb年龄及构造意义

发布时间：2018-04-05 17:32

本文选题：构造意义　切入点：铜镍矿　出处：《地质学报》2017年04期

【摘要】：冰沟南镁铁—超镁铁质岩体位于东昆仑造山带西段祁漫塔格岩浆岩带内,邻近昆北断裂,主要由橄榄辉石岩、辉长岩、闪长岩及辉长辉绿岩脉构成,铜镍矿体仅赋存于橄榄辉石岩中。岩体地质特征、岩石地球化学特征及矿体地质特征表明,成矿岩体为铁质系列的基性-超基性岩,岩性为含长橄榄辉石岩。锆石SHRIMP U-Pb同位素测年获得含长橄榄辉石岩年龄为377.8±3.4Ma,为晚古生代岩浆作用的产物,这也是东昆仑造山带目前发现时代较新的岩浆铜镍矿床。岩石Sr-Nd同位素特征表明,(~(87)Sr/~(86)Sr)_i值在0.7057~0.7105之间,变化范围相对较宽,ε_(Nd)(t)值变化在2.35~3.81之间,均为正值。推测矿床形成过程为幔源岩浆上涌过程中,由于地壳物质的加入,伴随着同化混染作用的发生,岩浆中S达到饱和,进而硫化物发生不混溶作用,富含硫化物的岩浆运移至东昆仑造山带邻近昆北断裂构造薄弱的部位成岩成矿。冰沟南铜镍矿床可能是形成于造山后伸展背景,与夏日哈木超大型铜镍硫化物矿床形成时的构造背景不同,本次研究对东昆仑造山带同类矿床的勘查评价工作具有一定指导意义。
[Abstract]:The binggounan mafic ultramafic rock body is located in the Qimantage magmatic rock belt of the western section of the eastern Kunlun orogenic belt and is adjacent to the northern Kuntun fault. It is mainly composed of olivine pyroxenite, gabbro, diorite and pyroxenite veins.The copper-nickel orebody only exists in olivine pyroxenite.The geological characteristics of rock mass, geochemistry and ore-body geology indicate that the ore-forming rock mass is a basic-ultrabasic rock of iron series, and the lithology is a feldspathic pyroxenite.Zircon SHRIMP U-Pb isotopic dating obtained an age of 377.8 卤3.4 Ma. which is the product of late Paleozoic magmatism, which is also a relatively new magmatic copper-nickel deposit discovered in the East Kunlun orogenic belt at present.The Sr-Nd isotopic characteristics of the rocks show that the value of S / P / S / S / S / S / T is between 0.7057 and 0.7105, and the range of variation is relatively wide, and the variation of the value of 蔚 ~ (+) is in the range of 2.35 ~ 3.81, all of which are positive.It is inferred that the formation process of the deposit is mantle magma upwelling, due to the addition of crustal material and the occurrence of assimilation mixing, the S in the magma reaches saturation, and the sulphide occurs immiscible solution.The sulfide-rich magma migrates to the diagenetic and metallogenic position of the east Kunlun orogenic belt adjacent to the weak structure of the northern Kunlun fault.The Binggounan Cu-Ni deposit may have been formed in the post-orogenic extensional setting, which is different from the tectonic setting of the formation of the summer Hamu super-large copper-nickel sulfide deposit.This study has certain guiding significance for the exploration and evaluation of the similar deposits in the East Kunlun orogenic belt.
【作者单位】：国土资源部岩浆作用成矿与找矿重点实验室西安地质矿产研究所;
【基金】：国土资源部公益性行业科研专项(编号:201511020) 中国地质调查局地质调查项目(编号:DD20160013)资助的成果
【分类号】：P597.3;P618.41;P618.63

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