新疆东天山红石岗北铜镍矿化镁铁质岩体岩石成因及成矿潜力分析

发布时间：2018-04-11 08:12

本文选题：红石岗北 + 铜镍矿化镁铁质岩体　；参考：《地质学报》2017年04期

【摘要】：红石岗北岩体是新疆有色地质勘查局704队于2014年新发现的,产于东天山康古尔—黄山韧性剪切带内。岩体地表主要岩性为闪长岩、角闪辉长岩和橄榄辉长岩,硫化物主要由磁黄铁矿、镍黄铁矿和黄铜矿组成。为准确评价岩体深部找矿潜力,本文在对该岩体开展系统的锆石U-Pb年代学、矿物晶体化学、岩石地球化学及Sr-Nd同位素研究基础上,结合其地球物理特征,将其与东天山已知典型铜镍矿床进行了系统对比研究。结果表明红石岗北岩体锆石U-Pb谐和年龄为276.1±5.4Ma,表明其形成于早二叠世。橄榄石Fo值为69.9~72.6,属贵橄榄石,Ni含量变化范围为101×10~(-6)~1326×10~(-6);单斜辉石主要为顽透辉石—透辉石;斜方辉石主要为古铜辉石。MgO与SiO_2、CaO和Al_2O_3之间呈明显的负相关性,与FeO~T呈明显的正相关性。在稀土元素球粒陨石标准化图解上,所有样品均呈轻稀土略富集的右倾型,相对富集大离子亲石元素(Cs、Sr、Ba),具有明显的Nb、Ta负异常。样品(~(87)Sr/~(86)Sr)_i=0.70342~0.70349,ε_(Nd)(t)=+7.51~+8.25(t=276Ma),Sr、Nd同位素模拟计算表明母岩浆上升过程中遭受了约5%的地壳物质混染。与东天山地区已知典型铜镍矿床相比,红石岗北岩体中橄榄石Fo值及主量元素含量明显偏低,且变化范围较小,但其形成时代、微量元素和Sr-Nd同位素特征和同化混染程度均相似,表明红石岗北岩体与黄山东、黄山等矿床的岩浆源区性质、构造背景、母岩浆成分及演化过程具有相似性,暗示红石岗北岩体深部应存在超镁铁质岩石。红石岗北岩体地表磁异常、剩余重力异常和视电阻率均与东天山已知铜镍矿床具有相似性,表明其深部可能存在赋矿的超镁铁质岩体。综上所述,我们认为红石岗北岩体深部具有较大的铜镍找矿潜力。
[Abstract]:The northern Hongshigang rock body was discovered by 704 team of Xinjiang Nonferrous Geological Survey Bureau in 2014 and is located in the Kangguer-Huangshan ductile shear zone of East Tianshan Mountain.The main lithology of the rock body is diorite, hornblende gabbro and olivine gabbro, and sulfides are mainly composed of pyrrhotite, nickel pyrite and chalcopyrite.In order to accurately evaluate the ore-prospecting potential in the deep part of the rock mass, based on the systematic study of zircon U-Pb chronology, mineral crystal chemistry, rock geochemistry and Sr-Nd isotopes, this paper combines its geophysical characteristics.It is compared with known typical copper-nickel deposits in East Tianshan.The results show that the U-Pb harmonic age of zircon is 276.1 卤5.4 Ma, indicating that it was formed in the early Permian.In the standardized diagram of chondrites of rare earth elements, all the samples are slightly enriched in light rare earths, and are relatively enriched in the large ion lithophile elements, Csfr, Sr-Baan, and have obvious negative anomalies of NB and Ta.The isotopic simulation calculation of Sr / R / 86 ~ (86) S ~ (+) S ~ (+) S ~ (-1) I ~ (0.70342) ~ 0.70349, 蔚 ~ (+) D ~ (+) N ~ (D) T ~ (+) = 7.51 ~ 8.25 t ~ (27 ~ 6) Ma ~ (2 +) shows that the parent magma is contaminated by about 5% of the crustal materials during the process of the magma rising.Compared with the known typical copper-nickel deposits in the East Tianshan area, the Fo value and the content of principal elements of olivine in the North Hongshigang rock body are obviously lower, and the range of variation is relatively small, but the formation age of olivine is relatively small.The characteristics of trace elements and Sr-Nd isotopes and the degree of assimilation are similar, indicating that the magmatic source, tectonic setting, composition and evolution of the parent magma are similar to those of Huangshan and Huangshan deposits.It suggests that there should be ultramafic rocks in the deep part of the northern Hongshigang rock body.The surface magnetic anomaly, residual gravity anomaly and apparent resistivity of the North Hongshigang rock body are similar to those of the known Cu-Ni deposit in the East Tianshan Mountains, indicating that the ore-bearing ultramafic rocks may exist in the deep part of the body.To sum up, we think that the deep part of Hongshigang North body has great potential for copper and nickel prospecting.
【作者单位】：国土资源部岩浆作用成矿与找矿重点实验室中国地质调查局西安地质调查中心;新疆维吾尔自治区有色地质勘查局704大队;
【基金】：国土资源部公益性行业科研专项(编号:201511020) 国家自然科学基金(青年)项目(编号:41302052,41402071) 中国地质调查局地质矿产调查项目(编号:DD20160013)共同资助成果
【分类号】：P618.41;P618.63;P581

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