东天山图拉尔根铜镍钴硫化物矿床岩相、岩石地球化学特征及其形成的构造背景

新疆图拉尔根铜镍钴矿产于康古儿塔格—黄山韧性剪切带的北东段,是由硫化物深部熔离成矿为主兼就地熔离、热液叠加成矿多重作用形成的半隐伏矿床。1号岩体以全岩矿化为特征,可分为4个岩相:角闪橄榄岩、辉石橄榄岩、角闪辉石岩、辉长岩。岩性具有单期岩浆多次脉动上涌成矿特征。岩体m/f值为3.1～4.8,属于铁质超镁铁岩类,且具有低钛、低碱、低Al2O3特征,与黄山—镜儿泉镁铁质-超镁铁质杂岩带岩石化学特征相似。由稀土元素配分曲线和微量元素、过渡族元素蛛网图可知1号和2号岩体具有同源性,并具有互补性,预示2号岩体深部成矿潜力很大,虽然其地表辉长岩矿化微弱。根据横穿1号和2号岩体的大地电磁测深剖面图可以看出两个岩体在深部具有同一个岩浆通道,也验证了两岩体属于同一岩浆来源。较低的La/Sm(<2)和Th/Ta值(4.6)表明成矿岩浆为地幔来源,岩体就位时很少受到地壳的混染。

Petrographic and geochemical characteristics of the Tulargen Cu-Ni-Co sulfide Deposit, East Tianshan, Xinjiang, and its tectonic setting

The Tulargen Cu-Ni-Co deposit,lying in the northeastern segment of the Kangurtag-Huangshan ductile sheer zone,is a semi-hidden deposit formed mainly by deep-level liquation of sulfide,combined with in-situ liquation and hydrothermal superimposition.Intrusion No.1 is characterized by whole-rock mineralization and can be divided into four rock facies:hornblende peridotite,pyroxene peridotite,hornblende pyroxenite and gabbro.The rocks show the features of repeated pulsatory magmatic upwelling and ore formation in a single phase.The m/f ratio of the intrusion varies from 3.1 to 4.8,falling into the range of ferrous-ultramafic rocks.The intrusion is featured by low Ti,low total alkalis and low Al2O3,similar to the petrochemical characteristics of the Huangshan-Jing'erquan mafic-ultramafic complex.The REE distribution patterns and trace element and transition element spidergrams indicate that the No.1 and No.2 mafic-ultramafic intrusions in the Tulargen ore district are comagmatic and supplementary,implying that the deep part of the No.2 intrusion has a great ore potential though gabbro of the No.2 intrusion shows weak mineralization at the surface.According to the MT section across both the No.1 and No.2 intrusions,it is clear that they share only one magma conduit at depth and originated from the same magma source.Lower La/Sm(<2)and Th/Ta(4.6)ratios suggest a mantle origin of the ore magma and little contamination with crustal material during the emplacement of the intrusion.