西澳州Cattle Creek地区铜镍硫化物矿床成矿潜力探讨

THE METALLOGENIC POTENTIAL OF COPPER-NICKEL SULFIDE DEPOSIT OF CATTLE CREEK AREA, WESTERN AUSTRALIA

西澳州Catlle Creek地区位于金伯利地块西缘霍尔斯克里克(Halls Creek)活动带上,附近发育有深大断裂。研究区内发现多处基性-超基性小岩体及岩脉且存在两处矿化点(带),存在两处1∶5万土壤地球化学甲类综合异常区,二者均主要由Cu、Ni、Au、Mo、Co等元素组成,多个浓集中心,异常套合较好,Cu、Ni的极大值均超过或接近边界品位,甚至工业品位,二者与矿化等信息套合良好。岩体中岩石样品主量元素特征显示其具有辉长岩-苏长岩的成矿专属性特征;在AFM图解上,岩石样品显示原始岩浆为高MgO拉斑玄武岩系列。微量元素原始地幔标准化蛛网图表明岩体岩浆演化过程中发生过明显的陆壳物质同化混染作用。稀土元素配分图反映出成岩过程中有相似的分异演化过程,并表明岩浆在演化过程中存在明显橄榄石分离结晶作用。研究区与萨凡纳矿床具有很高的可对比性,同时符合古大陆内小岩体成矿系统理论。表明研究区具较高的成矿潜力。

The Cattle Creek Area is located in Halls Creek Mobile Zone, which arose from the orogeny of westem margin of Kimberley block, adjacent to deep faults. There are multiple small basic-ultrabasic intrusive bodies and dikes, two mineralized spot（belt）, and two Class-A 1 ： 50000 synthetical pedogeochemical anomalies in the study area. Both of the two anomalies consist of Cu, Ni, Au, Mo, Co and other elements, and have multiple concentration centers. The single element anomaly nests well with each other. The maximum values of Cu, Ni are more than or close to the cutoff grades, or even minimum mining grade. Both of the two anomalies nest well with the mineralization. Analysis results of the major elements show that the mineralized intrusive bodies have the characteristics of metallogenic specialization of gabbro- norite. In the AFM diagram, the samples show that the primitive magma of the intrusive bodies belongs to high-MgO tholeiite series. The PM-normalized trace element spiderdiagrams show that there is assimilation and contamination of continental crust during magmatic evolvement of the intrusive bodies. Chondrite-normalized REE patterns show that the magmatic evolvement processes of the intrusive bodies are similar, with the fractional crystallization of olivines There is a high correlation between the study area and Savann deposit, both of which accord with the metallogenic theory of small intrusions forming large deposits. There is high mineralization potential in the study area.