安徽马头铜钼多金属矿区复式花岗岩体成因及与成矿的关系

Petrogenesis of compound granites and its relationships with mineralization in Matou Cu-Mo polymetallic orefield, Anhui Province, China

马头矿区复式花岗岩体发育于江南过渡带池州段,主要由花岗闪长(斑)岩和钾长花岗岩组成,与该地区铜钼等多金属矿化有着密切的联系。花岗闪长(斑)岩表现出类似埃达克质岩的地球化学特征,富集LILE(尤其是Sr和Ba)和LREE,Eu负异常不显著,相对亏损HREE和Y,被认为是富集岩石圈地幔部分熔融的产物,在成岩过程中也有一定程度的地壳组分混染。钾长花岗岩则表现出高硅、高钾的地球化学特征,其锆石饱和温度(近液相线温度)接近于低共熔花岗岩,很可能是早期形成岩体在压力释放过程中再次熔融的产物。综合来看,在马头矿区,铜钼(金)等亲硫成矿元素的物质来源很可能与花岗闪长(斑)岩的侵位有关,但钾长花岗岩在钼的富集和强烈矿化过程中起到了催化媒介的作用。

Matou compound granites occurr in the Chizhou segment of Jiangnan transitional zone, consist mainly of granodiorite-porphyry and moyite, and are closely related to the Cu-Mo polymetallic mineralization in this area. The granodiorite-porphyry has high LILEs （especially Sr and Ba） and LREEs, and low HREEs and Y contents and insignificant negative Eu anomalies, similar to the adakitic rocks. It is identified that the product is derived from the partial melting of enriched lithospheric mantle, and also contaminates some crustal components in its diagenetic processes. The moyite is characterized by high silica and high potassium, and its zircon saturation temperature is close to that of eutectic granite. It may be the product of the partial melting of the pre-exist granites during the depressurizing. In Matou Cu-Mo polymetallic orefield, the materials source of the sulfur ore-forming elements, such as Cu, Au and Mo, is probably related to that of the emplaced granodiorite-porphyry, and the moyite plays a catalytic role in the molybdenum concentration and intensive mineralization.