湖南省七宝山钙矽卡岩-镁矽卡岩共生型多金属矿床地质地球化学特征

七宝山多金属矿床是一种罕见的钙矽卡岩和镁矽卡岩共生型矿床。矿床赋存于印支期-早燕山期斑状花岗岩与中-上石炭统碳酸盐岩地层的接触带及附近。矿床的形成经历2个成矿期：早期以形成钙-镁矽卡岩和磁铁矿为主的金属矿物为特征，后期以发生多次金属硫化物的矿化为特征。矿床的物质组成十分复杂，可利用的组分除Cu、Pb、Zn之外，Ga、Ge、In、Cd、Au、Ag、Te、Fe等亦可综合利用。斑状花岗岩是幔源岩浆与上地壳物质同熔混染的产物，同位素组成特征显示成矿流体为岩浆水，成矿物质主要来自岩浆。地质地球化学证据一致支持斑状花岗岩为成矿母岩；围岩的化学性质变化决定了矽卡岩化的类型。七宝山多金属矿床既属特殊的成因类型，又极具工业价值，值得进一步深入研究。

Geological and Geochemical Characteristics of Qibaoshan Ca-skarn and Mg-skarn Intergrowth-type Polymetallic Deposit in Hunan Province

Qibaoshan polymetallic deposit is a rare skarn intergrowth type deposit that the Ca-skarn and Mg-skarn types occur together in the same deposit but different locations. The polymetallic deposit is located in the contact zone between Indosinian-Early Yanshanian porphyritic granite and carbonate beds of the mid-upper series of Carboniferous. Mineralization of the deposit can be divided into two periods. The early period is characterized by the formation of Ca-Mg skarn and magnetite, and the late period is characterized by multi-polymetallic sulfide mineralization. The ore composition of the deposit is complicated. Besides Cu, Pb, Zn, elements such as Ga, Ge, In, Cd, Au, Ag, Te, Fe also can be utilized. The results of isotopic geochemical analysis show that the porphyritic granite is the product of assimilation and hybridization of mantle-origin magma and upper crust material. Ore-forming fluid is mainly magmatic water while ore-forming material mainly comes from magma. Metal particles transport in the magmatic water in the form of chlorine complexes, and precipitate due to chemical reaction after the formation of skarn. Geologic and geochemical evidences suggest that porphyritic granite is the parent rock of mineralization. The chemical property of wall rock determines the type of skarnization. The Qibaoshan polymetallic deposit is not only special in genesis, but also is of great economic industrial value, and it should be researched further.