南秦岭凤太盆地金矿与铅锌矿的成矿模式

通过对凤太盆地八卦庙金矿和八方山二里河铅锌矿的矿床地质、矿床地球化学、流体地球化学的研究,发现两类矿床δ(30Si)分布范围与海底喷流沉积成因硅质岩的硅同位素接近,表明其属热水沉积成因。矿床δ(34S)比较接近,但铅锌矿矿石中硫源来源更广。碳酸盐的碳、氧同位素特征显示两类矿床均具有热水沉积特点,金矿的样品更趋向于火成岩,表明受后期岩浆热液影响更大。经过流体包裹体测温,金矿床均一温度变化范围大,具有多期次多阶段的特征。矿床同位素和流体包裹体特征表明,金矿床与铅锌矿床在成矿物源、成矿流体特征等方面都存在很多相似性,反映出热水喷流作用与两类矿床成因有密切的关系,但二者又存在差异。结合成矿地质背景,认为铅锌矿的形成与定位受区域热变质改造和动力作用控制,而金矿的形成主要受晚期岩浆热液活动控制,由此建立了金矿与铅锌矿的成矿模式。

Space-time Relationship of Gold Deposit to Lead-Zinc Deposit in Fengtai Ore Field in South Qinling

Geological and geochemical fluid geochemistry study of Baguamiao Gold deposit and Bafangshan-ErliheLead-Zinc deposit in Fengtai basin show that the range ofδ(30Si)values of Gold deposits and Lead-Zinc depositare close to the values of submarine exhalation, indicating its hydrothermal sedimentary origin. The value ofδ(34S)are also close to each other, but the Sulphur source of Lead-Zinc deposit is more complicated and broadly.Carbon and Oxygen isotope of carbonate have the characteristic of the hydrothermal sedimentary while that ofGold deposit are more close to igneous rock, which indicates that deuterism have more effect. The study of fluidinclusions shows that the range of homogenizations temperatures of Gold deposit are more widely and have thecharacteristic of polyphase. All evidence indicates that Gold deposit and Lead-Zinc deposit are similarity inmineralization resource, fluid, isotope. which reflect that there is a certain genetic relation between thehydrothermal exhalation and Gold, Lead-Zinc mineralization. At the same time Gold mineralization are differentfrom Lead-Zinc mineralization. Considering the metallogenic environment, it is pointed that the Zincmineralization and location is controlled by the thermal altered metamorphism and dynamometamcrphism and theGold deposit is controlled by the late-magmatic hydrothermalism. A minerogenetic model of Gold and Lead-Zincdeposit in Fengtai basin is set up.