江西彭山岩体的地球化学特征及成矿关系探讨

彭山岩体是由白云母碱长花岗岩、二云母碱长花岗岩和黑云母二长花岗岩组成的钙碱性花岗复式岩体.其地球化学特征表明它是一种富硅、富碱、贫钙、过铝且轻稀土相对富集的陆壳重熔型花岗岩.通过与典型矿区铅、硫同位素及稀土元素的对比,发现其侵位与多金属矿床的形成有着密切的联系.区域上基底深断裂的活化及板块间的相互作用,为该区燕山晚期的岩浆活动创造了条件.岩浆活动在提供了大量热动力的同时,也为本区带来了丰富的成矿物质,岩浆在侵位过程中进行了较为彻底的结晶分异,最终成矿物质在彭山穹窿构造及各级次级构造中富集成矿.

Geochemical characteristics and related mineralization of Pengshan granitic body in Jiangxi Province

The Penshan granitic body is a calc-alkaline pluton composed of muscovite alkali granite,two-mica alkali feldspar granite and biotite adamellite. It is geochemically characteristzed by rich in Si,alkali,aluminum,comparatively rich in LREE and poor in calcium,belonging to crust-source remelting granitoids. Study of lead-sulfur isotopes and REE geochemistry shows that polymetallic mineralization in the study area is of close relationship with emplacement of the Pengshan granitic body: magmatism provided not only heat source but also ore-forming materials;the deposition of metals in the Pengshan dome and its secondary structures from the metallogenetic fluid formed after crystallization differentiation resulted in mineralization. The re-activation of regional basement faults and plate collision might provide tectonic condition for Late Yanshanian magmatism.