四川根深沟钨锡矿二长花岗岩特征及其成矿作用

根深沟钨锡矿位于松潘—甘孜造山带之鲜水河断裂带东部,产于云祝措二长花岗岩株内外接触带。云祝措二长花岗岩是钨锡成矿母岩,其硅、铝过饱和,富碱,低钙、铁、镁,属钙碱性岩,岩浆分异程度高;微量元素配分型式与正常大陆弧花岗岩类似,稀土分配模式为右倾轻稀土富集型,负铕异常,轻重稀土分馏明显,属褶皱造山后期陆壳重熔被动侵位形成的"S"型花岗岩;花岗岩同位素年龄为112.4 Ma,岩体侵位时间为燕山晚期;岩浆期后成矿热液向内外接触带运移,于节理、裂隙中充填交代成矿。

On the Characteristics and Mineralization of a Monzonite Granite W-Sn Deposit in Sichuan

Genshengou W-Sn deposit situates in Songpan-Ganzi orogenic belt of east Xianshuihe fault.The monzonite granite are saturated in Si,Al,rich in alkali,low in Ca,Fe,Mg,indicting Calc-alkaline series and high differentiation degree.The pattern of trace element is similar to that of normal continental arc granite with orogenic granite features.The characteristic of REE distribution pattern is LREE-enriched right deviation.The REE trend also shows apparent negative anomaly of Eu,and obvious fractionation of LREE and HREE.Both of the features of trace elements and REE suggest that the magma origin from the upper crust.The magma formed by the remelting of the continental crust during the late stage of folding orogenic period.The passive intrusion of melts created this ＂S＂-type granite.The isotopic element data of the granite shows that it formed at around 112.4 Ma ago,in the late Yanshan period.The monzonite granite is W,Sn ore rock.In the post-magmatic hydrothermal mineralization within and outside the contact zone to the migration,in the joints,filling cracks in the account of mineralization.