滇西上芒岗红色粘土型金矿的元素地球化学特征及其物质来源探讨

对滇西上芒岗红色粘土型金矿的主元素，微量元素和稀土元素地球化学特征进行了详细的研究。结果表明，主元素Al2O3,Fe2O3和K2O在红色粘土剖面中共迁移同沉淀，SiO2的变化却与它们相反，这揭示了上芒岗红色粘土型金矿的红色粘土层除了残积带红土化程度高外，总体上SiO2含量高，去硅作用不完全，红土化程度低；与地层，矿化蚀变岩的对比分析结果表明，红色粘土是在加勐嘎组泥岩基础上经红土化作用形成的，红色粘土的微量元素表现为Au,Hg,As,Sb,Cu,Pb,Zn和Mo等元素的共生,在红土化好的残积带明显富集；红色粘土的大离子元素分布模式与矿化蚀变岩和嘎组的相似，红色粘土的稀土分布模式与矿化蚀变岩和地层的相似，表现为轻稀土富集的右倾型平缓曲线，稀土元素分蚀明显的地方金富集，以上分析揭示，此金矿的成矿物质主要来自矿化蚀变岩，红色粘土主要来源于勐嘎组和矿化蚀变岩。

Geochemistry of element of the Shangmanggang red-clay-type gold deposit in West Yunnan and the source of ore-forming materials

Geochemistry of major elements,tra ce elements and REEs in the red clays o f the Shangmanggang red-clay-type gold deposit in West Y unnan are researched in detail.The r esults show that Al 2 O 3 ,Fe 2 O 3 and K 2 O migrated and precipitated together in the red clay profile,but change of SiO 2 was in contrast with them.As a whole,content of SiO 2 is high,desilication is incomplete,and degree of laterization is low,e xcept for high degree of laterization in eluvial zone.In con trast with strata and mineralized an d altered rocks,red clays come from M engga Formation mudstone with laterization.Au,Hg,As,Sb,Cu,Pb,Zn and Mo are coextensive elements in the red clay profile,and they are obviously enriched in the eluvial zone where la terization is complete.Patterns of crust-normalized large-ion-lithophile elements for red clays are simi lar to those of both mineralized and a ltered rocks and Mengga Formation.Patterns of ch ondrite-normalized REEs for red cla ys are also similar to those of both altered and mineralized rocks and Mengga Formation.LREEs are enriched,and gold concentrated where REE fractionate d strongly.It is concluded that gold c omes mainly from the mineralized and altered rocks,and the red clays come mainly from Mengga Formation and the mineralized and altered rocks.