西藏雄村斑岩型铜金矿红柱石成因矿物学特征

雄村斑岩铜金矿中广泛分布有红柱石,红柱石主要呈三种产出状态:①石英-钾长石-白云母/绢云母-红柱石组合；②红柱石-石英-绢云母/白云母组合；③石英-红柱石-硫化物脉.矿物组合关系、红柱石结构和成分等特征均表明红柱石属热液成因.早期钾硅酸盐化带中的石英-钾长石-白云母/绢云母-红柱石组合形成于高温(大于550℃)、低+K...

Genetic Mineralogy of Andalusite in Xiongcun Porphyry Copper-Gold Oredeposit, Tibet

There are abundant andalusites in the Xiongcun porphyry copper-gold deposit.Three major assemblages are recognized,i.e.,quartz-K-feldspar-muscovite/sericite-andalusite assemblage,andalusite-quartz-sericite/muscovite assemblage,and quartz andalusite sulfide veins.The mineral association,texture and composition of andalusites indicate that the andalusites are of hydrothermal type.The quartz-K-feldspar-muscovite/sericite-andalusite assemblage in early K-silicate alteration zone was formed under the conditions of fairly high temperatures(above 550℃) and relatively low + K/+ H ratios.Early K-silicate alteration was replaced by later phyllic/sericitic alteration under lower P-T and higher + K/+ H conditions,and meteoric water probably entered the collapsed hydrothermal system during this period.Quartz-andalusite-sulfide veins with sericite alteration envelope occur rather rarely and are only observed within the phyllic alteration zone.This assemblage was formed under lower P-T and higher + K/+ H condition.Andalusite assemblages are similar to the El Salvador porphyry copper deposit in Chile.Volcanic tuff and porphyry stock had rich Al 2 O 3,which was favorable for the formation of andalusite.The andalusite within different assemblages helps reconstruct the P-T condition of the magmatic-hydrothermal process.