Mineralogical Characteristics and Genesis Discussion of Skarn in Nanyangtian Sheelite Deposite of Southestern Yunnan

Nanyangtian sheelite deposite is a rare giant sheelite deposite in southwestern China. The stratiform ore body was hosted in skarn. The main Skarn minerals are pyroxene, garnet and minor vesuvianite. The altered minerals are chlorite, hornblende, epidote, actinolite, apatite etc. The result of chemical composition obtained by electron probe analysis demostrated that clinopyxene is composed of (1) major sahlite, sahlite-alike and augite, minor ferrosalite and tiny diopside, (2) garnet majorly consists of grossularite, minor almandine and pyrope, (3)hornblende is tremolite-actinolite isomorphic series.Some metamorphic minerals, such as tourmaline and piedmontite, also occur in skarn rock.Compared with typical sheelite deposites, it is demonstrated that the compostion of skarn in Nanyangtian sheelite deposite is obviously different from traditional magmatic metasomatism skarn, but is very similar to that of Broken Hill Ettlewood sheelite deposite of Astrinia which derived from calc-silicate rocks precipitated in hot water. It is indicated that the mineralization of Nanyangtian sheelite deposite possibly is related to the hot spring from mesoproterozoic and neoproterozoic rift valley.