Discussion The Genesis Of Stratoid Scheelite Of Gouyanghe Mining Area In Malipo County,Yunnan Province

Scheelite deposit of the Gouyanghe Mining Area is located in the eastern side of the around the Laojun Mountain pluton which is stratoid and occurs in Proterozoic regional metamorphic rocks.This article systematically summarizes the type of scheelite ore-bearing rocks,the type of regional metamorphic rocks and metamorphic grade which are related to scheelite,and correspondingly discuses genesis of this deposit through the deeply study of mining area,and detailed indoor appraisal of rock&ore and tested geochemistry characteristic of the sample.Regional metamorphic rocks of the area have achieved the amphibolite facies through the study of regional metamorphic rocks.And two-mica schist is widely distributed in the region which is the wall rock of ore-bearing skarn rock,and its protolyte is arenaceous rocks and greywacke,which distinguishes with protolyte of scheelite skam.Protolyte of scheelite skarn has characteristics of calcareous rocks.The study of scheelite ore has shown that the main ore-bearing rocks of scheelite deposit contain skarn,greisen(including tourmaline quartzite)and biotite monzonite in Gouyanghe Mining Area.We infer that these ores belong to the same period of the magmatic activity through preliminary study of several types of scheelite ore.The study finds that scheelite skarn has been formed since 155 ±0.96Ma,which belongs to the late Jurassic.The skarn is product of early Yanshan magmatic melt which assimilated calcareous rocks,and then intruded into regional metamorphic rocks along bedding plane.Through study of the biotite of greisen and regional metamorphic rocks,we have determined that the biotite of scheelite belongs to magnesium-rich crust-mantle derived type which is related to greisen.However,the biotite of the regional metamorphic rocks is iron-rich crust derived type,both of which exist apparently difference on the composition and genesis.Thus it can be illustrated indirectly that the scheelite is not formed in process of the regional metamorphism.In addition,the article also studies the petrography and geochemistry of Laochengpo pluton in detail which is named as gneissic granite.It has generally characteristics of silicate-rich,calcalkalic,high potassium and peraluminum.The pluton has been formed since 415±5.2Ma,which belongs to the syn-collision granite,and is product of collision of Yangtze plate and Cathaysian plate in the Caledonian period.