Skarn-type rare metal mineralization in the Mount Shisha Pangma region:Petrological characteristics,mineralization age and its geological significance
In recent years,breakthroughs have been made in prospecting and researching Himalayan rare metals,making the Himalaya a new strategic mineral resource base in China.This study studied the petrography,mineralogy and chronology of skarn in the Tsalung and Gangbu districts in the northern of Gyirong pluton and Nyalam district,Mount Shisha Pangma region and pointed out that skarns are mainly composed of garnet,diopside,vesuvianite,epidote and amphibolite.The Tsalung skarn had apparent Li-Be-Sn mineralization,and the ore-forming elements mainly existed in vesuvianite(Li:469 × 10-6～3162 × 10-6;Be:47.9 × 10-6～2010 × 10-6;Sn:58.1 × 10-6～1767 × 10-6)and mica(Li:2900 × 10-6～3570 × 10-6)with the high contents of Rb(1572 × 10-6～2364 × 10-6),Cs(390 × 10-6～749 × 10-6)and Ga(68.2 × 10-6～111 × 10-6).The Gangbu skarn was also dominated by Li-Be mineralization,and the Li-Be-Sn bearing minerals were vesuvianite(Li:833 × 10-6～1624 × 10-6;Be:401 × 10-6～1664 × 10-6;Sn:87.8 × 10-6～181 × 10-6)and titanite(Sn:30340 × 10-6～48600 × 10-6).Sn mineralization also occurred in Nyalam skarn,and the Sn-bearing minerals were garnet(92.3 × 10-6～571 × 10-6)and epidote(86.0 × 10-6～2003 × 10-6).The Tsalung skarn was formed at 19～18Ma,and Gangbu and Nyalam skarn was formed at 24～23Ma,which was consistent with the reported ages of albite granite and tourmaline muscovite granite and was the product of the reaction between the hydrothermal fluid that dissolved from the evolved granitic melt and the Ca-rich country rock,reflecting the characteristics of periodic mineralization of Himalayan rare metals.Hydrothermal fluid temperature decreased from～680℃ to～520℃,and the late stage was an oxidation environment.The increase of porosity caused by decarbonization and CO2 release provided a channel for subsequent ore-forming fluid addition and heat transfer.Tectonic fissures controlled the attitude of ore-forming skarn.The high degree of magma differentiation enriched Li,Be,Sn in the melt,and the contact metasomatic metamorphism reaction of the late hydrothermal fluid that dissolved from the evolved granitic melt with the carbonate rocks was the primary mechanism of the skarn-type Li-Be-Sn mineralization in the Gyirong-Nyalam area.The Himalayan orogenic belt has an excellent metallogenic prospect of rare metals,and the study of contact metamorphic zone and alteration should be strengthened in the future to find more hydrothermal rare metal deposits.
HimalayaSkarnRare metal mineralizationContact metasomatic metamorphismHydrothermal fluid
NETL
NSTL
万方数据
维普
