Characteristics and Geological Significance of Late Miocene Skarn-Type Tungsten Mineralization in Ramba,Southern Tibet
Ren Chunmeng
Zheng Yuanchuan
Li Xin
Gao Lei
Xu Peiyan
Wu Changda
Yang Zhusen
Abstract：The Ramba leucogranite,located in the eastern part of the Northern Himalaya,is mainly composed of two-mica granite.The amphibolite in contact with it is commonly skarnized and accompanied by scheelite mineralization.To qualify the diagenetic and metallogenic ages and the ore-forming fluid characters,an integrated approach involving zircon U-Pb and mica Ar-Ar dating,and mineral geochemistry was carried out.The Ar-Ar age(6.3 Ma)of muscovite from the scheelite-bearing quartz vein yielded is comparable to the zircon U-Pb age(7.3 Ma)of two-mica granite,indicating that the granite emplacement and associated tungsten mineralization both occurred in the Late Miocene,which is the youngest known rare-metal mineralization event in the region.The iron ratios of garnet and pyroxene mineral pairs within the scheelite-bearing skarn(3.12 to 3.74),and the relatively low Mo content(12.0×10-6-56.8×10-6)of scheelite,collectively indicate that the ore-forming fluid is reduced,which is consistent with the magmatic zircon oxygen fugacity calculated results(ΔFMQ=-5.78 to-2.08).The rare-earth element characteristics of scheelite are inherited from the leucogranite granite,further indicating that the W-rich ore-forming fluid was dissolved from the evolved granitic melt and subsequently reacted with the Ca-rich wall rocks to induce the precipitation of scheelite.This study reveals that the contact metamorphic zone between Himalayan leucogranite and surrounding wall rock is a favorable site for rare-metals,and deserves attention in future prospecting.
Keywords：Himalaya leucogranitecontact metamorphic zonetungsten mineralizationRambamineralogy
Publication Date：2024-10-15
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：19( 3610-3628 )