ZHANG Jia-wei1, 2, ZHU Cheng-ming3*, LUO Tai-yi2, HUANG Zhi-long2, MA Yi-bo1, WANG Bo1, TANG Zuo-qi1
(1. Guizhou Geological Survey, Bureau of Geology and Mineral Exploration and Development of Guizhou Province, Guiyang 550004, China; 2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China; 3. Laboratory for High Temperature & High Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China)
Abstract: Basalt and granite from Gejiu tin deposit were selected to carry out high temperature and pressure petrological studies on their respective capability of containing tin. The experimental results show that both in granitic and basaltic magma, Sn4+ can replace Si4+ abundantly, forming tin-rich magma. Gejiu granitic magma can carry up to 36% of SnO2. Whereas, the basaltic magma also contain higher than 14.9% of SnO2. Tin-bearing minerals are exsolved from magma in the form of liquid droplets as the granitic magma cools, indicating that the genesis of the tin deposit is directly related to the granite formation. Due to high temperature of formation and the quenching effect, no Sn-minerals can form in the basaltic magma. Yet despite this, the possibility of basaltic magma as an ore-forming source cannot be completely excluded. The genesis of the tin deposit may be related to both granitic and basaltic magmas. The key point is whether the magma absorbed a large amount of Sn during the melting process and transportation.
Keywords: Gejiu tin deposit; basalt; granite; high temperature and high pressure experiment; metallogeny
ACTA MINERALOGICA SINICA Vol. 35, No. 2, 2015, Page 159-166
