EXPERIMENTAL STUDY ON FUSION OF TIN-BEARING GRANITES IN GUANGXI,SOUTHERN CHINA

Experiments have been carried out for studying the melting characteristics of two representative types of granite complexes relating to tin ore deposits in Guangxi. The curves of the beginning melting of the Longxiangai porphyritic biotite granite (LPBG), the Longxiangai granular biotite granite (LGBG), the margin phase and central phase of the rocks of the Pinyin granite (MPPG and CPPG) are determined by the experiments. The results of the experiments show that the temperature of the beginning melting points of the tin -bearing granite not only depends on the type and features of the rocks, but also varies with the total water vapour pressure (PH2O) and the one of the different granites decrease with the increasing pressure. In different ranges of the pressure,the variance gradient of the beginning melting points sharply varies. When PH2O is less than or equal to 136 MPa, the beginning melting temperatures of LPBG somewhat lower than those of LGBG ;Whe P H2O is larger than 136MPa,The beginning temperatures of LPBG are higher than those of LGBG. The beginning teperatures of CPPG are always higher than those of MPFG at the conditions of PH2O from 75 to 250 MPa.