Abstract:

Abstract:  Two sets of dehydrationmelting with a natural solid amphibolite(56vol.% hornblende, 43vol.% plagioclase), collected from the DabainengLeyu profile in the southern Ailaoshan orogenic belt, Honghe County, Yunnan Province, have been carried out in multianvil apparatus(YJ3000t and JL3600t) at 1035 GPa and 950 ℃ for 20300 h. One is keeping the temperature at 950  ℃ and the annealing time of 100 h, varying the pressure (1035 GPa). The other is keeping the pressure at 30 GPa and temperature at 950 ℃, varying the annealing time (20300 h). The products are inspected with microscope and electron probe. The results indicate that at 950 ℃, annealing time of 100 h, as the pressure in the range of 1015 GPa, the mineral assemblage in the products is clinopyroxene+garnet+melt. As the pressure larger than 15 GPa, the mineral assemblage in the products is clinopyroxene+garnet+melt+Jadeite+SiO2±kyanite. However, at 30 GPa and 950 ℃, as the annealing time in the range of 20100 h, the mineral assemblage of clinopyroxene+garnet+melt+Jadeite+SiO2±kyanite appears successively with time  in the products. As the annealing time longer than 100 h, the mineral assemblage of clinopyroxene+garnet+melt appears in the products. The distribution of the newlyformed minerals and melt is restricted by the texture of the started amphibolite. Based on the mineral distribution and assemblage in the run products at 1035 GPa and 950 ℃ for 20300 h, the textural development of amphibolite during the partial melting process,  the metamorphic reaction, and the garnet corona generation are  discussed.

Key words:

Key words: high temperature and high pressure; dehydrationmelting in amphibolite; textural development; metamorphic reaction; garnet corona