EVOLUTION OF FLUID PHASE IN A SINGLE MIAROLITIC CAVITY OF GRANITIC PEGMATITE ON THE BASIS OF QUARTZ-HOSTED FLUID INCLUSION STUDY (VERHNESHIBANOVSKY DEPOSIT, PRIMORYE, RUSSIA)

摘要

The obtained results demonstrate that the hydrothermal medium of the miarolitic cavity was heterogeneous at the early stages and become homogeneous at the end of the quartz crystallization. Early fragments were formed from medium consisted of relatively diluted liquid aqueous fluid and brine. Salinity of the both fluids decreased with decreasing temperature. Early aqueous fluids were rich in Pb, Zn, Fe, Mn, Ca, As, and Sb, which were dissolved in form of chloride compounds with minor carbonates, sulfates, and, probably, borates. Intermediate fragment were formed from the fluids with simpler compositions. These fluids where composed mostly of Na-K chloride aqueous solutions with minor Fe and Mn. The latest zones were formed from homogeneous K-Na chloride solutions. The transition from high-concentrated heterogeneous medium to diluted homogeneous one occurs at the level of the fragment 3. It was accompanied by dramatic change in chemical and phase composition of the miarolitic fluids and manifested through the change of color of quartz. Our study provides an example of evolution of the aqueous fluid, which segregated from pegmatite magma and participated in the formation of postmagmatic mineralization. The data obtained will be used to develop a model of postmagmatic mineralization from the magmatic aqueous fluid. The study was carried out with the financial support of Russian Fund for Basic Research (grant N 13_05_90728_mol_rf_nr).