Study On The Text Methods Of Homogenization Experiment Of Melt Inclusions And Water Content Of Melt

Silicate-melt inclusions (MIs) are natural samples of silicate melt entrapped in magmaticminerals which are the ideal samples used to studing the magmatic evolution. The content ofvolatile in the melt plays an important role in understanding the melt-fluid evolution andmineralization. On the basis of petrographic analysis, through Hydrothermal DiamondAnvil-Cell(HDAC), LinkamTS1500high temperature stage, laser-raman spectrum and FTIR, themelt inclusions in quartz porphyry sampled from Yixingzhai gold deposit, Zhijiadi silver depositand Diaoquan silver copper deposit are analyzed systematically. According to the measuredhomogenization temperature and water content, capture state of melt inclusions, melt-fluidevolution and the emplacement depth of magma are studied deeply. The results will have asignificant effect on understanding the regional diagenesis and mineralization as well as findingmines in this area. Main progress and understanding are listed as follows.The petrographic observation shows: most of the melt inclusions in Zhijiadi silver depositare glass melt inclusions, while most of them in Diaoquan silver copper deposit and Yixingzhaigold deposit are crystalline melt inclusions, beside which there are primary vapor-rich,vapor-fluid, crystal-bearing fluid inclusions. The vapor components of melt inclusions coincidewith the fluid inclusions. According to the homogenization processes, the melt inclusions arededuced to be saturated or supersaturated state at the time of capture. At the process of cooling,fluid exsolves from the melt, which is the key to the formation of ore-forming fluid.This paper employs the Hydrothermal Diamond Anvil-Cell(HDAC) to test thephase-transition temperature and homogenization temperature. The results are compared withthoses of Linkam TS1500high temperature stage. Comparison shows that HDAC can provideproper external pressure at the time of heating, which is more applicable to melt inclusions withhigh volatile contents.The water content of melt inclusions which are heated and unheated is tested by FTIR.Results show that water content of melt inclusions which are heated lies in0.16~0.53%, that ofsamples which are not heated lies in0.31~1.18%. The water content test result are significantlylower than previous research, the reasons for which are discussed in this paper.According to the phase-transition temperature tested by HDAC, the paper employs the first melting temperature geological pressure gauge of melt inclusions to estimate the late stagecrystallization depth of the quartz porphyry from Diaoquan silver copper deposit, Yixingzhaigold deposit and Zhijiadi silver deposit are2.0～5.2km,3.8～5.8km and4.3～6.0kmrespectively. This conclusion is consistent with that inferred by water contents of melt inclusions.