5:15 PM - 5:30 PM
[SCG58-15] X-ray CT and Raman spectroscopy analyses of polyphase fluid inclusions of quartz crystals from Tsushima granite
Keywords:polyphase fluid inclusion, X-ray CT, Ramn spectroscopy, phase idetification
Results from SR-XCT and Raman spectroscopy of two polyphase-inclusion samples, 1A and 1B, show presence of daughter crystals of halite, sylvite, saltonseaite (K3NaMnCl6) siderite, and Fe-OH mineral (goethite?) in the inclusions. The crystals of saltonseaite, siderite, and Fe-OH mineral, were not reported by the previous SEM-EDS observations (Kurosawa, 2014). Saltonseaite was first reported by Kampf et al. (2013) and was first observed in Japan. In addition, crystals of calcite and Fe-Cl mineral reported by Kurosawa (2014) could not be observed in this study. The calculated LAC from liquid phase value has the larger value than that calculated from the saturated solution of NaCl or KCl. Thus, it needs to add about 8 mol% Fe to saturated solution of NaCl. We also estimated the volume ratios of the solid, liquid and vapor phases and the bulk chemical composition of each sample. The ratio of vapor to whole inclusion had different values between two neighboring polyphase-inclusions, although the ratios of solid and liquid phases and bulk chemical composition were almost same. This suggests the possibility that these inclusions had been captured at the different period, because fluid inclusions formed at the same generation have usually almost the same volume ratios among vapor and liquid phases. Furthermore, we dug in the quartz to directly observe and analyze the daughter phase in other polyphase-inclusion sample using focused ion beam. Daughter crystals of hematite and unknown phases, which could not be detected in XCT samples, were observed. Because there is a possibility of transiting from Fe-OH mineral observed by XCT and Raman spectroscopy to hematite in vacuum condition.
Kurosawa et al. (2012) 2012 Annual meeting japan association of mineralogical sciences (Japanese), Kurosawa (2014) 2014 Annual meeting japan association of mineralogical sciences (Japanese), Kampf et al. (2013)American Mineralogist,98,231.