Presentation Information
[R8-P-04]Salinity and homogenization temperature of fluid inclusions in rodingite and listvenite within serpentinite exposed in the Omi area, Itoigawa, Japan
*Takami Hashimoto1, Tatsuhiko Kawamoto1, Satomi Enju2, Shirose Yohei2, Takahiko Ogawara3 (1. Shizuoka Univ. Sci., 2. Ehime Univ. Sci., 3. Fossa Magna Museum)
Keywords:
Fluid inclusions,Rodingite,Listvenite
The Omi area of Itoigawa City, located west of the Itoigawa-Shizuoka Tectonic Line, has been historically known for its jadeite occurrences. In this area, the Renge metamorphic belt, a high-pressure, low-temperature metamorphic belt, is exposed along the Omi River, where high-pressure, low-temperature schists and serpentinites can be observed (Tsujimori et al., 2000, Journal of the Geological Society of Japan).
Our study aims to elucidate the fluid composition and pressure-temperature conditions in this region by investigating fluid inclusions in rodingite, which is believed to have formed through Ca metasomatism; listvenite, formed by the metasomatism of serpentinite by CO2-bearing fluids; and carbonate veins within serpentinite. We use both Raman spectroscopy and microthermometry for this research.
In Kanayama-dani, a tributary of the Omigawa River, there's a rodingite outcrop where rodingite occurs as veins within serpentinite. Two-phase (vapor-liquid) fluid inclusions are present in the calcite veins within this rodingite. Raman spectroscopy indicates the liquid is saline fluids, with an estimated salinity of 2.3 ± 0.7 wt.% NaCl equivalent (n=30) based on the final melting temperature of ice. The homogenization temperature for the vapor and liquid phases is 233 ± 33°C (n=30).
Furthermore, listvenite collected from an outcrop of the Omi River downstream from Kanayama-dani is primarily composed of magnesite and quartz. The veins within this listvenite consist of dolomite and magnesite. Fluid inclusions in the dolomite have a salinity of 1.8 ± 0.3 wt.% NaCl equivalent (n=9) and a homogenization temperature of 211 ± 39°C (n=9) for the vapor and liquid phases, showing values close to those found in the rodingite veins.
In our presentation, we plan to compare the fluid inclusions from the rodingite and listvenite mentioned above, as well as those from ophicarbonate in the vicinity of the listvenite, to discuss fluid-rock interaction in the Omi area.
Our study aims to elucidate the fluid composition and pressure-temperature conditions in this region by investigating fluid inclusions in rodingite, which is believed to have formed through Ca metasomatism; listvenite, formed by the metasomatism of serpentinite by CO2-bearing fluids; and carbonate veins within serpentinite. We use both Raman spectroscopy and microthermometry for this research.
In Kanayama-dani, a tributary of the Omigawa River, there's a rodingite outcrop where rodingite occurs as veins within serpentinite. Two-phase (vapor-liquid) fluid inclusions are present in the calcite veins within this rodingite. Raman spectroscopy indicates the liquid is saline fluids, with an estimated salinity of 2.3 ± 0.7 wt.% NaCl equivalent (n=30) based on the final melting temperature of ice. The homogenization temperature for the vapor and liquid phases is 233 ± 33°C (n=30).
Furthermore, listvenite collected from an outcrop of the Omi River downstream from Kanayama-dani is primarily composed of magnesite and quartz. The veins within this listvenite consist of dolomite and magnesite. Fluid inclusions in the dolomite have a salinity of 1.8 ± 0.3 wt.% NaCl equivalent (n=9) and a homogenization temperature of 211 ± 39°C (n=9) for the vapor and liquid phases, showing values close to those found in the rodingite veins.
In our presentation, we plan to compare the fluid inclusions from the rodingite and listvenite mentioned above, as well as those from ophicarbonate in the vicinity of the listvenite, to discuss fluid-rock interaction in the Omi area.