3:30 PM - 5:00 PM
[SCG48-P08] Re-examination of the crystallization pressure of the Kaikomagatake pluton, Izu collision zone: For practical application of the melt inclusion in zircon geobarometer
Keywords:zircon, melt inclusion, geobarometer, granitoid, the Kaikomagatake pluton
We compare the results of MELt Inclusion in Zircon (MELIZ) geobarometer (Taniwaki et al., under review) and Al-in-hornblende geobarometer for the Kaikomagatake pluton in the Izu collision zone, central Japan. Emplacement pressures of 240–220 MPa have been estimated for the pluton based on Al-in-hornblende geobarometer (Watanabe et al., 2020, JMPS).
Using the melt inclusion composition of zircons in the granodiorite sample from the Kaikomagatake pluton, pressure of < 100 MPa and 76 ± 34 MPa are estimated from norm Qz-Ab-Or geobarometer (Blundy and Cashman, 2001, CMP) and Rhyolite-MELTS geobarometer (Gualda et al., 2012, CMP), respectively. These pressures estimated from melt compositions are significantly lower than those resulted from Al-in-hornblende geobarometer for the pluton (Watanabe et al., 2020 JMPS). It has been suggested that both norm Qz-Ab-Or and Rhyolite-MELTS geobarometers underestimate the effect of An component, which results in lower pressure estimates (Wilke et al., 2017, JPet). Therefore, correction is required for the results of MELIZ geobarometer, in case the sample is relatively rich in An component (i.e., granodiorite and/or tonalite).
Using the melt inclusion composition of zircons in the granodiorite sample from the Kaikomagatake pluton, pressure of < 100 MPa and 76 ± 34 MPa are estimated from norm Qz-Ab-Or geobarometer (Blundy and Cashman, 2001, CMP) and Rhyolite-MELTS geobarometer (Gualda et al., 2012, CMP), respectively. These pressures estimated from melt compositions are significantly lower than those resulted from Al-in-hornblende geobarometer for the pluton (Watanabe et al., 2020 JMPS). It has been suggested that both norm Qz-Ab-Or and Rhyolite-MELTS geobarometers underestimate the effect of An component, which results in lower pressure estimates (Wilke et al., 2017, JPet). Therefore, correction is required for the results of MELIZ geobarometer, in case the sample is relatively rich in An component (i.e., granodiorite and/or tonalite).