[S-CG47] Petrology, Mineralogy & Resource Geology

[SCG47-P09] Homogenization experiments of zircon melt inclusions: Example of Miocene Miuchi granitoid pluton

*Yuka Taniwaki¹, Kazuya Shimooka¹, Satoshi SAITO¹ (1.Department of Earth Sciences, Graduate School of Science and Engineering, Ehime University)

Keywords:melt inclusions, granite, zircon, crystallization depths

We have performed homogenization experiments of melt inclusions in zircons separated from a biotite granite sample in the Miocene Miuchi pluton with a piston-cylinder type high-pressure apparatus. The melt inclusion compositions obtained through SEM-EDS analysis are granitic and their SiO₂ contents (75–80 wt %) are higher than whole-rock composition of the zircon extracted sample (72 wt % SiO₂). Comparing with whole-rock chemical trends of Miuchi pluton, major element compositions of zircon melt inclusions are close to evolved samples of the Miuchi pluton suggesting that zircon grains trapped fractionated melts in the crystallizing granitoid magma. This is consistent with zircon occurrences under microscope observation showing that zircon grains mostly occur between main mineral constituents. In the normative Q-Ab-Or diagram, dominant melt inclusion plot along the cotectic curves of 180–50 MPa. The pressure range is broadly consistent with field and petrographic observations suggestive of magma emplacement at shallow crustal level, including occurrences of andalusite in the metasedimentary xenoliths and miarolitic cavities in the vicinity of intrusive contact with country rocks.