HR: 1340h
AN: V13B-1466    [Abstracts]
TI: Crystallization and differentiation of Cenozoic Granitic Melts, Taitao Peninsula, Chile
AU: * Kon, Y
EM: ykon@geo.titech.ac.jp
AF: Tokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Tateno, S
EM: stateno@geo.titech.ac.jp
AF: Tokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Komiya, T
EM: tkomiya@geo.titech.ac.jp
AF: Tokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AU: Annma, R
EM: anma@arsia.geo.tsukuba.ac.jp
AF: University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki, 305-8577 Japan
AU: Maruyama, S
EM: smaruyam@geo.titech.ac.jp
AF: Tokyo Institute of Technology, Department of Earth and Planetary Sciences, Tokyo Institute of Technology 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8551 Japan
AB: Geochemistry of the granitoid is significant for understanding the crustal growth on the earth. It is still controversial whether the characteristics originate from the distinctive composition of source, differences of pressure and temperature condition at the formation of melts, or differences of crystallized condition. One of the most serious problems in this issue is that the whole rock chemistry of such a coarse-grained rock is most unlikely to represent the nature of primary magma because they would have suffered from high fractionation during their fractionation. In this study, we present spot analysis of rare earth elements (REE) of relict igneous plagioclase, because the REE pattern of plagioclase reflects the melt composition, which the plagioclase was crystallized. Moreover, we estimated the primary magma of Phanerozoic granitoids to examine source, pressure and temperature path, which Taitao Peninsula granitoids went through. For this method, we conducted experiments to get the partition coefficient for REE between plagioclase and granitic melt. The partition coefficient is significant factor to estimate the melt composition. Nonetheless, previously reported partition coefficient for REE between plagioclase and melt were determined in implausible conditions for the Petrogenesis of granite (e.g., basaltic system, dry condition, or 1atm condition). We conducted experiments to synthesize plagioclase coexisting melt in a hydrous granitic system at 1.2 GPa and 900C in a piston-cylinder apparatus.
DE: 9360 South America
DE: 9604 Cenozoic
DE: 8110 Continental tectonics--general (0905)
DE: 3670 Minor and trace element composition
DE: 1020 Composition of the crust
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting