Japan Geoscience Union Meeting 2014

Presentation information

Oral

Symbol S (Solid Earth Sciences) » S-MP Mineralogy & Petrology

[S-MP46_28PM2] Deformed rocks, Metamorphic rocks and Tectonics

Mon. Apr 28, 2014 4:15 PM - 6:00 PM 414 (4F)

Convener:*Tetsuo Kawakami(Graduate School of Science, Kyoto University), Kazuhiko Ishii(Department of Physical Science, Graduate School of Sciences, Osaka Prefecture University), Chair:Takeshi Ikeda(Department of Earth and Planetary Sciences,Graduate School of Scinece, Kyushu University), Fumiko Higashino(Graduate School of Science, Kyoto University)

5:15 PM - 5:30 PM

[SMP46-P07_PG] Time scale for formation of diffusion zoning in response to breakdown reaction

3-min talk in an oral session

*Takeshi IKEDA1 (1.Kyushu University)

Keywords:diffusion zoning, duration time, cooling rate

In high-grade metamorphic rocks, garnet commonly represents an increase in Mn or Fe toward margin. This feature has been interpreted as diffusion zoning owing to garnet-consuming reactions during retrograde metamorphism. In this process, the zoned thickness can be described in terms of distances of internal diffusion and surface retreating. This study preliminaly formulated to express these distances as a function of time and retreating velocity of the surface. Applying the formulation to some high-temperature metamorphic belts yielded that the diffusion zoning with zoned thickness of 0.04 to 0.1 mm was formed by 1 to several million years. This result may be applied to estimate cooling rate provided that the surface equilibrium was mainetained during the formation of diffusion zoning.