HR: 1340h
AN: V23B-1446    [Abstracts]
TI: Possible Transitional Process in Fission-Track Annealing of Zircon, Inferred by Remodeling of Laboratory Based Kinetics
AU: * Yamada, R
EM: ryamada@bosai.go.jp
AF: National Research Institute for Earth Science and Disaster Prevention, Tennodai 3-1, Tsukuba, 305-0006, Japan
AU: Murakami, M
AF: Department of Earth and Planetary Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
AU: Tagami, T
AF: Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto, 306-8502, Japan
AB: Annealing kinetics of fission tracks (FTs) in zircon was remodeled to fit data from 43 laboratory experiments in three previous papers using spontaneous FT lengths in zircon of the Nisatai Dacite. The ranges of heating temperature and time are 350 - 912 deg. C and 0.001 - 10000 h, respectively. Because the transition in annealing process appears at a certain temperature zone in the data plots, two types of models are created to describe the annealing behavior involving the possible transitional process with improved goodness of fit; (a) the hybrid-linear model that consists of the fanning-linear model at low temperature and the parallel-linear model at high temperature, connected with a transitional temperature zone, and (b) the parallel-curvilinear model that traces smoothly the transition in the annealing process. The validity of the extrapolation of these models to geological time scale is assessed by comparison with FT data from some deep borehole core samples. The length estimates by the hybrid-linear model agree well with the borehole data, while the estimates by the parallel- curvilinear model show a significant disagreement with highly annealed borehole samples although this model provides good agreement with the experimental data.
DE: 1100 GEOCHRONOLOGY
DE: 1115 Radioisotope geochronology
DE: 1140 Thermochronology
DE: 1194 Instruments and techniques
DE: 3600 MINERALOGY AND PETROLOGY
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting