活断層のTL年代評価 : 細粒試料がより若いTL年代を示すとは限らない

概要

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We tried TL dating for the quartz inclusion from the fracture zone of the Tsuruga Fault. As the growth curves showed a tendency of saturation, we evaluated the equivalent doses by a curve fitting to a exponential function. Although the natural TL intensity of the fine grains is lower than that of the coarse ones, the equivalent doses, and so the TL ages have no dependency on grain size. The differences of TL characteristics of samples show the circumstances well. ① The finer grains have the lower saturation level. ② All fine grains do not always give the younger TL age. The fact that the decrease of effective trap number has extensively occurred to fine grains after faulting is responsible for the former. The latter infers the existence of a certain limited grain size, for the sample of which, the paleodose is zeroed most effectively. TL age of the Tsuruga Fault is 33±3 ka. It gives only the upper age limit of the latest faulting, for complete zeroing is not confirmed.
奈良教育大学の論文