JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG59] Evolution and movement of the crustal surface and application of geo- and thermochronology

convener:Noriko Hasebe(Institute of Nature and Environmental Technology, Kanazawa University), Shigeru Sueoka(Japan Atomic Energy Agency), Frederic Herman(University of Lausanne), Takahiro Tagami(Graduate School of Science, Kyoto University)

[SCG59-P06] Dating marine terraces by terrestrial cosmogenic nuclides: applicability and limitations

★Invited Papers

*Yuki Matsushi1, Tetsuya Komatsu2, Shigeru Sueoka2, Yusuke Yonaga2, Yumi Ogawa2, Natsuko Fujita2, Yoko Saito-Kokubu2 (1.Disaster Prevention Research Institute, Kyoto University, 2.Japan Atomic Energy Agency)

Keywords: terrestrial cosmogenic nuclide, marine terrace, exposure dating, uplift rate

This study overviews methodology for application of terrestrial cosmogenic nuclides for dating marine terraces. Accumulation of in-situ produced cosmogenic nuclides in near-surface bedrock reflects several factors such as exposure duration, sedimentation, and denudation of the landform. For cases of uplifted coastal surfaces, inheritance accumulated under pre-emergence erosional environment also affects the age accuracy, which can be inferred from the nuclide concentration of a representative modern wave-cut bench. We simulated evolution of subsurface depth profiles of cosmogenic 10Be concentration in quartz in terrace bedrock emerged at marine isotope stages (MIS) 1, 5e, 7, 11, and 13 with different parameter settings. Applicability and limitation of this method were then tested by comparing those model curves to actual depth-concentration profiles measured using boring cores extracted at two uplifted marine terraces in Muroto Peninsula, southern-east Shikoku, Japan, elevated to ~160 m above the present sea level.

Acknowledgements: This study was carried out under a contract with METI (Ministry of Economy, Trade and Industry) as part of its R&D supporting program for developing geological disposal technology.