Japan Geoscience Union Meeting 2014

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Oral

Symbol S (Solid Earth Sciences) » S-GL Geology

[S-GL42_29AM2] Geochronology and Isotope Geology

Tue. Apr 29, 2014 11:00 AM - 12:45 PM 419 (4F)

Convener:*Takahiro Tagami(Graduate School of Science, Kyoto University), Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Chair:Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Takahiro Tagami(Graduate School of Science, Kyoto University)

12:25 PM - 12:40 PM

[SGL42-P04_PG] Luminescence dating and analysis of environmental change of fine grained sediments from Lake Yogo, Japan

3-min talk in an oral session

*Kazumi ITO1 (1.Geological Survey of Japan, AIST)

Keywords:OSL dating, pIRIR dating, lake sediments

We applied optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), post-IR IRSL (pIRIR) and 14C dating to the sediment core YG11-3 (294cm) from Lake Yogo, Japan. The fine grained quartz and polymineral sample are used for equivalent dose (De) estimation. As a result of several basically test, the preheat temperature of 200 oC for 10 s and a cut heat of 160 oC were suitable to all OSL measurements. The accepted aliquots are about 90 % per measurement discs and the range of Des are 0.3 ~ 3.5 (Gy). The bulk 14C ages are ca. 300 years older than these of plant residue. After subtracting this age difference from bulk 14C ages, the corrected ages agree with the OSL ages except the ages of sediments from some depths. Two excepted OSL ages are older than the corrected bulk 14C ages (YG11-3-245, YG11-3-343) and these layers include a lot of plant residue enough to analyze the plant residue 14C ages. It seems that these sediments from two layers have been transported quickly in muddy stream based on a temporary environmental event. Additionally, the result of the IRSL50/225 and pIRIR225 age confirms the existence of this temporary event. By comparing the OSL ages with 14C, IRSL and pIRIR ages, the quartz from the small catchment area can be applied to reconstruct the age model of sediment core in Japan.