Integrated study to refine high-precision dating for the geomorphic and geologic time scales of the Late Quaternary

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Low-background liquid-scintilation counter for high-precision radiocarbon dating in Hiroshima University began routine measurement. Microsopic observation with digital image records helps to examine radiocarbon samples to evaluate the possibility of contamination by young organic matters. Serial dates from geologic sections were submitted to Bayesian analyses using dendrocorrection programs. With this method, objective and reliable procedures were established to determine the ages of event horizons such as volcanic eruptions and earthquakes. Through all core boring of Aso and Kuju Holocene tephra sections in central Kyushu, standard method for high-precision tephrochronology was established. The core also brought the best stratigraphic sequence of volcaninc activities in central Kyushu and standard chrno-stratigraphic information. For the reconstruction of environmental changes in Late Holocene, complete geologic sections of one to two thousand years were retrieved from three bore holes in northern Kyushu. Radiocarbon dating, micro- and macro-paleontological analyses are underway.