11:30 〜 11:45
[MIS23-10] Pliocene–Pleistocene magnetostratigraphy and geomagnetic reversal structure from marine, terrestrial, and coastal successions in Japan
キーワード：古地磁気層序、地磁気逆転、酸素同位体層序、珪藻、有孔虫
The Pliocene–Pleistocene magnetostratigraphy is a significant stratigraphic marker to constrain the age of geological archives and to conduct inter-basin correlations on paleoclimatic proxies. However, the stratigraphic relationship between polarity transitions and the glacial-interglacial cycle climatic variation is unclear, yet. The stratigraphic uncertainty is likely because of the stability of the primary paleomagnetic signal in sediments, the long-term dominance of the transition field, the heterogenous geomagnetic configuration during geomagnetic reversals, the effects of local water temperature and salinity on oxygen isotope stratigraphy, the lead/lag of seawater δ18O variation due to the thermohaline circulation, and so on. On the other hand, a recent model study, which reconstructed the Matuyama–Brunhes geomagnetic reversal to compile paleomagnetic records, suggested that the polarity change has generally co-occurred on the globe while the inception age of the transition filed dominance has depended on observation sites. Considering the inherent uncertainties in the age models, it is controvertible. To resolve these problems, it is necessary to clarify the stratigraphic relationship between the polarity transitions and marine isotope stages and reveal the structure of each geomagnetic reversal at each basin. In this presentation, I introduce Pliocene–Pleistocene magnetostratigraphies and high-resolution paleomagnetic variations across polarity transitions from marine and terrestrial successions and coastal sediments, distributed in Japan, which can be a type of magnetostratigraphy in the northwestern Pacific.