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Lookup NU author(s): Professor Takeshi Nakagawa
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The 250-m Choshi core (CHOSHI-1), drilled from hemipelagic muds of the Inubo Group, has been physically, geochemically and tephrochronologically analyzed back to 1Ma. We provide pollen results for the 19-169 m section of the core (400-780 ka) bracketed by the marker tephra Ty1 (equivalent to J4) and the Brunhes-Matuyama paleomagnetic boundary. The results show good agreement with the corresponding oxygen isotope (δ18O) profile, with high δ18O intervals dominated by boreal conifers Picea, Abies, Pinus (subgen. Haploxylon) and Tsuga (diversifolia), whereas low δ18O intervals are dominated by temperate conifers Cryptomeria, Taxaceae-Cephalotaxaceae-Cupressaceae and Sciadopitys. In order to confirm pollen-climate relations for the relevant taxa, a modern surface pollen dataset for the Japanese archipelago was consulted. In this analysis, the ratios of Cryptomeria/Picea and temperate/boreal conifers serve as proxies for the 100-kyr glacial/ interglacial cycle during the Middle Pleistocene. Distinct signals for marine isotope stages (MIS) 11, 12, 13-15, 16, 17 and 18-19 are recognized in accordance with the tephrochronology and δ18O of the same core. Application of the criteria to an independent pollen record from Lake Biwa provides an integrated pollen stratigraphy for mid-latitude Japan during the past 800 ky. Some degree of uncertainty remains in the chronology of the MIS13-15 interval, relating to the uncertainty in the eruption age of widespread tephra Ks11. © 2006 The Authors; Journal compilation © 2006 Blackwell Publishing Asia Pty Ltd.
Author(s): Okuda M, Nakazato H, Miyoshi N, Nakagawa T, Okazaki H, Saito S, Taira A
Publication type: Article
Publication status: Published
Journal: The Island Arc
Year: 2006
Volume: 15
Issue: 3
Pages: 338-354
Print publication date: 01/09/2006
ISSN (print): 1038-4871
ISSN (electronic): 1440-1738
URL: http://dx.doi.org/10.1111/j.1440-1738.2006.00533.x
DOI: 10.1111/j.1440-1738.2006.00533.x
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