[S-GL38] 上総層群における下部ー中部更新統境界GSSP

[SGL38-P01] 下部ー中部更新統境界GSSP候補地へのご案内

*吉田 剛¹、荻津 達¹、風岡 修¹、岡田 誠²、菅沼 悠介³、亀尾 浩司⁴、楡井 久⁵、会田 信行⁶、熊井 久雄⁷、西田 尚央⁸、泉 賢太郎⁹ (1.千葉県環境研究センター地質環境研究室、2.茨城大学、3.国立極地研究所、4.千葉大学、5.GEM日本支部、6.秀明大学、7.大阪市立大学、8.産業技術総合研究所、9.東京大学)

キーワード：田淵セクション, 下部・中部更新統

The Tabuchi section is a continuous marine sedimentary succession exposed in the Boso peninsula and is a Lower - Middle Pleistocene boundary GSSP candidate.
From the geological advantages and the easy access to the outcrops, the Tabuchi section seems to be the most suitable for the Lower - Middle Pleistocene boundary GSSP.

Geological characteristics
*Tabuchi section is only candidate representing the Pacific realm.
*Thick L - M Pleistocene sedimentary succession (>3000 m) (2.4 ? 0.5 Ma) .
*Well exposed along the Yoro River with high sed. rates (ca. 2 m/kyr) & no visible breaks.
*Well preserved calcareous nannofossils, planktonic foraminifera, diatoms.
*Standard section for Japanese Pleistocene tephrostratigraphy (>50 ash beds).
*Well established d18O isotope stratigraphy: Kokumoto Fm. corresponds to MIS 20?18.
*M?B boundary is located ca. 1 m above a distinctive, widespread tephra bed (Byk-E).
*High-precision U-Pb zircon age of the Byk-E.
Consistent with the latest astrochronology of marine sediments and Antarctic ice core.
*A basis for immediate comparisons between, magnetostratigraphy, biostratigraphy, O isotope stratigraphy, absolute ages (40Ar/39Ar & U-Pb), and astrochronology.
*Taking the M?B boundary as the primary guide to the L?M Pleistocene boundary, the Byk-E bed would serve as an appropriate level for the GSSP.

Access
There are well developed public transportations. You can reach to Tabuchi section within 2 hours from Tokyo and 3 hours from both international airports. There are big car parks. There are lodge and toilet.
The access to the Tabuchi section is very easy and convenient by car, bus and train with very small walk.