Holocene Deposits and the Paleoenvironments in the Tokyo International Airport Haneda Northwest part of Tokyo Bay, Central Japan

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1 No pp Holocene Deposits and the Paleoenvironments in the Tokyo International Airport Haneda Northwest part of Tokyo Bay, Central Japan Katsuhisa SEKIMOTO, Kunihiko ENDO and Keisuke SHIMIZU Received September 30, 2007 Paleoenvironmental change in Tokyo Bay area in the latest Pleistocene and Holocene was investigated using the cores of Chuseki-so at Tokyo International Airport near the northwest Tokyo Bay. Foraminifer analysis clarified the changing processes of environment in Haneda Area. During the later stage of the Nanagochi Formation, the boundary of sea / fresh water might be situated near the center of Tokyo Bay, and the environment was river mouth to brackish water area. In the early to middle stage of the Yurakucho Formation, sequential changes in foraminiferal assemblages and wide occurrence of oyster reefs indicate quick sea-level rise and transgression occurred from 10,000 to 9,000 ca. years ago. Sea level of 10,000 ca. years ago must be -40 m. In the early to middle stage of the Yurakucho Formation, around 8,000 ca. years ago, inner bay environment extended and transgression advanced to the northern or inner part. Such trend in environmental changes mainly from 10,000 to 8,000 years ago, is nearly consistent with those in the previous studies such as Ishiwata 2004 and Endo in press in Tokyo coastal areas and Endo et al in Nakagawa Lowland. Keywords: Chuseki-so, Yurakucho Formation, Nanagochi Formation, Holocene, Paleoenvironment, Foraminifera, Oyster reef, Tokyo Bay Geological Science Research; , Daitakubo, Minami-ku Saitama City, Saitama Prefec., Japan Department of Geosystem Sciences, College of Humanities and Sciences, Nihon University; , Sakurajosui, Setagaya-ku, Tokyo, Japan Former Bureau of Port and Harbor, Tokyo Metropolitan Government; , Takashimadaira, Itabashi-ku, Tokyo, Japan

2 m 1 A-A, B-B,C-C 2 4 Fig. 1 Location map A-A, B-B and C-C show location of schematic geological section Figs A-A B-B C-C A-A - 1 Table 1 Stratigraphy and paleoenvironmental changes of Haneda offshore area

3 2 A-A Fig. 2 Schematic geological section of A-A Line 4 C-C Fig. 4 Schematic geological section of C-C Line 3 B-B Fig. 3 Schematic geological section of B-B Line 30m 55m 60m BG B-B m 50m BG 4 C-C A-A B-B 500m 1 A-A 60m 70m

Pleistocene) in northwest area of Tokyo Bay. 6 14 Fig.

4 5 Fig. 5 Typical columnar sections showing the ostrea bed. 7 Fig. 7 Contour map showing the base of Chuseki-so (Holocene and Latest Pleistocene) in northwest area of Tokyo Bay Fig. 6 Distribution of the ostrea bed and 14 C ages m 10 40mm 2 4m BG mm BG 10 15m

5 15m 37m 43m A-A m m2 3m 14 C 8,800 9,300yrs. BP 6 26m 7,300yrs. BP K-Ah A-A C 46.0m 10, m 42m 8,800 9,300yrs. BP cal cal.10656yrs C Fig. 8 Diagram of fossil foraminifers from the analyzed core

6 2 14 C 2005 Table 2 List of 14 C ages from the ostrea bed and peat Cal. ages are calculated based on Endo C m GaK , ,084 GaK , ,656 GaK , ,072 GaK , ,513 GaK , ,321 GaK , , m 14 9, yrs. BP ,560yrs 300m 37.5m yrs. BP yrs. BP m m TP-42.0m 12 20g mesh 0.075mm 200mesh Fissurina cucurbitasema bispinata 2 Ammonia beccarii 3 4 Ammonia beccarii, Elphidium somaense, Elphidium clavatum

7 3 Elphidium subarcticum 4 Elphidium excavatum, Miliolinid 5 7 Ammonia japonica, Pseudorotalia gaimardii, Nonionella stella Elphidium excavatum Quinqueloculina Massilina Miliolinid 1g Ammonia japonica, Nonionella stella, Miliolinid Pseudorotalia gaimardii Ammonia beccarii, Elphidium somaense, Elphidium excavatum, Epistominella tamana, Fissurina cucurbitasema bispinata K-Ah Ca7,300yrs 11 Fissurina cucurbitasema bispinata, Miliolinid Ammonia beccarii, Ammonia japonica, Elphidium somaense 12 1mTrochammina hadai B-B 43.1m 14 C 14, m2 41.5m Ammonia beccarii, Fissurina cucurbitasema bispinata m 42m m Ammonia beccarii, Elphidium somaense, Elphidium clavatum m 32.5m Ammonia japonica, Pseudorotalia gaimardii Nonionella stella, Miliolinid m Pseudorotalia gaimardii Ammonia japonica, Nonionella stella Miliolinid 2006 Fissurina cucurbitasema bispinata, Miliolinid Ammonia beccarii, Ammonia japonica,

8 Elphidium somaense 1987 Ujiie: 1962, 1963 Endo et.al, ; Sekimoto and Endo, m Trochammina hadai Pb 1950 Nonionella stella Trochammina hadai Morishima C , Fig. 9 Relative sea level change curve in the central part of Kanto Plain (Endo, 2005) peat and wood, indicating terrestrial environment molluscan shells living in intertidal zone molluscan shells living in sublittoral zone of inner bay 10,000 9,000 40m

9 No.31, No.32, p.27-34, p P.70-71, CD- ROM No.21, No.14, p No.16, p Endo K., Sekimoto K. and Takano T. (1982) Holocene Stratigraphy and Paleoenvironments in the Kanto Plain, in relation to the Jomon Transgression. Inst. Nat. Sci. Human. Sci., Nihon Univ., Earth Sci., No.17, p p C-14 vol.5, p p No.23, p p p. Morishima K. (1955) Deposits of Foraminiferal Tests in the Tokyo Bay, Japan. Memoirs of the College of Science, Univ. of Kyoto, Series B, vol.22, p p.42-50bp Sekimoto K. and Endo K. (1980) Foraminiferal Assemblages and Paleoenvironments of the Holocene Shimobara Formation along the Lower Reaches of the River Nakamura, Kanagawa Prefecture, Japan. Proc. Inst. Nat. Sci. Coll. Human and Sci., Nihon Univ., Earth Sci. No.15, p No.24, p N0.18, p No.41, p p p p. Ujiie H. (1962) Introduction to Statistical Foraminiferal Zonation. The Journal of the Geological Society of Japan, Vol.68, p

Microfossil Analysis and Paleoenvironmental Changes of Kazusa and Shimousa Groups from Cores in the Port of Tokyo, Central Japan

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