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Kazusa Group (Ida et al., 1956) Tokuhashi and Endo, 1984

Invalid synonym (Tama hills): Minamitama Group

• Type locality: Yorogawa river, Chiba prefecture
• Coherent formation
• Fore-arc basin sediments (Kazusa trough) formed by subduction of Pacific plate and Philippine Sea plate
• late Pliocene - middle Pleistocene
• Boso peninsula: early - middle Pleistocene (2.4 - 0.45 Ma, Calcareous nannofossils, Foraminifera, Paleomagnetic, Tephra)

• Sedimentary facies: Brackish, Shallow marine
• Sedimentary facies: Fluvial, Inland bay
• Sedimentary facies: Oceanic current dominated shelf
• Sedimentary facies: Turbidite
• Depth of water: Mudflat, Intertidal, Confinental shelf, Bathyal
• Lithofacies: Mudstone dominant
• Lithofacies: Sandstone, Mudstone, Siltstone
• Lithofacies (Minor): Conglomerate

• Thickness (Boso peninsula): 4,000 m
• Thickness (Miura peninsula): 800 m
• Upper limit (Shimosa Group): Erosion surface by the low sea level formed during marine oxygen isotope stage (MIS)12
• Upper limit: Unconformity (Shimosa Group, Tokyo Formation, Musashino Terrace Deposit, Kanto Loam, Setagaya Formation, Toyooka Formation, Mine Formation, Imokubo Formation, Gotentoge Formation, Kobiki Terrace Deposit, Hino Terrace Deposit, Narimasu Formation, Tachikawa 2 Formation, Aoyagi Formation, Kamikurata Formation, Oshinuma Formation, Tsurumi Formation, Nakadai Formation, Naganuma Formation, Isumi 1 (Yoshifu) Terrace Deposit, Isumi 2 Terrace Deposit)
• Lower limit: Kurotaki Unconformity (Awa Formation), Unconformity (Tate Formation)

------ Conformity, ~~~~~~ Unconformity, ~~~--- Local unconformity, '''/,, Interfingered, :::::: Fault, /--/-- Thrust, +__+__ Ground surface, ?--?-- Unknown

• Distribution: Sayama hills, Saitama pref.; Northwestern Tama hills, Tokyo metropolis; Middle - Southern Tama hills, Kanagawa pref.; Northern Miura peninsula, Kanagawa pref.; Boso peninsula, Chiba pref.
• Distribution: Yoro river, Chiba pref.; underground of Setagaya, Tokyo
• Tephra: SGO, HM-Kd16, GS, NK, Noborito-Kd17, SG-Kd18, MT, NG-YR, YU, YM, KK, Ob4b-1 (HU₁), Omine-SK110 (HU₂)

• Utsunomiya and Ooi (2019) Geology of the Kazusa-Ohara District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 127p. (in Japanese with English abstract 4p.)
• Majima et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.9, pp.655-683 DOI
• Nakazawa et al. (2019) Jour. Geol. Soc. Japan, vol.125, no.5, pp.367-385 DOI
• GSSP proposal group (2019) Jour. Geol. Soc. Japan, vol.125, no.1, pp.5-22 DOI
• Nanayama et al. (2016) Geology of the Mobara District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 101p. (in Japanese with English abstract 4p.)
• Suzuki et al. (2016) Jour. Geol. Soc. Japan, vol.122, no.7, pp.343-356, DOI
• Utsunomiya et al. (2014) Jour. Geol. Soc. Japan, vol.120, no.8, pp.221-231 DOI
• Kusu et al. (2014) Jour. Geol. Soc. Japan, vol.120, no.2, pp.53-70 DOI
• Ueki et al. (2013) Geology of the Hachioji District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 137p. (in Japanese with English abstract 6p.)
• Suzuki and Murata (2011) Jour. Geol. Soc. Japan, vol.117, no.7, pp.379-397 DOI
• Nakazawa and Tanabe (2011) Geology of the Noda District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 72p. (in Japanese with English abstract 3p.)
• Tamura et al. (2010) Jour. Geol. Soc. Japan, vol.116, no.7, pp.360-373 DOI
• Nakazawa et al. (2009) Jour. Geol. Soc. Japan, vol.115, no.2, pp.49-63 DOI
• Nakajima and Watanabe (2005) Geology of the Futtsu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 102p. (in Japanese with English abstract 8p.)
• Eto et al. (1998) Geology of the Yokosuka District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 128p. (in Japanese with English abstract 3p.)
• Suzuki et al. (1990) Geology of the Nago District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 48p. (in Japanese with English abstract 3p.)
• Tokuhashi and Endo (1984) Geology of the Anesaki District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 136p. (in Japanese with English abstract 6p.)
• Oka et al. (1984) Geology of the Tokyo-Seinambu District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 148p. (in Japanese with English abstract 7p.)
• Mitsunashi and Kikuchi (1982) Geology of the Yokohama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 105p. (in Japanese with English abstract 4p.)
• Oka et al. (1979) Geology of the Fujisawa District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, 111p. (in Japanese with English abstract 5p.)