Chikura Group

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Chikura Group (Naruse et al., 1951) Nakao et al., 1986

Invalid synonym: Chikura Formation

Type locality: Chikura village, Minamiboso city, Chiba prefecture
Coherent formation
Trench fill sediments, Landward slope basin of trench
late Pliocene - early Pleistocene

Depth of water: Lower - Upper bathyal (Foraminifera)
Lithofacies: Interbedded sandstone and siltstone
Sedimentation rate: 70 cm/kyr (averate)

Thickness: ca. 1,000 m
Upper limit: Unconformity (Nagaogawa I Terrace Deposit, Nagaogawa II Terrace Deposit, Nagaogawa III Terrace Deposit, Nagaogawa IV Terrace Deposit, Nagaogawa V Terrace Deposit, Nagaogawa VI Terrace Deposit, Nagaogawa VII Terrace Deposit)

Chikura Group (Northern part)
[ Upper ]
?--?--?--?--?-
Negata Formation
--------------
Sagashi Formation
?--?--?--?--?-
[ Lower ]

Chikura Group (Southern part)
[ Upper ]
?--?--?--?--?-
Hata Formation
-------'''/,,,
Mera Formation
--------------
Shiramazu Formation
--------------
Shirahama Formation
?--?--?--?--?-
[ Lower ]

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

Distribution: Chikura village, Minamiboso city, Chiba pref.

Utagawa et al. (2017) Jour. Geol. Soc. Japan, vol.123, no.11, pp.969-976 DOI
Okada et al. (2012) Jour. Geol. Soc. Japan, vol.118, no.2, pp.97-108 DOI
Kawakami and Shishikura (2006) Geology of the Tateyama District, Quadrangle Series, Scale 1:50,000, Geological Survey of Japan, AIST, 82p. (in Japanese with English abstract 5p.)