Geology of Ikego Region in Zushi City, Miura Peninsula

It is described for the stratigraphy and geological structure of the late Cenozoic sequence distributed in the Ikego U.S. Military Facilities Area in Zushi City, Kanagawa Prefecture. The sequence in the area consists of the Pliocene Zushi and Ikego Formations of the Miura Group, the Urago and Nojima Formations of the Kazusa Group, the late Pleistocene Younger loam distributed partly and the Holocene Alluvium in ascending order. The parallel unconformity can be observed between the Ikego and Urago Formations. The upper parts of the Ikego Formation and Kazusa Group trend east-west and dip gently north. The Zushi Formation and the lower parts of the Ikego Formation are irregularly destributed, that are in fault contact with each other. Pyroclastic beds in the lower parts of the Ikego Formation at the Hisagi Tunnel are interbedded with debris flow deposits ranging more than 72m long, the debris flow could be resulted from submarine sliding. It can be interpreted that the sliding activity and faulting between the both Zushi and Ikego Formations mentioned above occurred locally during the period of the so-called Kurotaki Movement