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HPQ-01 General contributions to Quaternary geology
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Subsurface geology of Kansai International Airport: Sequence related to global glacial - interglacial cycles
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Keiji Takemura, Kyoto University (Japan)
Naoko Kitada, Geo-research Institute (Japan)
Teruaki Furudoi, KANSAI International Airport Land Development CO., LTD. (Japan)
Kojiro Nakaseko, Osaka University (Japan)
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Tectonic sedimentary basins aligned in the central part of Japan during Quaternary. Thick sediments deposited in these basins provide useful records of climatic changes and tectonics throughout Quaternary. The Osaka sedimentary basin including Osaka Bay and area of Kansai International Airport is one of them. The Quaternary Osaka sedimentary basin has developed at an eastern contractional bend of a major transcurrent fault system named the Median Tectonic Line, which divides the southwest Japan arc. The thickness of Pliocene - Pleistocene sediments reaches to ca 3500m at the deepest part. These sequences are called the Osaka Group and are distributed in the Osaka Bay and exposed in the surrounding mountain areas. The Osaka Group is characterized by alternating sequences of marine and nonmarine strata. The subsurface sediments of Kansai International Airport (KIX) is composed mainly of Pliocene - Pleistocene sediments, which is characterized by alternating sequences of marine and nonmarine strata related to glacial - interglacial cycles.
The stratigraphy at KIX was established by micropaleontological, tephrochronological and magnetostratigraphical method. The sedimentary sequence at KIX is divided into two main units (Kukojima and Sennanoki Formations in ascending order) with the uncomformity within two units. Although thick marine clay units are mainly of the subsurface sequence, characteristics of coarser sediment units have an important role of moving of water during construction of the reclaimed land.
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