Origin and Evolution of Natural Diversity;Proceedings


Paleoceanographic Changes of the Sea of Japan During 3.5-0.8 Ma

Kitamura, Akihisa

Permalink : http://hdl.handle.net/2115/38464
KEYWORDS : Sea of Japan;Warm Tsushima current;Fossil record;Shallow-marine deposits;Pliocene;Pleistocene


On the basis of fossil record from marine deposits in and around the Sea of Japan, the environment during 3.5-0.8 Ma is divided into two stages. During the old stage (3.5-1.71 Ma (stage 60/59)), cold surface water prevailed, except for the short term inflow (< 41 ky duration) of warm Tsushima Current at 3.5, 3.2, 2.9, 2.4 and 1.9 Ma. During the young stage (1.71-0.8 Ma), the Tsushima Current flowed into the sea at every interglacial highstand. This change was caused by opening of the southern channel due to crustal stretching in the northern Okinawa Trough. The onset of inflow of the Tsushima Current caused intrusion of warm-water organisms into the Sea of Japan during interglacial stages and barrier to migration of land organisms between East Asia and Japan. In summary, the environments and organisms in and around the Sea of Japan since 3.5 Ma have been strongly controlled by the development of southern channel (1.71 and 1.35 Ma) and global climate changes (glacial/interglacial cycles).