Millennial- to decadal-scale fluctuation in the paleo-Kuroshio current documented in the middle Pleistocene shelf succession on the Boso Peninsula, Japan

Millennial-, century-, and decadal-scale cyclicities were identified in a transgressive shelf succession of the Middle Pleistocene (ca. 0.7 Ma) on the Boso Peninsula, Japan. The shelf succession consists mainly of a sandridge complex and associated outer shelf deposits. The deposition was interpreted to have been controlled by fluctuation in speeds and paths of the paleo-Kuroshio Current. In general, the modern Kuroshio Current approaches the southern coasts of the Boso Peninsula in response to its large meander that is interpreted to respond to the El Nino episodes. Depositional cycles in the Kuroshio-Current-controlled shelf succession are interpreted to document high-frequency paleoclimatic oscillation in the equatorial Pacific region during the Middle Pleistocene time. The finding indicates that high-frequency paleoclimatic instability, that has been strongly expressed in the Upper Pleistocene successions in the North Atlantic region, was pervasive in time and space back to the Middle Pleistocene. (C) 2000 Elsevier Science B.V. All rights reserved.