SLOPE TURBIDITE PACKETS IN A FORE-ARC BASIN FILL SEQUENCE OF THE PLIOPLEISTOCENE KAKEGAWA GROUP, JAPAN - THEIR FORMATION AND SEA-LEVEL CHANGES

The Plio-Pleistocene Kakegawa Group crops out in western Shizuoka, Jap an. It consists of submarine fan and slope to alluvial deposits and fo rms a third-order sequence. The slope deposits of the upper Kakegawa G roup (upper Horinouchi and Hijikata formations) are characterized main ly by alternations of sand and silt (turbidites). Individual sand laye rs commonly show either small lobe or channel features. In the upper H orinouchi (TST) and middle Hijikata formations (HST), sand turbidite p ackets (2-15 m) consist of small channel and lobe complexes. The slope sand turbidite packets are different between TST and HST. The differe nces result from the dissimilar net amplitude of sea-level excursions when fourth- or fifth-order sea-level changes superimposed on a third- order sea-level change with different trend. Other important variables are rate of sediment supply and width of shelf.