Precipitation history of the Lake Biwa area in central Japan over the last 145 ka

The fluvial quartz flux (FQF, g cm^-2 ka^-1) to Lake Biwa of central Japan is developed as a proxy of variations in palaeoprecipitation over the lake catchment. Lake Biwa sediments spanning the last c. 145 ka are characterized by 4 main intervals when the FQF values were significantly greater than 2 g cm^-2 ka¹, and 5 main periods during which FQF values were lower. Three of the intervals with high FQF values occur from c. 128 to 78 ka BP, with peak values at c. 122, 101 and 82 ka BP; the fourth of two narrow peaks exists between c. 48 and 35 ka BP. Three main periods with lower FQF values intervene between intervals of high FQF values, and two others lie before c. 128 ka BP and after c. 35 ka BP. The data imply that palaeoprecipitation over the lake catchment increased during the intervals of high FQF values, and decreased during the periods of lower FQF values. High FQF values between c. 48 and 35 ka BP are interpreted to reflect an effective runoff of meltwater from the surrounding mountains during the interstade of the last glaciation. Relatively low FQF values during the early Holocene are interpreted to reveal a sluggish northward retreat of the polar front in the North Pacific Ocean that suppressed the northward advance of the summer monsoonal front and regional precipitation. During the last interglaciation, the increasing trend of FQF values is interpreted to indicate a progressive expansion of the Sea of Japan related to the rise in global sea level, which increased moisture advection to, and precipitation within, the Lake Biwa region.