REGIME OVER THE EVOLUTION OF THE SUMMER MONSOON LOESS PLATEAU OF THE LAST 150 KA

On the magnetic susceptibility data of 30 sections covering the Loess Plateau, contour maps of susceptibility are drawn out for 5 time inter vals including the last second glaciation (150 ka B.P.), the last inte rglaciation (130-73 ka B.P.), the interstadial of the last glaciation (24-59 ka B.P.), the last glacial maximum (18 ka B.P.) and the Holocen e optimum (9 ka B.P.). The susceptibility value of the last glaciation maximum loess is regarded as the base value of pedogenic loess or pal eosol. The susceptibility increment to the base indicates the summer m onsoon activity and its strength. On this assumption and the susceptib ility contour maps, the variation sequence of the summer regime an rec onstructed for the last 150 ka. The extent and the northern boundaries of the summer monsoon front activity are also estimated for every sta ge. It is suggested that the evolution history of the summer monsoon r egimes revealed by the susceptibility contour maps not only provides i nformation of position, strength and their configuration of the climat e members influencing the summer monsoon, but also provides some clima tic signals from the polar region and southern hemisphere.