SEDIMENTOLOGICAL STUDY OF THE STRATIGRAPHY AT THE SITE OF HOMO ERECTUS YUNXIANSIS IN THE UPPER HANJIANG RIVER VALLEY, CHINA

Geomorphological and sedimentological investigations and observations were carried out in the upper Hanjiang River valley. The sediments in the profile at the site of Homo erectus yunxianensis was sampled systematically. Magnetic susceptibility, loss-on-ignition, particle size distribution and geochemical elements were analyzed in the laboratory. The results show that the medium sand and gravel of the lower part of the profile are fluvial deposit of the third terrace of the Hanjiang River, and the upper part is a blanket of eolian loess and palaeosol deposited from dust storms. According to Stratigraphical correlation and palaeomagnetic dating, the carbonate nodules enwrapping the fossils of Homo erectus yunxianensis and other animals were formed during 810~785 ka. The palaeosol overlying the fossil layer is defined as the S₈ that was developed during the MIS19, and the loess below the fossil layer is defined as L₉ that was deposited during MIS20. These loess and palaeosol are similar to those over the Loess Plateau and correlatable with those in the Luochuan loess profile. They are very different from the fluvial deposits in the Hanjiang River valley. These results are very important in understanding the environment of Homo erectus yunxianensis in the upper Hanjiang River valley.