Geomorphological Chronology of Pleistocene Terraces and Pediments used for the Loess-paleosol Sequence in Korea

Abstract

Loess began to deposit at the Chinese Loess Plateau and in Central Asia in 2.5 Ma, at the beginning of 41 ka climate cycle. After 0.78 Ma, loess was deposited at the beginning of the 0.1 Ma climate cycle around the world. Loess in East China started to be deposited in 0.78 Ma, while Korean loess-paleosols deposited from MIS 11 (0.4 Ma) have been observed in many places recently. In the near future, a continuous loess-paleosol sequence from MIS 18 (0.78 Ma) to MIS 1 (present) might be found in Korea. Korean paleosols are characterized by MIS 3 brown soils and MIS 5 red soils and MIS 11 more reddish soils. Chongokni loess-paleosol stratigraphy is defined from MIS 9 at least on Chongok basalt (0.5 Ma). Loess-paleosols from MIS 6 were deposited on Chatan basalt (0.15 Ma). Loess consists of a mixture of eolian dust from the northern Asian continent and from the dried sea floor of the Yellow Sea dating from the glacial ages. There are four river terraces along the middle reaches of the Hongcheon River. From the stratigraphy of loess-paleosol on the Hongcheon terraces, the development age of river terraces I to IV can be correlated with MIS 7, 6, 4, and 2, respectively. Pediments developed during the initial stages and the final stages of each glacial age. Loess is a useful material for determining the geomorphological chronology of such features as pediments, and river and marine terraces, as well as the archaeological chronology of paleolith. Using loess-paleosol stratigraphy, we can easily estimate the age of paleolith. It also provides a key to correlations in other regions within East Asia. Korean loess represents the most significant terrestrial proxy of Late Quaternary climatic change and paleo-environmental data in East Asia.