关键词: 老红砂, 多期沉积, 玉木冰期, 闽粤沿海

Abstract: The "old red sand" is widely distributed on the coasts of Fujian and Guangdong. In recent years,we investigated in detail the "old red sand" in the field. The sections of the "old red sand" found at many localities on the coasts of Fujian and Guangdong are composed of many layers alternating tighten sand with loose sand, red color with yellow color and coarser grains with finer grains. The boundary between the upper cemented red layer with finer grains and lower half-cemented yellow layer with coarser grains is not apparent in the sections. The red color changes gradually downward into yellow one. However, the interface between the base of the yellow layer and the underlying red one can be clearly identified and some times forms step landforms in the field. This interface represents a break in the depositional process of the "old red sand", indicating existence of multi stages of the process. Dating of thermoluminescence (TL) and electron spin resonance (ESR) denote that the "old red sand" is the deposits in middle and later stages of late Pleistoncene time. Two depositional periods of 68~42 ka and 30~10 ka can be classified and the later is the time of the later Würm glacier. The "old red sand" in the period of 30~10 ka developed on the largest scale and had the widest distribution induced by dryer and colder climate, more powerful winter monsoons and stronger aeolian activities. Such environment in the later Würm glacier period can also be shown by the depositional ratio being calculated from the sections of the "old red sand". The ratio of the lower part in the sections is 2.2 cm·ka^-1 while that in the upper part is 3.8 cm·ka^-1, indicating a quicker depositional ratio in later Würm period than that in early Würm period.

Key words: "old red sand", multi depositional stages, Würm glacier, coasts of Fujian and Guangdong