关键词: 老红砂, 粒度特征, 沉积旋回, 气候变迁, 土壤带迁移, 海坛岛

Abstract: The "Old Red Sand" of Qingfeng Profile in northwestern Haitan Island is characterized by its cyclical variaton of red-brown sand layers and yellow-orange sand layers. In this paper, we focused on further research of the grain size characteristics and the paleoenvironmental significance of Qingfeng Profile. The results showed that: (1) The red-brown sand layers are mainly composed of fine sand, and the yellow-orange sand layers are medium sand. The Qingfeng Profile is featured with its alternating cycle of fine sand and medium sand. (2) The grain size frequency distribution curves of Qingfeng Profile present similar singlet with a thin tail, showing that the "Old Red Sand" contains a certain amount of silt and clay. Although the long-probability curves are both given priority to three stages, there are still some differences in component and slope. (3) The variation of grain size parameters with depth of Qingfeng Profile presents obvious fluctuation changes, showing that the wind conditions, transport dynamic and weathering intensity in sedimentary period have experienced cyclical change. The red-brown sand layers show the process of latosolic red soil in the warm-wet climate, and the yellow-orange sand layers show the process of yellow soil in the cold-dry climate. The sedimentatry cycles of Qingfeng Profile may be recorded the alternating change of south subtropic(latosolic red soil) and warm temperate(yellow soil) in the east coast of Fujian Province since the late Quaternary.

Key words: Old Red Sand, grain size characteristics, sedimentatry cycles, climatic variation, soil migration, Haitan Island