A Study On Formation And Characteristics Of Sandy Dunes In The Eastern Coast, Changle, Fujian

This research covers the geomorphology and geodynamics of the coastal dunes at east coast of Changle, Fujian, China. As far as the scales and relief types are concerned, they can be considered as one of the typical examples for the China's southeastern dune formations.This paper particularly focuses on these problems, such as, granularity characteristic of sands and internal sedimentary structures, and the contrast analyse between beach sands and dunes , and the cause of formatting and shape of sand dune and general patterns and mechanism of wind induced sand movement.The author discuss the formation of coastal dune in this area, on the basis of other's research, the wind, sand source, and the landform. Otherwise, according to the spatial combinations, shape characters, and the physiognomy of these coastal dunes, this area was divided into five sections and made a detailed description.Through the analyse of sand granularity we can reach the result that mean granularity of beach sands is between 1.23～2.53Φamong which silver sand occupied most, and the standard deviation is between 0.41～0.55, which means selected well, bigger than 3 and very edge. The scatter plot diagrams of the four size parameters of the beach sands and dunes have a definite disciplinarian relatively, but there is difficult to distinguish them.The sedimentary structures are classified into five types in details which also include internal deformational structures of the dunes on the basis of the observations and outcomes of this research. These are: horizontal bedding, tabular cross-bedding, "scalloped" cross bedding, wedged cross-bedding and contemporaneous deformation structure.As the beach sands and the dune sands in this zone in China can not be distinguished by use of the parameter plot of grain size and component analysis method, the method to distinguish the beach sands and the dune sands, which make use of fractal dimensions of grain size distribution, is made. The application of this method in Changle Fujian zone in China tell us the result that the fractal dimensions of grain size distribution of beach sands in the zone are between 2.33 and 2.48, on the other hand the fractal dimensions of grain size distribution of dune sands are between 2.54 and 2.63.It demonstrates that this method is very effective in distinguishing the beach sands and the dune sands.The geomorphological features and patterns, the variations of wind speed and direction, aeolian sand transport mechanism and processes, dune formation stages are also investigated. Under the light of existed knowledge, assessments of dune prevention and mitigation measures are also considered.