关键词: 海岸, 横向沙脊, 粒度分异, 河北昌黎

Abstract:

A total of 47 samples were collected on typical coastal transverse ridge at Changli Golden Coast in Hebei Province, which is one of the most typical coastal aeolian distribution regions in China and is famous for the tall and typical coastal transverse ridges. The parameters of grain size of the 47 samples were analysed and calculated by use of the number of mean size, standard deviation, skewness and kurtosis. The results showed that, as for the deposits on the surface of transverse ridges in Changli Golden Coast, under the same depositional environment the particle size at windward slope base, windward slope, dune crest, leeward slope and leeward slope base as a whole belonged to the medium sand with better sorting, approximately symmetric skewness and moderate kurtosis.Some differences existed in the particle-size parameter value at different sites, especially the mean particle size at different sites of the transverse ridges surface greatly, i.e. , the particle size became finer and the sorting became much better from windward slope base and leeward slope base to the crest of transverse ridges, particle size at leeward slope was relatively finer than at the windward slope, the sorting at leeward slope also better than at the windward slope. As for the whole dune surface, the particle size was the coarsest at leeward slope base and the finest at the crest of transverse ridges. The distribution characteristics of grain size on coastal transverse ridge could be concluded as the finest and the best sorting sands distributed on the crest of coastal transverse ridge and the coarsest sands distributed at the leeward slope base, which is a new distribution model of grain size on dunes. The surface particle-size distribution model of the transverse ridge in Changli Golden Coast resulted from the combined effects of the alternation variation of the region's prevailing wind direction and strong wind direction and wind force difference as well as asymmetry on both sides of the dune. In which, the large height and asymmetrical dune shape were the main factors resulted in the distribution characteristics of grain size on coastal transverse ridge. The alternating variations of wind direction made the slope bases on both sides of the transverse ridge constantly in a coarsening state, but becoming finer and in the sorting state on the crest and both side slopes. The wind force difference strengthened the process and its degree above.

Key words: coastal zone, transverse ridge, distribution of grain size, Changli County in Hebei Province