Differentiation of Geochemical Element in the Modern Aeolian Sands on the Surface of Coastal Aeolian Dunes

Key words: 
• surface over coastal aeolian dune /
• geochemical element /
• differentiation /
• coastal aeolian transverse ridge /
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Abstract: Taking a typical coastal Aeolian transverse ridge at Changli Gold Coast in Hebei province as an example, which is one of the most typical coastal aeolian distribution regions in China and famous for the tall and typical coastal transverse ridges, the distribution characteristics of 21 kinds of geochemical element in the modern aeolian sands on the surface of coastal aeolian dune(coastal Aeolian transverse ridge)are analysed. The research results show, in 21 geochemical elements which are contained in the modern aeolian sands on the surface of coastal aeolian transverse ridge, the differentiations of three geochemical elements at different sites over the surface of coastal dune are obvious, which are Co and Zr as well as Mg. The differentiations at different sites over coastal dune surface of Cr, Pb, Ti, Nb, As, Mn, Zn and Ba, are moderate,but the differentiations of some geochemical elements are slight, such as Y, Ca Fe, Na, Al, Sr, P, K, Rb and Si. The change features of geochemical elements in the modern aeolian sands at different sites, such as windward slope base, windward slope, dune crest, leeward slope and leeward slope base, on the surface of coastal aeolian transverse ridge are different, which could be concluded into different change models. The features and models of differentiation of geochemical elements at different sites over the surface of coastal aeolian transverse ridge are mainly controlled by the depositional environment, chemical characteristics of geochemical elements as well as grainsize of aeolian sands and so on. For examples, the geochemical elements such as Y, Ca Fe, Na, Al, Sr, P, K, Rb and Si, their differentiation features are mailly affected by depositional environment, but the differentiation of some microelements, such as Cr and Co, is mailly controlled by grain size of sands and the wind force. Based on the conclusions above, because there are clear differentiations of some geochemical elements such as some microelements at different sites over the surface of coastal aeolian transverse ridge, it should be very modest to use the change of microelements in different stratum profiles to deduce the change of coastal environment or climate by use of traditional environment analysis ways as usual.