闽东南沿海老红砂的地球化学特征  

Geochemical Characters of the “Old Red Sands” along the Coast of Southeast Fujian

作　　者：曾从盛[1] 

机构地区：[1]福建师范大学地理研究所,福建福州350007

出　　处：《中国沙漠》2000年第3期248-251,共4页Journal of Desert Research

基　　金：国家自然科学基金项目!( 4 96710 12 );福建省自然科学基金项目!(D960 0 6)

摘　　要：闽东南沿海老红砂的地球化学分析表明 ,B、Ga、Sr、Ba、K、Cr、Ni和 V等微量元素含量及 B/ Ga和 Sr/ Ba比值指示老红砂应为陆相沉积 ,其磷酸钙组分和古盐度亦指示为陆相。老红砂的化学全量组合特征与花岗岩风化壳相似 ,但 Si O2 含量较花岗岩风化壳大 ,而 Al2 O3的含量明显少于花岗岩风化壳。从老红砂垂直剖面变化看 ,其硅铝铁率一般从上往下增加 ,分解系数 ( Fe2 O3/ Mg O)一般从上往下减少。The “old red sands” are the Quaternary sediments with distinctive features along the coast of Southeast China. There are consistently different views for the origins such as “marine deposits” or “aeolian deposits”. Some geochemical characters revealed by the contents of trace elements and their ratios of the old red sandy sediment samples from the coastal area of Fujian may give reference for comprehensively judging the sedimental environment of the “old red sands”. The contents and ratios of some trace elements of the “old red sands” from the coast of Fujian show that B has low content between 8 46×10\+\{-6\}~23\^65×10\+\{-6\}, and Ga between 7\^89×10\+\{-6\}~19\^13×10\+\{-6\},B/Ga between 0\^95~1\^48,and the contents of B and Ga relatively change from high to low in old red sandy sedimental profile from up to down. The contents of Sr have general relatively low values between 17\^72×10\+\{-6\}~54\^16×10\+\{-6\},and Ba comparatively high values between 164\^15×10\+\{-6\}~386\^8×10\+\{-6\}, therefore the ratios of Sr/Ba are only 0\^094~0\^188. In addition, the highest content of K is 1 238\^4×10\+\{-6\}, and the lowest is 295\^4×10\+\{-6\}; the percent contents of Cr,Ni and V of 12 samples of the old red sandy deposits are 15\^04,8\^69 and 27\^34,respectively. The ratios of Ca/(Ca+Fe) in sedimentary phosphate are between 0\^24~0\^41, and the paleosalinities of total 16 samples are about 0\^1%. These mentioned above don't indicate that the “old red sands” belong to marine facies.The chemical elements composition of the old red sandy sediments in proper order is SiO\-2\_Al\-2O\-3—Fe\-2O\-3\_MgO—CaO—FeO, which is similar to that of weathered granite layers.But the content of SiO\-2 in the old red sandy deposits is more than that of weathered granite layers,and the content of Al\-2O\-3 of the old red deposits is evidently less than that of weathered granite layers . The ratios of SiO\-2/(Al\-2O\-3+Fe\-2O\-3) in vertical sediment profile of the “old red sands” generally inc

关 键 词：地球化学 微量元素 老红砂 闽东南沿海 

分 类 号：P595[天文地球—地球化学]