莱州湾晚第四纪以来沉积物元素地球化学特征及来源

Geochemical characteristics and their geological implication in sediments from Laizhou Bay since late Quaternary

元素地球化学信息对于地层划分和物源分析具有重要的指示意义。通过分析莱州湾BH1302孔岩芯沉积物常微量元素特征发现,元素含量在地层分界处发生明显变化,可以作为晚第四纪地层划分的重要指标。结合钻孔岩性相、粒度特征和测年数据,将研究区晚第四纪以来的沉积划分为4段,分别对应于晚中更新世、MIS 5期、MIS 4—3期和MIS 1期。钻孔岩芯沉积物常微量元素在垂向上变化存在着共生的关系,除Na_(2)O、Ba和Sr外,大部分常微量元素变化与粒径强相关。R型因子分析揭示陆源细颗粒碎屑沉积、陆源粗颗粒碎屑沉积和海洋自生元素供应对BH1302孔沉积物的地球化学组成具有重要作用,但不同时期影响作用有所差异,陆源细颗粒碎屑沉积占主导地位,但短时期内陆源粗颗粒碎屑沉积或海洋自生元素供应也可能成为主导因素。

Element geochemical information is important for stratigraphic division and provenance analysis.The characteristics of major and trace elements in the sediments of core BH1302 in Laizhou Bay are analyzed,whose concentrations change obviously at the stratigraphic boundary and can be used as an important index for the classification of late Quaternary strata.Combined with the lithologic facies,grain size and dates of core BH1302,the sediments in the study area since the late Quaternary can be divided into four phases,which corresponding to late Middle Pleistocene,MIS 5,MIS 4—3 and MIS 1,respectively.In vertical,the changes of major and trace elements of the core are characterized by a symbiotic relationship.Except for Na_(2)O、Ba and Sr,most of the major and trace elements are strongly correlated with the mean particle size in the vertical distribution.R-type factor analysis revealed that the supply of terrigenous fine and coarse particulate and marine authigenic elements had important effects on the geochemical composition,but the effects are different in different periods.Terrigenous fine particulate supply is the dominant factor,but terrigenous coarse particulate supply or marine authigenic elements supply may also be the dominant factor in a short period.