太平洋CC区西部沉积物地球化学特征及其成因

对太平洋CC区西部7根沉积物短柱样的常微量元素进行浓度测试,以了解沉积物元素时空分布特征及其来源和控制因素.与上地壳元素平均值(UCC)相比,研究区沉积物中MnO、P2O5、Co、Ni、Cu、Mo、Ba明显富集,Al2O3、K2O、Fe2O3、CaO、Sr等亏损.聚类和因子分析表明研究区沉积物元素有4种来源,其中Al2...

Geochemical Characteristics and Genetic Mechanisms of Sediments from Western Clarion-Clipperton Zone,Pacific Ocean

The major and trace elements of sediments in seven short cores collected from the western Clarion-Clipperton Zone in the Pacific Ocean were measured， with an attempt to understand their spatial and temporal distributions and genetic mechanism. Compared to the Upper Continental Crust （UCC）， the sediments in the study area are significantly enriched in MnO， P₂O₅， Co， Ni， Cu and Mo. They are depleted in Al₂O₃， K₂O， Fe₂O₃， CaO and Sr. Cluster and factor analysis show that the elements of the sediments are derived from four sources: 1） Al₂O₃， Fe₂O₃， K₂O， MgO， TiO₂， V， Cr， Co， Rb， Zr， Nb， Cs， Hf， Ta， Pb， Th and U from terrestrial clay； 2） CaO and Sr from calcareous biogenous sediments； 3） MnO， P₂O₅， B， Ni， Cu， Zn， Mo， Ba are hydrogenous； and 4） Na₂O is of volcanic-hydrothermal origin. Sediments sampled to the north of latitude 10.2° N were terrigenous， hydrogenous and calcareous biogenous； sediments to the south were terrigenous， hydrogenous and volcano-hydrothermal genesis. The terrestrial material mainly comes from aeolian material carried by upper air currents from Asia. Hydrogenous enrichment of metal elements in the sediments is related to oxygen-rich Antarctic Bottom Water （AABW）. The spatial and temporal variation of biogenous CaO and Sr is related to the ocean depths of the cores， and the changes of carbonate compensation depth （CCD） responding to falling sea levels and productivity change during the glacial period. The volcanic-hydrothermal activity indicated by the Ba/Ti ratio in the cores weakened over geological time， and its impact on the sediments also weakened northward.