Chemical composition of bottom sediments from the northern part of the Deryugin Trough, Sea of Okhotsk

Distribution trace element contents in the upper (up to 5 m) Holocene-Upper Pleistocene sediment layer along the northern and southern sublatitudinal profiles in the northern part of the Deryugin Trough is discussed. Mathematical processing of chemical analysis data has been made. On the basis of the cluster analysis 16 elements have been combined into 5 geochemical groups. Two of them (1 - Ag-Mo group and 2 - Mn-Ba-Ni-Sr group) were considered in detail. Analysis of Ag and Mo distributions in the sediments and findings of molybdenite permitted to conclude that enrichment of the sediments by these elements resulted from edaphic washing of magmatic rocks containing Ag-Mo mineralization and probably located on the northwestern slope of the Deryugin trough. The second geochemical group is most likely connected with hydrothermal barite mineralization found in the northeastern part of the Deryugin trough. Considering Mn distribution in bottom sediment cores supply of Mn was pulsating. This allows concluding that during Holocene - Late Pleistocene three cycles of hydrothermal activity occurred in the Deryugin Trough, and the most intensive one was in Holocene.

本文探讨了德留金海槽（Deryugin Trough）北部区域沿南北亚纬度剖面的全新世-上更新统上部（深度可达5米）沉积层内的微量元素含量分布特征。研究已完成化学分析数据的数学处理工作，基于聚类分析将16种元素划分为5个地球化学组，并对其中两组（第1组为Ag-Mo组，第2组为Mn-Ba-Ni-Sr组）进行了详细解析。通过分析沉积物中Ag与Mo的分布特征，结合辉钼矿的发现结果，可得出结论：沉积物中该两类元素的富集源于含Ag-Mo矿化的岩浆岩的地表淋滤作用，此类岩浆岩大概率分布于德留金海槽西北坡。第二地球化学组大概率与德留金海槽东北部发现的热液重晶石矿化存在关联。通过分析海底沉积岩芯中的锰元素分布特征，可知锰的补给具有脉动性，据此可推断在全新世-晚更新世时期，德留金海槽共发生三期热液活动，其中以全新世的热液活动强度最高。