Sediment properties, contents and accumulation rates of Hg in cores of Upper Quaternary sediments from the Deryugin Basin, Okhotsk Sea

The Hg distribution and some mineralogical-geochemical features of bottom sediments up to a depth of 10 m in the Deryugin Basin showed that the high and anomalous Hg contents in the Holocene deposits are confined to a spreading riftogenic structure and separate fluid vents within it. The accumulations of Hg in the the sediments were caused by its fluxes from gas and low-temperature hydrothermal vents under favorable oceanological conditions in the Holocene. The two mainly responsible for the high and anomalous Hg contents are infiltration (fluxes of hydrothermal or gas fluids from the sedimentary cover) and plume (Hg precipitation from water plumes with certain hydrochemical conditions forming above endogenous sources). The infiltration anomalies of Hg were revealed in the following environments: (1) near gas vents on the northeastern Sakhalin slope, where high Hg contents are associated only with Se and were caused by the accumulation of gases ascending from beneath the gas hydrate layer; (2) in the area of inferred occasionally operating low-temperature hydrothermal seeps in the central part of the Deryugin Basin, in which massive barite chimneys, hydrothermal Fe-Mn crusts, and anomalous contents of Mn, Ba, Zn, and Ni in sediments develop.

对德尔尤金盆地（Deryugin Basin）10米以浅的底沉积物开展的汞（Hg）分布及部分矿物学-地球化学特征研究表明，全新世沉积物中偏高且异常的汞含量，均局限于扩张裂谷构造及其内部的独立流体喷口。沉积物中汞的富集，源于全新世时期有利海洋学条件下，气体与低温热液喷口输入的汞通量。造成汞含量偏高与异常的两大主要作用机制为渗滤作用与羽流作用：前者指来自沉积盖层的热液或气体流体通量，后者指在内源源上方形成的特定水化学条件下，汞从水羽流中沉淀析出。两类渗滤型汞异常分别发现于以下环境：（1）萨哈林东北斜坡的气体喷口附近，该区域的高汞含量仅与硒（Se）伴生，其成因是天然气水合物层下方上升的气体发生富集；（2）德尔尤金盆地中部被推断存在间歇性活动的低温热液渗流区，该区域发育有块状重晶石烟囱、热液铁锰结壳，以及沉积物中锰（Mn）、钡（Ba）、锌（Zn）、镍（Ni）的异常含量。