多金属结核的沉积物地球化学场

Sediment Geochemical Field of Polymetallic Nodules

远洋沉积物是多金属结核赖以生长的场所，本文系统地研究了沉积物中主要成矿元素水成组分在不同地球化学场和不同沉积阶段的地球化学特征，以及水成组分的含量比与成矿作用的相互关系。研究表明，Ｍｎ、Ｆｅ、Ｃｏ、Ｎｉ、Ｃｕ都是一些比较活泼的元素，它们共处于多金属结核、沉积物和大洋水的统一体系中，当结核形成时，Ｍｎ、Ｆｅ、Ｎｉ、Ｃｕ在结核与沉积物中的含量呈负相关，而Ｃｏ含量呈正相关。研究区东部结核以富含Ｍｎ、Ｎｉ、Ｃｕ贫Ｆｅ、Ｃｏ为特征，其伴生沉积物相对贫Ｍｎ、Ｎｉ、Ｃｕ、Ｃｏ，而富Ｆｅ，可称之为贫化的地球化学场。研究区西部结核富含Ｆｅ、Ｃｏ而贫Ｍｎ、Ｎｉ、Ｃｕ，其伴生沉积物则相应贫Ｆｅ，而富Ｍｎ、Ｎｉ、Ｃｕ、和Ｃｏ，可称之为富化的地球化学场。可以看出，贫化的沉积物地球化学场，恰恰是寻找富矿结核的最佳场所。早中新世以来的沉积物，根据水成组分的含量或含量比，也可相应于结核的形成分为三大沉积阶段，其中的第Ⅱ阶段具有贫化的地球化学特征。

Pelagic sediments are the place where polymetallic nodules grow.The present paper has systematically studied geochemical characteristics of hydrogenic components of main ore-form-ing elements within sediments in different geochemical fields and at different sedimentary stages as well as the relationship between contents of hydrogenic components and mineralizaton. Studies show that Mn,Fe,Co,Ni and Cu are some fairly active elements existent together in an unified system of polymetallic nodules,sediments and ocean water. When nodules are formed,Mn Fe,Ni and Cu contents in nodules are in negative correlation with their contents in sediments,whereas things are just the opposite for Co content.Nodules in the eastem part of the study area are characterized by rich Mn, Ni, Cu and poor Fe, Co, while sediments asso-ciated with these nodules are relatiyely deficient in Mn,Ni,Cu, Co but rich in Fe, and canthus be called an impoverished geochemical field.Nodules in the western part of the study area are rich in Fe,Co but deficient in Mn,Ni, Cu,whereas their saaociated sediments are corre-spondingly poor in Fe but rich in Mn,Ni,Cu,Co,and can hence be called an enriched geo-chemical field.It is thus known that the impoverished sediment geochemical field is just the best place in search for rich ore nodules.Corresponding to the formation of nodules,the sedi-ments since Early Miocene,in accordance with contents of content ratios of hydrogenic compo-nents,can be divided into three major sedimentary stages.of which No.Ⅱstage shows geo-chemical characteristics of impoverishment,and is the most favorable period for the formation of polymentallic nodules.