个旧锰结核矿床地质地球化学与成因初步研究

PRELIMINARY DISCUSSION OF GEOLOGY-GEOCHEMISTRY AND GENESIS OF GEJIU MANGANESE NODULE DEPOSIT

个旧锰结核矿床产在锡石-多金属硫化物矿田顶部的第四系砂锡矿之中。从矿床地质产状、化学组成、微量元素、稀土元素、矿物组合等方面进行了讨论,认为个旧锰结核属于异地海相成因,后经搬运沉积在第四系砂锡矿之中;与中太平洋海山CAD19锰结核的物质组成和微量元素进行对比,表明个旧和CAD19锰结核有相类似的稀土模式,相对富集轻稀土,并出现明显的Eu负异常和Ce的正异常。

The Gejiu manganese nodule deposit in the Quaternary system placer is situated at the top of the cassiteritepolymetaUic sulfide orefield. This paper further deals with the Gejiu manganese nodules in the following six aspects： （ 1 ） Geological occurrence; （2） chemical composition; （3） trace elements; （4） REE; （5） mineral association; and （6） conclusions. The Gejiu manganese nodules are of marine origin in a strange land, and they were transported and later deposited in the Quaternary system placer. At the same time, systematic studies were conducted on material composition and trace elements of manganese nodules （CAD19）. The relevant data from the Central Pacific Seamount are alsop resented. REE studies indicated that the REE patterns are similar for Gejiu and CAD19 manganese nodules. The REE patterns of manganese nodules are characterized by relative HREE enrichment and remarkable negative Eu and positive Ce anomalies.