Annotated record of the detailed examination of Mn deposits retrieved from lakes Krasnoye (Punnusjarvi) and and Borisovskoye (Borisov), Russia

The study of lake deposits containing iron-manganese nodules is of significant interest for the understanding of one of the continental manganese and iron concentration processes. In the USSR, much attention has been given to the formation conditions of ore accumulations in the Leningrad region and Karelia. Semenovich came to the conclusion that Fe super(+3) and Mn super(+4) entered the lake during a long period of drought and were buried together with organic matter of plant origin. In the lake muds, manganese and iron are reduced; readily soluble compounds of Fe super(+2) and Mn super(+2) are transported by bottom waters. Oxidation of iron and manganese to Fe super(+3) and Mn super(+4) occurs, precipitating oxides on the bottom that form nodules and incrustations. This scheme of lacustrine ore genesis by the accumulation of manganese and iron is well founded.针对含有铁锰结核（iron-manganese nodules）的湖泊沉积物（lake deposits）开展研究，对于认知大陆铁锰富集过程之一具有重要学术价值。在苏联（USSR），学界对列宁格勒地区（Leningrad region）与卡累利阿（Karelia）的矿床富集形成条件给予了广泛关注。谢梅诺维奇（Semenovich）得出结论：三价铁（Fe³+）与四价锰（Mn⁴+）在长期干旱时期汇入湖泊，并与植物源有机质一同被埋藏。湖泥中的铁与锰会发生还原反应，二价铁（Fe²+）与二价锰（Mn²+）的易溶性化合物可通过底层水进行迁移。随后铁与锰被氧化为三价铁与四价锰，其氧化物在湖底沉淀形成结核与结壳。这套通过铁锰富集形成湖相矿床的成因模式，证据充分、立论可靠。