(Table I, page 1348) Composition of ferromanganese oxide concretions from lake Ontario (Extract)

A large deposit of ferromanganese oxide concretions has been found in the northern portion of Lake Ontario. The concretions occur mainly in the form of coatings on sand grains but manganese nodules are present at several localities. Mineralogically, the ferromanganese oxide phases are amorphous, and their Fe and Mn contents are similar to those in concretions from other environments. However, their Ni, Co, and Cu contents are significantly higher than those reported in previously described North American lacustrine ferromanganese concretions, and this may, in part, be a reflection of their probable low rates of accumulation.

本次研究在安大略湖北部湖区发现了一处大规模的铁锰氧化物结核（ferromanganese oxide concretions）沉积体。该类结核主要以砂粒表面包壳的形式产出，但在多处采样点均可见锰结核分布。从矿物学角度而言，该类铁锰氧化物物相呈非晶质状态，其铁、锰元素含量与其他环境产出的结核体基本一致。然而，其镍（Ni）、钴（Co）及铜（Cu）含量显著高于已有文献记载的北美湖相铁锰结核，这在一定程度上或可反映其较低的沉积速率。