【摘要】 <正> 湖泊沉积物中的铁锰结核,目前报导的还很少,对其了解也很不够。1979年笔者在罗加湖工作时首先发现了湖底沉积物中有铁锰结核,并开始对它的物理性质,化学成分进行观察测定。现将罗加湖铁锰结核的一些情况介绍如下。更多还原

【Abstract】 Being situated in eastern part of Southwest Plateau, Luojia Lake is the second deepest lake formed by graben in China. It covers 211 km² in area, and the meximum depth resches 155m with 89m as its mean. The altitude of the lake surface is 1721m above sea level .Gravity-sampling driller was used as an instrument to collect samples in 1979, and we found lots of Fe-Mn-nodules in the south of the lake, near east of Isolate-island with an area of 3 - 4 km² and the depth of 60-70m.The grain of the nodule is gray-black or black beanshaped, less rou nded,smooth on the surface and with luster of glass. The grain is generally 0.3 × 0.25 × 0.2 cm is size, the maximum is 1.1 × 1.9 × 0.5 cm and the minimum is abont 0.1 cm. With less hardness each nodule can be broken with finger-nail. The nodule becomes harder after being dried. The type of fracture of the lusterless nodule is uneven and shows brown-yellow colour. We have found that it is a small spherical aggregate without condensation under electromicroscope and the nodules are arranged like grapes.The layer of Fe-Mn-nodule is buried 15-20 cm beneath the bottom of the lake and mixed with brown clay.The chemical analysis of the nodule by the methods of differential thermal and energy spectrum and plasma emmission spectroscopy give: Fe₂O₃, 68.5%, and MnO, only 0.62%. In fact, the content of nodule is dominantly iron so the nodule can be called Fe-nodule. The content of trace element such as Cr, Co, Ni, and Cu are less than the average abundance of the earth. The contents of Zn, V and Mo are lower several times than those of the earth. They are greatly lower than the Mn-nodule contents of sea bottom.Studying the formation mechanism of the nodule and its process we have separated and measured the soluble part of iron and insoluable part of nodule by the method of mixed solution of hydroxylamine hydrochloide （ NH2 OH·HCl）with ethanoic acid, and got the constituents. The result shows that the detrital group （ insoluble ） makes 99.2%, and the authigenic group （ soluble ） 0.8% .According to the measurement result we have deduced that the form of Fe-Mn-nodule of the Luojia Lake derives chiefly from the terrigenous granule （ insolule iron ） whieh transforms into nodule during the slow sinking in water. It does not belong to the chemical precipitation.更多还原