Iron‐rich rhythmically laminated sediments in Lake of the Clouds, northeastern Minnesota1
Iron‐rich rhythmically laminated sediments in Lake of the Clouds, northeastern Minnesota1
复制标题
明尼苏达州东北部云湖富含铁的有节奏的层状沉积物1
DOI：
10.4319/lo.1977.22.1.0045
复制
发表时间：
1977
影响因子：
4.5
通讯作者：
R. Anthony
中科院分区：
文献类型：
--
作者：
R. Anthony
来自云之湖最深处（31米）的沉积物在整个柱体的底部都有节奏地分层。纹层可以与湖泊中的事件在年周期。二价铁（最大值620 ppm）积聚在湖最深处约2 m厚的水层中。只有在沉积物中被这些富含铁的死水覆盖的地方，才能形成层状结构。偶联的浅色部分可能是由秋季和春季翻转期间部分氧化的底层水沉淀的氧化铁形成的，深色层来自夏季沉淀的有机残留物。化学分析和电子探针研究表明，在亮层中铁和锰的浓度比在暗层中高得多。Vivianite [Fe：！（POa）z * 8H，O]和褐铁矿（FcaOs * nHzO）可能广泛存在于整个岩芯的结核中。用X射线衍射法鉴定了菱铁矿（FeCG）。在光层中出现大量的橙子球状聚集体。沉积柱的铁和锰剖面表明，在沉积物的铁含量至少为4%的地方发现了最明显的纹层。
Sediments from the deepest part of Lake of the Clouds (31 m) are rhythmically laminated throughout all but the basal part of the column. The laminations can be correlated with events in the lake cluring the annual cycle. Ferrous iron (maximum 620 ppm ) accumulates in a layer of water about 2 m thick in the deepest part of the lake. The laminations form in the sediments only where overlain by this stagnant iron-rich water. The lightcolored portion of the couplet presumably forms from iron oxides precipitated from partially oxygenated bottom water during fall and spring overturns, the dark layer from organic remains that settle out during summer. Chemical analysis and electron-microprobe studies reveal a much higher concentration of iron and manganese in the light layers than in the dark. Vivianite [Fe:!( POa)z * 8H,O] and probably limonite ( FcaOs * nHzO) occur extensively in nodules throughout the core. Siderite (FeCG) was identified by X-ray diffraction. Numerous orange spherical aggregates occur in the light layers. An iron and manganese profile of the sediment column suggests that the most distinct laminae are found where the iron content of the sediment is at least 4%.