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首页> 外文期刊>Limnology >Spatial uniformity in the mineralogical and geochemical compositions of surface sediments in Lake Qinghai and their controlling factors
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Spatial uniformity in the mineralogical and geochemical compositions of surface sediments in Lake Qinghai and their controlling factors

机译：青海湖表层沉积物矿物地球化学组成的空间均匀性及其影响因素。

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摘要

To advance the understanding of the spatial variability of sediment composition and its controlling factors in a large hydrologically closed lake, the spatial distributions in the mineralogy and geochemistry of 18 surface sediment samples along three transects across the deepest part of Lake Qinghai on the northeastern Tibetan Plateau were investigated. The data show (1) that the surface lake sediments are almost the same in the XRD patterns, (2) that the sediments do not have considerable changes in geochemical compositions along three transects and (3) that the standard deviations of the lake sediments are low in grain size, elemental abundances, delta C-13 and delta O-18 values of carbonates, and total organic carbon and nitrogen, with the exception of one sample (QH-11) from the westernmost part of the northern sub-basin. These characteristics indicate that the spatial variability of the surface sediment across Lake Qinghai is very low in geochemical and silicate mineralogical compositions, with limited differences in the chemical composition of carbonates associated with river water dilution. Sample QH-11 has anomalously high levels of MgO, a high carbonate content, and positive delta C-13 and delta O-18 values in bulk and fine-grained carbonates, probably because of the effect of calcareous tufa. Spatial uniformity in the mineralogical and geochemical compositions of surface sediments in Lake Qinghai can be attributed to the flat topography of the lakebed and stable sediment provenances, the latter dominated by dust deposition and authigenic carbonates. The spatial uniformity and dominance of dust and authigenic aragonite of surface sediments across Lake Qinghai provide a potential record of the hydroclimate in the past, which is associated with changes in the Westerlies and the summer monsoons.
机译：为了进一步了解大型水文封闭湖泊沉积物组成的空间变异性及其控制因素，青藏高原东北部青海湖最深处三个样带的18个地表沉积物样品的矿物学和地球化学空间分布被调查了。数据显示（1）XRD图案中的表层湖泊沉积物几乎相同;（2）沿三个样点的沉积物的地球化学组成没有明显变化;（3）湖泊沉积物的标准偏差为除北部子盆地最西端的一个样品（QH-11）以外，其晶粒尺寸，元素丰度，碳酸盐的δC-13和δO-18值以及总有机碳和氮含量低。这些特征表明，青海湖地表沉积物的空间变异性在地球化学和硅酸盐矿物组成上非常低，与河水稀释有关的碳酸盐化学组成差异有限。样品QH-11具有异常高的MgO含量，高的碳酸盐含量，以及散装和细粒碳酸盐中的正Cδ和O-18正值，可能是由于钙质石灰石的影响。青海湖表层沉积物的矿物学和地球化学组成的空间均匀性可以归因于湖床的平坦地形和稳定的沉积物源，后者以粉尘沉积和自生碳酸盐为主。青海湖上表层沉积物的粉尘和自生文石的空间均匀性和优势提供了过去水文气候的潜在记录，这与西风和夏季风的变化有关。

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