Spatial uniformity in the mineralogical and geochemical compositions of surface sediments in Lake Qinghai and their controlling factors
- 279 Downloads
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, δ13C and δ18O 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 δ13C and δ18O 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.
KeywordsSpatial distribution Lake Qinghai surface sediment Mineralogical and geochemical compositions Sediment provenance Qinghai-Tibetan Plateau
This work was financially supported by the National Natural Science Foundation of China (no. 41225015), the National Post-Doctoral Foundation Grant of China (no. 2013M532087), and the State Key Laboratory of Loess and Quaternary Geology (no. SKLLQG1233). We especially thank Weiguo Liu, Xiangzhong Li and Jun Xiao of the Institute of the Earth Environment, CAS, for their helpful comments and suggestions that improved the manuscript. Two anonymous reviewers are thanked for their critical comments that improved the manuscript.
- An ZS, Colman SM, Zhou WJ, Li XQ, Brown ET, Jull AJT, Cai YJ, Huang YS, Lu XF, Chang H, Song YG, Sun YB, Xu H, Liu WG, Jin ZD, Liu XD, Cheng P, Liu Y, Ai L, Li XZ, Liu XJ, Yan LB, Shi ZG, Wang XL, Wu F, Qiang XK, Dong JB, Lu FY, Xu XW (2012) Interplay between the Westerlies and Asian monsoon recorded in Lake Qinghai sediments since 32 ka. Sci Rep 2:619. doi: 10.1038/srep00619 PubMedCentralPubMedGoogle Scholar
- Jin ZD (2010) The inorganic carbon budget of Lake Qinghai. Quat Sci 30(6):1162–1168Google Scholar
- Jin ZD, Zhang F, Li FC, Chen LM, Xiao J, He MY (2013) Seasonal and interannual variations of the lake water parameters and particle flux in Lake Qinghai: a time-series sediment trap study (in Chinese with English abstract). J Earth Environ 4:1306–1313Google Scholar
- LIGCAS (Lanzhou Institute of Geology of Chinese Academy of Sciences) (1979) A synthetically investigation report on Qinghai Lake (in Chinese). Science Press, BeijingGoogle Scholar
- LZCAS (Lanzhou Branch of Chinese Academy of Sciences), WCRECAS (West Center of Resource and Environment, Chinese Academy of Sciences) (1994) Evolution of recent environments in Qinghai Lake and its prediction (in Chinese). Science Press, BeijingGoogle Scholar
- Opitz S, Wünnemann B, Aichner B, Dietze E, Hartmann K, Herzschuh U, IJmker J, Lehmkuhl F, Li SJ, Mischke S, Plotzki A, Stauch G, Diekmann B (2012) Late Glacial and Holocene development of Lake Donggi Cona, north-eastern Tibetan Plateau, inferred from sedimentological analysis. Palaeogeogr Palaeoclim Palaeoecol 337–338:159–176CrossRefGoogle Scholar
- Taylor SR, McLennan SM (1985) The continental crust: its composition and evolution. Blackwell, LondonGoogle Scholar
- Yu JQ, Zhang L (2008) Lake Qinghai: Paleoenvironment and Paleoclimate. Science Press, BeijingGoogle Scholar
- Zhang Q, Zhang BZ (1994) The C and O isotopic compositions of ostracod shell in shallow-seated sediments and sinters in bottom of Qinghai Lake and their palaeoclimatic implications (in Chinese with English abstract). Geochemica 23:386–391Google Scholar