DOI: 10.1016/j.palaeo.2014.10.002
论文题名: Paleoenvironmental implications of uranium concentrations in lacustrine calcareous clastic-evaporite deposits in the western Qaidam Basin
作者: Yang Y. ; Fang X. ; Li M. ; Galy A. ; Koutsodendris A. ; Zhang W.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2015
卷: 417 起始页码: 422
结束页码: 431
语种: 英语
英文关键词: Evaporite
; Lacustrine sediments
; Paleoredox conditions
; Qaidam basin
; Tibetan plateau
; Uranium
英文摘要: Uranium (U) provides especially useful information for reconstructing paleoredox conditions due to its unique geochemical properties and behavior in supergene environments. Its proxy potential under suboxic. -oxic conditions associated with salinization of surface water in closed hydrologic systems, however, has not been adequately explored. This study examined the abundance and distribution of U in a sedimentary sequence of calcareous lacustrine clastics and salt layers from a high quality (938.5. m-long) core drilled in the western Qaidam Basin, NE Tibetan Plateau. This study examined U concentrations in calcareous clastic sediments (including carbonates, acid insoluble fractions, as well as the amounts of iron and manganese oxides/oxyhydroxides) and salt layers. In the calcareous clastic sediments, variations in U concentrations within the acid insoluble fraction follow the fluctuations of reconstructed lake levels based on lithologic investigations, providing a tool for tracing redox conditions in paleolake bottom water. Correlations between the variations in carbonate content with U and Sr concentrations in the carbonate fractions demonstrate that the types and abundance of carbonate minerals control the U distribution in carbonates. In the salt layers, U and Al concentrations correlate closely, implying that both derived mainly from the detrital fraction in the salt layers. However, enrichments of U and Mg are systematically higher in salt minerals formed in more concentrated brine and lower in those formed in less concentrated brine. These results indicate that during the process of carbonate precipitation, carbonate might effectively remove U from lake water. During the subsequent stage of salt mineral precipitation, U behavior is conservative, and U resides for a long period in dissolved forms within the saline water, giving rise to enhanced U enrichment in the more concentrated brines and the associated precipitated salt minerals. Our study suggests, however, that U-related redox proxies should be interpreted with caution in suboxic-oxic environments during the long-term paleolake evolution. © 2014 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69119
Appears in Collections: 过去全球变化的重建
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作者单位: Key Laboratory of Continental Collision and Plateau Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, China; Key Laboratory of Western China's Environmental Systems, Ministry of Education of China and College of Resources and Environment, Lanzhou University, Lanzhou, China; Centre de Recherches Pétrographiques et Géochimiques (CRPG), UMR7358, CNRS, Université de Lorraine, 15 rue Notre Dame des Pauvres, Vandoeuvre les Nancy Cedex, France; Paleoenvironmental Dynamics Group, Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234, Germany
Recommended Citation:
Yang Y.,Fang X.,Li M.,et al. Paleoenvironmental implications of uranium concentrations in lacustrine calcareous clastic-evaporite deposits in the western Qaidam Basin[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2015-01-01,417