The importance of microbial mats for dolomite formation in the Dohat Faishakh sabkha, Qatar

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• 作者：Marisa Brauchli ; Judith A. McKenzie ; Christian J. Strohmenger…
• 刊名：Carbonates and Evaporites
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：31
• 期：3
• 页码：339-345
• 全文大小：2,690 KB
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geology
  Earth sciences
  Mineral Resources
  Mineralogy
  
• 出版者：Springer Berlin Heidelberg
• ISSN：1878-5212
• 卷排序：31

文摘

The Dohat Faishakh sabkha in Qatar is one of the rare modern environments where it is possible to study the formation of dolomite, a mineral whose origin has been long debated. In previous studies, dolomite formation in this area was considered to be the result of a penecontemporaneous replacement of aragonite, occurring in the presence of Mg-rich evaporated pore-waters. However, a re-investigation of the sabkha revealed that dolomite is not forming exclusively under the evaporitic conditions that characterize the supratidal zone, but also in microbial mats that colonize the lower intertidal zone, indicating that evaporated pore-waters are not a strict requirement for the mineralization process. Moreover, in the supratidal zone, portions of the sediment that are rich in dolomite are also relatively richer in organic material, which derives from partially degraded microbial mats buried in the sediments. Extracellular polymeric substances (EPS) that constitute microbial mats are recognized as an important component for the formation of Mg-rich carbonates. The presence of living and decaying microbial mats comprising EPS, rather than a replacement process, may be the key factor for dolomite formation in the Dohat Faishakh sabkha.KeywordsDolomiteMicrobial matExopolymeric substancesBiomineralEvaporitesSabkha