Organic Matter Distribution, Water Circulation and Dolomitization Beneath the Abu Dhabi Sabkha (United Arab Emirates)

  1. Bruce Purser,
  2. Maurice Tucker and
  3. Donald Zenger
  1. F. Baltzer1,
  2. F. Kenig2,†,
  3. R. Boichard3,
  4. J.-C. Plaziat1 and
  5. B. H. Purser1

Published Online: 14 APR 2009

DOI: 10.1002/9781444304077.ch23

Dolomites: A Volume in Honour of Dolomieu

Dolomites: A Volume in Honour of Dolomieu

How to Cite

Baltzer, F., Kenig, F., Boichard, R., Plaziat, J.-C. and Purser, B. H. (1994) Organic Matter Distribution, Water Circulation and Dolomitization Beneath the Abu Dhabi Sabkha (United Arab Emirates), in Dolomites: A Volume in Honour of Dolomieu (eds B. Purser, M. Tucker and D. Zenger), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444304077.ch23

Author Information

  1. 1

    URA 723 CNRS, Laboratoire de Pétrologie Sédimentaire et Paléontologie, Bâtiment 504, Université de Paris Sud, 91405 Orsay, France

  2. 2

    IFP; B.P.311, 92506 Rueil Malmaison cédex, France

  3. 3

    TOTAL CFP, CST, Route de Versailles, 78470 St Rémy lès Chevreuse, France

  1. Organic Geochemistry Unit, Delft Technical University, de Vries van Heystplantsoen 2, 2628RZ Delft, the Netherlands

Publication History

  1. Published Online: 14 APR 2009
  2. Published Print: 25 MAY 1994

ISBN Information

Print ISBN: 9780632037872

Online ISBN: 9781444304077

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Keywords:

  • dolomitization and organic matter;
  • organic matter distribution, water circulation and dolomitization beneath Abu Dhabi Sabkha (United Arab Emirates);
  • Ras Ghanada sabkha and lagoon complex;
  • morphosedimentary units and vegetal zonation;
  • stratigraphy of Ras Ghanada sabkha;
  • dolomitization, hydrology and organic matter;
  • modern sediment mineralogy;
  • hydrocirculation patterns – factor in developing model for near-surface formation of dolomite;
  • dolomitization and active circulation of near-surface waters

Summary

At the northeastern extremity of the Abu Dhabi sabkha, less than 1 m below the surface, a lithified lenticular dolomitic body immediately overlies Holocene regressive mangrove deposits. The persistent association of this dolomite lens with the palaeosol appears to have a genetic significance.

Field measurements of salinities, pH and Eh of interstitial waters clearly indicate lateral interstitial input of water from the lagoon. This movement is favoured by the porosity created by the dense network of buried mangrove roots and by the diagenetic evolution of the sediment. There is no indication of a control of the chemistry of the interstitial waters by flood recharge through the sabkha surface. pH and Eh profiles also indicate the influence of organic matter on the circulating fluids. In the lower part of the section, decay of the organic matter in the mangrove palaeosol results in an anoxic environment with slightly acidic conditions, probably responsible for the dissolution of aragonite observed in the palaeosol and overlying white mud. The evaporative processes, especially active in the upper microbial mat and sabkha deposits, favour reoxidation by diffusion of ions, resulting in slightly basic, oxic conditions. Dolomite occurs in the transitional zone between these anoxic and oxic environments.

The carbon isotopic signature of the dolomite-rich layer is less (down to 0‰) than that of aragonite in the same location (3‰). As proposed by McKenzie (1981), a contribution of carbon from the decaying organic matter to the carbonate pool is indicated.