Penecontemporary Dolomite in the Persian Gulf&lt;xref ref-type="fn" rid="ch06fn1"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/xref&gt;

Illing, L. V.; Wells, A. J.; Taylor, John

doi:10.2110/pec.65.07.0089

Cited by 137 publications

(91 citation statements)

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“…These are intertidal algal mats which develop in the protection of barrier islands in the large lagoon, Khor a1 Bazam. Similar algal mats are known from other Trucial Coast lagoons and from around Qatar (Illing, Wells and Taylor 1965). If this analogy is correct, the gently folded stromatolites of the Carboniferous can be interpreted as indicative of intertidal conditions on a protected shoreline.…”

Section: B Carbonate Rocksmentioning

confidence: 70%

The Carboniferous Limestone of Chipping Sodbury and Wick, Gloucestershire

Murray

Wright

1971

Geological Journal

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Section: B Carbonate Rocksmentioning

confidence: 70%

The Carboniferous Limestone of Chipping Sodbury and Wick, Gloucestershire

Murray

Wright

1971

Geological Journal

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“…Sampling sites were selected based on previous studies confirming the presence of many forms of precipitates and predicting potential dolomite formation (Illing et al, 1965;Brauchli et al, 2016).…”

Section: Description Of the Sampling Sitementioning

confidence: 99%

“…Dohat Faishakh, a hypersaline coastal sabkha in Qatar, has received much attention since the 1960s as a rare modern geological environment where dolomite formation occurs (Illing et al, 1965). The most recent work in Dohat Faishakh, confirmed the importance of living and non-living microbial mats in the formation of authigenic dolomite (Brauchli et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Evidence of a Role for Aerobic Bacteria in High Magnesium Carbonate Formation in the Evaporitic Environment of Dohat Faishakh Sabkha in Qatar

Disi

Jaoua

Bontognali

et al. 2017

Front. Environ. Sci.

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Dolomite (MgCa(CO 3 ) 2 ) is an important petroleum reservoir rock mineral common in ancient sedimentary rocks which is infrequently found in modern environments. The mechanism of dolomite formation remains poorly understood, although recent research has focused on the contribution of microbial processes. Sabkha is the Arabic term for saline mudflats occurring in regions characterized by extreme environmental conditions (high temperature, salinity, light intensity, and aridity), where diverse halophilic and extremophilic microorganisms are found. The dynamic evaporitic systems characteristic of sabkhas are crucial for the precipitation of minerals and a role for microorganisms in sabkhas in the process of mineralization has been proposed. In this study the Dohat Faishakh Sabkha in Qatar was investigated for evidence of the role for aerobic bacteria in mediating the formation of high magnesium carbonates and dolomite, two minerals that commonly occur in the sabkha sediments. Twenty-nine strains of aerobic microbes were obtained through inoculation on agar plates from two different cores sampled from the sabkha and identified by 16S rRNA gene sequencing as belonging to the genera Bacillus, Salinivibrio, Staphylococcus and, primarily, Virgibacillus. All strains examined caused the pH of an artificial growth medium to increase from 7 to 8.5; however, not all were capable of mediating mineral formation. Only Salinivibrio and Virgibacillus spp. isolates mediated the formation of detectable solid phases within the agar plates. Light microscopy, scanning electron microscopy energy dispersive X-ray (SEM/EDX), and X-ray diffraction (XRD) analyses indicate that the solid phase produced in the presence of these bacterial strains is MgCa(CO 3 ) 2 with a MgCO 3 mol% varying from 0 to 40%. The results of these laboratory experiments suggested that, in the Dohat Faishakh Sabkha, aerobic bacteria may contribute in the formation of very high Mg calcite, a mineral that is considered the precursor of ordered dolomite.

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“…1), formed at the distal edge of a mixed carbonate-evaporite system, with a view to giving a better understanding of the biogeochemical interactions and OM composition in such environments. The first reports on Qatar microbial mats were given by Illing et al (1965) and Shinn (1972); however, these early investigations focused only on organic mat descriptions. Recently, Al-Thani et al (2014) presented a more detailed microbiological description of a hypersaline microbial mat from Um Alhool sabkha (just 1 km north of the site discussed here) and concluded that halobacteria and eukaryotes were predominant in all mat layers.…”

Section: Introductionmentioning

confidence: 99%

Biogeochemistry of intertidal microbial mats from Qatar: New insights from organic matter characterisation

Słowakiewicz

Whitaker

Thomas

et al. 2016

Organic Geochemistry

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms AbstractUnderstanding early organic matter alteration and preservation in marine carbonate-evaporite systems could improve understanding of carbon cycling and hydrocarbon source rock prediction in such environments. It is possible that organic-rich microbial mats are important contributors to preserved hydrocarbons, and to explore this we examined changes in lipid composition in such a mat from a mesohaline intertidal lagoon, eastern Qatar. The mat reaches > 5 cm thickness over a carbonate mud substrate, rich in seagrass, gastropods and other small bioclasts. Clear lamination, with distinct downward colour changes from green to pink to brown, reflects different microbial mat communities. The layers contain spheroids of probable dolomite, the precipitation of which was plausibly bacterially-mediated. Lipids [n-alkanes, fatty acids (FAs), hopanoids, isoprenoid hydrocarbons, dialkyl glycerol diethers (DAGEs), and isoprenoid (0 to 4) and branched (Ia to IIIa) GDGTs] reflect the diverse mat-building phototrophic, heterotrophic and chemoorganotrophic microorganisms, as well as some likely allochthonous material (i.e. steroids, n-alkanols, high molecular weight nalkanes). The lipids clearly document the change in microbial community, with phytene being the predominant hydrocarbon in the phototrophic surface layer. Oxygen and pH drop significantly 0.2 cm below the mat surface, coincident with the predominance of Deltaproteobacteria and increased concentrations of archaeal and bacterial glycerol dialkyl glycerol tetraether lipids andC 15 /C 16 and C 16 /C 17 dialkyl glycerol ether lipids in the deeper layers. Archaeol, likely of methanogen origin, is most abundant in the deepest layer. Allochthonous inputs occur throughout the mat, including abundant steroids, especially dinosterol and dinostanol, that are possibly related to periodic algal (dinoflagellate) blooms in the Arabian Gulf. Both n-alkanes and n-alkanols appear to be derived from seagrass. Organic matter contents decrease in the deepest mat; this suggests an overall low preservation potential of OM in intertidal mesohaline-hypersaline mats of the Arabian Gulf, which in turn suggests that these are not the major source of hydrocarbons in microbially-dominated carbonateevaporite systems.2

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Penecontemporary Dolomite in the Persian Gulf<xref ref-type="fn" rid="ch06fn1"><sup>1</sup></xref>

Cited by 137 publications

References 0 publications

The Carboniferous Limestone of Chipping Sodbury and Wick, Gloucestershire

The Carboniferous Limestone of Chipping Sodbury and Wick, Gloucestershire

Evidence of a Role for Aerobic Bacteria in High Magnesium Carbonate Formation in the Evaporitic Environment of Dohat Faishakh Sabkha in Qatar

Biogeochemistry of intertidal microbial mats from Qatar: New insights from organic matter characterisation

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