Petrography, diagenesis and isotope geochemistry of dolostones and dolocretes in the Eocene Dammam Formation, Kuwait, Arabian Gulf

Khalaf, Fikry I.; Abdullah, Fowzia A.; Gharib, I.M.

doi:10.1007/s13146-016-0330-5

Cited by 12 publications

(40 citation statements)

References 61 publications

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“…The middle Eocene dolostone of the Kachchh Basin, western India, is an example of the Cenozoic dolostone. It is also found that dolomites are commonly well ordered and stoichiometric with respect to MgCO 3 and CaCO 3 in Palaeozoic or older rocks, whereas less ordered and calcian in composition in Cenozoic carbonates (e.g., Jones & Luth, ; F. I. Khalaf et al, ; Rao, Kessarkar, Krumbein, Krajewski, & Schneider, ; Sanz‐Montero, Rodriguez Aranda, & Garcia Del Cura, ; Suzuki et al, ; Wanas & Sallam, ; Wheeler et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…Although dolostone occurs in rocks of all ages, it appears to have formed in association with Cenozoic seawater in only a few localities (e.g., Budd, ; Jones & Luth, ; F. I. Khalaf et al, ; Suzuki et al, ; Vahrenkamp, Swart, Purser, Tucker, & Zenger, ; Wheeler, Aharon, & Ferrell, ). The middle Eocene dolostone of the Kachchh Basin, western India, is an example of the Cenozoic dolostone.…”

Section: Discussionmentioning

confidence: 99%

“…A negative correlation of Sr with SiO 2 ( r 2 = −0.58) suggests that the Sr was also supplied from the seawater contrary to silica. In case of penecontemporaneous and shallow‐burial dolomitization, seawater is recorded as the major source of Mg (e.g., F. I. Khalaf et al, ; Land, ; Lee & Friedman, ; Sena et al, ; Shaaban, Holail, & Rashed, ; Warren, ). Thus, it is suggested that the MgO and Sr were supplied from seawater, while the rest of the oxides were supplied in suspension and dissolved states from the meteoric water.…”

Section: Discussionmentioning

confidence: 99%

“…Dolostones account for about 50% of all carbonate rocks and can hold significant volumes of oil and natural gas (Braithwaite, Rizzi, & Darke, ). They are formed in a variety of distinctly different settings, for example, lacustrine (Wanas, ; Wanas & Sallam, ), supratidal to intertidal zones in evaporitic conditions (Machel, ), sub‐tidal or lagoonal, and near‐shore shallow marine, and at different stages of diagenesis, such as during early diagenesis, in a meteoric‐marine mixing zone, to burial diagenesis in the deeper offshore regions, because of the release of dolomitizing fluid from the associated mudrocks (Anan & Wanas, ; F. I. Khalaf, Abdullah, & Gharib, ; Machel, ; Ren & Jones, ) and/or due to microbial activities (Bontognali et al, ; Vasconcelos, McKenzie, Bernasconi, Grujic, & Tien, ; Warren, ).…”

Section: Introductionmentioning

confidence: 99%

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Sedimentological and geochemical characteristics of the late middle Eocene dolostone succession, Kachchh, western India

2018

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Dolostones form by many processes, and their origins are enigmatic. The present study focuses on the origin of the newly recorded 16.5‐m‐thick late middle Eocene dolostone succession of the Kachchh Basin, western India. To achieve this target, a comprehensive field, petrographic, scanning electron microscopy and geochemical studies have been carried out. This dolostone succession shows a sharp contact with the underlying middle Eocene Fulra Limestone Formation. The petrographic study shows a dominance of unimodal, planar‐euhedral idiotopic mosaics of dolomite rhombs along with replacement texture. The X‐ray diffraction pattern confirms it as non‐stoichiometric type dolomite (average molar% MgCO3 = 47.19). SEM‐EDS study deciphers perfectly developed zoned planar‐e dolomite rhombs (40–100 μm) with minor variation in the concentrations of elemental Mg (47.67% to 43.33%) and Ca (52.33% to 56.67%). Among the major oxides, CaO and MgO are the dominant components, indicating that the major mineral phase is dolomite. The positive correlation of CaO with SiO2, Al2O3, and Fe2O3 and a negative correlation of MgO and ∑REE with them suggest that the CaO was mainly contributed from the rivers, while the MgO was contributed from the lagoonal brine/seawater. The low concentration of Sr (144–234 ppm) in the studied dolostone is compatible with the marginal marine mixing origin. The ∑REE content in the dolostones is comparatively lower (18.22 ppm) than the average value of typical marine carbonates (28 ppm), thus suggesting meteoric mixing conditions. The superchondritic Y/Ho values (35.21–100) and Post‐Archaean Australian Shale‐normalized REY patterns of the dolostone facies exhibit typical shallow (bathymetry <50 m) seawater‐like patterns. A strong positive correlation between ΣREE and Y, and low Er/Nd ratios (~0.1) in the dolostone facies indicate incorporation of minor terrigenous influx during dolomitization in a meteoric‐marine mixing condition. The authigenic uranium (0.4–1.7) and slightly negative Ce anomaly suggest that the dolostone succession was precipitated in oxic to dysoxic conditions. The prevalence of planar (euhedral and subhedral) dolomite texture indicates that the dolomitization occurred in a shallow marine environment under low salinity and temperature conditions. Thus, the absence of evaporitic association and physical compaction or deep burial features and the presence of large channelized vugs, mouldic pores along with partially replaced shallow marine fossils, anhydrite cement, and marginal‐marine values of Sr, Na, Ba, Mn, and Fe support the meteoric‐marine mixing model of dolomitization under shallow marine condition of this dolostone succession.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sedimentological and geochemical characteristics of the late middle Eocene dolostone succession, Kachchh, western India

2018

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“…Petersen et al, 1963;Von der Borch, 1976;Garcia del Cura et al, 2001), saline-evaporitic (e.g. Outgassing of CO 2 at groundwater discharge zones, as well as mixing of fresh and saline groundwaters around saline lakes (El-Sayed et al, 1991;Colson and Cojan, 1996;Khalaf et al, 2018), may result in increased alkalinity and therefore CO 3 2activity relative to HCO 3 -, promoting dolomite precipitation (Eugster, 1980;Morrow, 1982). Models of dolocrete formation demonstrate the importance of hydrochemical modification along the flow path, primarily from evaporative concentration and the precipitation of calcite upgradient, increasing salinity of groundwater and the Mg/Ca ratio (Eugster, 1980).…”

Section: Introductionmentioning

confidence: 99%

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi‐arid Hamersley Basin, northwest Australia

Mather

Nash

Dogramaci

et al. 2019

Earth Surf Processes Landf

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Groundwater dolocretes may exert an important geomorphic control on landscape evolution within sub‐humid to arid regions. However, the geomorphic and hydrogeological settings of dolocrete remain poorly described. The hydrochemical conditions of dolomite precipitation in groundwater environments are also not well known. Classic models of dolocrete formation explain dolomite precipitation from highly evolved groundwaters at the terminus of major drainage but do not explain dolocrete distributed in regionally elevated landscapes, upgradient of major drainage. This study investigated the mineralogy, micromorphology and stable carbon and oxygen isotope compositions of three dolocrete profiles within a regionally elevated sub‐basin of the Hamersley Ranges in the Pilbara region of northwest Australia. We sought to establish the environmental and hydrochemical conditions and present a model for dolocrete formation. We found that dolocrete formed within zones of emerging groundwater under saline‐evaporitic conditions within internally draining sub‐basins, most likely during the Late Miocene and Pliocene. Saline‐evaporitic conditions were indicated by: (i) the mineralogy, dominated by dolomite, palygorskite and smectite; (ii) desiccation features and the presence of phreatic and vadose cements, indicative of a shallow fluctuating water table, and; (iii) dolomite δ18O values (median = –5.88 ‰). Dolomite precipitation was promoted by evaporation and carbon dioxide degassing from shallow magnesium (Mg)‐rich groundwater. These factors appear to have been the major drivers of dolocrete development without a requirement for significant down‐dip hydrochemical modification. Primary dolomite precipitation was possible due to the presence of microbial extracellular polymeric substances (EPS). EPS provided negatively charged nucleation sites, which bound Mg2+, overcoming kinetic effects. High microbial activity within groundwater systems suggest these processes may be important for dolocrete formation worldwide and that groundwater dolocretes may be more pervasive in landscapes than currently recognized. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

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Surface Geology of Kuwait

Alrefaei

Najem²,

Amer³

et al. 2022

The Geology of Kuwait

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This chapter represents a comprehensive review of Kuwait’s surface geology and stratigraphy from previous works accomplished by numerous geoscience researchers in the past decades. The surface of Kuwait is characterized by nearly flat topography, featureless to gently undulating, apart from a few tens of meters of escarpments in the north and south, and flat low to moderately elevated hills and ridges. It predominantly consists of siliciclastic sediments and sedimentary rock units ranging in age from Middle Eocene to Holocene. The main stratigraphic exposed successions are located in Jal Az-Zor escarpment, Al-Subyiah (Bahrah) area, Ahmadi Quarry, the Khiran Ridges, and the Enjefa Beach. The oldest exposed rock units are represented by the Middle Eocene Dammam Formation, which is exposed at the Ahmadi Quarry, whereas the youngest recent deposits cover most of Kuwait’s surficial area and lie on top of the Kuwait Group’s deposits. This chapter will illustrate the geology and stratigraphy of Kuwait's surface sediments and sedimentary rock strata. Recommendations and future insights were also documented as part of the way forward to improve the presently available work for the surface geology of Kuwait.

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Petrography, diagenesis and isotope geochemistry of dolostones and dolocretes in the Eocene Dammam Formation, Kuwait, Arabian Gulf

Cited by 12 publications

References 61 publications

Sedimentological and geochemical characteristics of the late middle Eocene dolostone succession, Kachchh, western India

Sedimentological and geochemical characteristics of the late middle Eocene dolostone succession, Kachchh, western India

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi‐arid Hamersley Basin, northwest Australia

Surface Geology of Kuwait

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