Kuwaiti dolocrete: petrology, geochemistry and groundwater origin

El-Sayed, Mohamed I.; Fairchild, Ian J.; Spiro, Baruch

doi:10.1016/0037-0738(91)90023-7

Cited by 52 publications

(28 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Spheroidal Dolomite.-Spheroidal dolomites have been reported in ground-water dolocretes and karstified sequences of various geological ages (Gunatilaka 1989;Khalaf 1990;El-Sayed et al 1991;Spötl and Wright 1992;Nielsen et al 1997). Some of these spheroidal dolomites have been Bellanca et al (1992), Cañaveras (1994, and Calvo et al (1995). interpreted as bacterially induced primary precipitates, although in some examples ''dolomitization cannot be entirely ruled out'' (Spötl andWright 1992, p. 1132).…”

Section: Other Alternative Precursorsmentioning

confidence: 94%

Pseudospherulitic fibrous calcite in paleo-groundwater, unconformity-related diagenetic carbonates (Paleocene of the Ager Basin and Miocene of the Madrid Basin, Spain)

Rossi¹,

Cañaveras²

1999

Journal of Sedimentary Research

View full text Add to dashboard Cite

Massive, decimeter-thick intervals formed by mosaics of subspherical calcite crystals displaying an intracrystalline fibrous microfabric have been found in Paleocene and Miocene strata in Spain. The fibrous microfabric is marked by inclusion-defined fibers that radiate from the central parts of the crystals, which can be termed pseudospherulites and not spherulites, because they are single crystals and not polycrystalline aggregates. The horizons of pseudospherulitic calcite appear in meter-scale, laterally persistent levels of crystalline limestones that exhibit complex pseudospar fabrics, they are interbedded with peritidal and/or lacustrine deposits, they grade downward into bedded dolomicrites, and they can be linked to unconformities several meters higher in the section, above intervening unaltered limestones. The pseudospar zones are interpreted as early-diagenetic, paleogroundwater alteration products after dolomicrites.The pseudospherulites are composed of low-Mg calcite with low contents of Fe and Mn, and they have a stable-isotope composition indicative of precipitation from meteoric water. They form xenotopic mosaics in which goethite, palygorskite, and sepiolite may be present as inclusions and in the intercrystalline matrix. Cathodoluminescence microscopy reveals peripheral growth of the pseudospherulites, which results from several phases of precipitation and even of dissolution. The first phase of crystal growth may show rhombic habits and may contain corroded dolomite inclusions, interpreted as an indication of growth at the expense of dolomicrite by a dissolution/precipitation process. The second phase of crystal growth is fibrous sensu stricto, exhibits lobate growth laminae, and shows indications of displacive growth.The pseudospherulitic fabric is not relict and the pseudospherulites do not represent speleothems, recrystallized Microcodium, or neomorphosed spherulitic carbonate. Instead, they are interpreted as split crystals that grew within dolomicritic host sediments, in part by dissolution-precipitation and in part by displacement. The hypothesis of a dolomicritic host is supported by the geological and diagenetic setting, by the presence of corroded dolomite inclusions within the pseudospherulites, and by the relationship between their growth and the authigenesis of sepiolite, palygorskite, and goethite. The pseudospherulites grew in the shallow subsurface, at or near the water table, from predominantly oxidizing meteoric water, and under periodically fluctuating geochemical conditions (saturation, redox) caused by fluctuations of the water table during periods of subaerial exposure. The presence of fossil bacteria within the pseudospherulites, the anastomosing pattern of the inclusion-defined fibers, and the lobate growth forms of the fibrous calcite suggest some bacterial influence in the genesis of the pseudospherulitic fabric.

show abstract

Section: Other Alternative Precursorsmentioning

confidence: 94%

Pseudospherulitic fibrous calcite in paleo-groundwater, unconformity-related diagenetic carbonates (Paleocene of the Ager Basin and Miocene of the Madrid Basin, Spain)

Rossi¹,

Cañaveras²

1999

Journal of Sedimentary Research

View full text Add to dashboard Cite

show abstract

“…Phreatic carbonate typically precipitates within the most porous and permeable facies, consists of intergranular spar, and is not intimately associated with pedogenic features or horizons (e.g., Tandon and Narayan, 1981;Machette, 1985;El-Sayed et al, 1991;Wright, 1992;Pimental et al, 1996;Mack et al, 2000). The carbonate in the study section is disseminated microsparitic to sparitic dolomite, concentrated in a discrete zone at or near the top of a paleosol profile, and commonly covaries with clay content (Bt horizons).…”

Section: Potential Controls On Clay and Carbonate Enrichmentmentioning

confidence: 98%

Paleoclimatic inferences from paleopedology and magnetism of the Permian Maroon Formation loessite, Colorado, USA

Tramp

Soreghan

Elmore

2004

Geo. Society Am. Bull.

View full text Add to dashboard Cite

“…The lower member of the Dibdibba Formation, consisting of coarse-grained poorly sorted sandstone with carbonate cement and scattered pebbles, is found in the south-western part of the country. The southern part of Kuwait is underlain by the Undifferentiated Fars and Ghar Formation, which consists of interbedded sand and clayey sand, sandstone, and limestone (Hunting Geology & Geophysics, 1981;El-Sayed et al, 1991). Additional information on the geology of Kuwait Figure 2.…”

Section: Climatic and Geological Conditions In Kuwaitmentioning

confidence: 98%