Dedolomites associated with karstification. An example of early dedolomitization in lacustrine sequences from the Tertiary Madrid basin, central Spain

Cañaveras, Juan Carlos; Sánchez‐Moral, Sergio; Calvo, J.P.; Hoyos, M.; Ordóñez, S.

doi:10.1007/bf03175788

Cited by 48 publications

(34 citation statements)

References 52 publications

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“…Processes of karstification are well illustrated in marine carbonates (see for example Esteban and Klappa, 1983), but less known in the case of lacustrine host rocks. Cafiaveras et al (1996) have shown that the results of karst-related processes on terrestrial carbonates are similar to those developed in marine environments. However, the geochemical and textural changes may be different, since the initial chemistry, mineralogy and texture of the rocks were also different.…”

Section: Diagenesismentioning

confidence: 58%

Palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record

Alonso-Zarza¹

2003

Earth-Science Reviews

495

321

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Section: Diagenesismentioning

confidence: 58%

Palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record

Alonso-Zarza¹

2003

Earth-Science Reviews

495

321

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“…Due to the larger molar volume of 2 moles of calcite as compared to 1 mole of dolomite this reaction leads to an increase in solid volume and thereby a decrease in porosity ( Figure 6). Dedolomitization may however also lead to the creation [11,51,52] or the preservation of porosity [6]. A pseudomorphic volume-pervolume replacement is defined by the reaction stoichiometry of 1.74 : 1 which is the ratio between the molar volume of dolomite and calcite.…”

Section: Approachmentioning

confidence: 99%

Dedolomitization Potential of Fluids from Gypsum-to-Anhydrite Conversion: Mass Balance Constraints from the Late Permian Zechstein-2-Carbonates in NW Germany

2018

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The Zechstein-2-Carbonates represent one of the most prolific hydrocarbon systems of Central Europe. Carbonate reservoir quality is primarily controlled by mineralogy, with dolomite representing moderate-to-good porosities and calcite commonly representing low porosities. Current models suggest that this calcite is the result of a basin-wide phase of dedolomitization. The calcium (Ca) source for the dedolomites is thought to be derived from the fluids liberated during gypsum-to-anhydrite conversion. We present an easy-to-use and generally applicable template to estimate the dedolomitization potential of these fluids. Depending on reaction stoichiometry, salinity, and temperature, we estimate that between 2.8 * 10 −3 m 3 and 6.2 * 10 −3 m 3 of calcite may replace dolomite for each m 3 of anhydrite created. Within the constraints dictated by the environment of the late Permian Zechstein basin, we estimate that about 5 * 10 −3 m 3 of dedolomite is created for each m 3 of anhydrite. Mass balance constraints indicate that fluids derived from gypsum-to-anhydrite conversion account for less than 1% of the observed dedolomite in most of the studied industry wells from northern Germany.

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“…The dolomite was in turn replaced by calcite. Dedolomitization is closely linked to karstification (Cañaveras et al 1996). This process might have contributed to release Sr 2+ , which combined with SO 2− 4 , promoted precipitation of celestite (cf.…”

Section: Paragenesismentioning

confidence: 99%

Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil

Paz

Rossetti

2006

An. Acad. Bras. Ciênc.

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An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposed in the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishing between primary and secondary evaporites, and reconstructing their post-depositional evolution. Seven evaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gypsum or anhydrite; 3. fibrous to acicular gypsum; 4. mosaic gypsum; 5. brecciated gypsum or gypsarenite; 6. pseudo-nodular anhydrite or gypsum; and 7. rosettes of gypsum. The three first phases of gypsum display petrographic characteristics that conform to a primary nature. The fibrous to acicular and mosaic gypsum were formed by replacement of primary gypsum, but their origin took place during the eodiagenesis, still under influence of the depositional setting. These gypsum morphologies are closely related to the laminated evaporites, serving to demonstrate that their formation was related to replacements that did not affect the primary sedimentary structures. The pseudo-nodular anhydrite or gypsum seems to have originated by mobilization of sulfate-rich fluids during burial, probably related to halokinesis. The rosettes of gypsum, which intercept all the other gypsum varieties, represent the latest phase of evaporite formation in the study area, resulting from either intrastratal waters or surface waters during weathering.

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Dedolomites associated with karstification. An example of early dedolomitization in lacustrine sequences from the Tertiary Madrid basin, central Spain

Cited by 48 publications

References 52 publications

Palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record

Palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record

Dedolomitization Potential of Fluids from Gypsum-to-Anhydrite Conversion: Mass Balance Constraints from the Late Permian Zechstein-2-Carbonates in NW Germany

Petrography of gypsum-bearing facies of the Codó Formation (Late Aptian), Northern Brazil

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