Dolomitization kinetics of hydrothermal bombs and natural settings

Sibley, Duncan F.; Nordeng, Stephan; Borkowski, Michelle L.

doi:10.1306/d4267e29-2b26-11d7-8648000102c1865d

Cited by 97 publications

(61 citation statements)

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“…8). On the other hand, it is well known that at room temperature and atmospheric pressure the nucleation of dolomite is kinetically hindered (Sibley et al 1994;Land 1998). In most systems where contemporary dolomite formation is observed, the process is microbially mediated (Machel 2004).…”

Section: Discussionmentioning

confidence: 99%

Distribution and composition of Mg-calcite and dolomite in the water and sediments of Lake Balaton

Tompa

Nyírő-Kósa

Rostási

et al. 2014

Central European Geology

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Lake Balaton is a large and shallow lake that is of great economic and cultural importance in landlocked Hungary. Even though the lake has been studied extensively in the last century from a large number of scientific aspects, the mineralogy of its sediments has not been fully explored. The mud at the bottom of the lake consists mostly of silt-sized grains of carbonate minerals with compositions between those of calcite (CaCO 3 ) and dolomite CaMg (CO 3 ) 2 . In order to understand the processes of carbonate precipitation and the influence of water budget fluctuations on the mineralogical character of the sediment, we used X-ray powder diffraction to analyze the changes of cell parameters of carbonate minerals in the upper half meter of the sediment. The major carbonate phase is Mg-calcite that shows a distinct reduction in cell parameters from west to east, reflecting an increase of its Mg-content, in parallel with a gradient of dissolved Mg/Ca ratio in the water. Intriguingly, dolomite, the other widespread carbonate phase in the sediment, also shows a change in cell parameters from west to east, with the deviations from values of stoichiometric dolomite being largest in the Eastern Basin of the lake. The similar pattern of cell parameter changes of Mg-calcite and dolomite suggests that ordered dolomite with slightly anomalous, Ca-rich composition also forms in the lake, probably by direct precipitation from the water. In contrast, protodolomite forms within the sediment through diagenetic processes. Based on our X-ray powder diffraction measurements, we propose a model of carbonate mineral formation and transformation in Lake Balaton. Since the Mg/Ca ratio of the water appears to be the major factor in controlling the compositions of carbonate minerals, and this ratio in turn is governed by the amount of water supply, the properties of the precipitating carbonate minerals are affected by the actual level of the lake water.

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Section: Discussionmentioning

confidence: 99%

Distribution and composition of Mg-calcite and dolomite in the water and sediments of Lake Balaton

Tompa

Nyírő-Kósa

Rostási

et al. 2014

Central European Geology

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“…Laboratory synthesis of dolomite under both wet and dry conditions, beginning with the classic work of Julian Goldsmith and coworkers (Graf andGoldsmith, 1955, 1956;Goldsmith and Heard, 1961) and others (Rosenberg and Holland, 1964;Rosenberg et aL, 1966;Katz and Matthews, 1977;Baker and Kastner, 1981;Gaines, 1968Gaines, , 1974Gaines, , 1980Sibley, 1990;Sibley et al, 1987Sibley et al, , 1994, has been successful at high to moderate temperatures, generally exceeding 150°C. This experimental dataset forms the basis for our understanding of equilibrium phase distributions in the CaCO3-MgCO3 system.…”

Section: Introductionmentioning

confidence: 99%

Tentative kinetic model for dolomite precipitation rate and its application to dolomite distribution

Arvidson

Mackenzie

1997

Aquat Geochem

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The 'dolomite problem' has a long history and remains one of the most intensely studied and debated topics in geology. Major amounts of dolomite are not directly forming today from seawater. This observation has led many investigators to develop geochemical/hydrologic models for dolomite formation in diagenetic environments. A fundamental limitation of the current models for the growth of sedimentary dolomite is the dearth of kinetic information for this phase, in contrast to that available for calcite and aragonite.We present a simple kinetic model describing dolomite growth as a function of supersaturation using data from published high temperature synthesis experiments and our own experimental results. This model is similar in form to empirical models used to describe precipitation and dissolution rates of other carbonate minerals. Despite the considerable uncertainties and assumptions implicit in this approach, the model satisfies a basic expectation of classical precipitation theory, i.e., that the distance from equilibrium is a basic driving force for reaction rate. The calculated reaction order is high (,-~ 3), and the combined effect of high order and large activation energy produces a very strong dependence of the rate on temperature and the degree of supersaturation of aqueous solutions with respect to this phase.Using the calculated parameters, we applied the model to well-documented case studies of sabkha dolomite at Abu Dhabi (Persian Gulf), and organogenic dolomite from the Gulf of California. Growth rates calculated from the model agree with independent estimates of the age of these dolomites to well within an order of magnitude. A comparison of precipitation rates in seawater also shows the rate of dolomite precipitation to converge strongly with that of calcite with increasing temperature. If correct, this result implies that dolomite may respond to relatively modest warming of surface environments by substantial increases in accumulation rate, and suggests that the distribution of sedimentary dolomite in the rock record may be to some extent a temperature signal.

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“…Most studies, however, focused on the stability 83 relationships in carbonate-fluid systems (e.g., Graf and Goldsmith, 1955;Rosenberg and Holland, 84 1964; Johannes, 1966;1968;1969;Rosenberg et al, 1967), on the influence of fluid composition 85 on the chemical composition and mineralogy of the reaction product (e.g., Grover and Kubanek,86 1983; Sibley, 1990), and the stoichiometry of the product dolomite (e.g., Kaczmarek and Sibley,87 2007; 2011; 2014). The Ca:Mg ratio of the fluid has proven to be an important factor controlling 88 the rate of dolomitization (e.g., Sibley, 1990;Sibley et al 1994; Kaczmarek and Sibley, 2007;89 2011).…”

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confidence: 99%

Hydrothermal replacement of biogenic and abiogenic aragonite by Mg-carbonates – Relation between textural control on effective element fluxes and resulting carbonate phase

Jonas

Müller

Dohmen

et al. 2017

Geochimica et Cosmochimica Acta

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Dolomitization kinetics of hydrothermal bombs and natural settings

Cited by 97 publications

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Distribution and composition of Mg-calcite and dolomite in the water and sediments of Lake Balaton

Distribution and composition of Mg-calcite and dolomite in the water and sediments of Lake Balaton

Tentative kinetic model for dolomite precipitation rate and its application to dolomite distribution

Hydrothermal replacement of biogenic and abiogenic aragonite by Mg-carbonates – Relation between textural control on effective element fluxes and resulting carbonate phase

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