Estimation of dolomite formation: Dolomite precipitation and dolomitization

Banerjee, Amlan

doi:10.1007/s12594-016-0430-9

Cited by 36 publications

(22 citation statements)

References 58 publications

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“…Moreover, it should be interesting to perform molecular dynamic calculations on the (10.4) face of dolomite growing in aqueous solution, to verify the reliability of our growth model. We also highlight that our results are not in contrast with the re-precipitation model of dolomite [42][43][44], i.e., ordering in dolomite progresses by dissolution of disordered dolomite and re-precipitation of more ordered dolomite. Indeed, also in the case of a re-precipitation, according to our calculations, the surface should be disordered, whereas the bulk of the crystal should be ordered.…”

Section: Discussioncontrasting

confidence: 68%

(10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism

Bruno

Bittarello

2018

Minerals

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In this study, the stability of the (10.4) face of dolomite was systematically investigated. The surface energies at 0 K of the different (10.4) surfaces resulting from the cut of both ordered and disordered bulk structures were determined and compared, to establish how different atomic configurations (surface terminations) can affect the stability of the investigated face. To study the thermodynamic behavior of a surface, a 2D periodic slab model and the ab initio CRYSTAL code were adopted. The surface energies of the (10.4) faces of calcite and magnesite were also calculated in order to compare them with those of the different terminations of the (10.4) face of dolomite. Our calculations showed that the bulk of the dolomite crystal must have an ordered structure to reach the minimum of the energy, whereas the (10.4) surface is more stable when its structure is disordered. A growth model of the (10.4) face has been proposed: the peculiarity of this model consists in the existence of some disordered layers forming at the interface crystal/solution, which arrange in an ordered structure once covered by others disordered layers resulting by the spiral steps propagation.

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Section: Discussioncontrasting

confidence: 68%

(10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism

Bruno

Bittarello

2018

Minerals

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“…Reported seawater alkalinity and Mg 2+ and Ca 2+ concentrations in the late Ediacaran are similar to (or slightly higher than) those of present day oceans (Brennan et al ., ; Spence et al ., ), with both being supersaturated with respect to dolomite (Hardie, ). However, precipitation and reactive‐transport models suggest that even (significantly) supersaturated solutions rarely precipitate primary dolomite at Earth surface temperatures due to kinetic barriers (Land, ; Banerjee, ). Numerous studies have addressed these issues (Vasconcelos & McKenzie, ; Burns et al ., ; Petrash et al ., ) and an improved understanding of (seemingly) direct marine precipitation of dolomite cement in the Ediacaran is clearly of interest.…”

Section: Interpretation and Discussionmentioning

confidence: 99%

Formation, diagenesis and palaeoenvironmental significance of upper Ediacaran fibrous dolomite cements

Cai

Liu

et al. 2019

Sedimentology

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Neoproterozoic marine dolomite cements represent reliable, albeit complex, archives of their palaeoenvironment. Petrological and high-resolution geochemical data from well-preserved fibrous dolomite and pyrite in the upper Ediacaran (ca 551Á1 to 548Á0 Ma) Dengying Formation in south-west China are presented and discussed here. The aim of this research is to reconstruct the redox state of late Ediacaran shallow seawater and porewater in the Sichuan Basin using early marine diagenetic fabrics. Based on crystalline texture and axis, four basic types of fibrous dolomite cements formed penecontemporaneously in a microbialite reef setting at the platform margin: (i) bladed dolomites (replacement from a high-Mg calcite precursor); (ii) fascicular fast dolomites (replacement from an aragonitic precursor); (iii) fascicular slow dolomites; and (iv) radial slow dolomites. The latter two fabrics are considered direct marine porewater precipitates due to their length-slow character, cathodoluminescent zonation, and enriched copper and cobalt concentrations. Marine cements yield rare earth element and yttrium patterns comparable to modern seawater and represent a refined set of archive data relative to previously published bulk dolostones. Redox-sensitive elements and cathodoluminescence indicate that the fascicular fast dolomites formed in suboxic seawater, while fascicular slow and radial slow dolomites formed in euxinic marine porewaters. Microbial sulphate reduction during the formation of fascicular slow and radial slow dolomites is recognized by nanometre-scale spheroidal ankerite and sulphur-containing dolomite, and intergrown pyrite grains with U-shaped d 34 S transects. Data shown here suggest predominantly suboxic shallow late Ediacaran seawater and euxinic marine porewaters, with microbial activity promoting the direct precipitation of dolomite.

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“…In the Causses Basin, the Hettangian dolomite was tentatively interpreted as both primary dolomite (at least partly; Alabouvette Gauthier & Disnar, 1984;Defaut et al, 1990) and early diagenetic dolomite, suggesting multiorigins (Hamon, 2004). The palaeoenvironmental hypothesis of a tidal flat marsh can be supported by the following arguments: penecontemporary dolomite is identified in current environments such as shallow lagoons, subtidal and evaporitic intertidal to supratidal mud flats with strong microbial mat influence (e.g., sabkhas; Skinner, 1963;Illing et al, 1965;Shinn et al, 1965;Irion & Müller, 1968;Bontognali et al, 2010); laboratory experiments demonstrated that microbial activity facilitate and increase the formation of dolomite (Bontognali et al, 2010(Bontognali et al, , 2014Banerjee, 2016 and references therein); and dolomite is formed where tidal flooding and storm sediments are followed by many days of subaerial exposure (Shinn et al, 1965).…”

Section: Palaeoenvironmental Reconstructionmentioning

confidence: 99%

Underground dinosaur tracksite inside a karst of southern France: Early Jurassic tridactyl traces from the Dolomitic Formation of the Malaval Cave (Lozère)

Moreau

Trincal

André³

et al. 2018

IJS

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Abstract:Although underground dinosaur tracksites inside anthropic cavities such as mines or tunnels are well-known throughout the world, footprints inside natural karstic caves remain extremely rare. The Malaval Cave (Lozère, southern France) is well-known by speleologists for the abundance and the exceptional quality of acicular and helictite aragonite speleothems. Recent palaeontological prospecting inside this cave allowed the discovery of tridactyl dinosaur tracks.Here, a detailed study of theropod footprints was for the first time conducted inside a natural karstic cave, using photogrammetric imaging technique. Tracks from the Malaval Cave are located inside the "Super-Blanches" galleries. More than 26 footprints were identified. They are Hettangian in age (Lower Jurassic) and preserved as both in situ convex hyporeliefs and ex situ concave epireliefs. Tree morphotypes are distinguished, (i) "DilophosauripusKayentapus" morphotype, (ii) "Eubrontes" morphotype, and (iii) "Grallatorid" morphotype. Sedimentological and mineralogical analyses of the tracksite indicate that the depositional environment varied from periodically emergent subtidal to intertidal/supratidal flat marsh. This work highlights the great interest and importance of palaeoichnological prospecting in karst caves. This is particularly true for the Causses Basin where hundreds of natural cavities were reported by speleologists in the formations yielding dinosaur traces.

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Estimation of dolomite formation: Dolomite precipitation and dolomitization

Cited by 36 publications

References 58 publications

(10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism

(10.4) Face of Ordered and Disordered Dolomite, MgCa(CO3)2: A Computational Study to Reveal the Growth Mechanism

Formation, diagenesis and palaeoenvironmental significance of upper Ediacaran fibrous dolomite cements

Underground dinosaur tracksite inside a karst of southern France: Early Jurassic tridactyl traces from the Dolomitic Formation of the Malaval Cave (Lozère)

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