The Origin of Massive Dolomite

Land, Lynton S.

doi:10.5408/0022-1368-33.2.112

Cited by 483 publications

(317 citation statements)

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“…Dolomite, which is common throughout the hole, appears to be the result of exsolution of magnesium from magnesian calcites and the dissolution of aragonite. Additional magnesium influx from seawater also may occur (Sailer, 1984;Land, 1985;Mullins et al, 1985a). Isotopic ratios and their uniform downhole trend support our interpretation that all diagenetic transformations in sub-bottom depths occurred in an open, deep-marine diagenetic environment.…”

Section: Site Summarysupporting

confidence: 81%

A Regional Perspective of Shallow-Burial Diagenesis of Deep-Water Periplatform Carbonates from the Northern Bahamas

Dix¹,

Mullins²

1988

Proceedings of the Ocean Drilling Program

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Detailed studies of carbonate mineralogy and geochemistry using samples recovered by deep-sea drilling in the northern Bahamas document shallow-burial (<250 mbsf) diagenetic trends that occur in two stages. Stage 1 diagenesis (0-10 meters below the seafloor, mbsf) results in rapid, extensive calcitization and local dolomitization in marine-derived pore fluids. Stable oxygen isotopes are quickly enriched, while carbon values are depleted. Aragonite undergoes dissolution and high-magnesian calcite exsolves to low-magnesian calcite. Below 10 to at least 185 mbsf, stage 2 diagenesis continues to alter primary components, leading to ooze-chalk and chalk-limestone transformations and low amounts of dolomite, while rates and amplitudes of change are considerably less than in stage 1. Oxygen-and carbon-isotope ratios indicate that diagenesis still occurs in marine-derived pore fluids.Overall, shallow-burial diagenesis of periplatform carbonates proceeds much more readily than diagenesis of deepsea pelagic ooze. This is because of higher diagenetic potential related to the influx of metastable shallow-water-derived components in a deep-marine realm. Subsurface calcitization and lithification of periplatform sediments occurs rapidly with depth in regions of moderate accumulation rates (20-60 m/m.y.; north of Little Bahama Bank). This is a result of an interpreted greater rate of diagenetic alteration with burial, and in deep (3000 m) water is related to seawater saturation levels relative to carbonate mineralogy. Calcitization and local dolomitization may occur at or near the sediment/ water interface during formation of disconformities. In contrast, metastable aragonite and high-magnesian calcite are present in significant amounts at depth in regions with high accumulation rates (>90 m/m.y., Exuma Sound), despite lithification that produces chalk and limestone. The presence of metastable components in porous limestones in Exuma Sound underscores the current high diagenetic potential for these rocks and the development of reservoir potential in periplatform deep-water limestones at shallow sub-bottom depths.

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Section: Site Summarysupporting

confidence: 81%

A Regional Perspective of Shallow-Burial Diagenesis of Deep-Water Periplatform Carbonates from the Northern Bahamas

Dix¹,

Mullins²

1988

Proceedings of the Ocean Drilling Program

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“…In contrast, we use "recrystallization" 413 to mean the dissolution and re-precipitation of carbonate minerals (that may include but does not 414 require a change in mineralogy) and can result in geochemical exchange with porewaters (Machel, 415 1997). Finally, the timing of dolomitization and its fluid source remain challenging to infer, but 416 numerous models indicate that both seawater and external fluids can be involved in this process 417 (e.g., Land, 1985 (Komar and Zeebe, 2016). Figure 7D; Holmden et al, 2012b).…”

mentioning

confidence: 99%

The influence of seawater carbonate chemistry, mineralogy, and diagenesis on calcium isotope variations in Lower-Middle Triassic carbonate rocks

et al. 2017

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“…The controversy surrounding the origin of sedimentary dolomites is known as the ''Dolomite Problem'' (Van Tula 1916;Land 1985). Very fine crystalline dolomites are widely formed in varied types of lacustrine systems (Meister et al 2011;Mauger and Compton 2011;Last et al 2012;Casado et al 2014;Meng et al 2014a, b;Köster and Gilg 2015;Lu et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China

et al. 2016

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The genesis of the fine crystalline dolomites that exhibit good to excellent reservoir properties in the upper fourth member of the Eocene Shahejie Formation (Es 4 s ) around the Sikou Sag, Bohai Bay Basin, is uncertain. This paper investigates the formation mechanisms of this fine crystalline dolomite using XRD, SEM, thin section analysis and geochemical data. The stratigraphy of the Sikou lacustrine carbonate is dominated by the repetition of metre-scale, high-frequency deposition cycles, and the amount of dolomite within a cycle increases upward from the cycle bottom. These dolomite crystals are 2-30 lm in length, subhedral to anhedral in shape and typically replace both grains and matrix. They also occur as rim cement and have thin lamellae within ooid cortices. Textural relations indicate that the dolomite predates equant sparry calcite cement and coarse calcite cement. The Sr concentrations of dolomites range from 900 to 1200 ppm. Dolomite

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The Origin of Massive Dolomite

Cited by 483 publications

References 0 publications

A Regional Perspective of Shallow-Burial Diagenesis of Deep-Water Periplatform Carbonates from the Northern Bahamas

A Regional Perspective of Shallow-Burial Diagenesis of Deep-Water Periplatform Carbonates from the Northern Bahamas

The influence of seawater carbonate chemistry, mineralogy, and diagenesis on calcium isotope variations in Lower-Middle Triassic carbonate rocks

Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China

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