The Mid-Atlantic Ridge near 45° 00′ north. VIII. Carbonate lithification on oceanic ridges and seamounts

Bartlett, Grant A.; Greggs, Robert G.

doi:10.1139/e70-024

Cited by 11 publications

(6 citation statements)

References 10 publications

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“…210-225 for compilations). Low-magnesian calcite cements have been found only sporadically (Milliman, 1966;Bartlett & Greggs, 1970;Mecarini, Shiniakoa& Krause, 1965;Thompson et a/., 1968) and have been interpreted as alteration products of original high-magnesian calcites (Milliman, 1966). The findings of Gomberg & Bonatti (1970), as well as our observations on skeletal material, strongly suggest that W .…”

Section: Magnesium In the Calcite Cementsupporting

confidence: 55%

“…A third important exception is the magnesian calcite found by Bartlett & Greggs 1970 on the Mid-Atlantic Ridge at depths of 1400-3000 111.…”

Section: Magnesium In the Calcite Cementmentioning

confidence: 98%

“…Sea-floor lithification of deep-water carbonates was recognized in the nineteenth century, when deep-sea expeditions discovered extensive limestone crusts covering the sea-floor in the Mediterranean, off Florida and elsewhere. In the past decade, as a result of the debate on fresh-water versus marine cementation, these reports have been thoroughly reviewed (Fischer & Garrison, 1967;Milliman, 1974), and new evidence added by modern petrographic descriptions and isotope analyses of limestone crusts recovered from the deep sea (Milliman, 1966;Gevirtz & Friedman, 1969;Gibson & Schlee, 1967;Thompson et al, 1968;Garrison & Fisher, 1969, p. 29;Bartlett & Greggs, 1970;Marlowe, 1971 : Neumann, Kofoed & Keller, 1977).…”

Section: Introductionmentioning

confidence: 99%

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Low‐magnesian calcite limestones forming at the deep‐sea floor, Tongue of the Ocean, Bahamas

1978

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Carbonate ooze in the deep troughs between the Bahama Banks is a mixture of pelagic and bank‐derived material. It consists of aragonite, calcite and magnesium calcite in a ratio of about 3:2:1. Where exposed in erosional cuts at the sea floor, this ooze lithifies within 100,000 years and is transformed into calcite micrite of only 3.5‐5 mol % MgCO3. Where buried, the ooze maintains its original composition for at least 200,000‐400,000 years and remains unlithified for tens of millions of years. Quite unexpectedly, the path of sea‐floor diagenesis of peri‐platform ooze was found to be the same as that of freshwater diagenesis. Most of the aragonite is leached, pteropod shells often leaving cement‐lined moulds behind; magnesian calcite recrystallizes and loses magnesium; polyhedral calcite of 2‐4 μm size appears as cement. The setting and the carbon‐oxygen isotope ratios rule out any freshwater influence. Carbon isotope ratios remain heavy, oxygen ratios shift towards equilibrium with the cold bottom water. The calcite cement has 3.5‐5 mol % MgCO3 and can be interpreted as the least soluble form of calcite emerging from alteration at the sea floor or, alternatively, as a direct precipitate from cold sea water. The change in the composition of calcite cements with water depth supports the second interpretation. In the Bahamas and elsewhere in the world ocean, magnesium in calcite cements decreases from the warm surface waters down to 700‐1200 m, i.e. the boundary between intermediate and cold deep‐water masses. Below this level, calcite prevails and magnesian calcite and aragonite cements are restricted to semi‐enclosed seas with exceptionally warm bottom waters.

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Section: Magnesium In the Calcite Cementsupporting

confidence: 55%

“…A third important exception is the magnesian calcite found by Bartlett & Greggs 1970 on the Mid-Atlantic Ridge at depths of 1400-3000 111.…”

Section: Magnesium In the Calcite Cementmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Low‐magnesian calcite limestones forming at the deep‐sea floor, Tongue of the Ocean, Bahamas

1978

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“…-Jurassic Tethyan hardgrounds have now been recognised as prime examples of ancient submarine lithification (Garrison & Fischer, 1969;Zankl, 1969), and there are now numerous well-documented Recent cases of this (e.g. Fischer & Garrison, 1967, and references therein;Shinn, 1969;Bartlett & Greggs, 1970). With Tethyan red limestones, however, the formation of hardgrounds may be aided somewhat by cementation with ferromanganese minerals, in much the same way as described by Morgenstein (1967) for some Recent deep-sea sediments.…”

Section: Submarine Solution and Lithificationmentioning

confidence: 93%

“…Submarine solution and lithification can also occur on modern seamounts (Milliman, 1966;Bartlett & Greggs, 1970); and the limestone in these environments may be heavily bored. Pratt (1963Pratt ( , 1967 has illustrated a well-cemented, solution-pitted limestone surface from the upper terrace of Great Meteor Seamount which is indistinguishable from some Tethyan Jurassic hardgrounds.…”

Section: Environment and Palaeobathymetrymentioning

confidence: 99%

The Genesis of Condensed Sequences in the Tethyan Jurassic

Jenkyns

1971

LET

109

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Pelagic limestones of the west Sicilian Middle Jurassic are used as type examples in this examination of Tethyan condensed sequences. Two main processes were involved in the genesis of this type of deposit: stratigraphic condensation (minimal sediment input) and reworking. The lack of nannoplankton during most of the Jurassic caused stratigraphic condensation, and the particular environment in which these beds were deposited – that of topographic high – was considerably influenced by currents; thus reworking led to a further reduction in sediment thickness. The presence of algal stromatolites in certain condensed sequences and the traces of boring algae in associated ferromanganese nodules suggest deposition within the photic zone. A maximum depth of 200 metres is inferred. Many features of condensed sequences are comparable with those on Recent seamounts; these include presence of ferromanganese nodules and crusts, mixed faunas, calcarenite lenses, algal biscuits, and evidence of submarine solution and lithification. Jurassic Tethyan condensed sequences can thus be interpreted as ancient seamount deposits.

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Sedimentation on Ontong Java Plateau: Observations on a Classic “Carbonate Monitor”

Berger¹,

Johnson²,

Hamilton³

1977

The Fate of Fossil Fuel CO2 in the Oceans

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The Mid-Atlantic Ridge near 45° 00′ north. VIII. Carbonate lithification on oceanic ridges and seamounts

Cited by 11 publications

References 10 publications

Low‐magnesian calcite limestones forming at the deep‐sea floor, Tongue of the Ocean, Bahamas

Low‐magnesian calcite limestones forming at the deep‐sea floor, Tongue of the Ocean, Bahamas

The Genesis of Condensed Sequences in the Tethyan Jurassic

Sedimentation on Ontong Java Plateau: Observations on a Classic “Carbonate Monitor”

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