Genesis and transformation of metalliferous sediments from the East Pacific Rise, Bauer Deep, and Central Basin, northwest Nazca plate

Heath, G. Ross; Dymond, Jack

doi:10.1130/0016-7606(1977)88<723:gatoms>2.0.co;2

Cited by 236 publications

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“…Smectite clays in the near-ridge-crest sediments have a range of compositions from the end-member of Fe 2 Si 4 O 10 (OH) 2 , which is approached in nontronite formed near Galapagos hydrothermal vents, to mixed-layer smectite with Fe/Al ratios of 3, typical of East Pacific Rise Femontmorillonite (McMurtry et al, 1983). The formation of authigenic Fe-smectite may be from the reaction of Fe-hydroxides, transported from ridge vents, with biogenic Si (Heath and Dymond, 1977;Aoki et al, 1974), or it may be the Fe-smectite clay, and not the Fe-hydroxide, that was transported (McMurtry et al, 1983). The source of Al in these smectites in ridge settings may either be as detrital (Al) montmorillonite mixing with authigenic (Fe) nontronite, or from Al-rich volcanic detritus allowing Al-rich nontronite to form (reviewed in Weaver, 1989).…”

Section: Clay Componentmentioning

confidence: 99%

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Ogg¹,

Stattegger²,

Behl³

1992

Proceedings of the Ocean Drilling Program

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Sedimentation in the central Pacific during the Jurassic and Early Cretaceous was dominated by abundant biogenic silica. A synthesis of the stratigraphy, lithology, petrology, and geochemistry of the radiolarites in Sites 801 and 800 documents the sedimentation processes and trends in the equatorial central Pacific from the Middle Jurassic through the Early Cretaceous. Paleolatitude and paleodepth reconstructions enable comparisons with previous DSDP sites and identification of the general patterns of sedimentation over a wide region of the Pacific.Clayey radiolarites dominated sedimentation on Pacific oceanic crust within tropical paleolatitudes from at least the latest Bathonian through Tithonian. Radiolarian productivity rose to a peak within 5° of the paleoequator, where accumulation rates of biogenic silica exceeded 1000 g/cm 2 /m.y. Wavy-bedded radiolarian cherts developed in the upper Tithonian at Site 801 coinciding with the proximity of this site to the paleoequator. Ribbon-bedding of some radiolarian cherts exposed on Pacific margins may have formed from silicification of radiolarite deposited near the equatorial high-productivity zone where radiolarian/clay ratios were high. Silicification processes in sediments extensively mixed by bioturbation or enriched in clay or carbonate generally resulted in discontinuous bands or nodules of porcellanite or chert, e.g., a "knobby" radiolarite. Ribbon-bedded cherts require primary alternations of radiolarian-rich and clay-rich layers as an initial structural template, coupled with abundant biogenic silica in both layers. During diagenesis, migration of silica from clay-rich layers leaves radiolarian "ghosts" or voids, and the precipitation in adjacent radiolarite layers results in silicification of the inter-radiolarian matrix and infilling of radiolarian tests. Alternations of claystone and clay-rich radiolarian grainstone were deposited during the Callovian at Site 801 and during the Berriasian-Valanginian at Site 800, but did not silicify to form bedded chert.Carbonate was not preserved on the Pacific oceanic floor or spreading ridges during the Jurassic, perhaps due to an elevated level of dissolved carbon dioxide. During the Berriasian through Hauterivian, the carbonate compensation depth (CCD) descended to approximately 3500 m, permitting the accumulation of siliceous limestones at near-ridge sites. Carbonate accumulation rates exceeded 1500 g/cm 2 /m.y. at sites above the CCD, yet there is no evidence of an equatorial carbonate bulge during the Early Cretaceous. In the Barremian and Aptian, the CCD rose, coincident with the onset of mid-plate volcanic activity.Abundance of Fe and Mn and the associated formation of authigenic Fe-smectite clays was a function of proximity to the spreading ridges, with secondary enrichments occurring during episodes of spreading-center reorganizations. Callovian radiolarite at Site 801 is anomalously depleted in Mn, which resulted either from inhibited precipitation of Mn-oxides by lower pH of interstitial waters in...

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Section: Clay Componentmentioning

confidence: 99%

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Ogg¹,

Stattegger²,

Behl³

1992

Proceedings of the Ocean Drilling Program

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“…Oxygen isotopic investigations (McMurtry et al 1983;Cole 1983;Singer et al 1984) indicate that authigenic nontronites have formation temperatures of 30~ to 150~ This large temperature range, combined with variability of redox conditions, raised questions about the chemical processes involved in their genesis. Most of the studies suggested processes of direct precipitation from hydrothermal fluids and combination of Feoxyhydroxides with hydrothermal (or biogenic) silica under more or less anoxic conditions (Heath and Dymond 1977;Cole and Shaw 1983;Cole 1985). Based on synthesis experiments, Harder (1976Harder ( , 1978 concluded that Fe-smectites could only form from solutions containing Fe z+ and/or Mg 2+.…”

Section: Introductionmentioning

confidence: 99%

Biogenic Nontronite from Marine White Smoker Chimneys

Köhler

1994

Clays and clay miner.

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Abstract--Clay samples of greenish colour were collected from submarine hydrothermal chimneys of the Galapagos Rift and Mariana Trough. Mineralogical and chemical investigations of the clay by scanning and transmission electron microscopy, X-ray diffraction, differential thermal analysis, infrared-spectroscopy, X-ray fluorescence, and determination of specific surface area, and oxygen isotope composition identify it as a well crystallized nontronite. This nontronite ofhydrothermal origin has a nearly monomineralic character, a low Al-content, and a formation temperature of 21.5 to 67.3"C. The most remarkable characteristic, however, of the nontronite deposit is its mierostructure, a network of microtubes composed of fine frequently folded clay sheets. These delicate filaments show close similarity in size and form to sheath forming bacteria. The correlation between clay mineral and chemical characteristics, as well as biological conditions at marine hydrothermal smoker chimneys, let us suggest that Fe oxidizing, sheath forming bacteria are playing a decisive role in nontronite formation at these sites.

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“…These profiles are explained by the degradation of the organic-Cu carrier during early diagenesis; this results in a release of Cu into the bottom-water (e.g. HEATH and DYMOND, 1977;HEIN et aI., 1979 and BOWSER, 1980;ELDERFIELD, 1981;KLINKHAMMER et al, 1982;GRAYBEAL and HEATH, 1984;LYLE et al, 1984;PEDERSEN et al, 1986;HEGGIE et al, 1987;CHESTER et al, 1988;SHAW et al, 1990). Manganese pore-water concentrations often show an increase with depth (e.g.…”

Section: Introductionmentioning

confidence: 99%

Occurrence of thin, metal-rich layers in deep-sea sediments: a geochemical characterization of copper remobilization

Visser

Middelburg

et al. 1993

Deep Sea Research Part I: Oceanographic Research Papers

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Abstract-Distinctly coloured trace metal enriched fronts with a six-fold Cu-enrichment occur in the interbedded pelagic-turbiditic sediments from the Madeira Abyssal Plain. To decipher their mode of formation. two sequential extraction techniques, an acid-gradient and a "Tessier-type" scheme, were applied. Two different front types could be distinguished: Type-l fronts are mostly black and enriched in Co, Zn, Ni and Cu, and associated with the oxidation fronts that developed after deposition of turbidites. Type-2 fronts are purple, extremely enriched in Cu, and associated with sulphur. These fronts are sometimes found in relation with a relict oxidation front, but often show no clear relation with lithology. Two different modes of formation are postulated. (1) The transition-metal enrichment in the type-l fronts is typical for a manganese-oxide association often found in marine sediments. After the dissolution of manganese-oxide during sub-oxic diagenesis, the transition metals were liberated and subsequently relocated and precipitated in response to a redox-gradient. (2) The Cu-S association in type-2 fronts is also formed during sub-oxic diagenesis. The main process leading to the formation of this Cu-S enrichment is the mobilization of inherited Cu-S compounds from organic-rich turbidites. The accumulation of these compounds is possibly related to redox changes at relict oxidation fronts and to gradual. probably slowly evolving. redox changes that occur at present.

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Genesis and transformation of metalliferous sediments from the East Pacific Rise, Bauer Deep, and Central Basin, northwest Nazca plate

Cited by 236 publications

References 0 publications

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Jurassic through Early Cretaceous Sedimentation History of the Central Equatorial Pacific and of Sites 800 and 801

Biogenic Nontronite from Marine White Smoker Chimneys

Occurrence of thin, metal-rich layers in deep-sea sediments: a geochemical characterization of copper remobilization

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