The nature and origin of authigenic smectites in some recent marine sediments

Cole, Thomas G.; Shaw, H. F.

doi:10.1180/claymin.1983.018.3.02

Cited by 87 publications

(47 citation statements)

References 29 publications

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“…Sudo et al (1981) described Fe-montmorillonite with lath-like, platy panicles without well-defined borders, with some panicles having a feather-like appearance. Cole and Shaw (1983) and Kurnosov et al (1982) described fibrous nontronites, but the fibers were much coarser than those of the KL9 clay. Grim and Giiven (1978) showed trioctahedral Mg-smectites from the Amargosa Valley, Nevada, that exhibit sheaf-like aggregates of fibers.…”

Section: Differential Thermal Analysismentioning

confidence: 93%

Nontronite in a Deep-Sea Core from the South Pacific

Singer

Stoffers

Heller-Kallai

et al. 1984

Clays and clay miner.

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Abstract--Smectite close to the pure Fe end member of the nontronite-beidellite series was found in the fine clay separated from a 354-cm deep sediment core in the southwestern Pacific Basin. The mineral has a b-axis of 9.09/~ and an unusually low dehydroxylation temperature of 454~ and is composed of sheaves of fibers less than 50/~ wide. Its charge density is 5.09 x 10 -4 esu/cmL The charge originates mainly from the presence of 18% of the total Fe in tetrahedral positions, as determined by Mrssbauer analysis. Slight deviations of the infrared spectra from those reported for nontronites are probably due to the presence of more octahedral Mg. The presence of authigenic quartz in the same sample permits some speculation on the concentration of dissolved silicon during nontronite genesis. A 6~80 value of 26 + 0.3%o indicates a temperature of formation of about 22~ The Sr isotope ratio suggests that the nontronite formed at least 12 million years ago.

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Section: Differential Thermal Analysismentioning

confidence: 93%

Nontronite in a Deep-Sea Core from the South Pacific

Singer

Stoffers

Heller-Kallai

et al. 1984

Clays and clay miner.

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“…This conclusion is based on the low concentrations of smectite in aeolian dusts and nearshore surface waters along the African coast (Chester et al, 1972;Behairy et al, 1975) and also in clay samples from sediment traps deployed in the ACC region at di¡erent depth levels (Petschick, unpublished data). Most smectite probably is introduced through Drake Passage via the ACC, originating from the erosion of hydrothermal and authigenic smectite-bearing sediments, widespread in the southeastern Paci¢c Ocean (Gorbunova, 1976;Honnorez, 1981;Cole and Shaw, 1983). Likewise, the scouring of exposed pre-Pleistocene sediments on the Falkland Plateau contributes to smectite £uxes in the ACC (Robert and Maillot, 1983;Walter et al, 2000).…”

Section: Sources Of Terrigenous Mud and Modes Of Detrital Inputmentioning

confidence: 99%

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

Kuhn

Diekmann

2002

Palaeogeography, Palaeoclimatology, Palaeoecology

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During Leg 177 of the Ocean Drilling Program, an expanded sequence of Pliocene to Holocene calcareous muds was recovered at Site 1089 on a drift deposit in the southern Cape Basin (SE South Atlantic). The reconstruction of detrital sources and modes of sediment transport gives insight into the operational modes of regional current systems in response to climate variability over the last 590 kyr, as inferred from sedimentological and mineralogical parameters of the terrigenous sediment fraction. Terrigenous sediments mainly originate from African sources with minor contributions from distant southern sources (South America and Antarctica) and are supplied by circumpolar water masses, North Atlantic Deep Water (NADW), and surface currents of the Agulhas Current. Changes in clay mineralogy as tracers of deep and shallow ocean circulation, best displayed by variations in quartz/feldspar ratios and kaolinite/chlorite ratios of clay, reflect both the northward displacement of NADW injection into the Antarctic Circumpolar Current and a weakening of Agulhas Current leakage from the Indian Ocean around South Africa to the South Atlantic during glacial stages, sub-stages, and stadials. Modifications of these regional current patterns are consistent with perturbations in global conveyor circulation and climate variability on Milankovitch and subMilankovitch time scales. Elevated mass-accumulation rates of terrigenous matter generally document high particle fluxes and focusing effects by bottom-current action throughout the late Quaternary. Current sorting and coarsening of terrigenous mud, independently of its source signals, prevails during interglacial periods and is linked to a stronger flow of Antarctic Bottom Water and the invigoration of deep contour currents in response to long-term changes (100-kyr cyclicity) in Antarctic ice-sheet dynamics, high-amplitude fluctuations in global sea level, and increased bottomwater formation. ß

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“…Nontronite has long been considered the most abundant authigenic smectite in recent marine sediments (Cole and Shaw, 1983).…”

Section: Introductionmentioning

confidence: 99%

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

Charpentier

Buatier

Jacquot³

et al. 2011

Geochimica et Cosmochimica Acta

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Wheat. Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling. Geochimica et Cosmochimica Acta, Elsevier, 2011Elsevier, , 75 (6), pp.1397Elsevier, -1410Elsevier, . 10.1016Elsevier, /j.gca.2010 Conditions and mechanism for the formation of iron- AbstractIron-rich smectite is commonly described in the diagenetic fraction of deep-sea sediment, as millimeter to centimeter aggregates dispersed in the sediment, or as a coating on sedimentary particles or nodules. This study examines several factors to elucidate formation mechanisms of a particular iron-rich smectite and its potential transformation to glauconite. The study combines a detailed mineralogical investigation on natural samples and a chemical modeling approach to assess mineralogical reactions and pathways.Transmission electron microscopy (TEM) observations and analytical electron microscopy (TEM-AEM) analyses were conducted on microtomed samples of millimeter-to centimeter-long green grains. These grains are widespread in pelagic calcareous sediment from the Costa Rica margin. They are composed of pyrites that are partially dissolved and are surrounded by amorphous or very poorly crystallized iron-rich particles. Iron-rich montmorillonite grows from an amorphous precursor and its formation requires the input of Si, O, Mg, K, Na and Ca; our results suggest that these inputs are supported by the dissolution of sedimentary phases such as volcanic glasses, siliceous fossils and silicates.Thermodynamic modeling of fluid-sediment interactions was conducted with the geochemical computer code PhreeqC, using mineralogical and pore fluid compositions from sediment samples and calculated estimates for thermodynamic constants of smectites that are not maintained by the computer code. Simulations confirm the possibility that the green grains are the product of pyrite alteration by seawater under oxidizing conditions. The extent of smectite production is controlled by the kinetics of pyrite dissolution and fluid migration. The absence of aluminum in the Costa Rica margin system explains the formation of an iron-rich montmorillonite instead of glauconite, whereas the presence of calcite that buffers the system explains the formation of an iron-rich montmorillonite instead of iron oxides.

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The nature and origin of authigenic smectites in some recent marine sediments

Cited by 87 publications

References 29 publications

Nontronite in a Deep-Sea Core from the South Pacific

Nontronite in a Deep-Sea Core from the South Pacific

Late Quaternary variability of ocean circulation in the southeastern South Atlantic inferred from the terrigenous sediment record of a drift deposit in the southern Cape Basin (ODP Site 1089)

Conditions and mechanism for the formation of iron-rich Montmorillonite in deep sea sediments (Costa Rica margin): Coupling high resolution mineralogical characterization and geochemical modeling

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