Early diagenesis in deep sea turbidites: The imprint of paleo-oxidation zones

Journal Article · Thu Dec 01 04:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90158-5· OSTI ID:5020948

Buckley, D E; Cranston, R E ^[1]

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1. Bedford Institute of Oceanography, Dartmouth, Nova Scotia (Canada)

Sediment cores up to 35 m long have been removed from turbidite sequences in the Madiera Abyssal Plain and the Southern Nares Abyssal Plain. Detailed geochemical analyses of these sediments (Si, Al, Fe, Mn, Ca, organic and inorganic carbon) and associate pore waters (nitrate, ammonia, silicate, Fe{sup 2+}, Mn{sup 2+} and alkalinity) provide representative profiles of both steady-state and nonsteady-state diagenetic reactions initiated by oxidation and reduction processes. Models demonstrate that chemical transport in the pore water system is diffusion dominated. Over periods of a few thousands of years to several hundreds of thousands of years Mn and Fe mobilized in the subsurface mildly reducing sediments sediments are precipitated as easily reducible oxyhydroxides in the near-surface oxidized sediments. Paleo-oxidation zones can be recognized in old turbidites by distinct changes in color between lower and upper portions of the deposit. Depletion of carbonate content in the oxidized zones in the Southern Nares Abyssal Plain is particularly significant in that as much as 80% of the initial carbonates have been lost. Also the relative amounts of weak acid soluble Fe and Mn are generally less in the paleo-oxidized zones, due to the initial oxidation of metal-carbonate and metal hydroxide forms to easily reducible oxide forms, which are then subsequently solubilized under the mildly reducing conditions at depth in the sediment column.

• OSTI ID: 5020948
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:12; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ATLANTIC OCEAN
BIODEGRADATION
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
CHEMISTRY
DECOMPOSITION
DEPOSITION
DIAGENESIS
DRILL CORES
GEOCHEMISTRY
GEOLOGIC DEPOSITS
GEOLOGIC MODELS
GROUND WATER
HYDROGEN COMPOUNDS
INTERFACES
INTERSTITIAL WATER
IRON COMPOUNDS
MANGANESE COMPOUNDS
ORGANIC MATTER
OXIDATION
OXIDIZERS
OXYGEN COMPOUNDS
PRECIPITATION
REDOX REACTIONS
SEAS
SEDIMENT-WATER INTERFACES
SEDIMENTS
SEPARATION PROCESSES
SURFACE WATERS
TRANSITION ELEMENT COMPOUNDS
WATER