Alteration of magnetic mineralogy at the sulfate–methane transition: Analysis of sediments from the Argentine continental slope

Garming, J. F. L.; Bleil, Ulrich; Riedinger, Natascha

doi:10.1016/j.pepi.2005.04.001

Cited by 91 publications

(85 citation statements)

References 63 publications

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“…Based on thermal demagnetization of the SIRM, hematite is identified as a major remanence carrier within the upper sapropelic layer. The presence of resistant hematite in sulfidic environment has already been observed in several studies (Yamazaki et al, 2003;Liu et al, 2004;Garming et al, 2005;Rey et al, 2005). This result is in agreement with recent measurements on the reactivity of iron oxides toward dissolved sulfide (Poulton et al, 2004) showing that hematite is 2 to 3 times more resistant to dissolution than magnetite.…”

Section: Magnetic Properties Of Sapropels and Their Environmental Sigsupporting

confidence: 90%

Paleomagnetic and geochemical record from cores from the Sea of Marmara, Turkey: Age constraints and implications of sapropelic deposition on early diagenesis

et al. 2015

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We present results of a multi-proxy analysis of two sediment cores from the Marmara Sea. The cores were analyzed using paleomagnetic and geochemical measurements. Two sapropels are documented in the last 11 kyr and are recorded in several locations across the Marmara Sea. These two sapropels have contrasting magnetic properties. The magnetic record is affected by intense early diagenesis; the most recent upper sapropelic layer has low remanence and susceptibility values. A record of paleomagnetic inclinations could still be isolated above the diagenesis front and is compared with secular variation models. The lower sapropel is identified in the deep part of the oldest studied core (Klg07) and has distinct magnetic properties characterized by high remanence and susceptibility values. Using the magnetic properties it is possible to constrain bottom water ventilation and reconnection episodes between the Marmara Sea and the Black Sea following the sea level rise during the last glacial to inter-glacial transition.

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Section: Magnetic Properties Of Sapropels and Their Environmental Sigsupporting

confidence: 90%

Paleomagnetic and geochemical record from cores from the Sea of Marmara, Turkey: Age constraints and implications of sapropelic deposition on early diagenesis

et al. 2015

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“…It is therefore plausible that these silicate grains contain submicron magnetic inclusions in the form of SD to PSD sized Fe-Ti oxides. Such composites have been found and described in various oceanic sedimentary environments, e.g., in SW Pacific back-arc basins [Vali et al, 1989], at Indian Ocean ridges [Hounslow and Maher, 1996], and the Argentine continental margin [Garming et al, 2005]. The abundance of the silicates varies between about 1 -5% and does not show any particular tendency in all samples along the westeast transect except in case of the interglacial sample from the SLR, where silicate grains make up $30% of the magnetic extracts.…”

Section: Silicates With Magnetic Inclusionsmentioning

confidence: 75%

Magnetic petrology of equatorial Atlantic sediments: Electron microscopy results and their implications for environmental magnetic interpretation

et al. 2007

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[1] The magnetic microparticle and nanoparticle inventories of marine sediments from equatorial Atlantic sites were investigated by scanning and transmission electron microscopy to classify all present detrital and authigenic magnetic mineral species and to investigate their regional distribution, origin, transport, and preservation. This information is used to establish source-to-sink relations and to constrain environmental magnetic proxy interpretations for this area. . Sediments from two depths corresponding to marine isotope stages 4 and 5.5 were processed. This selection represents glacial and interglacial conditions of sedimentation for the western, central, and eastern equatorial Atlantic and avoids interferences from subsurface and anoxic processes. Crystallographic, elemental, morphological, and granulometric data of more than 2000 magnetic particles were collected by scanning and transmission electron microscopy. On basis of these properties, nine particle classes could be defined: detrital magnetite, titanomagnetite (fragmental and euhedral), titanomagnetite-hemoilmentite intergrowths, silicates with magnetic inclusions, microcrystalline hematite, magnetite spherules, bacterial magnetite, goethite needles, and nanoparticle clusters. Each class can be associated with fluvial, eolian, subaeric, and submarine volcanic, biogenic, or chemogenic sources. Large-scale sedimentation patterns are delineated as well: detrital magnetite is typical of Amazon discharge, fragmental titanomagnetite is a submarine weathering product of mid-ocean ridge basalts, and titanomagnetite-hemoilmenite intergrowths are common magnetic particles in West African dust. This clear regionalization underlines that magnetic petrology is an excellent indicator of source-to-sink relations. Hematite encrustations, magnetic spherules, and nanoparticle clusters were found at all investigated sites, while bacterial magnetite and authigenic hematite were only detected at the more oxic western site. At the eastern site, surface pits and crevices were seen on the crystal faces indicating subtle early diagenetic reductive dissolution. It was observed that paleoclimatic signatures of magnetogranulometric parameters such as the ratio of anhysteretic and isothermal remanent magnetizations can be formed either by mixing of multiple sources with separate, relatively narrow grain size ranges (western site) or by variable sorting of a single source with a broad grain size distribution (eastern site). Hematite, goethite, and possibly ferrihydrite nanoparticles occur in all sediment cores studied and have either high-coercive or superparamagnetic properties depending on their partly ultrafine grain sizes. These two magnetic fractions are generally discussed as separate fractions, but we suggest that they could actually be genetically linked.

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“…The iron needed for biomineralization by magnetotactic bacteria is likely to have been provided by diagenetic iron reduction that released Fe 3+ from the most reactive iron-bearing minerals, including hydrous ferric oxide and lepidocrocite (Poulton et al, 2004). Magnetite and hematite are more resistant to dissolution (Yamazaki et al, 2003;Poulton et al, 2004;Garming et al, 2005;Roberts et al, 2011) and, therefore, survived this mild iron reduction that occurred under iron-reducing but not anoxic conditions. Thus, simultaneous delivery of enhanced organic carbon, reactive iron-bearing aeolian dust particles and non-reactive aeolian hematite particles to the seafloor would have released the existing limitation on key nutrients (carbon and iron) for an existing, but small, population of magnetotactic bacteria to produce the observed magnetic signatures.…”

Section: Ocean Iron Fertilization and Magnetotactic Bacterial Abundanmentioning

confidence: 99%

Enhanced primary productivity and magnetotactic bacterial production in response to middle Eocene warming in the Neo-Tethys Ocean

Savian

Jovane

Frontalini

et al. 2014

Palaeogeography, Palaeoclimatology, Palaeoecology

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Alteration of magnetic mineralogy at the sulfate–methane transition: Analysis of sediments from the Argentine continental slope

Cited by 91 publications

References 63 publications

Paleomagnetic and geochemical record from cores from the Sea of Marmara, Turkey: Age constraints and implications of sapropelic deposition on early diagenesis

Paleomagnetic and geochemical record from cores from the Sea of Marmara, Turkey: Age constraints and implications of sapropelic deposition on early diagenesis

Magnetic petrology of equatorial Atlantic sediments: Electron microscopy results and their implications for environmental magnetic interpretation

Enhanced primary productivity and magnetotactic bacterial production in response to middle Eocene warming in the Neo-Tethys Ocean

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