Replacement of pyrite framboids by magnetite in limestone and implications for palaeomagnetism

Suk, Dongwoo; Peacor, Donald R.; Voo, R. Vand Der

doi:10.1038/345611a0

Cited by 136 publications

(103 citation statements)

References 17 publications

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“…Oxidation of iron sulphides to magnetite would cause a newly formed chemical remanent magnetisation, acquiring the then ambient (reversed) field. The suggested driving mechanism for fluid migration in the SL section, would be a eustatic base level lowering, in contrast to other reported ancient remagnetisations where fluid migration is induced by tectonic stress [48].…”

Section: Remagnetisation In the Sifón De Librilla Sectionmentioning

confidence: 61%

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics

Garcés

Krijgsman²,

Agustí

1998

Earth and Planetary Science Letters

118

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The magnetostratigraphy of the mammal-bearing alluvial fan-fan delta sequences of the Fortuna basin (SE Spain) has yielded an accurate chronology for the late Turolian (Messinian) basin infill. From early to late Messinian (at least between 6.8 and 5.7 Ma), the Fortuna basin records the sedimentation of alluvial-palustrine deposits over a confined shallow basin. Changing environmental conditions in the latest Messinian are illustrated by the retreat of palustrine facies. A rapid progradation of the marginal clastic wedges and the initiation of an efficient basin drainage at ¾5.8 Ma (lower part of chron C3r) most likely represents the onshore response to the drastic drop of base level taking place during the Messinian salinity crisis. This study further provides improved age estimates for the late Turolian land mammal events in southern Spain. The oldest MN 13 locality in the studied sections is correlated to chron C3Ar at an age of 6.8 Ma. The entry of camels and the murid Paraethomys in southern Spain occurs in chron C3An.1n at 6.1 Ma, and gives further support for land mammal exchange between Africa and the Iberian peninsula prior to the salinity crisis, in good agreement with results from northern Africa [M. Benammi, M. Calvo, M. Prévot, J.J. Jaeger, Magnetostratigraphy and paleontology of Aït Kandoula basin (High Atlas, Morocco) and the African-European late Miocene terrestrial fauna exchanges, Earth Planet. Sci. Lett. 145 (1996) 15-29]. The age of the studied sequences provides important constraints on the understanding of the sedimentary evolution of the eastern Betic margin, and shows that previous interpretations of the evaporitic-diatomitic sequences of the Fortuna basin, as being coeval to the late Messinian salinity crisis in the Mediterranean, are not correct. The confinement leading to the emergence of the Fortuna basin occurred in the late Tortonian to earliest Messinian, similar to other intramontane basins in the Betics. Therefore, the inclusion of the Fortuna basin in a hypothetical marine Betic Corridor during the late Messinian is no longer tenable.

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Section: Remagnetisation In the Sifón De Librilla Sectionmentioning

confidence: 61%

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics

Garcés

Krijgsman²,

Agustí

1998

Earth and Planetary Science Letters

118

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“…Spherule shapes have also been described for fly ashes from industrial combustion [Matzka, 1997] or drilling contaminants, which are both irrelevant for our settings. Suk et al [1990] mention the possibility of magnetic spherule formation by oxidation of pyrite. However, the crystal structures of the spherules observed here does not comply with framboidal pyrite precursors.…”

Section: Magnetic Spherulesmentioning

confidence: 99%

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 oxidation rim is certainly magnetite. Replacement of pyrite by magnetite has been widely described in previous studies (e.g., [61,62]). Some alteration features are also observed in euhedral grains, which most likely represent dissolution features.…”

Section: Origin Of the Magnetic Assemblagementioning

confidence: 99%

Burial Diagenesis of Magnetic Minerals: New Insights from the Grès d’Annot Transect (SE France)

et al. 2014

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Abstract:The diagenetic evolution of the magnetic minerals during burial in sedimentary basins has been recently proposed. In this study, we provide new data from the Grès d'Annot basin, SE France. We analyze fine-grained clastic rocks that suffered a burial temperature from ~60 to >250 °C, i.e., covering oil and gas windows. Low temperature magnetic measurements (10-300 K), coupled with vitrinite reflectance data, aim at defining the magnetic mineral evolution through the burial history. Magnetite is documented throughout the entire studied transect. Goethite, probably occurring as nanoparticles, is found for a burial temperature <80 °C. Micron-sized pyrrhotite is highlighted for a burial temperature >200 °C below the Alpine nappes and the Penninic Front. A model of the evolution of the magnetic assemblage from 60 to >250 °C is proposed for clastic rocks, containing iron sulfides (pyrite) OPEN ACCESSMinerals 2014, 4 668 and organic matter. This work provides the grounds for a better understanding of the magnetic properties of petroleum plays.

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Replacement of pyrite framboids by magnetite in limestone and implications for palaeomagnetism

Cited by 136 publications

References 17 publications

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics

Chronology of the late Turolian deposits of the Fortuna basin (SE Spain): implications for the Messinian evolution of the eastern Betics

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

Burial Diagenesis of Magnetic Minerals: New Insights from the Grès d’Annot Transect (SE France)

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