Reductive diagenesis, magnetite dissolution, greigite growth and paleomagnetic smoothing in marine sediments: A new view

Rowan, Christopher J.; Roberts, Andrew P.; BROADBENT, T. A. A.

doi:10.1016/j.epsl.2008.10.016

Cited by 212 publications

(275 citation statements)

References 54 publications

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“…2f, i, j), which are often associated with the presence of greigite (e.g., Fu et al, 2008;Peters and Dekkers, 2003;Rowan et al, 2009). It is important to note that these parameters can sometimes provide ambiguous results; high SIRM / χ is not always accompanied by high GRM / NRM; however, MDFs are high if any of the former proxies are elevated.…”

Section: Magnetic Proxy Evaluationmentioning

confidence: 99%

“…On the other hand, the primary magnetic mineral assemblage of detrital origin is often overprinted by post-depositional alteration (Hounslow and Maher, 1999;Roberts et al, 1996). The latter results from changing redox conditions at the lake/sea floor and in subsurface sediments leading to dissolution of iron oxides and formation of ferrimagnetic iron sulfides, such as greigite and pyrrhotite (Demory et al, 2005;Froelich et al, 1979;Karlin and Levi, 1983;Rowan et al, 2009;Sagnotti, 2007;Vasiliev et al, 2007) or paramagnetic minerals, such as pyrite, siderite, and vivianite (Dong et al, 2000;Karlin and Levi, 1983).…”

Section: Introductionmentioning

confidence: 99%

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Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

et al. 2016

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Abstract. The bulk magnetic mineral record from Lake Ohrid, spanning the past 637 kyr, reflects large-scale shifts in hydrological conditions, and, superimposed, a strong signal of environmental conditions on glacial-interglacial and millennial timescales. A shift in the formation of early diagenetic ferrimagnetic iron sulfides to siderites is observed around 320 ka. This change is probably associated with variable availability of sulfide in the pore water. We propose that sulfate concentrations were significantly higher before ∼ 320 ka, due to either a higher sulfate flux or lower dilution of lake sulfate due to a smaller water volume. Diagenetic iron minerals appear more abundant during glacials, which are generally characterized by higher Fe / Ca ratios in the sediments.While in the lower part of the core the ferrimagnetic sulfide signal overprints the primary detrital magnetic signal, the upper part of the core is dominated by variable proportions of high-to low-coercivity iron oxides. Glacial sediments are characterized by high concentration of high-coercivity magnetic minerals (hematite, goethite), which relate to enhanced erosion of soils that had formed during preceding interglacials. Superimposed on the glacial-interglacial behavior are millennial-scale oscillations in the magnetic mineral composition that parallel variations in summer insolation. Like the processes on glacial-interglacial timescales, low summer insolation and a retreat in vegetation resulted in enhanced erosion of soil material. Our study highlights that rock-magnetic studies, in concert with geochemical and sedimentological investigations, provide a multi-level contribution to environmental reconstructions, since the magnetic properties can mirror both environmental conditions on land and intra-lake processes.

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Section: Magnetic Proxy Evaluationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

et al. 2016

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“…Neoformed magnetite is very common in sedimentary rocks. Many studies reported the presence of iron sulfides (pyrite, greigite) at a temperature < 50 °C (e.g., [6,63]). Iron sulfides are produced during early diagenesis by the destruction of the detrital magnetic minerals by bacterial activity (e.g., [19]).…”

Section: Toward a Burial Modelmentioning

confidence: 99%

“…In this perspective, the broad contours of the diagenesis of the magnetic minerals in argillaceous rocks were proposed from early burial (subsurface) to the lower greenschist facies metamorphism [1][2][3][4][5][6][7]. Recently, Aubourg et al [8] defined three magnetic windows where greigite (Fe 3 S 4 ; from subsurface to ~8 km of depth, i.e., up to ~200 °C), magnetite (Fe 3 O 4 ; ~2 to ~12 km of depth, i.e., ~50 to ~300 °C) and pyrrhotite (Fe 7 S 8 ; >8 km of depth, i.e., >200 °C) formed successively from low to deep burial by considering a geothermal gradient of 25 °C/km, which is typical in a foreland context.…”

Section: Introductionmentioning

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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“…Identification of the process(es) driving the magnetic response in any particular record can be a non-trivial undertaking as magnetic concentration, grain size and mineralogy can be sensitive to geological variations [2,23], sediment particle size [11,[30][31][32], sediment transport, delivery, and flux [4,7,9,25,26], anthropogenic pollution [13][14][15], and diagenetic [33][34][35][36][37], and authigenic [38][39][40] changes. When bulk magnetic properties are measured they often reflect this competition of different processes and magnetic mineral sources.…”

Section: Introductionmentioning

confidence: 99%

Particle Size-Specific Magnetic Measurements as a Tool for Enhancing Our Understanding of the Bulk Magnetic Properties of Sediments

Hatfield

2014

Minerals

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Bulk magnetic properties of soils and sediments are often sensitive proxies for environmental change but commonly require interpretation in terms of the different sources of magnetic minerals (or components) that combine to generate them. Discrimination of different components in the bulk magnetic record is often attempted through endmember unmixing and/or high resolution measurements that can require intensive measurement plans, assume linear additivity, and sometimes have difficulty in discriminating a large number of sources. As an alternative, magnetic measurements can be made on isolated sediment fractions that constitute the bulk sample. When these types of measurements are taken, heterogeneity is frequently observed between the magnetic properties of different fractions, suggesting different magnetic components often associate with different physical grain sizes. Using a particle size-specific methodology, individual components can be isolated and studied and bulk magnetic properties can be linked to, and isolated from, sedimentological variations. Deconvolving sedimentary and magnetic variability in this way has strong potential for increased understanding of how magnetic fragments are carried in natural systems, how they vary with different source(s), and allows for a better assessment of the effect environmental variability has in driving bulk magnetic properties. However, despite these benefits, very few studies exploit the information they can provide. Here, I present an overview of the different sources of magnetic minerals, why they might associate with different sediment fractions, how bulk magnetic measurements have been used to understand the contribution of different components to the bulk magnetic record, and outline OPEN ACCESSMinerals 2014, 4 759 how particle size-specific magnetic measurements can assist in their better understanding. Advantages and disadvantages of this methodology, their role alongside bulk magnetic measurements, and potential future directions of research are also discussed.

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Reductive diagenesis, magnetite dissolution, greigite growth and paleomagnetic smoothing in marine sediments: A new view

Cited by 212 publications

References 54 publications

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

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

Particle Size-Specific Magnetic Measurements as a Tool for Enhancing Our Understanding of the Bulk Magnetic Properties of Sediments

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Reductive diagenesis, magnetite dissolution, greigite growth and paleomagnetic smoothing in marine sediments: A new view

Cited by 212 publications

References 54 publications

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

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

Particle Size-Specific Magnetic Measurements as a Tool for Enhancing Our Understanding of the Bulk Magnetic Properties of Sediments

Contact Info

Product

Resources

About

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)

Environmental control on the occurrence of high-coercivity magnetic minerals and formation of iron sulfides in a 640 ka sediment sequence from Lake Ohrid (Balkans)