Magnetic enhancement of Baltic Sea sapropels by greigite magnetofossils

Reinholdsson, Maja; Snowball, Ian; Zillén, Lovisa; Lenz, Conny; Conley, Daniel J.

doi:10.1016/j.epsl.2013.01.029

Cited by 61 publications

(65 citation statements)

References 60 publications

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“…The magnetic signal associated with the lower sapropel thus contrasts sharply with the upper sapropelic layer. Similar behavior has been described by Roberts et al (1999) and Reinholdsson et al (2013) who noted a correlation between the degree of magnetic enhancement and the organic carbon content in sapropels, with high organic carbon corresponding to high concentrations of magnetic minerals. Reinholdsson et al (2013) associated this behavior to the activity of MTB population and production of greigite magnetosomes.…”

Section: Magnetic Properties Of Sapropels and Their Environmental Sigsupporting

confidence: 61%

“…This property was first attributed to the creation of an "unknown" ferrimagnetic iron sulfide phase during diagenesis (Roberts et al, 1999). Recently, Reinholdsson et al (2013) linked magnetic enhancement of laminated sapropels from the Baltic Sea to small single domain particles of greigite (Fe 3 S 4 ) interpreted as relict magnetosoms of magnetotactic bacteria (MTB). These authors suggest that magnetic properties associated to bacterial greigite could be a good proxy for hypoxia.…”

Section: Introductionmentioning

confidence: 99%

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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: 61%

Section: Introductionmentioning

confidence: 99%

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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“…Greigite has been reported within some sapropels with exceptionally high organic carbon contents. While this has been taken as an indication of a diagenetic origin (Roberts et al, 1999;Larrasoaña et al, 2003b), recent results from Baltic Sea sapropels (Reinholdsson et al, 2013) suggest that greigite in these sapropels might have a biogenic origin.…”

Section: Diagenetic Imprint On Magnetic Mineralsmentioning

confidence: 99%

Source-to-sink magnetic properties of NE Saharan dust in Eastern Mediterranean marine sediments: review and paleoenvironmental implications

et al. 2015

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“…4c). The latter parameter is often used as a magnetic grain-size indicator for low-coercivity minerals, especially magnetite, while SIRM / χ can be influenced by different mechanisms, ranging from changes in magnetic grain size (Peters and Dekkers, 2003) and magnetic mineralogy, including the presence of greigite Fu et al, 2008;Reinholdsson et Snowball, 1997b). Although paramagnetic minerals may contribute to the susceptibility, this bias would be expressed in both ratios, and a cross plot of those two parameters is valid to compare ferrimagnetic mineralogic properties between samples.…”

Section: Magnetic Proxy Evaluationmentioning

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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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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Magnetic enhancement of Baltic Sea sapropels by greigite magnetofossils

Cited by 61 publications

References 60 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

Source-to-sink magnetic properties of NE Saharan dust in Eastern Mediterranean marine sediments: review and paleoenvironmental implications

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)

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Magnetic enhancement of Baltic Sea sapropels by greigite magnetofossils

Cited by 61 publications

References 60 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

Source-to-sink magnetic properties of NE Saharan dust in Eastern Mediterranean marine sediments: review and paleoenvironmental implications

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)

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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)