Diagenetic modulation of the magnetic properties in sediments from the Northern Indian Ocean

Bouilloux, A.; Valet, Jean‐Pierre; Bassinot, Franck; Joron, Jean-Louis; Blanc-Valleron, Marie-Madeleine; Moréno, Eva; Dewilde, Fabien; Kars, Myriam

doi:10.1002/ggge.20234

Cited by 11 publications

(7 citation statements)

References 76 publications

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“…Many studies of coastal, hemipelagic, and pelagic sediments document progressive down‐core diagenetic dissolution of detrital iron oxides in reducing environments (Bouilloux et al, ; Chang, Bolton, et al, ; Channell & Hawthorne, ; Dillon & Bleil, ; Emiroglu et al, ; Garming et al, ; Karlin, , ; Karlin & Levi, , ; Kawamura et al, ; Leslie, Hammond, et al, ; Leslie, Lund, et al, ; Liu et al, ; Mohamed et al, ; Rey et al, ; Richter et al, ; Riedinger et al, ; Roberts, ; Roberts & Turner, ; Robinson et al, ; Rowan et al, ; Yamazaki et al, ). These studies provide a common picture of surface sediments, generally with all stages of organic matter diagenesis recognized in pore water profiles (Figure ; Roberts, ).…”

Section: Resultsmentioning

confidence: 99%

Signatures of Reductive Magnetic Mineral Diagenesis From Unmixing of First‐Order Reversal Curves

et al. 2018

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Diagenetic alteration of magnetic minerals occurs in all sedimentary environments and tends to be severe in reducing environments. Magnetic minerals provide useful information about sedimentary diagenetic processes, which makes it valuable to use magnetic properties to identify the diagenetic environment in which the magnetic minerals occur and to inform interpretations of paleomagnetic recording or environmental processes. We use a newly developed first‐order reversal curve unmixing method on well‐studied samples to illustrate how magnetic properties can be used to assess diagenetic processes in reducing sedimentary environments. From our analysis of multiple data sets, consistent magnetic components are identified for each stage of reductive diagenesis. Relatively unaltered detrital and biogenic magnetic mineral assemblages in surficial oxic to manganous diagenetic environments undergo progressive dissolution with burial into ferruginous and sulfidic environments and largely disappear at the sulfate‐methane transition. Below the sulfate‐methane transition, a weak superparamagnetic to largely noninteracting stable single domain (SD) greigite component is observed in all studied data sets. Moderately interacting stable SD authigenic pyrrhotite and strongly interacting stable SD greigite are observed commonly in methanic environments. Recognition of these characteristic magnetic components enables identification of diagenetic processes and should help to constrain interpretation of magnetic mineral assemblages in future studies. A key question for future studies concerns whether stable SD greigite forms in the sulfidic or methanic zones, where formation in deeper methanic sediments will cause greater delays in paleomagnetic signal recording. Authigenic pyrrhotite forms in methanic environments, so it will usually record a delayed paleomagnetic signal.

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Section: Resultsmentioning

confidence: 99%

Signatures of Reductive Magnetic Mineral Diagenesis From Unmixing of First‐Order Reversal Curves

et al. 2018

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“…[] documented long‐term magnetic property variations that were driven by climatically controlled, nonsteady state OC flux in eastern Mediterranean sediments. Several other studies also demonstrate the complexities associated with nonsteady state magnetic mineral diagenesis in sedimentary records [e.g., Riedinger et al ., ; Blanchet et al ., ; Itambi et al ., ; Abrajevitch and Kodama , ; Kawamura et al ., ; Bouilloux et al ., ; Roberts , ].…”

Section: Introductionmentioning

confidence: 99%

Asian monsoon modulation of nonsteady state diagenesis in hemipelagic marine sediments offshore of Japan

Chang

Bolton

Dekkers

et al. 2016

Geochem Geophys Geosyst

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We have identified millennial-scale variations in magnetic mineral diagenesis from Pacific Ocean sediments offshore of Japan that we correlate with changes in organic carbon burial that were likely driven by Asian monsoon fluctuations. The correlation was determined by identifying offsets between the positions of fossil diagenetic fronts and climatically induced variations in organic carbon burial inferred from magnetic and geochemical analyses. Episodes of intense monsoon activity and attendant sediment magnetic mineral diagenesis also appear to correlate with Heinrich events, which supports the existence of climatic telecommunications between Asia and the North Atlantic region. Several lines of evidence support our conclusions: (1) fluctuations in down-core magnetic properties and diagenetic pyrite precipitation are approximately coeval; (2) localized stratigraphic intervals with relatively stronger magnetic mineral dissolution are linked to enhanced sedimentary organic carbon contents that gave rise to nonsteady state diagenesis; (3) down-core variations in elemental S content provide a proxy for nonsteady state diagenesis that correlate with key records of Asian monsoon variations; and (4) relict titanomagnetite that is preserved as inclusions within silicate particles, rather than secondary authigenic phases (e.g., greigite), dominates the strongly diagenetically altered sediment intervals and are protected against sulfidic dissolution. We suggest that such millennial-scale environmental modulation of nonsteady state diagenesis (that creates a temporal diagenetic filter and relict magnetic mineral signatures) is likely to be common in organic-rich hemipelagic sedimentary settings with rapidly varying depositional conditions. Our work also demonstrates the usefulness of magnetic mineral inclusions for recording important environmental magnetic signals.

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“…High TOC values associated with low K levels reflect, therefore, diagenetic dissolution of magnetite while low TOC and high susceptibilities indicate very low iron reduction [ Snowball , ]. In contrast to what has been observed in the Gulf of Aden [ Bouilloux et al ., ], the absence of correlation between K and the S ratio indicates that the iron released after dissolution of fine magnetite grains was not remobilized in the formation of high coercivity material. In the present case, the dependence between TOC and K is not only observed over long periods but also over short timescales, specifically remarkable during MIS 3 (Figure ).…”

Section: Discussionmentioning

confidence: 99%

“…We applied the technique described in Joron et al [1997]. Here, we focus on four elements: iron (Fe), key component as far as magnetic properties are concerned; and Thorium (Th); Tantalum (Ta); and Hafnium (Hf ), which were successfully used to differentiate the sediment sources in sediments from the Northern Indian Ocean [Bouilloux et al, 2013].…”

Section: Elemental Composition Of Sedimentary Materialsmentioning

confidence: 99%

Influence of seawater exchanges across the Bab-el-Mandeb Strait on sedimentation in the Southern Red Sea during the last 60 ka

et al. 2013

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[1] The location of core MD92-1008 close to the southern edge of the Red Sea is ideal to study the evolution of seawater exchanges with the Northern Indian Ocean through the Bab-el-Mandeb narrow strait. The present study was aimed at documenting the paleoceanographic evolution of this area over the past 60 ka using high-resolution magnetic, sedimentological, and geochemical indicators. Two modes of variability dominate the records: (i) long-term, glacial-interglacial variations and (ii) rapid, millennial scale variability (Dansgaard-Oeschger type) during the last glacial period. Changes in magnetic concentration were documented from natural and laboratory magnetizations after proper normalization. They are inversely correlated to the total organic carbon (TOC) content, pointing out the key role played by reductive dissolution of magnetite on the evolution of magnetic concentration. Based on the temporal evolution of TOC, CaCO 3 , and planktonic δ 13 C, we suggest that past changes in the organic matter content (i) were closely linked to glacio-eustatic variations which modulated long-term seawater exchanges and nutrient supplies to the Red Sea through the narrow Bab-el-Mandeb Strait and (ii) reflect millennial-scale changes in productivity driven by monsoon wind intensity which controlled the amount of nutrient-rich intermediate waters upwelled in the Gulf of Aden during the summer season and advected into the Southern Red Sea. The sea level rise following the onset of deglaciation generated a rapid flush of detrital material that was accumulated on the continental margins and on the previously emerged zones of the Bab-el-Mandeb area.

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Diagenetic modulation of the magnetic properties in sediments from the Northern Indian Ocean

Cited by 11 publications

References 76 publications

Signatures of Reductive Magnetic Mineral Diagenesis From Unmixing of First‐Order Reversal Curves

Signatures of Reductive Magnetic Mineral Diagenesis From Unmixing of First‐Order Reversal Curves

Asian monsoon modulation of nonsteady state diagenesis in hemipelagic marine sediments offshore of Japan

Influence of seawater exchanges across the Bab-el-Mandeb Strait on sedimentation in the Southern Red Sea during the last 60 ka

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