When deep diagenesis in Arctic Ocean sediments compromises manganese-based geochronology.
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| Title: | When deep diagenesis in Arctic Ocean sediments compromises manganese-based geochronology. |
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| Authors: | Sundby, Bjorn1,2 bjorn.sundby@mcgill.ca, Lecroart, Pascal3 pascal.lecroart@u-bordeaux.fr, Anschutz, Pierre3 pierre.anschutz@u-bordeaux.fr, Katsev, Sergei4 skatsev@d.umn.edu, Mucci, Alfonso2 alfonso.mucci@mcgill.ca |
| Source: | Marine Geology. Aug2015, Vol. 366, p62-68. 7p. |
| Subjects: | Sediments, Manganese, Geological time scales, Gas hydrates |
| Geographic Terms: | Arctic Ocean |
| Abstract: | We used a diagenetic model to test the hypothesis that manganese-rich layers in gas hydrate-bearing Arctic Ocean sediments are reliable time markers for interglacial periods. In the model, diagenesis is fuelled by two sources of reactive carbon: particulate organic carbon settling to the sediment surface, and methane diffusing up from deep gas hydrate deposits. The model includes oxidation of organic carbon and soluble reduced manganese by oxygen supplied continuously from an invariant bottom-water oxygen reservoir; reduction of particulate manganese by hydrogen sulfide generated through anaerobic methane oxidation; transport of dissolved oxygen and manganese by diffusion; and advective transport of particulate components by burial. Particulate organic matter and particulate manganese are only supplied to the sediment during interglacials. Sulfate reduction is not modeled explicitly; instead, the effect of anaerobic methane oxidation on Mn reduction is simulated at the lower boundary of the model by prescribing that particulate manganese is reduced there to soluble Mn(II). The soluble reduced Mn then diffuses upward and is oxidatively precipitated to Mn(IV) by downward diffusing oxygen. The upward flux of soluble Mn(II) is thus a function of the rate at which particulate manganese is advected into the Mn-reduction layer at the bottom of the model; it is not synchronous with events at the sediment–water interface. Model runs reveal that, under idealized but realistic conditions for the Arctic Ocean, oxidation of upward-diffusing Mn(II) generates post-depositional manganese enrichments that cannot readily be distinguished from the manganese-rich sediment layers that accumulate during interglacials. This compromises the use of manganese-rich layers as proxies for interglacial periods. In contrast, manganese-rich layers may be used as first-order markers of interglacial periods in sediments where gas hydrates or other forms of reactive carbon are absent. [ABSTRACT FROM AUTHOR] |
| Copyright of Marine Geology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Header | DbId: egs DbLabel: Engineering Source An: 102980123 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: When deep diagenesis in Arctic Ocean sediments compromises manganese-based geochronology. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Sundby%2C+Bjorn%22">Sundby, Bjorn</searchLink><relatesTo>1,2</relatesTo><i> bjorn.sundby@mcgill.ca</i><br /><searchLink fieldCode="AR" term="%22Lecroart%2C+Pascal%22">Lecroart, Pascal</searchLink><relatesTo>3</relatesTo><i> pascal.lecroart@u-bordeaux.fr</i><br /><searchLink fieldCode="AR" term="%22Anschutz%2C+Pierre%22">Anschutz, Pierre</searchLink><relatesTo>3</relatesTo><i> pierre.anschutz@u-bordeaux.fr</i><br /><searchLink fieldCode="AR" term="%22Katsev%2C+Sergei%22">Katsev, Sergei</searchLink><relatesTo>4</relatesTo><i> skatsev@d.umn.edu</i><br /><searchLink fieldCode="AR" term="%22Mucci%2C+Alfonso%22">Mucci, Alfonso</searchLink><relatesTo>2</relatesTo><i> alfonso.mucci@mcgill.ca</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Marine+Geology%22">Marine Geology</searchLink>. Aug2015, Vol. 366, p62-68. 7p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Sediments%22">Sediments</searchLink><br /><searchLink fieldCode="DE" term="%22Manganese%22">Manganese</searchLink><br /><searchLink fieldCode="DE" term="%22Geological+time+scales%22">Geological time scales</searchLink><br /><searchLink fieldCode="DE" term="%22Gas+hydrates%22">Gas hydrates</searchLink> – Name: SubjectGeographic Label: Geographic Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Arctic+Ocean%22">Arctic Ocean</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We used a diagenetic model to test the hypothesis that manganese-rich layers in gas hydrate-bearing Arctic Ocean sediments are reliable time markers for interglacial periods. In the model, diagenesis is fuelled by two sources of reactive carbon: particulate organic carbon settling to the sediment surface, and methane diffusing up from deep gas hydrate deposits. The model includes oxidation of organic carbon and soluble reduced manganese by oxygen supplied continuously from an invariant bottom-water oxygen reservoir; reduction of particulate manganese by hydrogen sulfide generated through anaerobic methane oxidation; transport of dissolved oxygen and manganese by diffusion; and advective transport of particulate components by burial. Particulate organic matter and particulate manganese are only supplied to the sediment during interglacials. Sulfate reduction is not modeled explicitly; instead, the effect of anaerobic methane oxidation on Mn reduction is simulated at the lower boundary of the model by prescribing that particulate manganese is reduced there to soluble Mn(II). The soluble reduced Mn then diffuses upward and is oxidatively precipitated to Mn(IV) by downward diffusing oxygen. The upward flux of soluble Mn(II) is thus a function of the rate at which particulate manganese is advected into the Mn-reduction layer at the bottom of the model; it is not synchronous with events at the sediment–water interface. Model runs reveal that, under idealized but realistic conditions for the Arctic Ocean, oxidation of upward-diffusing Mn(II) generates post-depositional manganese enrichments that cannot readily be distinguished from the manganese-rich sediment layers that accumulate during interglacials. This compromises the use of manganese-rich layers as proxies for interglacial periods. In contrast, manganese-rich layers may be used as first-order markers of interglacial periods in sediments where gas hydrates or other forms of reactive carbon are absent. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Marine Geology is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.margeo.2015.04.005 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 7 StartPage: 62 Subjects: – SubjectFull: Sediments Type: general – SubjectFull: Manganese Type: general – SubjectFull: Geological time scales Type: general – SubjectFull: Gas hydrates Type: general – SubjectFull: Arctic Ocean Type: general Titles: – TitleFull: When deep diagenesis in Arctic Ocean sediments compromises manganese-based geochronology. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Sundby, Bjorn – PersonEntity: Name: NameFull: Lecroart, Pascal – PersonEntity: Name: NameFull: Anschutz, Pierre – PersonEntity: Name: NameFull: Katsev, Sergei – PersonEntity: Name: NameFull: Mucci, Alfonso IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 08 Text: Aug2015 Type: published Y: 2015 Identifiers: – Type: issn-print Value: 00253227 Numbering: – Type: volume Value: 366 Titles: – TitleFull: Marine Geology Type: main |
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