1
views
0
recommends
+1 Recommend
1 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Organomineral nanocomposite carbon burial during Oceanic Anoxic Event 2

      ,
      Biogeosciences
      Copernicus GmbH

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          <p><strong>Abstract.</strong> Organic carbon (OC) enrichment in sediments deposited during Oceanic Anoxic Events (OAEs) is commonly attributed to elevated productivity and marine anoxia. We find that OC enrichment in the late Cenomanian aged OAE 2 at the Demerara Rise was controlled by the co-occurrence of anoxic bottom water, sufficient productivity to saturate available mineral surfaces, and variable deposition of high surface area detrital smectite clay. Redox indicators show consistently oxygen-depleted conditions, while a strong correlation between OC concentration and sediment mineral surface area (<i>R</i><sup>2</sup> = 0.92) occurs across a range of total organic carbon (TOC) values from 9 to 33%. X-ray diffraction data indicate the intercalation of OC in smectite interlayers, while electron, synchrotron infrared and X-ray microscopy show an intimate association between clay minerals and OC, consistent with preservation of OC as organomineral nanocomposites and aggregates rather than discrete, μm-scale pelagic detritus. Since the consistent ratio between TOC and mineral surface area suggests that excess OC relative to surface area is lost, we propose that it is the varying supply of smectite that best explains variable organic enrichment against a backdrop of continuous anoxia, which is conducive to generally high TOC during OAE 2 at the Demerara Rise. Smectitic clays are unique in their ability to form stable organomineral nanocomposites and aggregates that preserve organic matter, and are common weathering products of continental volcanic deposits. An increased flux of smectite coinciding with high carbon burial is consistent with evidence for widespread volcanism during OAE 2, so that organomineral carbon burial may represent a potential feedback to volcanic degassing of CO<sub>2</sub>.</p>

          Related collections

          Most cited references47

          • Record: found
          • Abstract: not found
          • Article: not found

          Trace metals as paleoredox and paleoproductivity proxies: An update

            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            Geochemistry of oceanic anoxic events

              Bookmark
              • Record: found
              • Abstract: not found
              • Article: not found

              Preservation of organic matter in marine sediments: controls, mechanisms, and an imbalance in sediment organic carbon budgets?

                Bookmark

                Author and article information

                Journal
                Biogeosciences
                Biogeosciences
                Copernicus GmbH
                1726-4189
                2014
                September 18 2014
                : 11
                : 18
                : 4971-4983
                Article
                10.5194/bg-11-4971-2014
                4e740818-db77-4b12-8ce6-1e85494883c7
                © 2014

                https://creativecommons.org/licenses/by/3.0/

                History

                Comments

                Comment on this article