Geochemistry of middle Eocene-lower Oligocene pelagic sediments of ODP Hole 105-647A ...

• Main Authors: Arthur, Michael A, Dean, Walter E, Zachos, James C, Kaminski, Michael Anthony, Hagerty Rieg, S, Elmstrom, K
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA 1989
• Subjects: Drilling/drill rig; Leg105; Joides Resolution; Ocean Drilling Program ODP; Labrador Sea
• Online Access: https://dx.doi.org/10.1594/pangaea.745209; https://doi.pangaea.de/10.1594/PANGAEA.745209

Geochemical analyses of the middle Eocene through lower Oligocene lithologic Unit IIIC (260-518 meters below seafloor [mbsf]) indicate a relatively constant geochemical composition of the detrital fraction throughout this depositional interval at Ocean Drilling Program (ODP) Site 647 in the southern Labrador Sea. The main variability occurs in redox-sensitive elements (e.g., iron, manganese, and phosphorus), which may be related to early diagenetic mobility in anaerobic pore waters during bacterial decomposition of organic matter. Initial preservation of organic matter was mediated by high sedimentation rates (36 m/m.y.). High iron (Fe) and manganese (Mn) contents are associated with carbonate concretions of siderite, manganosiderite, and rhodochrosite. These concretions probably formed in response to elevated pore-water alkalinity and total dissolved carbon dioxide (CO2) concentrations resulting from bacterial sulfate reduction, as indicated by nodule stable-isotope compositions and pore-water geochemistry. ... : Supplement to: Arthur, Michael A; Dean, Walter E; Zachos, James C; Kaminski, Michael Anthony; Hagerty Rieg, S; Elmstrom, K (1989): Geochemical expression of early diagenesis in Middle Eocene-Lower Oligocene Pelagic sediments in the southern Labrador Sea, Site 647, ODP Leg 105. In: Srivastava, SP; Arthur, M; Clement, B; et al. (eds.), Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 105, 111-135 ...