Composition of Eocene claystones of ODP Hole 105-647A ...

• Main Authors: Bohrmann, Gerhard, Thiede, Jörn
• 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.745212; https://doi.pangaea.de/10.1594/PANGAEA.745212

Authigenic carbonates were recovered in lower to middle Eocene claystones at Ocean Drilling Program Site 647 in the Labrador Sea. Detailed chemical, petrographic, and X-ray investigations reveal that these diagenetic carbonates have a complex mineralogical composition. At least five different carbonate phases are identified: calcium-rich rhodochrosite, rhodochrosite, manganosiderite, siderite, and calcite. Manganese carbonates are the dominant carbonate phases formed throughout the section. Textural analyses show two major generations of carbonate formation. Early cementation of micritic carbonate in burrow structures was followed by carbonate cementation forming microsparry to sparry crystals.At approximately 620 meters below seafloor (mbsf), three concretions of iron carbonates occur, which indicates a special pore-water chemistry. Thin section analyses from this level show (1) several generations of diagenetic carbonates, (2) widespread secondary cavity formation in burrow structures, and (3) various ... : Supplement to: Bohrmann, Gerhard; Thiede, Jörn (1989): Diagenesis in Eocene claystones, ODP Site 647, Labrador Sea: formation of complex authigenic carbonates, smectites, and apatite. 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, 137-154 ...