Biogenic silica in ODP Hole 105-647A ...

• Main Authors: Bohrmann, Gerhard, Stein, Ruediger
• 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.744936; https://doi.pangaea.de/10.1594/PANGAEA.744936

Eocene to Holocene sediments from Ocean Drilling Program (ODP) Site 647 (Leg 105) in the southern Labrador Sea, approximately 200 km south of the Gloria Drift deposits, were investigated for their biogenic silica composition. Three sections of different diagenetic alteration products of primary siliceous components could be distinguished: (1) opal-A was recorded in the Miocene and the early Oligocene time intervals with strongly corroded siliceous skeletons in the Miocene and mostly well preserved biogenic opal in the early Oligocene; (2) opal-CT precipitation occurs between 250-440 meters below seafloor (mbsf) (earliest Oligocene to late Eocene); (3) between 620-650 mbsf (early/middle Eocene), biogenic opal was transformed to clay minerals by authigenesis of smectites. Using accumulation rates of biogenic opal, paleoproductivity was estimated for the early Oligocene to late Eocene interval. A maximum productivity of biogenic silica probably occurred between 35.5 and 34.5 Ma (early Oligocene). No evidence ... : Supplement to: Bohrmann, Gerhard; Stein, Ruediger (1989): Biogenic silica at ODP Site 647 in the southern Labrador Sea: occurrence, diagenesis, and paleoceanographic implications. 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, 155-170 ...