Abundance of calcareous nannofossils in sediments of the Fram Strait

Sediment cores from the Fram Strait are dated by means of calcareous nannofossil biostratigraphy and are shown to represent, at the most, the last 300 kyr (oxygen isotope stages 1-8). Differences in sedimentation rates are mainly controlled by the bottom topography and the intensity of ice-rafted deposition. Sedimentation rates are normally in the order of a few centimeters per kiloyear in the central Fram Strait but increase to over 10 cm/kyr in cores located on the continental slope. The highest sediment accumulation rates occurred on the shelf (several tens of centimeters per kiloyear).

Calcareous nannofossils of ODP Sites 149-897 and 149-901

Mesozoic calcareous nannofossil assemblages recovered during Ocean Drilling Program Leg 149 from the Iberia Abyssal Plain off the coast of Portugal were examined to determine the age of the rifting processes that affected the western Iberia Margin. Dark carbonaceous claystones (black shales) recovered from Site 901 contain highly diverse and abundant Tithonian calcareous nannofossil assemblages. Careful examination and documentation of this material has extended the ranges of numerous Jurassic and Cretaceous species and detailed a significant Late Jurassic assemblage turnover observed in the calcareous nannofossil record. The Lower Cretaceous sequence consists of intervals of serpentinized peridotite intercalated between various breccias and dark claystones. With the exception of a few samples, calcareous nannofossils are few and moderately preserved. The age of nannofossils within these varied sedimentary lithologies ranges from the late Barremian to the late Aptian. Eight new species are described: Ansulasphaera covingtonii, Clepsilithus meniscus, Conusphaera sinespina, Crepidolithus parvulus, Diazomatholithus galicianus, Percivalia arata, Rotelapillus pleoseptatus, and Tranolithus incus. Also proposed are five new combinations.