SEM imaging of dry and saturated porous rocks for modeling fluid distribution on pore scale. [POSTER]
Symposium of the Society of Core Analysts, September 2007, Calgary (Canada).
Scanning electron microscopy (SEM) features a high spatial image resolution, thus allowing to study details of the pore space morphology in sedimentary rocks, and providing the basis for a realistic description of the microstructure. Our intention is to generate SEM images of porous rocks that can be applied in an
advanced modeling tool for the distribution of two fluid phases in the pore network.
By analyzing sedimentary rocks saturated with oil and brine using SEM at low temperatures (Cryo-SEM), unique information on fluid saturations and wetting properties is gathered, and the model predictions can be compared with in situ fluid distributions in the pores.
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Long-term changes vs. short-term changes in calcareous dinoflagellates - examples from the Tertiary. [POSTER]
INA 10 (10th International Nannoplankton Association Conference), August/September 2004, Lisbon (Portugal).
The long-term development of calcareous dinoflagellates in the Tertiary had recently been investigated in several cores from the Ocean Drilling Program and Deep Sea Drilling Project, respectively. The results from the Indian Ocean (Sites 747 and 761) and South Atlantic Ocean (Sites 356, 357, and 689) indicate that the assemblages are characterised by significant changes with respect to absolute and relative abundances, in addition to changes in the distribution patterns of individual taxa, wall types, and archaeopyle types. Obviously, the evolution of calcareous dinoflagellates in the Tertiary was considerably influenced by the aftermaths of the extraterrestrial impact at the Cretaceous-Tertiary boundary as well as by Cenozoic climate change. Assemblage changes occurred in steps that correlate with the major steps of the Tertiary climatic development. In particular, strong cooling events seem to have caused irreversible assemblage shifts. Short-term and reversible changes have rarely been reported from the Tertiary. However, a sudden abundance increase of calcareous dinoflagellates in the >63 µm fraction of ODP Hole 689B has been attributed to a cooling event following at least two closely spaced impact events in the early late Eocene (Vonhof et al. 2000).
The consequences of climate warming have not yet been explicitly addressed in studies on Tertiary calcareous dinoflagellates, although those periods are of special interest as analogues to the modern and future global temperature rise. Even though the studies on the long-term development of calcareous dinoflagellates seem to indicate that climate warming did not cause irreversible assemblage changes in the Tertiary, short-term changes had apparently occurred. For instance, an abundance peak of calcareous dinoflagellates in correspondence with the pronounced negative carbon isotope excursion at the Paleocene-Eocene Thermal Maximum (PETM) was found to occur in the equatorial Pacific Ocean, ODP Leg 199 (Raffi, pers. commun.).
Our ongoing studies carried out at the University of Oslo focus for the first time on a higher resolution examination of short-term changes of calcareous dinoflagellates at warming events in the Paleogene. We currently examine material from the PETM of ODP Hole 1267A (Walvis Ridge, eastern South Atlantic Ocean) and of the Middle Eocene Climatic Optimum (MECO) of ODP Hole 748B (Kerguelen Plateau, southern Indian Ocean) for their content of calcareous dinoflagellates. By focussing on these critical periods of the Cenozoic climatic evolution we aim to elucidate the effects that warming events have on calcareous dinoflagellates. The results will further improve the applicability of calcareous dinoflagellates to depict short-termed climatic changes in the fossil record.
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