Stratigraphie und Korngrößenverteilungen an spätpleistozänen Sedimenten aus der zentralen Floridastraße

• Main Author: Lezius, Jeannette A. E.
• Format: Thesis
• Language: German
• Published: 2003
• Subjects: North Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/59067/; https://oceanrep.geomar.de/id/eprint/59067/1/Dipl_Lezius_J_A_E_2003.pdf

This thesis is a contribution to the GOLDFLOS project, which analyses the varying influence of near bottom currents on recent sediments and benthic communities in the southern Florida Straits. This study focuses upon grain size analysis and the development of an age model for core S016417-2. The recent current regime and the regional environment is depicted by grain size analyses. Surface sediments along a transect from the North Cay Sal Bank to the Florida slope demonstrate the predominant sedimentary and environmental conditions with their grain size distribution. There is a notable change in high sand content and mean sortable silt values on the Cay Sal slope to low sand content and lower mean sortable silt values at the bottom of the Florida slope. This difference in sediment composition is caused by near bottom current variations and lateral input of the Cay Sal carbonate platform. The analysis of planktonic oxygen isotopes of the late Pleistocene sediment core infers palaeoclimatologic and oceanographic conclusions. The core reaches the Ericson V Zone in a continuous sequence, with a basal age of 278900 calendar years, i.e. Oxygen Isotope Stage 8. The sand content shows an analogue pattern as in other cores from the Carribean. On the whole, the content is clearly smaller but during Marine Isotope Stadium 2-3 increases substantially. The Mean Sortable Silt in the interval 0-200cm (Isotope Stages 1-4) shows an increase of current velocities during Last Glacial Maximum. As there is no evidence for a change in provenance, a change in depth of the profile of the near-surface Florida current or, alternatively, an enhanced southward flow of North Atlantic Intermediate Water could be suggested as a possible cause. The Younger Dryas north Atlantic cold period and the meltwater spill at Temination lB is mirrored in variations of oxygen isotope values. In the Florida Straits, a slight warming is recognized during Younger Dryas and an approximate decrease in salinity of 2,5 %0 at Temination 1B is notable, probably ...