Late Quaternary paleoceanography in the South Tasman Region : implications of benthic foraminifers and grain size analysis

• Main Author: Rüggeberg, Andres
• Format: Thesis
• Language: English
• Published: 2000
• Subjects: Pacific; South Tasman Rise; Southern Ocean
• Online Access: https://oceanrep.geomar.de/id/eprint/59452/; https://oceanrep.geomar.de/id/eprint/59452/1/Dipl_R%C3%BCggeberg_A_2000.pdf

This Thesis was compiled as part of the TASQWA project, which is an international project for reconstructing the variability of the water masses in the southern Tasman Sea and the Southern Ocean (SW Pacific Sector) of the late Quaternary. The paleoclimatic and paleoceanographic reconstructions are concentrated on micropaleontological, mineralogical and sedimentological analyses. The studied area is the South Tasman Rise (STR), which is located in the southern extension of Tasmania/ Australia. This still poorly investigated area is thought to play a major role as a part of the "Global Ocean Conveyor Belt" for the global ocean circulation. The goal of this thesis was to perform micropaleontological and sedimentological investigations of two sediment cores (SO136-124 and SO136-155), retrieved during cruise SO 136 at the STR. The two sediment cores were studied for its benthic foraminiferal assemblages and grain sizes of the bulk silt-sized fraction (2-63 μm). Late Quaternary sediment Core SO136-155 presents a distribution into oxygen isotope Stages 1 to late 6. Epistominella exigua is dominating the assemblage of the most important factor, revealed by multivariate statistics. Its accumulation rate (BFAR = Benthic Foraminiferal Accumulation Rate) shows peaks during glacial Stages 2, 4 and 6 and indicates short-term fluxes of fresh organic matter to the sea floor. This correlates well with the distribution of the subfraction 4.5 - 9 μm, consisting of coccoliths, coccolithophorids and to a minor degree of diatoms. These features indicate a northward shift of the frontal system and the influence of the nutrient-rich Subantarctic Surface Water, which induced plankton-blooms during glacial periods. The faunal assemblage of Pullenia quinqueloba and Pullenia bulloides dominates a second factor and suggests a continuous organic matter supply during interglacial Stages 1 and 5 (in particular in Substage 5.5). The distribution of the silt fraction shows maxima in subfraction 2 - 4 μm ( dominantly consisting of individual ...