Mainz 2017 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 9: Accelerator Mass Spectrometry and Applications II

MS 9.8: Vortrag

Donnerstag, 9. März 2017, 16:15–16:30, RW 2

Mass spectrometry and the evolution of the western Namibian drainage systems — •Andreas Gärtner¹, Ulf Linnemann¹, Silke Merchel², Samuel Niedermann³, Axel Gerdes⁴, Georg Rugel², Andreas Scharf², Loic Le Bras², Mandy Hofmann¹, and Johannes Zieger¹ — ¹SNSD, Geochronologie, Dresden, Germany — ²HZDR, Dresden, Germany — ³GFZ, Potsdam, Germany — ⁴JWG-Universität Frankfurt, Institut für Geowissenschaften, Frankfurt, Germany

Our multi-method MS study (AMS, noble gas MS, LA-(MC)-ICP-MS) aims to constrain the evolution of the western Namibian drainages since the last ca. 40 Ma. Therefore, fluvial sediments of several rivers and their precursors were sampled. In order to obtain precise surface exposure ages of the various terrace levels, the routinely used cosmogenic nuclides ¹⁰Be, ²¹Ne, ²⁶Al (quartz), and ³⁶Cl (calcite) were applied either on surface samples or on depth-profiles consisting of 3 to 5 samples each. U-Pb small scale isochrone (SSI) ages of calcareous matrices were also used for terrace dating. Sedimentary provenances were revealed by detrital zircon (ZrSiO₄) geochronology using U-Th-Pb and Lu-Hf isotope systematics. They indicate varying detrital zircon patterns through time. Our approach facilitates the recognition of changes in the fluvial sediment provenance at certain points in time. Such combined studies have a huge potential for revealing the palaeohydrological history, and to estimate amplitudes and processing speeds of past events or changing sizes of catchment areas, which is of particular interest for modelling the palaeoclimate and palaeogeography.