000K utf8 1100 $c2000 1500 eng 2050 urn:nbn:de:gbv:8-diss-3647 3000 Emmermann, Peter 4000 Mineralogie, Geochemie und Mikrofazies spätquartärer Periplattformsedimente$dKarbonatexportzyklen und sekundäre Prozesse - Sanganeb Atoll und Abington Riff, Sudan, Mittleres Rotes Meer$hChristian-Albrechts-Universität zu Kiel [Emmermann, Peter] 4000 Mineralogy, geochemistry and microfacies of late Quaternary periplatform sediments$dCarbonate export cycles and secondary processes - Sanganeb Atoll and Abington Reef, Sudan, Central Red Sea$hChristian-Albrechts-Universität zu Kiel [Emmermann, Peter] 4030 Kiel$nChristian-Albrechts-Universität zu Kiel 4209 A set of sediment cores was obtained in the periplatform realm close to Sanganeb Atoll and Abington Reef, about 20 miles offshore the Sudanese coast in the central Red Sea. Microfacies, mineralogy and geochemistry of periplatform sediments were analysed to quantify glacial-interglacial variations in carbonate production and sediment export of the reefs in response to late Quaternary sealevel fluctuations. The present study showed that the periplatform sediments from the Sudanese shelf to great extend record variations in sediment export of the offshore reefs in tune with sealevel changes. This is clearly visible in the increased input of fine-grained, strontium- and aragonite-rich shallow-water derived sediment during the Holocene sealevel highstand, which is in good accordance with the highstand shedding model of carbonate systems. However, during the last interglacial sealevel highstands (marine isotope stage 5) this pattern is not clearly developed and generally no characteristic highstand bundling in the frequency of calciturbidites was observed in the Red Sea. Syn- and post-depositional processes play a significant role in the nearly isolated Red Sea basin with its unusual paleoceanographic and climatic conditions during the late Quaternary. Those processes to some extend changed the sealevel controlled sediment export signal. Of major importance is the submarine precipitation of aragonite and Mg-Calcite at the seafloor, which even led to the formation of a hard layer during marine isotope stage 2 when salinities of Red Sea surface- and bottom-waters rose over 50 ‰ during the sealevel lowstand. During high salinity phases of glacial sealevel lowstands biogenic carbonate production was drastically reduced because reefs and planktic organisms vanished nearly entirely from the Red Sea. Furthermore, glacial-interglacial changes in carbonate dissolution- and preservation at the seafloor occurred, partially in phase with monsoonal climate variations. Carbonate (aragonite) dissolution is generally increased during interglacials and a better preservation of this mineral was observed during humid phases (prevailing SW-monsoon) when stagnation of the basin led to oxygen depletion of the deeper water masses. 4950 https://nbn-resolving.org/urn:nbn:de:gbv:8-diss-3647$xR$3Volltext$534 4961 https://macau.uni-kiel.de/receive/diss_mods_00000364 5051 550 5550 14C-AMS ages 5550 Abington Reef 5550 accumulation rates 5550 aragonite 5550 calcite 5550 carbon 5550 carbonate crust 5550 carbonate mineralogy 5550 carbonate platform 5550 carbonate production 5550 Carbonatplattform 5550 climate 5550 climate stratigraphy 5550 corals 5550 deep water circulation 5550 Diagenese 5550 dissolution 5550 Geochemie 5550 grainsize 5550 hard layers 5550 highstand 5550 highstand shedding 5550 high-strontium aragonite 5550 HMC 5550 Holocene 5550 Indian monsoon 5550 inorganic precipitation 5550 last interglacial 5550 late Quaternary 5550 LGM 5550 LMC 5550 lowstand 5550 Mg-calcite 5550 microfacies 5550 OMZ 5550 oxygen 5550 oxygen depletion 5550 periplatform sediment 5550 pointcounting 5550 preservation 5550 red algae 5550 Red Sea 5550 reef 5550 Rotes Meer 5550 salinities 5550 Sanganeb Atoll 5550 sapropel 5550 scleractinian 5550 sealevel changes 5550 Sedimentation 5550 sedimentation rates 5550 sediment export 5550 SPECMAP 5550 stable isotopes 5550 strontium 5550 Sudan 5550 U/Th-ages