HR: 1330h
AN: PP23B-03    [Abstracts]
TI: Grain Size Analysis of Terrigenous Sediments from the SW African Margin
AU: * Perry, V R
EM: vperry4@student.gsu.edu
AF: Georgia State University, Department of Geology 24 Peachtree Center Ave 340 Kell Hall, Atlanta, GA 30303
AU: Shackford, J K
EM: jshackford1@student.gsu.edu
AF: Georgia State University, Department of Geology 24 Peachtree Center Ave 340 Kell Hall, Atlanta, GA 30303
AU: Christensen, B A
EM: bchristensen@gsu.edu
AF: Georgia State University, Department of Geology 24 Peachtree Center Ave 340 Kell Hall, Atlanta, GA 30303
AB: Median grain size of 18 samples from the Ocean Drilling Project (ODP) Leg 175 Site 1085B core are presented as part of a larger multi-proxy study to determine late Pleistocene paleoclimate for the Southwest African Margin. The site is located west of the Orange River. Site 1085 sediments contain a terrigenous component. Grain size is used as an indication of terrigenous sediment pathway (i.e. Orange River and eolian input). The fine fraction was digested in sodium acetate-acetic acid in order to remove calcite and in 30% hydrogen peroxide to remove organics (Jackson 1979). The samples were then analyzed on the Micrometrics SediGraph 5100 to determine median grain size. Our data show a range of median grain sizes from 0.3868μm to 1.8928μm with a peak between Marine Isotope Stages (MIS) 5 and 6. Similar results are seen between stages 2 and 1 (Shackford et al. 2004). Higher median grain sizes are used as an indication of eolian transport and lower median grain sizes as hemipelagic transport (Stuut, 2002). The data maintain an inverse relationship between median grain size and weight percent sand. Lower weight percent sand suggests increases carbonate dissolution, probably through greater influences from North Atlantic Deep Water (NADW).
DE: 3022 Marine sediments--processes and transport
DE: 4267 Paleoceanography
DE: 4558 Sediment transport
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2005 Joint Assembly