Fluctuations in Miocene climate and sea levels along the southwestern South African coast: inferences from biogeochemistry, palynology and sedimentology

Simple item page
dc.contributor.authorSciscio, Lara
dc.contributor.authorNeumann, Frank H.
dc.contributor.authorRoberts, Dave
dc.contributor.authorTsikos, Harilaos
dc.contributor.authorScott, Louis
dc.contributor.authorBamford, Marion
dc.date.accessioned2013-12-18T12:13:15Z
dc.date.available2013-12-18T12:13:15Z
dc.date.issued2013-12-18
dc.description.abstractThe largest deposit of excellently preserved Mio-Pliocene vertebrate faunas in South Africa is located at the well known Langebaanweg (LBW) site along South Africa’s west coast in the southwestern Cape. This research deals with a core (BH2) drilled at Langebaanweg ‘E’ Quarry, which captures Miocene fluvial deposits that unconformably underlie the Mio-Pliocene deposits. The aim of the study is to constrain fluctuations in climate and ecosystems in the region during the Miocene, using a combination of sedimentology, palynology, and biogeochemistry. The latter is a novel application and includes bulk C and N isotope measurements as well as branched GDGT (glycerol dialkyl glycerol tetraether) membrane lipid compositions of the organic fraction of the core. The mean annual temperature (MAT) at time of deposition and ambient pH values were calculated using the Methylation index of Branched Tetraethers (MBT) and Cyclization ratio of Branched Tetraethers (CBT) proxies. The core samples analysed spanned a depth interval of 17–33 m and had MATs ranging between 12.4°C and 26.6°C and pH range from 4.4 to 6.4. Furthermore, samples showed a low variance and light d13C distribution (from –25.52‰ to –24.27‰) and overall low C/N ratios. Palynological investigation supplemented earlier similar studies, reaffirming alternating sequences of tropical and subtropical elements including wetland taxa and complementing calculated MAT results. Pollen results from the lowermost subsection indicated a species-rich tropical/subtropical Podocarpus dominated forest with MATs at 16.2°C. The pollen-bearing middle subsection shows initially subhumid conditions, with MATs between 15.4 and 26.6°C, similar to the bottom of the section with high Podocarpaceae percentages, low Restionaceae and aquatics. Above this, local taxa, e.g. Restionaceae and algae increase, and a marine influence is indicated by abundant dinoflagellates. The uppermost subsection from a depth of 7.20–7.60 m shows similar conditions (with little marine influence) to that of the lower part of the middle subsection II. Biochemical and sedimentological data are not available for the uppermost subsection. The results suggest that regional Miocene climate showed high amplitude fluctuations (possibly driven by orbital forcing as seen in marine cores), underscoring the potential of biogeochemistry for unravelling past climates and ecosystems.en_ZA
dc.description.sponsorshipPalaeontological Scientific Trust NRF/DST Centre of Excellence in Palaeosciences South African National Research Foundation African Origins Platform/West Coast Fossil Park initiative (NRF AOP/WCFP) Claude Leon Foundation South African National Research Foundationen_ZA
dc.identifier.issn0078-8554
dc.identifier.urihttp://hdl.handle.net10539/13313
dc.language.isoenen_ZA
dc.publisherEvolutionary Studies Institute, University of the Witwatersranden_ZA
dc.subjectMioceneen_ZA
dc.subjectpalmsen_ZA
dc.subjectPodocarpaceaeen_ZA
dc.subjectglycerol dialkyl glycerol tetraethers (GDGTs)en_ZA
dc.subjectSouth Africaen_ZA
dc.titleFluctuations in Miocene climate and sea levels along the southwestern South African coast: inferences from biogeochemistry, palynology and sedimentologyen_ZA
dc.typeArticleen_ZA
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
2013.v48.SCISCIO_ET_AL_Fluctuations_Miocene_climate_sea level.pdf
Size:
1.54 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Volume 48 December 2013