PhD  Studentship at the University of Wales, Aberystwyth, UK

OSTRACOD GEOCHEMISTRY AS A RECORD OF ABRUPT HOLOCENE CLIMATIC CHANGE IN ETHIOPIA

CASE award with NERC Isotope Geosciences  Laboratory, Keyworth, Nottingham
Dr H.F. Lamb, Professor R.C. Whatley (Aberystwyth),   Dr MJ Leng (NERC-IGL)

Strandline and section evidence from lake basins of the Ethiopian Rift
Valley shows several abrupt arid intervals interrupting an early-to-mid
Holocene phase of enhanced monsoonal rainfall. Similar century-scale changes
have been identified in north and west Africa and central Asia, but there is
still no continuous core record of these events from Ethiopia. This project
will establish, for the first time in this key area, the precise nature and
timing of the events using palaeoecology, stable-isotope and ICP-MS
trace-element analyses of ostracods in cores already obtained from
contrasting lakes, interpreted with reference to the ecology and
geochemistry of living ostracod faunas and their host waters in a wide range
of habitats. d18O data will provide information on past variations in water
inputs (precipitation and surface runoff v groundwater), evaporative
concentration and water residence time. High d18O values should be found in
carbonates deposited during the inferred arid intervals.  d13C will provide
evidence for changes in carbon source, lake productivity, and water
residence time, as reflected in the degree of equilibration between
dissolved inorganic carbon and atmospheric CO2. Sr/Ca and Mg/Ca of the
ostracod calcite indicate past salinity and temperature variations. The
project is part of a multi-proxy approach to palaeoclimatic reconstruction,
central to the goals of the PANASH-PEP (Paleoclimate of the Northern and
Southern Hemispheres - Pole-Equator-Pole transects) Project of  PAGES (Past
Global Changes), a core project of  IGBP (International Geosphere-Biosphere
Programme).
The  student will join an inter-disciplinary team of researchers with a
unique configuration of expertise and experience in palaeolimnological
research. Training will include field sampling techniques (carried out in
collaboration with the Department of  Geology, Addis Ababa University),
ostracod extraction and identification and trace-element analysis at
Aberystwyth (Micropalaeontology Unit, ICP-MS, Dionex,) and stable-isotope
analysis at Keyworth (VG Isocarb + Optima MS).

Recent relevant publication:
Lamb, H.F., Gasse, F.,  Benkaddour, A., El Hamouti, N., van der Kaars, S.,
Perkins, W.T., Pearce, N.J. & Roberts, C.N. (1995)  Relation between
century-scale Holocene arid intervals in tropical and temperate zones.
Nature 373, 134-137

Further information may be obtained from:
 Dr H.F. Lamb
Institute of Earth Studies
University of Wales, Aberystwyth
Aberystwyth SY23 3DB

Tel: +44 -1970-622597
Fax: +44 -1970-622659
E-mail: [log in to unmask]
http://www.aber.ac.uk/~ieswww/
 Deadline for applications:  April 26 1996
Elibility restricted to European nationals