Reconstructing South African climate history from stalagmites: insights into past rainfall
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Project description
Background:
Stalagmites are key natural archives to reconstruct past climate: they can be accurately and precisely dated by radiometric methods and their presence in caves shelters them from potential degradation. The classic approach for reconstructing hydroclimate with stalagmites is the variability of oxygen isotopes in the calcite, which, in South Africa, reflects a combination of rainfall amount and rainwater sources. In addition, trace element ratios (i.e. Sr/Ca) in the carbonate provide complementary proxies for hydroclimate. Together, these proxies allow reconstructing local precipitation trends and broader regional climate patterns.
This project is part of the SapienCE Center of excellence which aims to explore how climate influenced human evolution in South Africa. Several stalagmites covering the timeframe ~50-90 thousand years ago (ka), a key period that saw significant cultural and cognitive changes in early humans, have been collected in caves close to key archeological sites. Data are already available from one cave, and we have recently collected additional stalagmites from two new caves that will be used in this project. Thereby, we can both cross-check the existing record for regional differences and extend the timeframe covered by the data back to > 110 ka. The candidate will be part of the dynamic speleothem research group at GEO and will work with state-of-the-art infrastructure at FARLAB.
Research questions:
- How did hydroclimate vary in South Africa during the last glacial cycle, in comparison to known climatic changes elsewhere?
- How consistent are the signals between different caves from the same region?
- Can drivers of climate changes be identified?
- Can we find links between the archeological record and the hydroclimate reconstruction?
Work plan:
The student will work on one or two stalagmites collected in the De Hoop Nature Reserve.The student will gain hands-on experience with U-Th dating and stable isotope analyses at FARLAB. Sr/Ca ratios could complement the isotope record if time permits. The data will be compared to existing data from other stalagmites, marine records, ice cores and climate model simulations.
Proposed course plan during the master's degree (60 ECTS)
Fall semester H25:
GEOV222 (10P)
GEOV324 (5P)
free choice (10P)
Spring semester V26:
GEOV302 (10P)
GEOV329 (10P)
GEOV342 (10P)
Fall semester H26:
GEOV300 (5P)
Field-, lab- and analysis work
- Labwork ~ 6 months, including U-Th dating, and Oxygen and Carbon isotope analyses.
- Fieldwork participation next year might be possible, though uncertain.
This project is funded bt the SFF SapienCE.
NB: This project is not yet approved by the program board.