Fields of study

The Kalkkop palaeolake is located at ~51km southwest of the town of Graaf-Reinet in Eastern Cape, South Africa. The lake was formed after a meteorite impact event. The lake is dated around 250±50ka based on U-Th series dating (Reimold et al., 1998). The palaeolake is 640m in diameter and 89m in depth (Koeberl et al., 1994). The geology of the palaeolake comprises of finely laminated limestone which is underlain by altered rocks of the Beaufort Group. The palaeolake falls within the semi-arid Nama-Karoo biome, which is globally recognized as a biodiversity hotspot containing a diverse range of vegetation. However, there is a poor understanding of climate variability in the region over time. Most studies focus on climate conditions along coastal regions and not enough on regions inland. Anomalies in the climate systems affecting southern Africa have led to climate variability over time. This project is focused on a new 89m core which was drilled from the center of the palaeolake in 2019. The paleoclimate will be characterized using using stable light isotopes δ18O and δ13C from the core. Variations in the δ18O values will indicate seasonality in the past climate and the sources of water to the palaeolake. Variations in the δ13C values will likely represent the composition of the vegetation around the crater lake. The modern climate will be defined using temperature and rainfall records dating from the early 1900s until 2023. This will be accessed from weather stations in the field area, via the South African Weather Services. The data will be examined to find any trends or patterns in weather conditions, which can range from a seasonal to decadal basis. Climate data reflecting the behaviour of weather systems (ENSO, IOD and SIOD) in southern Africa will be accessed via Koninklijk Nederlands Meteorologisch Instituut (KNMI). The data on surrounding weather systems will be used to further define the climate conditions of the Lower Karoo. This study compares the modern climate and palaeoclimate to determine the long-term climate variability of the Lower Karoo. Identifying climate trends will help with future predictions in the climate and in the water cycle.