Uganda Riftlink - Project B3

Linking source and sink in the Rwenzori Mountains and adjacent rift basins

Applicants: Prof. Dr. Matthias Hinderer, Dr. Jens Hornung

Funding: DFG 643/7-1 Research group RIFTLINK

Persons in charge: Sybille Roller, Sandra Schneider

Duration: 2006 – 2009

Summary

The RIFTLINK project (www.riftlink.de) adresses the causes of rift-flank-uplift in the East African Rift since the late Miocene, its impact on climate changes in East Africa, and the possible consequences of the evolution of hominids. The objective is to gain a process understanding of rift-flank uplift by investigating the origins of the >5000m high Rwenzori mountains, which are located in the Ugandan part of the Western Rift branch of the East African Rift System (EARS). Within the RIFTLINK integrated research the objectives of the sedimentological sub-project (B3) are to reconstruct the erosional evolution of the Rwenzori Mountains since their extreme uplift by merging information and data of DEM-based morphometric analysis, exposure dating with cosmogenic nuclides (TCN), dating of quartz detritus by optical stimulated luminescence (OSL), and stratigraphic field work in the rift basin deposits.

Sedimentological project work started in June 2006 and since then, three field campaigns have been performed during the dry seasons. During a circumferential reconnaissance tour, river sand of all major accessible rivers were sampled for determination of recent erosion rates by TCN exposure dating. Young alluvial fan and alluvial plain deposits of interesting areas, e.g. Mobuku and Kasaiga rivers, were sampled for dating by OSL and TCN.

The rift basin sedimentary record is best exposed NE of the northern Rwenzoris in the Nyaburogo-Kasaiga-Region. There, a suite of stratigraphic profiles has recently been recorded in several spatiotemporally spread outcrops of the rather variable clastic sedimentary succession. Further sampling was performed for analysis of clay mineralogy, biostratigraphy, palynology, grain size distribution, thermochronology, and geochemistry.

Most of the samples are in preparation as well as a synthesis of the field data, including the results of a master thesis (mapping in the Makondo area).