[Schäbitz] The Chew Bahir Coring Project: Climate-vegetation feedbacks during the African Humid Period in the southern Ethiopian Rift

German Title: The Chew Bahir Coring Project: Climate-vegetation feedbacks during the African Humid Period in the southern Ethiopian Rift

Abbreviation: 264

Current Status: completed

Main Applicant:Prof. Dr. Frank Schäbitz

Resources Recipient

Prof. Dr. Martin Trauth

Other Persons

Dr. Verena Förster

Conveyor Begin: 1 April, 2010
Conveyor End: 31 March, 2012
Conveyor Duration: 24
Year: 2010


We have collected six up to 18.86 m long sediment cores CB01–06 from the Chew Bahir basin, Southern Ethiopian Rift. The analysis of these cores has provided the necessary information about sedimentary processes in the Chew Bahir as required for detailed planning of deeper drilling in the Southern Ethiopian Rift within the framework of the ICDP Hominid Sites and Paleolakes Drilling Project (HSPDP) project that has already been delivered two up to 272 m long cores to be analyzed from mid April 2015 on. The core lithology of CB01-06 comprises lacustrine silty clays, intercalated with sandy coarse detrital layers, interpreted as resulting from erosional input by strong rainfall events from an arid, sparsely vegetated catchment; diatoms and ostracodes are present, mostly in discrete layers of the core profile; pollen and spore concentrations are low (Objective #1). The uppermost Chew Bahir basin sediments have been shown to be suitable for dating by radiocarbon, while the quartz and tephra content ensure strong potential for luminescence and Ar/Ar dating of the deeper sedimentary archive, supplemented by paleomagnetic geochronology. The mean sediment accumulation rate (SAR) determined from the pilot core is 0.7 mm/a, but the rate varies, with a relatively high value of 1.3 mm/a from 45 to 40 ka BP. After 40 ka BP, sedimentation rates decreased to 0.6 mm/a until ~35 ka BP), and then to 0.1 mm/a until 13 ka BP. The sedimentation rate then increased in two steps, from 0.4 mm/a between 13 and 3 ka BP, to 0.7 mm/a between 3 and 1 ka BP, reaching 1.3 mm/a during the last millennium (Objective #2). Geochemical, physical and biological indicators show that Chew Bahir responded to climatic fluctuations on millennial to centennial timescales, and to the precessional cycle, since the Last Glacial Maximum. Potassium content of the sediment appears to be a reliable proxy for aridity, showing that Chew Bahir reacted to the insolation-controlled humidity increase of the African Humid Period (ca. 15-5 kyr BP) with a remarkably abrupt onset and a gradual termination, framing a sharply defined arid phase (~12.8–11.6 ka cal BP) corresponding to the Younger Dryas chronozone. The Chew Bahir record correlates well with low- and high-latitude (mainly of the northern hemisphere) paleoclimate, demonstrating that the site responded to regional and global climate changes (Objective #3).

Related Publications

Förster, Verena, Decampo, Daniel M., Asrat, Asfawossen, Günter, Christina, Junginger, Annett, Krämer, Kai Hauke, Stroncik, Nicole A., Trauth, Martin H. (2018). "Towards an understanding of climate proxy formation in the Chew Bahir basin, southern Ethiopian Rift" Paleogeography, Paleoclimatology, Paleoecology 501 p111-123