Northwest African biomes and climate variability during the Pliocene

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This project strives for a much improved understanding of the variability of climate and vegetation in Northwest Africa and its driving forces during the Pliocene. Specifically, the role of enhanced overturning circulation and northward heat transport due to closure of the Central American Seaway (CAS) in causing the Mid-Pliocene Warm Period (MPWP) with increased tropical rainfall and extension of savannah woodland and forest biomes will be investigated. Therefore, we will utilize sediments from ODP Site 659, located ideally to record aeolian-transported signals from the savannah-forest transition. Past rainfall variability will be reconstructed by D/H analyses on plant waxes with information on the expansion of C4 grasses (emergence of the modern savannah biome) from lipid 13C analyses. In conjunction, marine palynology will provide detailed information on vegetation composition enabling biome reconstructions. Existing records of dust flux and deep-ocean circulation changes will be used for comparison. The period 3.6-3.0 Ma will be investigated in millennial-scale resolution. In the 3rd year, these analyses will be extended to the interval preceding the CAS closure (4.9- 4.6 Ma) with reduced northward heat transport and without Northern Hemisphere ice sheets to detect climatic and vegetation variability without these forcing factors.