by Christine S Lane,
from Department of Geography, University of Cambridge
Reconstructing past spatial and temporal variability of palaeoclimate and palaeoenvironmental change across a continent as climatically diverse as Africa, relies upon comparison of data from widespread and diverse archives. However, generating accurate, precise and independent chronologies for the comparison of detailed and varied palaeo-proxy records is challenging. In Eastern Africa, explosive eruptions of rift volcanoes generate blankets of ash that can be preserved in sedimentary basins over hundreds to thousands of kilometres from their source. Distal tephra (including cryptotephra-) research offers opportunities for direct dating of sediment sequences (e.g. by 40Ar/39Ar methods) and for making precise stratigraphic correlations between archives at single moments in time. Currently however, the volcanic eruption record for the East African Rift is patchy and for tephrochronology to reach its full potential, detailed local to regional eruption stratigraphies are needed.
Investigations into the presence of visible and non-visible (crypto-) tephra layers within lacustrine palaeoenvironmental records of the mid to late Pleistocene from across eastern Africa are revealing the potential for distal tephra research to (i) increase our knowledge of the history of Late Quaternary explosive volcanism in eastern Africa; (ii) provide age constraints for individual core chronologies, in particular beyond the limits of radiocarbon dating; and (iii) correlate palaeoclimate and archaeological archives within a regional tephrostratigraphic framework.Read more