T76 Geomorphology and Climate Change in Hot Deserts

Monday, 23 September 2019
8:00 AM - 12:00 PM
Room 221AB, North Building

LATE QUATERNARY SEDIMENTARY AND GEOMORPHIC RECORDS FROM THE EASTERN SAHARA AND NILE VALLEY: REGIONAL PALEOHYDROLOGY, PALEOENVIORONMENTS, AND CORRELATIONS WITH MARINE ISOTOPE STAGES

Paper number: T76-4
Program: Technical Sessions
Time: 8:40 AM – 8:55 AM

Authors

Abstract

Sedimentary sequences in the hyperarid Eastern Sahara Desert and the Nile Valley provide evidence of changing environmental conditions and geomorphic processes during the Late Pleistocene and Holocene. The sequences can be used to infer regional hydrological conditions and correlated with evidence for global scale climate in the marine isotope stage (MIS) curve. Late Pleistocene stratigraphic sequences at Bir Tarfawi and Bir Sahara (BT/BS) in southern Egypt document a series of “lake” events separated by intervals of aridity. Within the Nile Valley, north of Aswan, the sediments at Wadi Kubbaniya include alluvial deposits formed by local stream activity as well as dune, sandsheet, and Nilotic sediments reflecting fluvial-eolian geomorphic processes. The BT/BS deposits include freshwater carbonates and related lithofacies interpreted as evidence of palustrine environments and small perennial lakes associated with wetter climates during MIS 5e, 5b, and 5a. At Wadi Kubbaniya there are two major sets of deposits. The older sediments are associated with late Middle Paleolithic (LMP) artifacts and include basin silt, floodplain silt, sandsheet, and channel sand deposits. An erosional episode separates the LMP aggradation sequence from an overlying series associated with Late Paleolithic (LP) artifacts. The sediment series associated with LP artifacts includes playa-pond, dune, and Nilotic silt deposits (designated the LP aggradation, LPA). Underlying the LMP aggradational deposits are sands and gravels associated with local wadi activity. These older wadi deposits appear to reflect wetter local conditions when tributaries were fed by regional rains. These hydrologic conditions at Kubbaniya can be regionally correlated with the palustrine-lake deposits at BT/BS assigned to MIS 5a. The geomorphic record from BT/BS and Kubbaniya provides the basis for interpreting paleoenvironments in Northeast Africa and for correlations with global climate change.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-332674

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