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- Title
Spatially variable sedimentary responses to orbitally driven pluvial climate during Marine Oxygen Isotope Stage 5.1, Dakhla Oasis region, Egypt
- Authors
Brookes, Ian A.
- Abstract
Abstract: Pleistocene basinal sediments (PBS) in the Dakhla region of Egypt''s hyperarid Western Desert comprise four facies: (A) fluvio-lacustrine, (B) mixed lacustrine/pluvio-eolian, (C) pluvio-eolian, and (D) mixed eolian/pluvio-eolian. Contiguity of basins containing each facies, and their stratigraphic position between two bajada gravel formations, P/B-II and P/B-III, confirm their equivalence. Facies A and B, with lacustrine components, are attributed to orbitally forced poleward incursion of the Intertropical Convergence Zone (ITCZ), resulting in increased summer insolation/temperature/precipitation. Facies C and D, comprising pluvio-eolian and eolian sediments, reflect geologic/topographic influences overprinted on regional ''pluvial'' conditions, eliminating lacustrine response. A Th/U age of ∼62ka on lacustrine marl within Facies B is minimal, and an OSL age of 110±18ka on sediments immediately below Facies B is maximal. Since bajada gravels P/B-III are the youngest Pleistocene formation, they must represent the final strong incursion of the ITCZ into the Dakhla region at MIS 5.1, ∼80ka. Because PBS Facies A pass rapidly up into P/B-III bajada gravels, PBS are assigned to the rising limb of the MIS 5.1 insolation/temperature/precipitation curve, slightly younger than 80ka.
- Subjects
DAKHLA Oasis (Egypt); EGYPT; SPATIAL variation; PLUVIAL periods; OXYGEN isotopes; SEDIMENTS; PLEISTOCENE paleoclimatology; INTERTROPICAL convergence zone
- Publication
Quaternary Research, 2010, Vol 74, Issue 2, p252
- ISSN
0033-5894
- Publication type
Article
- DOI
10.1016/j.yqres.2010.05.001