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Title: Controls on aggradation and incision in the NE Negev, Israel, since the middle Pleistocene

Here, we investigated the mid-Pleistocene to recent aggradation-incision pattern of two drainage systems (Nahal Peres and Nahal Tahmas) in the hyperarid north eastern Negev desert, southern Israel. Although these drainage systems drain into the tectonically active Dead Sea basin, lake level fluctuations cannot account for the aggradation-incision pattern as bedrock knickpoints disconnect the investigated parts of these drainage systems from base level influence. We applied geomorphic mapping, soil stratigraphy, optically stimulated luminescence (OSL) and cosmogenic (in situ 10Be) exposure dating to reconstruct cycles of aggradation and incision of alluvial terraces and to study their temporal association with regional periods of humidity and aridity and global glacial-interglacial cycles. The spatial and temporal relationships between the alluvial units suggest changes in the drainage system behavior since the middle Pleistocene, and show a pattern in which prolonged periods of sediment aggradation alternated with short periods of rapid and intense degradation through erosion and incision into sediment and bedrock. We obtain ages for several Pleistocene-Holocene periods of incision: ~ 1.1 Ma, ~ 300 ka, ~ 120 ka, ~ 20 ka, ~ 12 ka and ~ 2 ka. Although broadly synchronous, the Nahal Peres and Nahal Tahmas systems exhibit temporal differences in aggradation and incision.
Authors:
 [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Hebrew Univ. of Jerusalem, Jerusalem (Israel)
  2. Hebrew Univ. of Jerusalem, Jerusalem (Israel); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Geological Survey of Israel, Jerusalem (Israel)
  4. CNRS-Aix-Marseille Univ. (France)
Publication Date:
OSTI Identifier:
1260488
Report Number(s):
LLNL-JRNL--677193
Journal ID: ISSN 0169-555X
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Geomorphology
Additional Journal Information:
Journal Volume: 261; Journal Issue: C; Journal ID: ISSN 0169-555X
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES alluvial terraces; aggradation; incision; Negev desert