Timing of Pleistocene glaciations in the High Atlas, Morocco: new 10Be and 36Cl exposure ages

Hughes, P. D., Fink, D., Rodés, Á. , Fenton, C. R. and Fujioka, T. (2018) Timing of Pleistocene glaciations in the High Atlas, Morocco: new 10Be and 36Cl exposure ages. Quaternary Science Reviews, 180, pp. 193-213. (doi: 10.1016/j.quascirev.2017.11.015)

Abstract

This paper presents data from 42 new samples yielding Late Pleistocene cosmogenic 10Be and 36Cl exposure ages of moraine boulders across a series of glaciated valleys in the Toubkal Massif (4167 m a.s.l.), High Atlas, Morocco. This represents the first comprehensive Pleistocene glacial chronology in North Africa and one of the largest datasets from the Mediterranean region. The timing of these glacier advances has major implications for understanding the influence of Atlantic depressions on moisture supply to North Africa and the Mediterranean basin during the Pleistocene. The oldest and lowest moraines which span elevations from ∼1900 to 2400 m a.s.l. indicate that the maximum glacier advance occurred from MIS 5 to 3 with a combined mean 10Be and 36Cl age of 50.2 ± 19.5 ka (1 SD; n = 12, 7 outliers). The next moraine units up-valley at higher elevations (∼2200–2600 m a.s.l.) yielded exposure ages close to the global Last Glacial Maximum (LGM) with a combined mean 10Be and 36Cl age of 22.0 ± 4.9 ka (1 SD; n = 9, 7 outliers). The youngest exposure ages are from moraines that were emplaced during the Younger Dryas with a combined mean 10Be and 36Cl age of 12.3 ± 0.9 ka (1 SD; n = 7, no outliers) and are found in cirques at the highest elevations ranging from ∼2900 to 3300 m a.s.l. From moraines predating the Younger Dryas, a large number of young outliers are spread evenly between 6 and 13 ka suggesting a continuing process of exhumation or repositioning of boulders during the early to mid-Holocene. This attests to active seismic processes and possibly intense erosion during this period.

• Item Type: Articles
• Additional Information: This research was funded by a Thesiger-Oman International Fellowship (2008) and Fieldcentre Grant (2013), both awarded by the Royal Geographical Society (with Institute of British Geographers). Funding was also received from the British Society for Geomorphology, the Quaternary Research Association and The University of Manchester. 10Be analyses at SUERC were funded by the UK Natural Environment Research Council (Cosmogenic Isotope Analysis Allocation # 9038.1007 & 9070.1009).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Fenton, Dr Cassandra and Rodes, Dr Angel
• Authors: Hughes, P. D., Fink, D., Rodés, Á., Fenton, C. R., and Fujioka, T.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: Quaternary Science Reviews
• Publisher: Elsevier
• ISSN: 0277-3791
• ISSN (Online): 1873-457X
• Published Online: 15 December 2017
• Copyright Holders: Copyright © 2017 Elsevier Ltd.
• First Published: First published in Quaternary Science Reviews 180: 193-213
• Publisher Policy: Reproduced in accordance with the publisher copyright policy