D. LeHeron
Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record
LeHeron, D.; Armstrong, H.A.; Wilson, C.R.; Howard, J.P.; Gindre, L.
Authors
H.A. Armstrong
C.R. Wilson
J.P. Howard
L. Gindre
Abstract
Detailed outcrop studies at the flanks of Al Kufrah Basin, Libya, reveal the nature of glacially-related sedimentation and post-depositional deformation styles produced in association with the Late Ordovician glaciation, during which ice sheets expanded northward over North Africa to deposit the Mamuniyat Formation. At the SE basin flank (Jabal Azbah), the Mamuniyat Formation is sand-dominated, and incises interfingering braidplain and shallow marine deposits of the Hawaz Formation. The glacially-related sediments include intercalations of mud-chip bearing tabular sandstones and intraformational conglomerates, which are interpreted as turbidite and debrite facies respectively. These record aggradation of an extensive sediment wedge in front of a stable former ice margin. An increase in mudstone content northward is accompanied by the occurrence of more evolved turbidites. A widespread surface, bearing streamlined NW–SE striking ridges and grooves, punctuates this succession. The structures on the surface are interpreted to have formed during a regional north-westward ice advance. Above, siltstones bearing Arthrophycus burrows, and Orthocone-bearing sandstones beneath tidal bars testify to glaciomarine conditions for deposition of the underflow deposits beneath. By contrast, the northern basin margin (Jabal az-Zalmah) is appreciably different in recording shallower water/paralic sedimentation styles and major glaciotectonic deformation features, although facies analysis also reveals northward deepening. Here, a siltstone wedging from 8 to 50 m toward the north was deposited (lower delta plain), succeeded by climbing ripple cross-laminated sandstones up to 60 m in thickness (distal through proximal delta mouth bar deposits) with occasional diamictite interbeds. These rocks are deformed by thrusts and > 50 m amplitude fault-propagation folds, the deformation locally sealed by a diamictite then overlain by conglomeratic lag during ultimate deglaciation. Integrating observations from both basin margins, a model of fluvial-dominated delta systems feeding a pulsed debrite and turbidite fan system in a shallow proglacial shelf is proposed.
Citation
LeHeron, D., Armstrong, H., Wilson, C., Howard, J., & Gindre, L. (2010). Glaciation and deglaciation of the Libyan Desert: The Late Ordovician record. Sedimentary Geology, 223(1-2), 100-125. https://doi.org/10.1016/j.sedgeo.2009.11.002
Journal Article Type | Article |
---|---|
Publication Date | Jan 1, 2010 |
Deposit Date | Nov 5, 2010 |
Journal | Sedimentary Geology |
Print ISSN | 0037-0738 |
Publisher | Elsevier |
Peer Reviewed | Peer Reviewed |
Volume | 223 |
Issue | 1-2 |
Pages | 100-125 |
DOI | https://doi.org/10.1016/j.sedgeo.2009.11.002 |
Keywords | Glacial, North Africa, Ordovician, Reservoir. |
You might also like
Climatic controls on late Pleistocene alluvial fans, Cyprus
(2010)
Journal Article
Downloadable Citations
About Durham Research Online (DRO)
Administrator e-mail: dro.admin@durham.ac.uk
This application uses the following open-source libraries:
SheetJS Community Edition
Apache License Version 2.0 (http://www.apache.org/licenses/)
PDF.js
Apache License Version 2.0 (http://www.apache.org/licenses/)
Font Awesome
SIL OFL 1.1 (http://scripts.sil.org/OFL)
MIT License (http://opensource.org/licenses/mit-license.html)
CC BY 3.0 ( http://creativecommons.org/licenses/by/3.0/)
Powered by Worktribe © 2024
Advanced Search