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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Geological Society L...arrow_drop_down
image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
Geological Society London Memoirs
Article . 2016 . Peer-reviewed
License: STM Policy #2
Data sources: Crossref
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The Hirnantian glacial landsystem of the Sahara: a meltwater-dominated system

Authors: D. P. Le Heron;

The Hirnantian glacial landsystem of the Sahara: a meltwater-dominated system

Abstract

During the Hirnantian (443 Ma), ice sheets expanded towards the present-day north over North Africa and the Arabian Peninsula when the western part of the Gondwana supercontinent straddled the South Pole. A glacigenic succession is exposed around the flanks of several Saharan cratonic basins, including Murzuq and Al Kufrah basins in Libya. As a result of the present-day hyper-arid context of the outcrops, a suite of palaeo-glacial landforms has been identified and, in some cases, mapped. These landforms occur along glacial erosion surfaces, defined as unconformities derived through direct ice sculpting, meltwater erosion or a combination of these processes. Unconformities, mostly resulting from ice sculpting and including glacially striated pavements and mega-scale glacial lineations (MSGLs), are identified at a number of locations along these erosion surfaces, in association with drumlinized features. The majority of reported examples are of ‘soft sediment character’; that is, generated through the deformation of unconsolidated sediment. Features mainly associated with meltwater erosion include tunnel valleys which occur in swarm-like belts, defining palaeo-grounding-line positions as the ice fronts retreated. A ‘smeared’ series of palaeo-ice-stream footprints, resulting from multiple advance–retreat cycles, is characteristic of the landsystem. Deformation of sediments into a series of push moraines, expressed as kilometre-scale fold–thrust belts, allows the locations of the former ice front to be identified. The Hirnantian glacial record of North Africa is a classic example of a continent-scale archive of an ancient palaeo-ice sheet. Expeditions to the Sahara during the late 1960s, focusing on the Algerian record, revealed a full suite of glacial indicators including striated pavements, pingos, roches moutonnees and a variety of meltwater channels (Beuf et al. 1971). Subsequently, largely as a result of their significance as hydrocarbon reservoirs, more recent studies re-evaluated these outcrops from a sedimentological perspective. Much effort focused on unravelling the glacial stratigraphy in neighbouring …

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
11
Top 10%
Average
Top 10%
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