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An exhumed Paleozoic glacial landscape in Chad

Daniel Paul Le Heron
An exhumed Paleozoic glacial landscape in Chad
Geology (Boulder) (January 2018) 46 (1): 91-94


In northern Chad, an outcrop belt of Paleozoic rocks occurs in the Ennedi-Bourkou range. There, satellite image interpretation reveals a series of clearly expressed paleo-ice stream pathways, which are encased in sandstone plateaux. At least five paleo-ice stream pathways are recognized, measuring 5-12 km wide. Each contains well-expressed belts of mega-scale glacial lineations (MSGLs) with occasional drumlins. The paleo-ice stream tracks are confined to present-day low-lying areas, representing ancient valley networks, and have sinuous geometries. The features occur on multiple plateau and/or stratigraphic levels. Their dissection by late Neogene rivers discounts a modern-day origin as eolian features, and offset suites of MSGLs by east-west-striking faults confirms their geologic antiquity. The paleo-ice stream pathways appear to have drained a newly discovered late Paleozoic paleo-ice sheet of probable Visean age that flowed northward toward present-day Libya, with an estimated <250-m-thick tidewater ice margin. This discovery has wide-ranging implications, increasing the known extent of late Paleozoic ice sheets, and potentially their effects on sea-level changes.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 46
Serial Issue: 1
Title: An exhumed Paleozoic glacial landscape in Chad
Affiliation: Royal Holloway-University of London, Department of Earth Sciences, Egham, United Kingdom
Pages: 91-94
Published: 201801
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 37
Accession Number: 2018-039553
Categories: Stratigraphy
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
N07°19'60" - N23°30'00", E13°30'00" - E24°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 2018
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