Chad's cabinet of icy curiosities

Autor(en)
Ricarda Wohlschlägl, Christoph Kettler, Daniel Paul Le Heron, András Zboray
Abstrakt

The Ennedi Plateau in Chad in north-central Africa exposes an outstanding example of a palaeo-ice stream glacial landsystem of late Palaeozoic age, with an assemblage of geomorphological structures of comparable preservation quality to those found in Quaternary deglaciated landscapes. Satellite images and various methods to combine acquired satellite data (e.g. band-ratio technique) have been used to interpret proglacial, ice-marginal and subglacial structures. The main goal of the study is to produce a detailed and more in-depth analysis of newly found structures that enhance our understanding of ice sheet behaviour in the Ennedi Plateau during the LPIA. We report the first known evidence of soft-sediment striated surfaces from outcrop, testifying to the existence of a soft-deformable bed. This deformable bed interpretation can probably be upscaled to explain the extensive swarms of mega-scale glacial lineations mapped previously across the plateau. Furthermore, we identify the first known fully preserved grounding zone wedge (GZW), replete with three-dimensional geometry, in the rock record. This unique structure exhibits a well pronounced slope and a convex topography. Its presence allows the position of the former coastline to be reconstructed as it is assumed that ice streams terminated into a former ocean basin. Building on the studies by Le Heron (2018) and Kettler et al. (this issue), our analyses permit unprecedented insights into the behaviour of a significant, mid-latitude, marine-terminating ice sheet during the LPIA.

Organisation(en)
Institut für Geologie
Externe Organisation(en)
Fliegel Jezerniczky Expeditions, GeoSphere Austria
Journal
Sedimentary Geology
Band
455
ISSN
0037-0738
DOI
https://doi.org/10.1016/j.sedgeo.2023.106483
Publikationsdatum
09-2023
Peer-reviewed
Ja
ÖFOS 2012
105121 Sedimentologie
Schlagwörter
ASJC Scopus Sachgebiete
Geology, Stratigraphy
Sustainable Development Goals
SDG 14 – Leben unter Wasser
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/d9b3d77a-df79-4719-8312-d008c083ca48