Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation
New field data demonstrate that during the Late Ordovician (Hirnantian) glaciation, an ice sheet expanding northwestwards over the Anti-Atlas range reached into the southern Meseta of northern Morocco. Its growth to a glacial maximum position resulted in extensive subglacial erosion and deformation...
Published in: | Palaeogeography, Palaeoclimatology, Palaeoecology |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2007
|
Subjects: | |
Online Access: | https://repository.royalholloway.ac.uk/items/8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1/ https://doi.org/10.1016/j.palaeo.2006.02.031 |
id |
ftholloway:oai:repository.royalholloway.ac.uk:8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1 |
---|---|
record_format |
openpolar |
spelling |
ftholloway:oai:repository.royalholloway.ac.uk:8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1 2023-05-15T16:40:01+02:00 Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation Le Heron, D.P. Ghienne, J.-F. El Houicha, M. Khoukhi, Y. Rubino, J.-L. 2007 application/pdf https://repository.royalholloway.ac.uk/items/8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1/ https://doi.org/10.1016/j.palaeo.2006.02.031 eng eng http://www.sciencedirect.com/science/journal/00310182 https://repository.royalholloway.ac.uk/items/8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1/ http://dx.doi.org/doi:10.1016/j.palaeo.2006.02.031 Palaeogeography, Palaeoclimatology, Palaeoecology, 245 (1-2) Glaciation Ordovician Morocco Ice sheet Gondwana Faculty of Science\Earth Sciences Research Groups and Centres\Earth Sciences\Ancient and Modern Earth Systems Research Groups and Centres\Earth Sciences\Geochemistry info:eu-repo/semantics/article info:eu-repo/semantics/submittedVersion 2007 ftholloway https://doi.org/10.1016/j.palaeo.2006.02.031 2022-09-26T13:01:30Z New field data demonstrate that during the Late Ordovician (Hirnantian) glaciation, an ice sheet expanding northwestwards over the Anti-Atlas range reached into the southern Meseta of northern Morocco. Its growth to a glacial maximum position resulted in extensive subglacial erosion and deformation including the development of soft-sediment striated surfaces and streamlined subglacial bedforms preserved between the High Atlas of Marrakech and Rehamna. These features imply that this ice mass extended >200 km further than previously thought, and increase its size by at least ca. 190, 000 km2 (comparable in area to the UK). Correlation between a measured section in the High Atlas of Marrakech and that of the southern Meseta identifies sedimentary evolution within an ice-contact system common to both. These findings imply that the West African Craton and northern Morocco were in full glaciological communication during the latest Ordovician. Palaeogeographic reconstruction shows that beyond the ice sheet, south and southeastward palaeoslopes persisted on the shelf. A palaeohigh beyond the main ice sheet was a major source for sand, feeding delta systems that grew along the shelf as far as the shelf break. This palaeohigh probably formed as a result of rift shoulder uplift and supported a satellite ice mass. In the eastern Meseta, a thick (350 m) underflow-dominated deep-marine fan was fed both from this shelf delta system and from glaciogenic debris derived fromthe main ice sheet. The occurrence of this unexpected deep-marine area in northern Morocco implies that continued northward advance of the ice sheet was hampered by a dramatic break in bathymetry. Two depositional units are recognised across the Meseta, containing four distinct sedimentary cycles, each recognised as a glacioeustatic response to the waxing and waning of ice masses elsewhere in West Gondwana. Article in Journal/Newspaper Ice Sheet Royal Holloway University of London: Royal Holloway Digital Repository Palaeogeography, Palaeoclimatology, Palaeoecology 245 1-2 200 226 |
institution |
Open Polar |
collection |
Royal Holloway University of London: Royal Holloway Digital Repository |
op_collection_id |
ftholloway |
language |
English |
topic |
Glaciation Ordovician Morocco Ice sheet Gondwana Faculty of Science\Earth Sciences Research Groups and Centres\Earth Sciences\Ancient and Modern Earth Systems Research Groups and Centres\Earth Sciences\Geochemistry |
spellingShingle |
Glaciation Ordovician Morocco Ice sheet Gondwana Faculty of Science\Earth Sciences Research Groups and Centres\Earth Sciences\Ancient and Modern Earth Systems Research Groups and Centres\Earth Sciences\Geochemistry Le Heron, D.P. Ghienne, J.-F. El Houicha, M. Khoukhi, Y. Rubino, J.-L. Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
topic_facet |
Glaciation Ordovician Morocco Ice sheet Gondwana Faculty of Science\Earth Sciences Research Groups and Centres\Earth Sciences\Ancient and Modern Earth Systems Research Groups and Centres\Earth Sciences\Geochemistry |
description |
New field data demonstrate that during the Late Ordovician (Hirnantian) glaciation, an ice sheet expanding northwestwards over the Anti-Atlas range reached into the southern Meseta of northern Morocco. Its growth to a glacial maximum position resulted in extensive subglacial erosion and deformation including the development of soft-sediment striated surfaces and streamlined subglacial bedforms preserved between the High Atlas of Marrakech and Rehamna. These features imply that this ice mass extended >200 km further than previously thought, and increase its size by at least ca. 190, 000 km2 (comparable in area to the UK). Correlation between a measured section in the High Atlas of Marrakech and that of the southern Meseta identifies sedimentary evolution within an ice-contact system common to both. These findings imply that the West African Craton and northern Morocco were in full glaciological communication during the latest Ordovician. Palaeogeographic reconstruction shows that beyond the ice sheet, south and southeastward palaeoslopes persisted on the shelf. A palaeohigh beyond the main ice sheet was a major source for sand, feeding delta systems that grew along the shelf as far as the shelf break. This palaeohigh probably formed as a result of rift shoulder uplift and supported a satellite ice mass. In the eastern Meseta, a thick (350 m) underflow-dominated deep-marine fan was fed both from this shelf delta system and from glaciogenic debris derived fromthe main ice sheet. The occurrence of this unexpected deep-marine area in northern Morocco implies that continued northward advance of the ice sheet was hampered by a dramatic break in bathymetry. Two depositional units are recognised across the Meseta, containing four distinct sedimentary cycles, each recognised as a glacioeustatic response to the waxing and waning of ice masses elsewhere in West Gondwana. |
format |
Article in Journal/Newspaper |
author |
Le Heron, D.P. Ghienne, J.-F. El Houicha, M. Khoukhi, Y. Rubino, J.-L. |
author_facet |
Le Heron, D.P. Ghienne, J.-F. El Houicha, M. Khoukhi, Y. Rubino, J.-L. |
author_sort |
Le Heron, D.P. |
title |
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
title_short |
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
title_full |
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
title_fullStr |
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
title_full_unstemmed |
Maximum extent of ice sheets in Morocco during the Late Ordovician glaciation |
title_sort |
maximum extent of ice sheets in morocco during the late ordovician glaciation |
publishDate |
2007 |
url |
https://repository.royalholloway.ac.uk/items/8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1/ https://doi.org/10.1016/j.palaeo.2006.02.031 |
genre |
Ice Sheet |
genre_facet |
Ice Sheet |
op_source |
Palaeogeography, Palaeoclimatology, Palaeoecology, 245 (1-2) |
op_relation |
http://www.sciencedirect.com/science/journal/00310182 https://repository.royalholloway.ac.uk/items/8596a26c-bad6-7d7a-31e4-4c3182d2d7a5/1/ http://dx.doi.org/doi:10.1016/j.palaeo.2006.02.031 |
op_doi |
https://doi.org/10.1016/j.palaeo.2006.02.031 |
container_title |
Palaeogeography, Palaeoclimatology, Palaeoecology |
container_volume |
245 |
container_issue |
1-2 |
container_start_page |
200 |
op_container_end_page |
226 |
_version_ |
1766030381154304000 |