Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance
The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in northwest Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded...
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2001
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Online Access: | http://hdl.handle.net/2440/13708 https://doi.org/10.1017/S0016756801005064 |
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ftunivadelaidedl:oai:digital.library.adelaide.edu.au:2440/13708 2023-05-15T17:35:18+02:00 Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance Williams, G. 2001 application/pdf http://hdl.handle.net/2440/13708 https://doi.org/10.1017/S0016756801005064 en eng Cambridge Univ Press Geological Magazine, 2001; 138(2):161-184 0016-7568 1469-5081 http://hdl.handle.net/2440/13708 doi:10.1017/S0016756801005064 Copyright © 2001 Cambridge University Press http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74663&fulltextType=RA&fileId=S0016756801005064 Journal article 2001 ftunivadelaidedl https://doi.org/10.1017/S0016756801005064 2023-02-05T19:14:51Z The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in northwest Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising >2650 measurements on trough cross-bedding are of low variability and show overall eastward flow. The projection upcurrent of regionally divergent flow directions for the lower part of the member indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian) normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in two main stages. Uplift of a western source area by movement on basin-bounding normal faults occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring further to the west and south along the line of the Minch Fault. The bulk of the Applecross Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental margins of the North Atlantic. The tectonic events may mark an early phase in the crustal extension that led ultimately to the opening of the Iapetus ocean. George E. Williams Article in Journal/Newspaper North Atlantic The University of Adelaide: Digital Library Geological Magazine 138 2 161 184 |
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Open Polar |
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The University of Adelaide: Digital Library |
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ftunivadelaidedl |
language |
English |
description |
The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in northwest Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising >2650 measurements on trough cross-bedding are of low variability and show overall eastward flow. The projection upcurrent of regionally divergent flow directions for the lower part of the member indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian) normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in two main stages. Uplift of a western source area by movement on basin-bounding normal faults occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring further to the west and south along the line of the Minch Fault. The bulk of the Applecross Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental margins of the North Atlantic. The tectonic events may mark an early phase in the crustal extension that led ultimately to the opening of the Iapetus ocean. George E. Williams |
format |
Article in Journal/Newspaper |
author |
Williams, G. |
spellingShingle |
Williams, G. Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
author_facet |
Williams, G. |
author_sort |
Williams, G. |
title |
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
title_short |
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
title_full |
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
title_fullStr |
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
title_full_unstemmed |
Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance |
title_sort |
neoproterozoic (torridonian) alluvial fan succession, northwest scotland, and its tectonic setting and provenance |
publisher |
Cambridge Univ Press |
publishDate |
2001 |
url |
http://hdl.handle.net/2440/13708 https://doi.org/10.1017/S0016756801005064 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=74663&fulltextType=RA&fileId=S0016756801005064 |
op_relation |
Geological Magazine, 2001; 138(2):161-184 0016-7568 1469-5081 http://hdl.handle.net/2440/13708 doi:10.1017/S0016756801005064 |
op_rights |
Copyright © 2001 Cambridge University Press |
op_doi |
https://doi.org/10.1017/S0016756801005064 |
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Geological Magazine |
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138 |
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2 |
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161 |
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184 |
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1766134428292087808 |