Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica
The LeMay Group of Alexander Island, Antarctica, is a Mesozoic accretionary prism that contains slivers of ocean floor and ocean island material, accreted under a range of conditions and depths. It provides a rare opportunity to compare the deformation mechanism paths between oceanic and trench-fill...
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Geological Society of London
1994
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ftnerc:oai:nora.nerc.ac.uk:516022 2023-05-15T13:15:17+02:00 Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica Doubleday, P. A. Tranter, T. H. 1994-06 http://nora.nerc.ac.uk/id/eprint/516022/ https://doi.org/10.1144/gsjgs.151.3.0543 unknown Geological Society of London Doubleday, P. A.; Tranter, T. H. 1994 Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica. Journal of the Geological Society, 151 (3). 543-554. https://doi.org/10.1144/gsjgs.151.3.0543 <https://doi.org/10.1144/gsjgs.151.3.0543> Publication - Article PeerReviewed 1994 ftnerc https://doi.org/10.1144/gsjgs.151.3.0543 2023-02-04T19:44:25Z The LeMay Group of Alexander Island, Antarctica, is a Mesozoic accretionary prism that contains slivers of ocean floor and ocean island material, accreted under a range of conditions and depths. It provides a rare opportunity to compare the deformation mechanism paths between oceanic and trench-fill lithologies during subduction and accretion by offscraping or underplating. Ocean floor slivers consist of a bedded basalt–volcaniclastite–chert rock association, overlain by trench-fill sedimentary rocks. The oceanic lithologies initially deformed by cataclasis, combined with particulate flow in the volcaniclastic rocks. At shallow levels the clastic trench-fill sedimentary rocks deformed by independent particulate flow, which changed to cataclastic flow at depth. At those depths crystal plasticity affected the cherts and jaspers. At the deepest levels achieved in the subduction zone, crystal plasticity was the dominant deformation mechanism in the clastic sedimentary rocks, whilst cataclasis continued in the lavas. Deformation was synchronous with metamorphism up to transitional greenschist–blueschist facies. All lithologies were affected by pressure solution after accretion, with the formation of a bedding-parallel or sub-parallel cleavage. The deformation mechanism paths indicate that (1) there is a crystal plastic deformation field at deep levels in the subduction zone, and (2) that the base of the pressure solution field is concordant with the decollement. A frontally accreted ocean island is exposed in the Lully Foothills, and consists of a basalt–volcaniclastite–tuff rock association. Deformation is represented only by a patchily distributed bedding-sub-parallel pressure solution cleavage in the tuffs and volcaniclastites, and is probably related to loading. Metamorphism does not exceed prehnite–pumpellyite facies. The accreted ocean island indicates that such features can be incorporated into accretionary prisms at shallow levels without significant segmentation. Article in Journal/Newspaper Alexander Island Antarc* Antarctica Antarctica Journal Ocean Island Natural Environment Research Council: NERC Open Research Archive Alexander Island ENVELOPE(-69.895,-69.895,-71.287,-71.287) Lully Foothills ENVELOPE(-69.625,-69.625,-70.791,-70.791) Journal of the Geological Society 151 3 543 554 |
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Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
The LeMay Group of Alexander Island, Antarctica, is a Mesozoic accretionary prism that contains slivers of ocean floor and ocean island material, accreted under a range of conditions and depths. It provides a rare opportunity to compare the deformation mechanism paths between oceanic and trench-fill lithologies during subduction and accretion by offscraping or underplating. Ocean floor slivers consist of a bedded basalt–volcaniclastite–chert rock association, overlain by trench-fill sedimentary rocks. The oceanic lithologies initially deformed by cataclasis, combined with particulate flow in the volcaniclastic rocks. At shallow levels the clastic trench-fill sedimentary rocks deformed by independent particulate flow, which changed to cataclastic flow at depth. At those depths crystal plasticity affected the cherts and jaspers. At the deepest levels achieved in the subduction zone, crystal plasticity was the dominant deformation mechanism in the clastic sedimentary rocks, whilst cataclasis continued in the lavas. Deformation was synchronous with metamorphism up to transitional greenschist–blueschist facies. All lithologies were affected by pressure solution after accretion, with the formation of a bedding-parallel or sub-parallel cleavage. The deformation mechanism paths indicate that (1) there is a crystal plastic deformation field at deep levels in the subduction zone, and (2) that the base of the pressure solution field is concordant with the decollement. A frontally accreted ocean island is exposed in the Lully Foothills, and consists of a basalt–volcaniclastite–tuff rock association. Deformation is represented only by a patchily distributed bedding-sub-parallel pressure solution cleavage in the tuffs and volcaniclastites, and is probably related to loading. Metamorphism does not exceed prehnite–pumpellyite facies. The accreted ocean island indicates that such features can be incorporated into accretionary prisms at shallow levels without significant segmentation. |
format |
Article in Journal/Newspaper |
author |
Doubleday, P. A. Tranter, T. H. |
spellingShingle |
Doubleday, P. A. Tranter, T. H. Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
author_facet |
Doubleday, P. A. Tranter, T. H. |
author_sort |
Doubleday, P. A. |
title |
Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
title_short |
Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
title_full |
Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
title_fullStr |
Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
title_full_unstemmed |
Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica |
title_sort |
deformation mechanism paths for oceanic rocks during subduction and accretion: the mesozoic forearc of alexander island, antarctica |
publisher |
Geological Society of London |
publishDate |
1994 |
url |
http://nora.nerc.ac.uk/id/eprint/516022/ https://doi.org/10.1144/gsjgs.151.3.0543 |
long_lat |
ENVELOPE(-69.895,-69.895,-71.287,-71.287) ENVELOPE(-69.625,-69.625,-70.791,-70.791) |
geographic |
Alexander Island Lully Foothills |
geographic_facet |
Alexander Island Lully Foothills |
genre |
Alexander Island Antarc* Antarctica Antarctica Journal Ocean Island |
genre_facet |
Alexander Island Antarc* Antarctica Antarctica Journal Ocean Island |
op_relation |
Doubleday, P. A.; Tranter, T. H. 1994 Deformation mechanism paths for oceanic rocks during subduction and accretion: the Mesozoic forearc of Alexander Island, Antarctica. Journal of the Geological Society, 151 (3). 543-554. https://doi.org/10.1144/gsjgs.151.3.0543 <https://doi.org/10.1144/gsjgs.151.3.0543> |
op_doi |
https://doi.org/10.1144/gsjgs.151.3.0543 |
container_title |
Journal of the Geological Society |
container_volume |
151 |
container_issue |
3 |
container_start_page |
543 |
op_container_end_page |
554 |
_version_ |
1766267894160687104 |