Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica
Abstract The Mesozoic forearc of Alexander Island, Antarctica, is one of the few places in the world where the original stratigraphic relationship between a forearc basin and an accretionary complex is exposed. Newlydiscovered sedimentary rocks exposed at the western edge of the forearc basin fill (...
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Cambridge University Press (CUP)
1993
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Online Access: | http://dx.doi.org/10.1017/s0016756800023128 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756800023128 |
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crcambridgeupr:10.1017/s0016756800023128 2024-09-15T17:36:32+00:00 Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica Doubleday, P. A. Macdonald, D. I. M. Nell, P. A. R. 1993 http://dx.doi.org/10.1017/s0016756800023128 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756800023128 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Geological Magazine volume 130, issue 6, page 737-754 ISSN 0016-7568 1469-5081 journal-article 1993 crcambridgeupr https://doi.org/10.1017/s0016756800023128 2024-07-31T04:04:15Z Abstract The Mesozoic forearc of Alexander Island, Antarctica, is one of the few places in the world where the original stratigraphic relationship between a forearc basin and an accretionary complex is exposed. Newlydiscovered sedimentary rocks exposed at the western edge of the forearc basin fill (the Kimmeridgian–Albian Fossil Bluff Group) record the events associated with the basin formation. These strata are assigned to the newly defined Selene Nunatak Formation (?Bathonian) and Atoll Nunataks Formation (?Bathonian-Tithonian) within the Fossil Bluff Group. The Selene Nunatak Formation contains variable thicknesses of conglomeratesand sandstones, predominantly derived from the LeMay Group accretionary complex upon which it is unconformable. The formation marks emergence and subsequent erosion of the inner forearc area. It is conformably overlain by the1 km thick Atoll Nunataks Formation, characterized by thinly-bedded mudstones and silty mudstones representing a marine transgression followed by trench-slope deposition. The Atoll Nunataks Formation marks a phase of subsidence, possibly in response to tectonic events in the accretionary prism that are known to have occurred at about the same time. The Atoll Nunataks Formation is conformably overlain by the Himalia Ridge Formation, a thick sequence of basin-wide arc-derived conglomerates. This transition from fine- to coarse-grained deposition suggests that a well-developed depositional trough (and hence trench-slope break) had formed by that time. The Atoll Nunataks Formation therefore spans the formation of the forearc basin, and marks the transition from trench-slope to forearc basin deposition. Article in Journal/Newspaper Alexander Island Antarc* Antarctica Cambridge University Press Geological Magazine 130 6 737 754 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract The Mesozoic forearc of Alexander Island, Antarctica, is one of the few places in the world where the original stratigraphic relationship between a forearc basin and an accretionary complex is exposed. Newlydiscovered sedimentary rocks exposed at the western edge of the forearc basin fill (the Kimmeridgian–Albian Fossil Bluff Group) record the events associated with the basin formation. These strata are assigned to the newly defined Selene Nunatak Formation (?Bathonian) and Atoll Nunataks Formation (?Bathonian-Tithonian) within the Fossil Bluff Group. The Selene Nunatak Formation contains variable thicknesses of conglomeratesand sandstones, predominantly derived from the LeMay Group accretionary complex upon which it is unconformable. The formation marks emergence and subsequent erosion of the inner forearc area. It is conformably overlain by the1 km thick Atoll Nunataks Formation, characterized by thinly-bedded mudstones and silty mudstones representing a marine transgression followed by trench-slope deposition. The Atoll Nunataks Formation marks a phase of subsidence, possibly in response to tectonic events in the accretionary prism that are known to have occurred at about the same time. The Atoll Nunataks Formation is conformably overlain by the Himalia Ridge Formation, a thick sequence of basin-wide arc-derived conglomerates. This transition from fine- to coarse-grained deposition suggests that a well-developed depositional trough (and hence trench-slope break) had formed by that time. The Atoll Nunataks Formation therefore spans the formation of the forearc basin, and marks the transition from trench-slope to forearc basin deposition. |
format |
Article in Journal/Newspaper |
author |
Doubleday, P. A. Macdonald, D. I. M. Nell, P. A. R. |
spellingShingle |
Doubleday, P. A. Macdonald, D. I. M. Nell, P. A. R. Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
author_facet |
Doubleday, P. A. Macdonald, D. I. M. Nell, P. A. R. |
author_sort |
Doubleday, P. A. |
title |
Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
title_short |
Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
title_full |
Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
title_fullStr |
Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
title_full_unstemmed |
Sedimentology and structure of the trench-slope to forearc basin transition in the Mesozoic of Alexander Island, Antarctica |
title_sort |
sedimentology and structure of the trench-slope to forearc basin transition in the mesozoic of alexander island, antarctica |
publisher |
Cambridge University Press (CUP) |
publishDate |
1993 |
url |
http://dx.doi.org/10.1017/s0016756800023128 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0016756800023128 |
genre |
Alexander Island Antarc* Antarctica |
genre_facet |
Alexander Island Antarc* Antarctica |
op_source |
Geological Magazine volume 130, issue 6, page 737-754 ISSN 0016-7568 1469-5081 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0016756800023128 |
container_title |
Geological Magazine |
container_volume |
130 |
container_issue |
6 |
container_start_page |
737 |
op_container_end_page |
754 |
_version_ |
1810490098965282816 |