Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance
New assemblages of Radiolaria, including some of the few occurrences of high southern latitude Jurassic and Cretaceous radiolarian faunas, show that several localities in the LeMay Group of Alexander Island range in age from latest Jurassic–earliest Cretaceous to at least Albian. By demonstrating th...
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Geological Society of London
1992
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ftnerc:oai:nora.nerc.ac.uk:518475 2023-05-15T13:15:17+02:00 Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance Holdsworth, B.K. Nell, P.A.R. 1992-11 http://nora.nerc.ac.uk/id/eprint/518475/ https://doi.org/10.1144/gsjgs.149.6.1003 unknown Geological Society of London Holdsworth, B.K.; Nell, P.A.R. 1992 Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance. Journal of the Geological Society, 149 (6). 1003-1020. https://doi.org/10.1144/gsjgs.149.6.1003 <https://doi.org/10.1144/gsjgs.149.6.1003> Publication - Article PeerReviewed 1992 ftnerc https://doi.org/10.1144/gsjgs.149.6.1003 2023-02-04T19:45:38Z New assemblages of Radiolaria, including some of the few occurrences of high southern latitude Jurassic and Cretaceous radiolarian faunas, show that several localities in the LeMay Group of Alexander Island range in age from latest Jurassic–earliest Cretaceous to at least Albian. By demonstrating that sedimentation and deformation in the LeMay Group was diachronous, younging oceanwards to the northwest, these new age assessments support the model of the LeMay Group as an accretionary complex. The polarity of subduction beneath Alexander Island was not affected by arc collisions from at least the Lower Jurassic to the Oligocene, and such a long period of continuous accretion appears to be unusual. Deposition of the LeMay Group spans the Kimmeridgian to Albian sedimentation in the Fossil Bluff Group fore-arc basin, thus making the earlier concept of the LeMay Group as pre-Jurassic ‘basement’ untenable. Allochthonous latest Jurassic–earliest Cretaceous radiolarian assemblages with some supposed Tethyan affinities are present in the LeMay Group. In contrast, an in situ latest Jurassic assemblage from the Nordenskjöld Formation of the back-arc basin and a further Jurassic assemblage from a probable trench-slope basin have characteristics believed diagnostic of high latitudes. The biogeographic affinities of radiolarians from cherts in the LeMay Group accretionary complex suggest that both these cherts, and associated basalts, are far-travelled slices of the Phoenix plate. Rocks from the probable trench-slope basin, formerly assigned to the younger Fossil Bluff Group fore-arc basin sequence, now appear to be part of a new, previously unrecognized formation. Article in Journal/Newspaper Alexander Island Antarc* Antarctic Antarctic Peninsula Natural Environment Research Council: NERC Open Research Archive Antarctic The Antarctic Antarctic Peninsula Alexander Island ENVELOPE(-69.895,-69.895,-71.287,-71.287) Nordenskjöld ENVELOPE(-60.583,-60.583,-64.667,-64.667) Fossil Bluff ENVELOPE(-68.274,-68.274,-71.332,-71.332) Journal of the Geological Society 149 6 1003 1020 |
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Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
New assemblages of Radiolaria, including some of the few occurrences of high southern latitude Jurassic and Cretaceous radiolarian faunas, show that several localities in the LeMay Group of Alexander Island range in age from latest Jurassic–earliest Cretaceous to at least Albian. By demonstrating that sedimentation and deformation in the LeMay Group was diachronous, younging oceanwards to the northwest, these new age assessments support the model of the LeMay Group as an accretionary complex. The polarity of subduction beneath Alexander Island was not affected by arc collisions from at least the Lower Jurassic to the Oligocene, and such a long period of continuous accretion appears to be unusual. Deposition of the LeMay Group spans the Kimmeridgian to Albian sedimentation in the Fossil Bluff Group fore-arc basin, thus making the earlier concept of the LeMay Group as pre-Jurassic ‘basement’ untenable. Allochthonous latest Jurassic–earliest Cretaceous radiolarian assemblages with some supposed Tethyan affinities are present in the LeMay Group. In contrast, an in situ latest Jurassic assemblage from the Nordenskjöld Formation of the back-arc basin and a further Jurassic assemblage from a probable trench-slope basin have characteristics believed diagnostic of high latitudes. The biogeographic affinities of radiolarians from cherts in the LeMay Group accretionary complex suggest that both these cherts, and associated basalts, are far-travelled slices of the Phoenix plate. Rocks from the probable trench-slope basin, formerly assigned to the younger Fossil Bluff Group fore-arc basin sequence, now appear to be part of a new, previously unrecognized formation. |
format |
Article in Journal/Newspaper |
author |
Holdsworth, B.K. Nell, P.A.R. |
spellingShingle |
Holdsworth, B.K. Nell, P.A.R. Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
author_facet |
Holdsworth, B.K. Nell, P.A.R. |
author_sort |
Holdsworth, B.K. |
title |
Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
title_short |
Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
title_full |
Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
title_fullStr |
Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
title_full_unstemmed |
Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance |
title_sort |
mesozoic radiolarian faunas from the antarctic peninsula: age, tectonic and palaeoceanographic significance |
publisher |
Geological Society of London |
publishDate |
1992 |
url |
http://nora.nerc.ac.uk/id/eprint/518475/ https://doi.org/10.1144/gsjgs.149.6.1003 |
long_lat |
ENVELOPE(-69.895,-69.895,-71.287,-71.287) ENVELOPE(-60.583,-60.583,-64.667,-64.667) ENVELOPE(-68.274,-68.274,-71.332,-71.332) |
geographic |
Antarctic The Antarctic Antarctic Peninsula Alexander Island Nordenskjöld Fossil Bluff |
geographic_facet |
Antarctic The Antarctic Antarctic Peninsula Alexander Island Nordenskjöld Fossil Bluff |
genre |
Alexander Island Antarc* Antarctic Antarctic Peninsula |
genre_facet |
Alexander Island Antarc* Antarctic Antarctic Peninsula |
op_relation |
Holdsworth, B.K.; Nell, P.A.R. 1992 Mesozoic radiolarian faunas from the Antarctic Peninsula: age, tectonic and palaeoceanographic significance. Journal of the Geological Society, 149 (6). 1003-1020. https://doi.org/10.1144/gsjgs.149.6.1003 <https://doi.org/10.1144/gsjgs.149.6.1003> |
op_doi |
https://doi.org/10.1144/gsjgs.149.6.1003 |
container_title |
Journal of the Geological Society |
container_volume |
149 |
container_issue |
6 |
container_start_page |
1003 |
op_container_end_page |
1020 |
_version_ |
1766267886529150976 |