Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica
Evidence for one late Eocene and four middle Oligocene eruptions of Mount Petras, Marie Byrd Land provides new insights into reconstructions of middle Tertiary ice sheet configurations, surface topography, and volcanism in West Antarctica. The interpretation presented here of the volcanic record at...
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Online Access: | http://dx.doi.org/10.1017/s0954102000000560 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102000000560 |
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crcambridgeupr:10.1017/s0954102000000560 2024-06-23T07:47:14+00:00 Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica Wilch, T.I. McIntosh, W.C. 2000 http://dx.doi.org/10.1017/s0954102000000560 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102000000560 en eng Cambridge University Press (CUP) https://www.cambridge.org/core/terms Antarctic Science volume 12, issue 4, page 477-491 ISSN 0954-1020 1365-2079 journal-article 2000 crcambridgeupr https://doi.org/10.1017/s0954102000000560 2024-06-12T04:05:08Z Evidence for one late Eocene and four middle Oligocene eruptions of Mount Petras, Marie Byrd Land provides new insights into reconstructions of middle Tertiary ice sheet configurations, surface topography, and volcanism in West Antarctica. The interpretation presented here of the volcanic record at Mount Petras, based on detailed analyses of lithofacies, petrography, 40 Ar/ 39 Ar geochronology, and geochemistry, is significantly different from previous interpretations based on reconnaissance studies. A massive, 25 m thick, mugearite lava near the summit of Mount Petras is 40 Ar/ 39 Ar dated to 36.11 ± 0.22 Ma (2 σ uncertainty), indicating an onset of Cenozoic alkaline volcanism in the Marie Byrd Land Volcanic Province in latest Eocene time. Middle Oligocene (29-27 Ma) hawaiite volcaniclastic lithofacies at Mount Petras are interpreted as products of mixed magmatic (Strombolian style) and phreatomagmatic (Surtseyan style) subaerial eruptions. The four hawaiite outcrop areas exhibit characteristics of near-vent tuff cone environments. The near-vent deposits are located at different elevations and positions on Mount Petras and suggest four separate eruptive centres, with eruptions dated to between 28.59 ± 0.22 Ma and 27.18 ± 0.23 Ma. The mixed Surtseyan and Strombolian eruptions imply local or intermittent contact with external water, which we infer was derived from melting of a thin, local ice cap or ice and snow on slopes. The 29-27 Ma volcanic deposits at Mount Petras provide the oldest terrestrial evidence for glacial ice in Marie Byrd Land. The 29-27 Ma tuff cone deposits overlie an erosional unconformity, with > 400 m of topographic relief. The relatively high relief pre-volcanic environment is suggestive of ongoing erosion and is inconsistent with previous interpretations of a regional, low relief, early Cenozoic West Antarctic Erosion Surface. Article in Journal/Newspaper Antarc* Antarctic Antarctic Science Antarctica Ice cap Ice Sheet Marie Byrd Land West Antarctica Cambridge University Press Antarctic Byrd Marie Byrd Land ENVELOPE(-130.000,-130.000,-78.000,-78.000) Mount Petras ENVELOPE(-128.650,-128.650,-75.867,-75.867) Petras ENVELOPE(-128.650,-128.650,-75.867,-75.867) West Antarctica Antarctic Science 12 4 477 491 |
institution |
Open Polar |
collection |
Cambridge University Press |
op_collection_id |
crcambridgeupr |
language |
English |
description |
Evidence for one late Eocene and four middle Oligocene eruptions of Mount Petras, Marie Byrd Land provides new insights into reconstructions of middle Tertiary ice sheet configurations, surface topography, and volcanism in West Antarctica. The interpretation presented here of the volcanic record at Mount Petras, based on detailed analyses of lithofacies, petrography, 40 Ar/ 39 Ar geochronology, and geochemistry, is significantly different from previous interpretations based on reconnaissance studies. A massive, 25 m thick, mugearite lava near the summit of Mount Petras is 40 Ar/ 39 Ar dated to 36.11 ± 0.22 Ma (2 σ uncertainty), indicating an onset of Cenozoic alkaline volcanism in the Marie Byrd Land Volcanic Province in latest Eocene time. Middle Oligocene (29-27 Ma) hawaiite volcaniclastic lithofacies at Mount Petras are interpreted as products of mixed magmatic (Strombolian style) and phreatomagmatic (Surtseyan style) subaerial eruptions. The four hawaiite outcrop areas exhibit characteristics of near-vent tuff cone environments. The near-vent deposits are located at different elevations and positions on Mount Petras and suggest four separate eruptive centres, with eruptions dated to between 28.59 ± 0.22 Ma and 27.18 ± 0.23 Ma. The mixed Surtseyan and Strombolian eruptions imply local or intermittent contact with external water, which we infer was derived from melting of a thin, local ice cap or ice and snow on slopes. The 29-27 Ma volcanic deposits at Mount Petras provide the oldest terrestrial evidence for glacial ice in Marie Byrd Land. The 29-27 Ma tuff cone deposits overlie an erosional unconformity, with > 400 m of topographic relief. The relatively high relief pre-volcanic environment is suggestive of ongoing erosion and is inconsistent with previous interpretations of a regional, low relief, early Cenozoic West Antarctic Erosion Surface. |
format |
Article in Journal/Newspaper |
author |
Wilch, T.I. McIntosh, W.C. |
spellingShingle |
Wilch, T.I. McIntosh, W.C. Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
author_facet |
Wilch, T.I. McIntosh, W.C. |
author_sort |
Wilch, T.I. |
title |
Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
title_short |
Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
title_full |
Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
title_fullStr |
Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
title_full_unstemmed |
Eocene and Oligocene volcanism at Mount Petras, Marie Byrd Land: implications for middle Cenozoic ice sheet reconstructions in West Antarctica |
title_sort |
eocene and oligocene volcanism at mount petras, marie byrd land: implications for middle cenozoic ice sheet reconstructions in west antarctica |
publisher |
Cambridge University Press (CUP) |
publishDate |
2000 |
url |
http://dx.doi.org/10.1017/s0954102000000560 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102000000560 |
long_lat |
ENVELOPE(-130.000,-130.000,-78.000,-78.000) ENVELOPE(-128.650,-128.650,-75.867,-75.867) ENVELOPE(-128.650,-128.650,-75.867,-75.867) |
geographic |
Antarctic Byrd Marie Byrd Land Mount Petras Petras West Antarctica |
geographic_facet |
Antarctic Byrd Marie Byrd Land Mount Petras Petras West Antarctica |
genre |
Antarc* Antarctic Antarctic Science Antarctica Ice cap Ice Sheet Marie Byrd Land West Antarctica |
genre_facet |
Antarc* Antarctic Antarctic Science Antarctica Ice cap Ice Sheet Marie Byrd Land West Antarctica |
op_source |
Antarctic Science volume 12, issue 4, page 477-491 ISSN 0954-1020 1365-2079 |
op_rights |
https://www.cambridge.org/core/terms |
op_doi |
https://doi.org/10.1017/s0954102000000560 |
container_title |
Antarctic Science |
container_volume |
12 |
container_issue |
4 |
container_start_page |
477 |
op_container_end_page |
491 |
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1802651324443000832 |