Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC
Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia’s central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and g...
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crcansciencepubl:10.1139/cjes-2023-0080 2024-04-07T07:53:15+00:00 Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC Hamilton, Tark S. Enkin, Randolph J. Li, Zhen Bednarski, Jan M. Stacey, Cooper D. McGann, Mary L. Jensen, Britta J.L. 2024 http://dx.doi.org/10.1139/cjes-2023-0080 https://cdnsciencepub.com/doi/full-xml/10.1139/cjes-2023-0080 https://cdnsciencepub.com/doi/pdf/10.1139/cjes-2023-0080 en eng Canadian Science Publishing https://creativecommons.org/licenses/by/4.0/deed.en_GB Canadian Journal of Earth Sciences volume 61, issue 1, page 58-85 ISSN 0008-4077 1480-3313 General Earth and Planetary Sciences journal-article 2024 crcansciencepubl https://doi.org/10.1139/cjes-2023-0080 2024-03-08T00:37:38Z Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia’s central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and glacial facies. The lavas are within-plate, differentiated (low MgO < 7%) Ocean Island Basalts, hawaiites, and mugearites that formed from ∼1% decompression melting of asthenosphere with residual garnet. Kitasu Hill, on glaciated bedrock, formed between 18 and 15 cal ka BP. Dipping, poorly stratified, admixed hyaloclastite, and glacial diamicton with large plutonic clasts and pillow breccia comprise its basal tuya platform (0–43 masl). Subaerial nested cinder cones, with smaller capping lava flows, sit atop the tuya. New marine samples show McGregor Cone formed subaerially but now sits submerged at 43–200 mbsl on an eroded moraine at the mouth of Finlayson Channel. Seismic data and cores reveal glaciomarine sediments draping the cone’s lower slopes and show beach terraces. Cores contain glaciomarine diamictons, ice-rafted debris, delicate glassy air fall tephra, and shallow, sublittoral, and deeper benthic foraminifera. Dates of 14.1–11.2 cal ka BP show volcanism spanned ∼2000 years during floating ice shelf conditions. The MSV have similar proximal positions to the retreating ice sheet, display mixed volcano-glacial facies, and experienced similar unloading stresses during deglaciation. The MSV may represent deglacially triggered volcanism. The dates, geomorphic and geological evidence, constrain a local relative sea level curve for Milbanke Sound and show how ice gave way to fire. Article in Journal/Newspaper Ice Sheet Ice Shelf Ocean Island Canadian Science Publishing Finlayson Channel ENVELOPE(-128.475,-128.475,52.643,52.643) Kitasu Hill ENVELOPE(-128.727,-128.727,52.501,52.501) Canadian Journal of Earth Sciences |
institution |
Open Polar |
collection |
Canadian Science Publishing |
op_collection_id |
crcansciencepubl |
language |
English |
topic |
General Earth and Planetary Sciences |
spellingShingle |
General Earth and Planetary Sciences Hamilton, Tark S. Enkin, Randolph J. Li, Zhen Bednarski, Jan M. Stacey, Cooper D. McGann, Mary L. Jensen, Britta J.L. Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
topic_facet |
General Earth and Planetary Sciences |
description |
Kitasu Hill and MacGregor Cone formed along the Principe Laredo Fault on British Columbia’s central coast as the Wisconsinan ice sheet withdrew from the Coast Mountains. These small-volume Milbanke Sound Volcanoes (MSV) provide remarkable evidence for the intimate relationship between volcanic and glacial facies. The lavas are within-plate, differentiated (low MgO < 7%) Ocean Island Basalts, hawaiites, and mugearites that formed from ∼1% decompression melting of asthenosphere with residual garnet. Kitasu Hill, on glaciated bedrock, formed between 18 and 15 cal ka BP. Dipping, poorly stratified, admixed hyaloclastite, and glacial diamicton with large plutonic clasts and pillow breccia comprise its basal tuya platform (0–43 masl). Subaerial nested cinder cones, with smaller capping lava flows, sit atop the tuya. New marine samples show McGregor Cone formed subaerially but now sits submerged at 43–200 mbsl on an eroded moraine at the mouth of Finlayson Channel. Seismic data and cores reveal glaciomarine sediments draping the cone’s lower slopes and show beach terraces. Cores contain glaciomarine diamictons, ice-rafted debris, delicate glassy air fall tephra, and shallow, sublittoral, and deeper benthic foraminifera. Dates of 14.1–11.2 cal ka BP show volcanism spanned ∼2000 years during floating ice shelf conditions. The MSV have similar proximal positions to the retreating ice sheet, display mixed volcano-glacial facies, and experienced similar unloading stresses during deglaciation. The MSV may represent deglacially triggered volcanism. The dates, geomorphic and geological evidence, constrain a local relative sea level curve for Milbanke Sound and show how ice gave way to fire. |
format |
Article in Journal/Newspaper |
author |
Hamilton, Tark S. Enkin, Randolph J. Li, Zhen Bednarski, Jan M. Stacey, Cooper D. McGann, Mary L. Jensen, Britta J.L. |
author_facet |
Hamilton, Tark S. Enkin, Randolph J. Li, Zhen Bednarski, Jan M. Stacey, Cooper D. McGann, Mary L. Jensen, Britta J.L. |
author_sort |
Hamilton, Tark S. |
title |
Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
title_short |
Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
title_full |
Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
title_fullStr |
Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
title_full_unstemmed |
Where ice gave way to fire: deglacial volcanic activity at the edge of the Coast Mountains in Milbanke Sound, BC |
title_sort |
where ice gave way to fire: deglacial volcanic activity at the edge of the coast mountains in milbanke sound, bc |
publisher |
Canadian Science Publishing |
publishDate |
2024 |
url |
http://dx.doi.org/10.1139/cjes-2023-0080 https://cdnsciencepub.com/doi/full-xml/10.1139/cjes-2023-0080 https://cdnsciencepub.com/doi/pdf/10.1139/cjes-2023-0080 |
long_lat |
ENVELOPE(-128.475,-128.475,52.643,52.643) ENVELOPE(-128.727,-128.727,52.501,52.501) |
geographic |
Finlayson Channel Kitasu Hill |
geographic_facet |
Finlayson Channel Kitasu Hill |
genre |
Ice Sheet Ice Shelf Ocean Island |
genre_facet |
Ice Sheet Ice Shelf Ocean Island |
op_source |
Canadian Journal of Earth Sciences volume 61, issue 1, page 58-85 ISSN 0008-4077 1480-3313 |
op_rights |
https://creativecommons.org/licenses/by/4.0/deed.en_GB |
op_doi |
https://doi.org/10.1139/cjes-2023-0080 |
container_title |
Canadian Journal of Earth Sciences |
_version_ |
1795668922581647360 |