On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA)
Master of Science Department of Geology Matthew E Brueseke The Maclaren River volcanic field (MRVF) of south-central Alaska consists of at least three monogenetic volcanoes that lie along the projection of the ca. ~1 Ma Yakutat slab tear. These volcanoes, which are <1 Ma. lie along a ~20 km south...
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ftkansassu:oai:krex.k-state.edu:2097/43414 2024-01-14T10:11:20+01:00 On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) Bearden, Alexander Thomas August application/pdf https://hdl.handle.net/2097/43414 en_US eng https://hdl.handle.net/2097/43414 Maclaren River volcanic field Petrogenesis Magmatism Thesis ftkansassu 2023-12-16T23:24:55Z Master of Science Department of Geology Matthew E Brueseke The Maclaren River volcanic field (MRVF) of south-central Alaska consists of at least three monogenetic volcanoes that lie along the projection of the ca. ~1 Ma Yakutat slab tear. These volcanoes, which are <1 Ma. lie along a ~20 km south-north transect within the Denali Gap, a region between the Aleutian and Wrangell Arcs previously considered to be amagmatic. In this study, I present results from geologic mapping, thin section petrographic analysis, whole rock major and trace element geochemical analysis, and Sr-Nd-Pb-Mg-B isotopic analyses of lavas and pyroclastic deposits of three MRVF volcanoes to document their physical volcanology and petrogenesis. Maclaren River volcanic field eruptive products (e.g., lavas and near-vent pyroclastic deposits) range from alkali basalt to subalkaline basaltic andesite and transitional basaltic trachyandesite/trachyandesite (~46-57 wt% SiO2). The studied volcanoes are named #1, #2, #3, from north to south. Volcano #1 (ca. 958 ka) lavas are porphyritic and contain olivine phenocrysts in a groundmass of clinopyroxene + plagioclase ± sparse biotite microlites. Volcano #2 lavas and scoria are porphyritic and their mineralogy is indicative of a more hydrated mantle source (abundant phlogopite + amphibole + olivine + clinopyroxene phenocrysts) and show evidence of crustal interaction (granitic xenoliths). Volcano #3 is located ~9 km south of volcano #2, but erupted coevally at ca. 422 ka. At volcano #3, the rocks consist of olivine + clinopyroxene + plagioclase + opacitic amphibole and show evidence of crustal interaction (plagioclase + quartz xenocrysts). Sr-Nd-Pb isotopic analysis was conducted on a subset of samples from each MRVF volcano via thermal ionization mass spectrometry and multicollector inductively coupled plasma mass spectometry. 87Sr/86Sri values range from 0.70343-0.70401 and are similar to modern Aleutian and Wrangell Arc magmas and the Holocene, Buzzard Creek maars. This similarity is also ... Thesis Yakutat Alaska Kansas State University: K-State Research Exchange (K-REx) |
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Open Polar |
collection |
Kansas State University: K-State Research Exchange (K-REx) |
op_collection_id |
ftkansassu |
language |
English |
topic |
Maclaren River volcanic field Petrogenesis Magmatism |
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Maclaren River volcanic field Petrogenesis Magmatism Bearden, Alexander Thomas On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
topic_facet |
Maclaren River volcanic field Petrogenesis Magmatism |
description |
Master of Science Department of Geology Matthew E Brueseke The Maclaren River volcanic field (MRVF) of south-central Alaska consists of at least three monogenetic volcanoes that lie along the projection of the ca. ~1 Ma Yakutat slab tear. These volcanoes, which are <1 Ma. lie along a ~20 km south-north transect within the Denali Gap, a region between the Aleutian and Wrangell Arcs previously considered to be amagmatic. In this study, I present results from geologic mapping, thin section petrographic analysis, whole rock major and trace element geochemical analysis, and Sr-Nd-Pb-Mg-B isotopic analyses of lavas and pyroclastic deposits of three MRVF volcanoes to document their physical volcanology and petrogenesis. Maclaren River volcanic field eruptive products (e.g., lavas and near-vent pyroclastic deposits) range from alkali basalt to subalkaline basaltic andesite and transitional basaltic trachyandesite/trachyandesite (~46-57 wt% SiO2). The studied volcanoes are named #1, #2, #3, from north to south. Volcano #1 (ca. 958 ka) lavas are porphyritic and contain olivine phenocrysts in a groundmass of clinopyroxene + plagioclase ± sparse biotite microlites. Volcano #2 lavas and scoria are porphyritic and their mineralogy is indicative of a more hydrated mantle source (abundant phlogopite + amphibole + olivine + clinopyroxene phenocrysts) and show evidence of crustal interaction (granitic xenoliths). Volcano #3 is located ~9 km south of volcano #2, but erupted coevally at ca. 422 ka. At volcano #3, the rocks consist of olivine + clinopyroxene + plagioclase + opacitic amphibole and show evidence of crustal interaction (plagioclase + quartz xenocrysts). Sr-Nd-Pb isotopic analysis was conducted on a subset of samples from each MRVF volcano via thermal ionization mass spectrometry and multicollector inductively coupled plasma mass spectometry. 87Sr/86Sri values range from 0.70343-0.70401 and are similar to modern Aleutian and Wrangell Arc magmas and the Holocene, Buzzard Creek maars. This similarity is also ... |
format |
Thesis |
author |
Bearden, Alexander Thomas |
author_facet |
Bearden, Alexander Thomas |
author_sort |
Bearden, Alexander Thomas |
title |
On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
title_short |
On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
title_full |
On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
title_fullStr |
On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
title_full_unstemmed |
On the Maclaren River volcanic field: Petrogenesis of Pleistocene Yakutat slab tear volcanism in south-central Alaska, (USA) |
title_sort |
on the maclaren river volcanic field: petrogenesis of pleistocene yakutat slab tear volcanism in south-central alaska, (usa) |
publishDate |
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url |
https://hdl.handle.net/2097/43414 |
genre |
Yakutat Alaska |
genre_facet |
Yakutat Alaska |
op_relation |
https://hdl.handle.net/2097/43414 |
_version_ |
1788066248604516352 |