Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland
At Undirhliðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring t...
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ftoberlincollege:oai:digitalcommons.oberlin.edu:honors-1203 2023-07-30T04:04:21+02:00 Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland Heineman, Rachel 2017-01-01T08:00:00Z application/pdf https://digitalcommons.oberlin.edu/honors/204 https://digitalcommons.oberlin.edu/context/honors/article/1203/viewcontent/Heineman_Glaciovolcanic_thesis_17.pdf unknown Digital Commons at Oberlin https://digitalcommons.oberlin.edu/honors/204 https://digitalcommons.oberlin.edu/context/honors/article/1203/viewcontent/Heineman_Glaciovolcanic_thesis_17.pdf Honors Papers Iceland Glaciovolcanic Subglacial volcano Basalt Megapillow Pillow Lava Geology text 2017 ftoberlincollege 2023-07-08T17:55:47Z At Undirhliðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring throughout this area demonstrate their role in the multi-stage construction of the ridge modeled by Pollock et al. (2014). The outcrops exhibit radial jointing, bands of vesicles and glassy rims, they occur in high relief surrounded by basalt breccia resembling pillow rubble, and are composed of plagioclase-phyric olivine basalt with plagioclase-rich groundmass. They occur in multiple pillow lava units formed from two distinct magma batches. Two groups of outcrops are represented that are petrographically, geochemically and geographically distinct, the first group is near to and consistent with the pillow units of Undirhliðar quarry described by Pollock et al. (2014), and the second group, located near the tephra cone, is derived from a more evolved unit of the same magma. Megapillows show significant plagioclase accumulation with variable phenocryst zoning, indicating the movement of multiple pulses of magma through the megapillows. Megapillows at Undirhliðar may represent a significant mechanism, demonstrated elsewhere at a marine megapillow by Goto and McPhie (2004), for magmatic distribution: feeding and then overrunning pillows which propagate and are fed from their basal margins at the eruptive front. Text Iceland Digital Commons at Oberlin (Oberlin College) Reykjanes ENVELOPE(-22.250,-22.250,65.467,65.467) |
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Digital Commons at Oberlin (Oberlin College) |
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Iceland Glaciovolcanic Subglacial volcano Basalt Megapillow Pillow Lava Geology |
spellingShingle |
Iceland Glaciovolcanic Subglacial volcano Basalt Megapillow Pillow Lava Geology Heineman, Rachel Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
topic_facet |
Iceland Glaciovolcanic Subglacial volcano Basalt Megapillow Pillow Lava Geology |
description |
At Undirhliðar tindar on the Reykjanes Peninsula, southwestern Iceland, megapillows are among the features formed during a series of ridge-building glaciovolcanic eruptions. Mapping of the northeastern 3 km of the ridge and petrographic and geochemical analysis of the megapillow outcrops occurring throughout this area demonstrate their role in the multi-stage construction of the ridge modeled by Pollock et al. (2014). The outcrops exhibit radial jointing, bands of vesicles and glassy rims, they occur in high relief surrounded by basalt breccia resembling pillow rubble, and are composed of plagioclase-phyric olivine basalt with plagioclase-rich groundmass. They occur in multiple pillow lava units formed from two distinct magma batches. Two groups of outcrops are represented that are petrographically, geochemically and geographically distinct, the first group is near to and consistent with the pillow units of Undirhliðar quarry described by Pollock et al. (2014), and the second group, located near the tephra cone, is derived from a more evolved unit of the same magma. Megapillows show significant plagioclase accumulation with variable phenocryst zoning, indicating the movement of multiple pulses of magma through the megapillows. Megapillows at Undirhliðar may represent a significant mechanism, demonstrated elsewhere at a marine megapillow by Goto and McPhie (2004), for magmatic distribution: feeding and then overrunning pillows which propagate and are fed from their basal margins at the eruptive front. |
format |
Text |
author |
Heineman, Rachel |
author_facet |
Heineman, Rachel |
author_sort |
Heineman, Rachel |
title |
Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
title_short |
Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
title_full |
Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
title_fullStr |
Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
title_full_unstemmed |
Glaciovolcanic Megapillows of Undirhliðar, Reykjanes Peninsula, Southwestern Iceland |
title_sort |
glaciovolcanic megapillows of undirhliðar, reykjanes peninsula, southwestern iceland |
publisher |
Digital Commons at Oberlin |
publishDate |
2017 |
url |
https://digitalcommons.oberlin.edu/honors/204 https://digitalcommons.oberlin.edu/context/honors/article/1203/viewcontent/Heineman_Glaciovolcanic_thesis_17.pdf |
long_lat |
ENVELOPE(-22.250,-22.250,65.467,65.467) |
geographic |
Reykjanes |
geographic_facet |
Reykjanes |
genre |
Iceland |
genre_facet |
Iceland |
op_source |
Honors Papers |
op_relation |
https://digitalcommons.oberlin.edu/honors/204 https://digitalcommons.oberlin.edu/context/honors/article/1203/viewcontent/Heineman_Glaciovolcanic_thesis_17.pdf |
_version_ |
1772815715069329408 |