Abstract

Bræðravirki Ridge is a hyaloclastite-dominated tindar in the Western Volcanic Zone of Iceland. Bræðravirki Ridge can provide insight as to what processes start at the beginning of a glaciovolcanic eruption These processes are no able to be witnessed as they happen. By studying the olivine crystals found in the samples collected from previous studies, it is possible to confirm their hypotheses of magma mixing and the ridge’s eruptive sequence. These samples consisted of pipes, pillow lavas, lapillistone, and intrusions. This study performed a random point count of olivine crystals in thin sections to find out their morphological distribution. Out of the polyhedral, tabular, hopper, and skeletal morphologies, most samples contained predominately polyhedral crystals. The distribution of polyhedral to other morphologies were similar between the pillow basalts and pipes. This can conclude that these two lithologies were made from the same magma and that the pipes acted as a feeding mechanism for the pillow basalts. The intrusions and the lapillistone had a noticeable increase of tabular, hopper, and skeletal in their morphological distribution. This indicates that these lithologies had a similar melt that experienced higher cooling rates for a longer duration. The observation that olivine was crystallizing during the emplacement of the extrusive units indicates that the mixing event from Topham’s (2023) hypothesis is confirmed and may have initiated the eruptive event. This could tell us that other mixing events cause eruptions within glaciovolcanic settings. A lack of dendritic morphologies alongside several embayments means more information needs to be conducted at Bræðravirki ridge.

Advisor

Pollock, Meagen

Department

Geology

Publication Date

2025

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2025 Hayden Jacoby