Abstract

The ancient Mid-Atlantic ridge began spewing lava between seven and fifteen million years ago forming multiple thin flow layers cooling on top of one another. The extensive volcanic and intrusive units that define the geology of Iceland are products of a unique correlation between the Mid-Atlantic ridge and the Icelandic hot spot. The accumulation of subsequent lava flows from the rift axis resulted in the formation of flexural subsidence due to the increased weight. These lava flows dipped towards the rift zone over time and were pushed laterally away. The process of zeolitization is controlled by host rock composition, aqueous silica activity, depth, and temperature, which is the most important variable in zeolite stability, partly because of their high water content. These factors determine when, where, and what zeolites will form or whether zeolites will form at all. Vatnsdalsfjall mountain range, near the southern end of the Skagi Peninsula, is a glacially carved ridge along the extinct Húnafloí-Skagi rift zone, and the Vatnsdalur Structural Basin (VSB) is an elliptical depression composed of tilted basaltic lava flows that have experienced even more localized subsidence. The formation of mineral filled vesicles called zeolites occurred in this region during three possible events: pre-subsidence, syn-subsidence, and post-subsidence of the VSB, and the earlier subsidence of the flexure zone. Zeolite formation can then be divided into two host rock environments: olivine dominate and tholeiitic dominate basalts. Then analysis of groupings of certain zeolite species can be separated into zones based on location in the monocline and their host rock composition. Further analysis of zeolite placement brings to light that zeolitization occurred during two geological events or phases; one while the initial lava flows were relatively flat-lying to the paleosurface, and the other during syn/post-subsidence of the monocline where the zone boundary cuts through stratigraphy.

Advisor

Pollock, Meagen

Department

Geology

Disciplines

Geology | Mineral Physics | Other Earth Sciences | Volcanology

Publication Date

2015

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2015 Olivia L. Brown