In the Siða-Fljotshverfi District of south Iceland, Pleistocene basaltic lava forms flame-like apophyses, dikes, and disaggregation structures that invade overlying hyaloclastite. Apophyses as well as underlying lavas are cube-jointed, indicating rapid cooling due to formation in a wet environment and suggesting that hyaloclastite and lava were emplaced almost concurrently, while hyaloclastite was wet and weak. Thermal modeling suggests that influx of heat from the underlying lava resulted in increased fluid pressure in the hyaloclastite matrix. Fracturing of the chilled rind that had formed atop the lava permitted injection of lava into the overlying hyaloclastite. Diffusion of pressure away from the injection site dragged the matrix apart, facilitating propagation of lava upward to form the apophyses.
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Most of Aztec Wash, a mid-sized Miocene pluton in the Colorado River Extensional Corridor, is characterized by mafic, intermediate, and felsic rocks that are interspersed on very small to large scale. Field relations suggest that this heterogeneous assemblage is the product of repeated injection of basaltic magma into a variably crystal-rich magma chamber and subsequent mechanical and chemical interactions. The most pristine manifestations of the intruding mafic magma are sheets and discrete pillow-like masses of basaltic material hosted by granite. The petrographic and textural similarity between sheets and pillows suggests that the latter formed from the former by disaggregation while still molten.
The goal of this study is to understand how mafic disaggregation into a cooler host works in these two specific settings, with potential application to magmatic systems as a whole.
| Identifer | oai:union.ndltd.org:VANDERBILT/oai:VANDERBILTETD:etd-05022008-153344 |
| Date | 14 May 2008 |
| Creators | Banik, Tenley Jill |
| Contributors | Calvin F. Miller, David Jon Furbish |
| Publisher | VANDERBILT |
| Source Sets | Vanderbilt University Theses |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.vanderbilt.edu/available/etd-05022008-153344/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Vanderbilt University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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