This project examines two separate aspects of the volcanic evolution of the Big Bend area. Detailed mapping of phreatomagmatic, basaltic air-fall and base-surge deposits at Peña Mountain shows that they represent the erosional remnants of at least two maars. The deposits intertongue with the Campanian upper shale member of the Aguja Formation, increasing the known extent of Cretaceous volcanism in the Big Bend region. Zircon grains extracted from basalt bombs in the pyroclastic deposits yield a UPb SHRIMP-RG age of 76.6 ± 1.3 Ma.
On the Pitcock Ranch and adjacent parts of the park, Eocene basaltic dikes and phreatomagmatic diatreme root zones show various styles of magma-sediment interaction with the Javelina, Black Peaks, and Hannold Hill Formations. Billowed dike margins, intrusive pillows, and different types of peperite developed in strata as old as the Late Cretaceous, which must have remained unconsolidated and rich in pore water into the Eocene.
| Identifer | oai:union.ndltd.org:TCU/oai:etd.tcu.edu:etd-07282006-104956 |
| Date | 28 July 2006 |
| Creators | Befus, Kenneth |
| Contributors | Richard Hanson |
| Publisher | Texas Christian University |
| Source Sets | Texas Christian University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf, application/msword |
| Source | http://etd.tcu.edu/etdfiles/available/etd-07282006-104956/ |
| 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 TCU 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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