FISSION TRACKS IN FLUORITE AND APATITE WITH GEOLOGIC APPLICATIONS
Abstract
This dissertation is a compilation of three studies of fission tracks in fluorite and apatite. The first section covers fluorite annealing experimental work, the second section is an application of the fluorite fission track technique to the Rio Grande rift, and the third section represents a preliminary study on the differences in spontaneous and induced fission track lengths in apatite. The first section establishes fluorite as a viable mineral for fission track dating. Although mineralization events can occassionally be dated by other methods, the ability to date fluorite is important because it commonly occurs as an ore and/or gangue material in mineral deposits. Fission track annealing experiments indicate that tracks are stable in fluorite and will be retained in the mineral up to temperatures of 90-110$\sp\circ$C for times up to 1 m.y. This temperature is the lowest of all the common fission track minerals and is very sensitive to thermal events. Fluorite fission track ages compared very well to K-Ar and other fission track dates in cases where the mineralization has been dated by other methods. To apply the fluorite fission track technique to undated mineral deposits the Rio Grande rift was chosen for study. Fluorite in the Rio Grande rift ranges in age from 125-10 m.y. Many of the fluorite occurrences that were thought to be related to Rio Grande rift tectonics (less than 30 m.y.) were instead shown to instead be related to older Laramide activity. Fluorite mineralization can be considered the manifestation of a thermal event. In the Rio Grande rift area fluorite of differing ages was found in the same deposit. Thus, it appears that once a route for mineralizing fluids has been established, subsequent mineralization will take place along these same conduits. During the initial annealing studies on both spontaneous and induced fission tracks in fluorite, differences in annealing rates were observed. These observations led to some preliminary experiments concerning the effects of strain on fission track lengths. The results from these experiments suggest that "natural" strain present in a crystal is enough to cause shorter spontaneous fission tracks. Straining of crystals can further reduce fission track lengths in spontaneous samples and reduce the track lengths in induced fission track samples.
Subject Area
Geology
Recommended Citation
HARDER, VICKI MARIE, "FISSION TRACKS IN FLUORITE AND APATITE WITH GEOLOGIC APPLICATIONS" (1987). ETD Collection for University of Texas, El Paso. AAI8721371.
https://scholarworks.utep.edu/dissertations/AAI8721371