A geophysical study of the Hollister mylonite zone, northeastern North Carolina / by Charles D. Fletcher.
| Author/creator | Fletcher, Charles D. author. |
| Other author | Lawrence, David P., 1943- degree supervisor. |
| Other author | East Carolina University. Department of Geology. |
| Format | Theses and dissertations |
| Production | 1992. |
| Description | 128 leaves : illustrations, maps ; 28 cm |
| Supplemental Content | Access via ScholarShip |
| Subjects |
| Summary | The purpose of this thesis is to identify the geophysical characteristics of the Hollister mylonite zone and its adjacent terranes using potential field surveys. The Hollister mylonite zone is an important constituent of the eastern Piedmont fault system in southeastern Virginia and northeastern North Carolina. It is a steeply westward-dipping, north trending ductile mylonite zone with an average width of one-half kilometer. The fault exhibits reverse, dextral strike-slip motion and is the boundary between the Spring Hope and Roanoke Rapids terranes. Some Alleghanian fault motion has been recorded in foliated parts of the western Butterwood Creek granite (⁸⁷Rb/⁸⁶Sr whole-rock age date of 292 ± 30 Ma). Tracing the fault southward, it skirts the west side of the Rocky Mount pluton, passes through the city of Wilson, and continues south toward Goldsboro, NC. The southern limit of exposure is near Rocky Mount; farther south, the fault is obscured by Coastal Plain sediments. However, magnetic and gravity data can be used to locate the unexposed segment of the fault zone. Detailed gravity data were collected in the proximity of the Hollister mylonite zone. Large- and small-scale regional Bouguer gravity maps and three-dimensional gravity grids were generated from reduced field data. Bouguer gravity maps of 14, 7 1/2-minute quadrangles were also produced. Measurements were concentrated where profiles were of interest. The profiles were modeled to reveal fault geometry and to investigate the geophysical characteristics of adjacent terranes. Gravity data collected along the trend of the fault reveal a steep gravity gradient across the shear zone and minor anomalies associated with faultbounded slices of varying densities in the mylonite zone. Ground magnetic surveys were conducted across the mylonite zone at several localities using a 10 meter spacing between stations. Magnetic profiles, despite varying degrees of cultural data contamination, exhibit signatures showing an interior region of magnetic lows [troughs] bounded by clusters of magnetic highs, interpreted as the outer limit of the shear zone. The magnetic lows within the mylonite zone may result from the presence of low-susceptibility granitic bodies, magnetite destruction and/or other physicochemical processes associated with hydrothermal activity. Aeromagnetic maps show truncation of anomalies by the fault and sigmoidal-shaped lows within the fault zone. East and west splays of the Hollister fault can be recognized on an aeromagnetic map. Integrating gravity and magnetic data established geophysical signatures of the mylonite zone that can be used to estimate the width, orientation. infrastructure of a mylonite zone and to locate major splays of a fault. |
| General note | Submitted to the faculty of the Department of Geology. |
| General note | Advisor: David P. Lawrence |
| Dissertation note | M.S. East Carolina University 1992 |
| Bibliography note | Includes bibliographical references (leaves 85-92). |
| Genre/form | dissertations. |
| Genre/form | Academic theses. |
| Genre/form | Academic theses. |
| Genre/form | Thèses et écrits académiques. |
Availability
| Library | Location | Call Number | Status | Item Actions |
|---|---|---|---|---|
| Joyner | University Archives | ASK AT SPECIAL COLLECTIONS DESK | ✔ Available | Request Material |
| Electronic Resources | Access Content Online | ✔ Available |