Structural analysis of the Brigham City-Weber segment boundary, Wasatch normal fault
Conference
·
· Geological Society of America, Abstracts with Programs; (United States)
OSTI ID:5022644
- Utah State Univ., Logan, UT (United States). Dept. of Geology
Structural analysis of the Brigham City-Weber segment boundary of the Wasatch normal fault shows that the segment boundary consists of a broad zone of footwall and hanging wall deformation which coincides with reorientation of the least principal stress. The study area is at a 45[degree] bend in the Wasatch fault at the southern end of the Brigham City segment (BCs), which has a left fault-step with respect to the Weber segment. Moderate- to steeply dipping, predominantly north-striking faults deform Archean gneisses in the footwall. The authors identify three sets of faults in the footwall: young, highly polished faults, weathered fault surfaces, and shallowly dipping chlorite phyllonites. This assemblage of faults reflect recurrent deformation of the footwall during slip on the Wasatch fault. Epidote, quartz, and hematite veins are present throughout the footwall of the fault. Fracture intensity appears greater in rocks near the southeast-striking strand than near the north-striking part of the BCs. The authors used ca. 1,000 slickenline measurements at eight localities for kinematic analysis, and inverted fault slip data to determine principal stress orientations along the bend of the BCs. In each area, orientation of [sigma][sub 3] are consistent with vein orientations. Local stress reorientations may occur at the fault tip. The combined data show a locally re-oriented [sigma][sub 3] and slip vectors indicative of a non-conservative barrier zone. Complex Quaternary scarps in the hanging wall of the southeast-striking strand and divergence of slip vectors on the north-striking and the southeast-striking parts of the BCs also indicate local re-orientation of [sigma][sub 3]. Structure contour maps based on map patterns and mesoscopic fault orientations indicate the bend in the fault may persist to 10--15 km depth. The results suggest that deformation of the segment boundary is accommodated in a broad zone in both hanging wall and footwall.
- OSTI ID:
- 5022644
- Report Number(s):
- CONF-9305259--
- Conference Information:
- Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
- Country of Publication:
- United States
- Language:
- English
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