Thesis
LIDAR results in a revised map and analysis of active faults in West Cache fault zone, Utah (Senior thesis)
(2018)
Abstract
Comprehensive image analyses confirm and greatly expand the map of active normal
faults within the Cutler Dam Quadrangle and areas surrounding it. The current study area
incorporates the Cutler Dam Quadrangle and extends south past Mendon, Utah along the east
edge of the Wellsville Range. New 0.5 meter LiDAR images in conjunction with gravity data
from Robert Q. Oaks, Jr. provide new significant data that permit a major revision of maps of
active faults along the south-central West-Cache fault zone. Careful examination reveals 1) the
first documented fault scarps of the Dayton-Oxford fault along the newly identified Cutler
Reservoir segment, 2) a lateral spread east of the Newton Hill gravel pit in Holocene and Salt
Lake Formation deposits of the Amalga Barrens area (Williams, 1962), 3) major fault scarps
within Mendon city limits, and 4) fault scarps that connect the Dayton-Oxford with the rest of
the West Cache fault zones. We also confirm the prior interpretation of Goessel et al. (1999) of
two subparallel active normal fault zones along the east margin of the Wellsville Range and
Junction Hills. Subsequent mappers omitted the low-elevation fault zones of Goessel et al.
from their compilation of active faults, yet we observe probable low-elevation fault scarps
along the East Wellsville fault zone and the East Junction Hills fault zone. Many faults of the
West Cache fault zone have dispersed and stepping traces, and this results in considerable
complexity. Details of the fault structure remains undetermined, but the new geometries are
quite clear.
Field observations in Newton Hill gravel pit confirm that the fault scarps mapped on the
Dayton-Oxford fault zone using the LiDAR dataset are tectonic. A normal fault in the gravel pit
displaces 40-65 Ka lake beds and soils by several meters and is due north of a fault scarp
imaged by the LiDAR. A less well-expressed second strand of the Dayton-Oxford fault zone may
be present near the West Cache Valley highway (Utah Highway 23).
The LiDAR data confirm that the main traces in the Cutler Reservoir fault array of
Jänecke and Evans (2017) are tectonic, that there are fault scarps along many closely spaced
fault traces within Holocene alluvial sediment and that the western half of the Cutler Reservoir
fault array is the southern segment of the Dayton-Oxford fault. This interpretation expands the
mapped traces of the Dayton-Oxford fault south-southwestward 18 km along strike to Mendon,
Utah. The east-southeast dipping normal faults in the western part of the Cutler-Reservoir fault
array are a dispersed fault zone with numerous subparallel and stepping strands. The
southernmost extension of the Dayton-Oxford fault has a branch zone with the Junction Hills
and the Wellsville fault in Mendon, Utah. The town of Mendon was built across an
approximately 30-m high fault scarp in the West Cache fault zone.
West-dipping faults that are concentrated east of Cutler Reservoir also displace
Holocene sediment, and they may be antithetic structures that are secondary to the dominant
Dayton-Oxford fault zone. Their consistent north-northwest strike may complicate that
interpretation, however. Therefore, we suggest that the Cutler Reservoir Array of faults be
classified as the southernmost segment of the Dayton-Oxford fault zone.
Keywords
- LIDAR,
- Holocene,
- Active fault,
- Dayton-Oxford fault zone,
- West Cache fault zone,
- Cache Valley
Disciplines
Publication Date
Summer August, 2018
Degree
BS
Field of study
Geology
Department
Geology
Advisor
Susanne U. Janecke
Comments
Senior thesis. We are making this document available to interested parties using the bepress site.
Citation Information
Ellis, N.R., and Jänecke, S.U., advisor, 2018, LIDAR results in a revised map and analysis of active faults in West Cache fault zone, Utah (Senior thesis): Utah State University Geology Department.