3D MODELING OF RANGE-BOUNDING FAULTS OF THE NORTHERN BASIN AND RANGE

The iconic, co-linear mountain ranges of the Basin and Range Province are bounded by master, range-bounding normal and strike-slip faults. Previous 3D models representing these important structures have been limited in extent and poorly constrained with respect to fault dip and orientation. Here, we synthesize known constraints on the 3D structure of major range-bounding faults in the northern Basin and Range to produce a more geologically informed model of active faults across the province. Surface traces of major active faults were created in a GIS database using data from the USGS Quaternary Fault and Fold Database, generally resulting in a single trace for each named fault. Each fault trace was attributed with orientation information, such as strike azimuth, inclination (max/min/mean), and constraint type (e.g., field measurement, cross section, earthquake clustering, focal mechanism, seismic line, etc.). Best-fit 3D mesh surfaces were constructed for each fault using the simplified fault surface traces and prescribed fault dip/dip directions from the GIS synthesis. The mesh surfaces naturally produce corrugations characteristic of the range-bounding faults due to well-mapped fault surface traces. The resultant 3D fault framework was combined with existing gravity models to construct a suite of 3D surfaces, offset by the faults, representing the base of the Cenozoic basin-fill sediments. This study demonstrates a viable method for building accurate, province-scale 3D geological models of faulted terrains. It also provides a base structural framework for other types of models that may focus on the Basin and Range (e.g., hydrogeological, geothermal, ore deposit, seismic hazards, 3D kinematic).