Integrated geologic and geophysical modeling across the Bartlett Springs fault zone, northern California (USA): Implications for fault creep and regional structure
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Abstract
The rate and location at depth of fault creep are important, but difficult to characterize, parameters needed to assess seismic hazard. Here we take advantage of the magnetic properties of serpentinite, a rock type commonly associated with fault creep, to model its depth extent along the Bartlett Springs fault zone, an important part of the San Andreas fault system north of the San Francisco Bay, California (western United States). We model aeromagnetic and gravity anomalies using geologic constraints along 14 cross sections over a distance of 120 km along the fault zone. Our results predict that the fault zone has more serpentinite at depth than inferred by geologic relationships at the surface. Existing geodetic models are inconsistent and predict different patterns of creep along the fault. Our results favor models with more extensive creep at depth. The source of the serpentinite appears to be ophiolite thrust westward and beneath the Franciscan Complex, an interpretation supported by the presence of antigorite, a high-temperature serpent ine mineral stable at depth, in fault gouge near Lake Pillsbury.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Integrated geologic and geophysical modeling across the Bartlett Springs fault zone, northern California (USA): Implications for fault creep and regional structure |
| Series title | Geosphere |
| DOI | 10.1130/GES02684.1 |
| Volume | 20 |
| Issue | 1 |
| Year Published | 2024 |
| Language | English |
| Publisher | Geological Society of America |
| Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
| Description | 23 p. |
| First page | 129 |
| Last page | 151 |
| Country | United States |
| State | California |
| Google Analytic Metrics | Metrics page |