A three-dimensional geologic map was created by assembling eight geologic cross sections derived from geologic mapping, potential field geophysics, and petroleum well logs. The central feature of the map is the San Andreas Fault, with many other prominent structural features depicted that express the regional transpressional tectonic setting.
The subsurface interpretation was based on existing two-dimensional geologic mapping and modified by new geologic mapping by USGS geologists between 2005-2014. Existing gravitational anomaly and magnetic anomaly maps helped guide subsurface interpretations. The result is a three-dimensional model that depicts the geologic units, faults, and folds of the region in a model that can be viewed from any perspective and sliced in any direction. Once the map was assembled, kinematic modeling was conducted using the modeling software’s forward and reverse deformation algorithms. These exercises were in part experimental, to assess how well the software’s kinematic algorithms work in this setting. But these experiments have also yielded insights into the geologic history of the region. An experiment with fault motion algorithms revealed a possible mechanism for the creation of secondary faults. Retro-deforming a syncline was also performed to approximate the amount of contraction caused by compressional stress in the region.