Small‐scale upper mantle convection and crustal dynamics in southern California

摘要: We present numerical modeling of the forces acting on base crust caused by small-scale convection upper mantle in southern California. Three-dimensional shear wave velocity structure is mapped to three-dimensional density that used load a finite element model instantaneous flow with respect rigid crust, providing an estimate tractions crust. Upwelling beneath Walker Lane Belt and Salton Trough region downwelling Great Valley eastern western Transverse Ranges dominate resulting crustal tractions. Divergent horizontal upward directed vertical create tensional transtensional stress state Trough, consistent tectonics these areas. Convergent downward cause approximately N–S compression, active shortening transpressional deformation near “Big Bend” San Andreas fault. Model predictions dilatation Mojave block compare favorably observations suggesting provides important contribution sum driving Accordingly, obliquity fault plate motions may be considered consequence, rather than cause, contractional Ranges, itself driven superimposed relative Pacific–North American motion.