PRELIMINARY CURIE DEPTH ANALYSIS OF THE SALTON SEA REGION, SOUTHERN CALIFORNIA

Aeromagnetic data were analyzed to determine the Curie point depth (CPD) by power density spectral and three-dimensional inversion methods within and surrounding Salton Trough in southern California. The Salton Trough, a large polyphase basin, lies in the transition zone between the East Pacific Rise (divergent plate boundary) and the right-lateral San Andreas Fault (transform boundary). The Salton Trough characterized by young volcanism and the presence of several pull-apart, and has been inferred to be in the early stage of evolution from continental to oceanic crust. 3D inversion methods were used to determine the CPD and preliminary results indicate that the Salton Sea region has shallower CPD than the surrounding reigons. The 3D model indicates that the depth to the bottom of the magnetic susceptible bodies varies between 6 and 9 km. These depths compare to CPD’s between 11 and 20 km in the regions east and west of the Salton Sea. The shallowest CPDs occur over the northern portions of the Salton Sea region with progressively deeper CPD’s toward the south. The 3D inversion results will be compared to CPD’s compute from the more traditionally calculated results from 2D power density spectral methods. The CPD will be calculated for 0.5-degree regions using 2D power density spectral methods and compared to the more laterally resolved 3D inversion methods. The 0.5-degree region may average areas that include shallow and deep CPDs, and because of this limitation, previous geophysical and subsurface crustal modeling studies suggest the Moho is 20 km deep to the southwest of the Salton Sea and deepens to 32 km in the region east of the Salton Trough and dome in shape. The shallow CPD values suggest that partially melted material may exist at depth. Previous subsurface crustal modeling shows a magmatic body to the southwest of the Salton Sea at a depth of about 18 km. The Salton Trough contains about 10 km of sediment and this sedimentation may play a strong role in reducing the apparent structural relief in the Salton Trough