HR: 1340h
AN: T23D-1663    [Abstracts]
TI: Geophysical and Thermal Crustal Study of Pull-Apart Basins: The Salton Trough and Death Valley, California Regions
AU: * Hussein, M J
EM: mjhussein@miners.utep.edu
AU: Doser, D
EM: doser@utep.edu
AU: Serpa, L F
EM: lfserpa@utep.edu
AB: We have constructed new crustal scale models of two unique pull apart basins, the Salton Trough of southwestern California, which is inferred to be an incipient ocean basin, and Death Valley to the east of the Salton Trough, which is a highly extended continental basin. For this work I have used receiver functions, controlled source seismic, gravity and magnetic data to constrain crustal structure. Analysis of gravity data shows that the anomalies in the Salton Trough are deeper than anomalies of Death Valley. My modeling suggests the Moho is 21 km deep south of the Salton Sea and deepens to 33 km in the region west of the Salton Trough, while in Death Valley the Moho is 26 km deep in the central part of the basin and deepens to 32 km on either side. Another significant difference between the two basins is the density of the lower crust, which is 2950 kg/m3 for the Salton Trough and 2750 kg/m3 for Death Valley. Density of the upper crust varies from 2.75 kg/m3 to 2.45 kg/m3 in the Salton Trough and from 2.6 kg/m3 to 2.4 kg/m3 in Death Valley. Sedimentary rocks and meta-sedimentary rocks in Death Valley are thick and reach a depth of 15 km, while in the Salton Trough the depth of sedimentary rocks and meta-sedimentary rocks is 8-9 km. The rate of deposition is higher in Death Valley than in the Salton Trough which is formed from magmatism in the lower crust and sedimentation in the upper crust. Rising of upper mantle material causes uplifting, thinning, and crustal extension (rifting) in the central part of the Salton Trough south of the Salton Sea, and in the southern part of Death Valley. Magnetic anomalies are shallow in both regions. The anomalies in Death Valley show higher relief (@ 420 nT, compared to 250 nT) than in Salton Trough. In the Salton Trough the magnetic anomalies are almost flat with some exceptions in the marginal areas. Magnetic data were processed to calculate the Curie point depth, wavelength of the magnetic bodies and depth of the magnetic bodies. Curie point depth in the Salton Trough ranges from 14-22 km, which is consistent with other geothermal studies and measurements. Curie point depth measurements for Death Valley range from 12- 20 Km.
DE: 1744 Tectonophysics
SC: Tectonophysics [T]
MN: 2007 Fall Meeting