Integrated and Comparative Geophysical Studies of Crustal Structure of Pull-apart Basins: The Salton Trough and Death Valley, California Regions

This is an integrated and comparative study of two California rifts. The available data make a comparative and integrated analysis worthwhile. For this work we 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. Our 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 2750 kg/m3 to 2450 kg/m3 in the Salton Trough and from 2650 kg/m3 to 2450 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 Salton Trough 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. Salton Trough magnetic anomalies are almost flat with some exceptions in the marginal areas.

Author(s): 
Year: 
Jan 1 2009 (All day)
Type: 
technical report
Keyword(s): 
geophysics
gravity
crustal model
receiver
Research Effort: 
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