Abstract
We use receiver function, gravity, and magnetic data to image the deep structures of central Death Valley. Receiver function analysis suggests the Moho is 24 km deep in the central part of the basin and deepens to 33 km to the east and 31 km to the west. The estimated lower crustal density is 2900 kg/m3, which suggests a gabbroic composition, whereas the upper crustal density, excluding basin sediments, is estimated to average 2690 kg/m3 or approximately a quartzofeldspathic composition. We modeled the magnetic sources as upper crustal to suggest a relatively shallow Curie depth in this region of high heat flow. We developed models to test the hypothesis that a low-density, non-magnetic body (magma or fluid-rich material?) within the lower crust at a depth of 15 km could coincide with the location of the Death Valley bright spot imaged on a deep seismic reflection profile. Those models suggest that if there is a low density region in the mid to lower crust in the area of the bright spot, then the region is also likely to be underplated by mafic or ultramafic materials which may have contributed to heating, uplift, and thinning of the crust during extension.
Highlights
Death Valley (Figure 1) is a deep topographic basin that extends for approximately 200 km in a north-northwest direction in southeastern California
We developed models to test the hypothesis that a low-density, non-magnetic body within the lower crust at a depth of 15 km could coincide with the location of the Death Valley bright spot imaged on a deep seismic reflection profile
Of particular interest here is the presence of a high amplitude seismic reflection anomaly, termed the Death Valley “bright spot” [8] (Figure 1) which has been suggested to be associated with a magmatic intrusion and volcanism in central Death Valley
Summary
Death Valley (Figure 1) is a deep topographic basin that extends for approximately 200 km in a north-northwest direction in southeastern California. Reference [9] did not find evidence for such a feature elsewhere in the region in his seismic studies and, a magnetotelluric study [10,11] north of the seismic study area did not find supporting evidence for magma in the crust. These studies suggest that if the bright spot is due to a magma body beneath central Death Valley, it is not regionally extensive and is probably relatively small or includes very little actual molten material. The bright spot can be associated with a magma body in the Death Valley subsurface and magma may extend from the surface into the upper mantle where it may be associated magmatic underplating of a large region around the Central Death Valley basin
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