Imaging the Deep Structure of the Central DeathValley Basin Using Receiver Function, Gravity,and Magnetic Data

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/m 3 , which suggests a gabbroic composition, whereas the upper crustal density, excluding basin sediments, is estimated to average 2690 kg/m 3 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.

Adakites without a slab: Remelting of hydrous basalt in the crust and shallow mantle of Borneo to produce the Miocene Sintang Suite and Bau Suite magmatism of West Sarawak

“…Association of magmatism with transtensional settings, similar to the Lupar Line fault system, is known from modern and ancient locations such as Death Valley, the Red River Fault, and the Midland Valley of Scotland (e.g. Calzia and Ramo, 2000;Monaghan and Parrish, 2006;Hussein et al ., 2011). Crustal thinning associated with tension allows the mantle to upwell and, hence, melt (McKenzie and Bickle, 1988).…”

Curie Point Depth Estimates from Aeromagnetic Data from Death Valley and Surrounding Regions, California

“…PARK (2004) concluded that partial melt is relatively uncommon beneath the Sierra Nevada and the California Basin and Range except for isolated regions beneath Miocene or younger basalt eruptions. Detailed gravity studies have provided constraints on the Death Valley basin thickness and geometry (KEENER et al 1993;BLAKELY et al 1999) and regional gravity studies combined with receiver function studies have been used to determine the crustal structure of the Death Valley region (HUSSEIN et al 2011). KEENER et al (1993) and BLAKELY et al (1999 analyzed Bouguer gravity anomalies and determined that the Death Valley basin has thicknesses varying between 3 and 5 km with steep sides along the edges of the basin.…”

Geophysical Investigation of Hot Springs in the Vicinity of Shoshone, California

“…The Bouguer anomaly map (figure 5) displays a smooth trend with values ranging from -114.77 mGal to -88.0 mGal. Low Bouguer anomalies are likely associated with the presence of unconsolidated sediments and sedimentary rocks (M. Hussein et al, 2011), or the presence of less dense tertiary volcanic rocks underlying the Holocene deposits which makes up the basin fill (Hillhouse et al, 1987). Alternatively, the low density within the basin can be associated with thicker pyroclastic sediments that are mainly less dense but have high magnetic susceptibility (Louie et al, 1996).…”

“…Various geophysical studies have been conducted in the Tecopa Basin (Louie, 1996;Serpa, 1988;Hillhouse, 1987;Wamalwa, 2011;Hussein, 2011) (Serpa et al, 1988). Two of the seismic lines cross the Tecopa Basin.…”