Article,
Images of crustal variations in the intermountain west
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH, 109 (B3): B03306 -- (March 2004)
Abstract
1 We develop a map of crustal thickness variations across the Great
Basin, Colorado Plateau, Rocky Mountain, and Great Plains Provinces
of the western United States using common conversion point stacking
of teleseismic receiver functions. Below the Rocky Mountains and High
Plains in Colorado we find the thickest crust in the region at 45-50
km thick. Beneath the Basin and Range, thinner, between 30 and 40 km,
crust is found. Thin, 30 km thick, crust is present in the northern
portion of Nevada and Utah despite elevations similar to those
farther south. Crustal thickness across the Colorado Plateau can be
characterized as a broad transitional region between the thin crust
of Basin and Range to the thicker crust of the Rocky Mountains. The
impedance contrast across the Mohorovicic discontinuity decreases
below the Colorado Plateau, as converted arrivals recorded in this
region appear weak compared to surrounding areas. Variations in
V-P/V-S across the region indicate higher values along the western
boundary of the Basin and Range, in the Rocky Mountains, and in the
western Great Plains. We are not able to characterize V-P/V-S in the
Colorado Plateau. We find that crustal thickness does not closely
correlate with surface topography within each region or across the
region as a whole. Differences in crustal thickness in each tectonic
province indicate the need for a mantle component to support the high
elevations across the western United States.
Tags
- and
- basin
- beneath;
- colorado
- crustal
- data;
- discontinuity
- extension;
- functions;
- mantle
- plateau;
- province;
- range
- receiver
- rocky-mountains;
- s.
- seismic-reflection
- shear
- stability;
- structure
- structure;
- tectonic
- teleseismic
- transition
- u.
- united-states;
- western
- zone;
