Crustal thickness variations across the Rocky Mountain Front from teleseismic receiver functions

Conference · Thu Apr 01 04:00:00 UTC 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5021177

Sheehan, A F ^[1]; Abers, G A; Lerner-Lam, A L ^[2]; Jones, C H ^[1]

---

1. Univ. of Nevada, Reno, NV (United States)
2. Lamont-Doherty Geological Observatory, Palisades, NY (United States)

The Rocky Mountain Front PASSCAL (Program for Array Studies of the Continental Lithosphere) experiment was designed to seismically image the transition from the stable craton in the eastern United States to the active tectonic west trough the use of travel times and waveforms of distant earthquakes. The Rocky Mountain Front experiment consisted of a two-phase deployment of broad band seismometers; a reconnaissance phase in 1991 consisting of eight broad band seismometers in an east-west line stretching across Colorado, and, in 1992, a deployment of 30 broad band seismometers throughout Colorado, eastern Utah, and western Kansas. Broad band receiver functions are examined in order to determine variations in crustal thickness from teleseismic P waveforms recorded with this array. For stations in the Great Plains, a strong P-to-S conversion interpreted to be from the Moho is observed from all azimuths. Within the Rocky Mountains, a weaker P-to-S conversion interpreted to be from the base of the Moho is observed. Based on the timing of these P-to-S conversions the crust does not appear to be thicker under the Rockies than under the Great Plains. Further west, in the Colorado Plateau, a weak Moho conversion is observed, which might be attributed to a smaller impedance contrast at the crust-mantle boundary or a transitional Moho. These results are in general agreement with refraction data, which indicate little change in crustal thickness between the Great Plains and the Rocky Mountains at these latitudes, and relatively thinner crust in the Colorado Plateau. These results suggest that the Rocky Mountains are not isostatically compensated by a simple Airy-type crustal root, as might be inferred solely from gravity data.

• OSTI ID: 5021177
• Report Number(s): CONF-9305259--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
COLORADO
COLORADO PLATEAU
DATA ANALYSIS
DETECTION
DEVELOPED COUNTRIES
DIMENSIONS
EARTH CRUST
GEOPHYSICAL SURVEYS
KANSAS
MEASURING INSTRUMENTS
MOUNTAINS
NORTH AMERICA
ROCKY MOUNTAINS
SEISMIC ARRAYS
SEISMIC DETECTION
SEISMIC DETECTORS
SEISMIC P WAVES
SEISMIC SURVEYS
SEISMIC WAVES
SEISMOLOGY
SURVEYS
THICKNESS
USA
UTAH