Tomographic Investigation of the Upper Mantle Beneath the Western Colorado Plateau and the Eastern Great Basin.
Abstract
The La RISTRA 1.5 project consisted of the deployment of 18 broadband seismic stations along a line extending from the center of the Colorado Plateau into the Great Basin along a northwest azimuth. P and S travel time data are inverted to determine mantle velocity perturbations relative to the IASPE91 velocity model. This 2-D slice extends previous tomographic work which, using the La RISTRA 1 data set, investigated mantle structure from the Great Plains in West Texas, over the Rio Grande Rift, to the center of the Colorado Plateau along a seismic line of the same orientation as La RISTRA 1.5. Combining data from the two experiments we present a high resolution P and S velocity model from the Great Plains across the entire Colorado Plateau into the Basin and Range. Preliminary travel time residuals indicate a laterally highly variable velocity structure of the mantle beneath the transition zone from the Plateau to the highly extended Great Basin. This is similar to the variations in structure seen at the eastern edge of the Plateau and the edge of the Great Plains. The variations observed may indicate vigorous small scale convection occurring at the edges of stable lithospheric blocks within the generally active western United States.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AGUFM.S43A1373S
- Keywords:
-
- 7230 Seismicity and tectonics (1207;
- 1217;
- 1240;
- 1242);
- 7270 Tomography (6982;
- 8180);
- 8109 Continental tectonics: extensional (0905);
- 8121 Dynamics: convection currents;
- and mantle plumes