Seismic reflection, bathymetric and tomographic constraints on Holocene fault activity and extension in the Great Salt Lake basin, Utah
Abstract
The Great Salt Lake basin consists of two NNW-SSE-trending, broadly asymmetric, depocenters that accommodate up to 4.8 km of Tertiary to recent basin-fill sedimentary rocks. These depocenters are bounded by two major Tertiary listric normal faults (the East Lake and Carrington faults). These faults are located 20-40 km west of the prominent Wasatch escarpment formed by the Wasatch fault. The Wasatch fault generally is the presumed active front of extensional deformation in the region, with the greatest likelihood of generating large earthquakes in the area. However, analysis of seismic reflection and bathymetric data points out that the faults that bound the Great Salt Lake (GSL) basin have accommodated a great deal of displacement over time and still appear to be active. Quantitative analyses of fathometer-recorded bathymetric data using gradient operators and spatial derivatives show abrupt changes in bathymetry that appear to be related to offset of the lake floor by active faults. Relations interpreted from seismic profiles in the lake show that the deeper faults intersect the lake floor at the traces of the bathymetric scarps. Development of fault scarps in a flat, very shallow, internally drained basin indicates very recent fault activity along the large faults beneath the Great Salt Lake. Furthermore, refraction tomographic analyses provide new information on near-surface (lake-bottom) velocity structure across the fault zones. Coupled with high fault-slip rates in the Pliocene (1.1 mm/yr) and Quaternary (0.7 mm/yr) inferred from the seismic reflection profiles, the bathymetric and tomographic data imply that the East Lake and Carrington faults remain tectonically active structures.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2005
- Bibcode:
- 2005AGUFM.T13C0492H
- Keywords:
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- 7230 Seismicity and tectonics (1207;
- 1217;
- 1240;
- 1242);
- 8015 Local crustal structure;
- 8109 Continental tectonics: extensional (0905);
- 8169 Sedimentary basin processes