See more from this Division: General Discipline Sessions
See more from this Session: Structural Geology / Tectonics / Neotectonics/Paleoseismology II
Abstract:
Both Quaternary faults and geophysically conspicuous basins are largely absent south of Lake Mead, where the only prominent gravity low corresponds to a structurally intact basin filled primarily with halite along the less extended, eastern margin of the corridor. Relatively continuous northeast-trending magnetic anomalies south of Lake Mead, presumably sourced by Proterozoic basement rocks, suggest that strike-slip displacement is negligible on many of the major normal faults. In contrast, magnetic anomalies are smeared along the Lake Mead fault system and Las Vegas Valley shear zone. These magnetic basement blocks located at the northern end of the Colorado River extensional corridor may mark an old easterly-striking crustal flaw that extends 150 km east onto the Colorado Plateau. Offset magnetic anomalies suggest left-lateral displacement of 12-20 km for the Hamblin Bay fault zone, 12-15 km for the Lime Ridge fault, and 12 km on the Gold Butte fault. These values are comparable to or lower than published estimates based on geologic mapping.
See more from this Division: General Discipline Sessions
See more from this Session: Structural Geology / Tectonics / Neotectonics/Paleoseismology II