Crustal Extension in Southern Great Basin
Explore the magnitude of crustal extension in the southern Great Basin region presented by Wernicke et al. in 1982. The study focuses on the challenges of accurately determining intracontinental extension and the methods used to estimate extension in the Basin and Range province.
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Presentation Transcript
1 Magnitude of crustal extension in the southern Great Basin Wernicke et al., 1982 Presented by Alex Holmwood
2 Problem & methods Difficult to accurately determine amount of intracontinental extension Authors: best method of estimating extension is by restoring offset of linear geologic features Reconstruction along ~E-W transform faults in southern Great Basin (Las Vegas) to estimate minimum extension in Basin and Range province
3 Garlock fault Matching correlated features along Garlock fault (sinistral) Dike swarms north and south of Garlock Extensional faulting accommodated 60 km of slip along Garlock fault Extensional faulting occurred over a transect ~115 km wide
4 Las Vegas Valley shear zone, Lake Mead fault system Dextral slip along Las Vegas Shear Zone Correlating thrust fault traces N and S of LVSZ Wheeler Pass thrust Gass Peak thrust 44-69 km of displacement Lake Mead fault system 20 km sinistral offset of Hamblian-Cleopatra stratovolcano Estimated total offset of system at ~65 km
5 Results & discussion 65% extension (140 km) between southern Sierra Nevada and Colorado Plateau Assumes no extension immediately N or S of fault traces (rigid) Uncertainties may increase estimate of extension; 140 km is a safe minimum estimate
