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Nicholas Christie-Blick (Lamont-Doherty Earth Observatory) on: Why Extensional Detachment Faults Are Still A Problem

By Denis Fougerouse 17 October 2019 Applied Geology Comments Off on Nicholas Christie-Blick (Lamont-Doherty Earth Observatory) on: Why Extensional Detachment Faults Are Still A Problem

Wed 23rd Octover@ noon, Rm 312.222

Abstract:

The Basin and Range Province of the western United States has been influential in the development of ideas concerning the extension of continental crust. New structural, geophysical and geochronological data from several field sites in eastern California, southern Nevada, Utah and southeastern Idaho call into question the role of regional detachment faults in engendering large-scale extension of the upper crust. Our data are instead consistent with the now-40-year-old interpretation of Proffett (1977) in the Yerington district, Nevada, that mid- to late Cenozoic extension was accommodated in brittlely deformed rocks by moderately to steeply inclined normal faults that tilted to lower dip during deformation, and were cut by one or more generations of younger, more favorably oriented faults. The application of critical Coulomb wedge theory to the still-contentious Sevier Desert detachment of west-central Utah implies a friction coefficient as low as 0.13. Our data have profound implications for the interpretation of detachment faults in other extensional and passive margin settings.

 

Short bio:

Nicholas Christie-Blick is a professor at Lamont-Doherty Earth Observatory, on sabbatical leave in Perth until June, 2020. His research deals with sedimentation processes, crustal deformation, and deep-time Earth history, with particular reference for the last several years to the low-angle normal fault paradox. He was an undergraduate at Cambridge (1974), and completed his PhD at the University of California, Santa Barbara with John Crowell (1979). He is best known in Australia for his work on the Ediacaran Period, with a new project under way in the Flinders Ranges of South Australia.

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