AEG Great Basin Chapter – Monthly Meeting
October 18, 2018
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Speaker: Rich Koehler, NBMG
Topic: Active Faulting in the North Valleys Region of Reno, Nevada: A Distributed Zone within the Northern Walker Lane
Abstract: At the latitude of Reno, Nevada, USA, ~15-25% of the Pacific/North American plate boundary strain is accommodated east of the Sierra Nevada through a combination of normal oblique (dextral) slip along the eastern Sierra Nevada range front and dextral slip along faults in the northern Walker Lane. The North Valleys region sits within the northern Walker Lane directly east of the Sierra range front and is characterized by a series of small north-striking basins bound by Quaternary active faults that accommodate dextral oblique extension. Geodetic studies of the North Valleys estimate that the faults collectively accommodate 0.9-1.7 mm/y of extension and <0.3 mm/y of dextral slip; however, few Quaternary geologic/paleoseismic studies have been conducted.
Here I summarize geologic observations on the tectonic geomorphic expression and relative activity of faults within and bounding the North Valleys based on interpretation of lidar-derived hillshade images and field reconnaissance. The results indicate that the faults all exhibit evidence of active late Quaternary deformation, including offset alluvial fan deposits and abrupt range-front escarpments and are characterized by extension rates on the order of hundredths to tenths of millimeters per year. Cumulative geologic extension rate estimates across the North Valleys are slightly less than rates measured geodetically. On-going mapping, paleoseismic trenching and numerical dating of displaced surfaces are being conducted to refine the style and amount of deformation with the goal of better understanding the role of the North Valleys in transferring dextral oblique extension from the Sierra Nevada range front to faults along the northeastern Walker Lane.
AEG Meeting Schedule—Fall 2018 / Spring 2019
October 18, 2018 – Rich Koehler, “Active Faulting in the North Valleys Region of Reno, Nevada”
November 8, 2018 – Gary Luce, “Burning Man Black Rock Playa Investigation”
December 13, 2018 – Meet & Greet Holiday Party & Fund Raiser
January 10, 2019 – Shawn Gooch, “Permitting Metals Mining in Nevada”
February 7, 2019 – Jahns Lecturer, Debbie Green, AEG Dinner Presentation
February 8, 2019 – Jahns Lecturer, Debbie Green, “Tale of Two Waste Sites” lecture on the UNR campus
March 14, 2019 – Wendy Calvin, “Core Spectral Imaging”
April 18, 2019 – Student Night
AEG Great Basin Chapter Chairperson: