Tectonic displacement and far-field isostatic flexure of pluvial lake shorelines, Dixie Valley, Nevada

Abstract

Shoreline features formed by the late Pleistocene pluvial Lake Dixie in Dixie Valley, central Nevada, record crustal deformation resulting from isostatic rebound of the Lake Lahontan basin, and from Holocene and historic surface faulting. Constructional beach bars on the east side of Dixie Valley show eastward tilt of 0.16 m/km, indicating that lithospheric flexure due to isostatic rebound is symmetrical with the west side of the Lahontan basin. The tilt signal is potentially complicated by post-Lake Dixie fault displacements on the west side of the valley. However, elevation changes recorded geodetically across the analogous 1983 Borah Peak, Idaho earthquake ruptures suggest that coseismic deformation is probably not significant on the east side of the valley relative to the shoreline elevation uncertainties and the overall tilt signal. A survey of faulted shorelines on the west side of the valley suggest that previous fault slip rates estimated from an earlier survey of these same shorelines are in error by nearly a factor of two. Better constrained slip rates from elsewhere along the fault indicate Holocene vertical slip rates of 0.3–0.5 mm/a, consistent with estimates of long term slip rates on the Dixie Valley fault. © 2004 Elsevier Ltd. All rights reserved.