Distributed extensional deformation in a zone of right‐lateral shear: Implications for geodetic versus geologic rates of deformation in the eastern California shear zone‐Walker Lane

Abstract

[1] The eastern California shear zone (ECSZ)-Walker Lane belt represents an important, evolving component of the Pacific-North America plate boundary. Geodetic data suggest the northern ECSZ is accumulating dextral shear at a rate of $9.3 mm/a, more than double the total measured late Pleistocene rate at $37.5 N. At this latitude, the Silver Peak-Lone Mountain (SPLM) extensional complex plays an important role in accommodating and transferring slip among the strike-slip and normal faults of the ECSZ and Walker Lane. To better understand the recent geodynamic evolution of this region, we determined late Pleistocene extension rates for the Clayton Valley fault zone, one of a series of down-to-the-northwest normal faults comprising the SPLM, using geologic mapping, differential GPS fault scarp surveys, and cosmogenic nuclide geochronology. Extension rates along the Clayton Valley fault zone are time-invariant at 0.1 AE 0.1 to 0.3 AE 0.1 mm/a (depending on fault dip) since $137 ka. When combined with other published fault slip rates at this latitude, the cumulative late Pleistocene geologic slip rate is $3.3 to 5.2 mm/a. This rate is lower than both the geodetic rate of dextral shear and other long-term slip rate budgets in the northern ECSZ. Our results suggest that deformation in Clayton Valley is spread across a diffuse set of normal faults and that not all of the deformation is recorded in the surficial geology. We suggest that the low cumulative geologic slip rate in the northern ECSZ may be a result of this distributed extension, which can cause long-term rates of deformation to be significantly underestimated.

Late Cenozoic displacement transfer in the eastern Sylvania Mountain fault system and Lida Valley pull-apart basin, southwestern Nevada, based on three-dimensional gravity depth inversion and forward models

“…Since the Pliocene and possibly since the mid-Miocene, displacement within the eastern California shear zone (Wallace, 1987;Dokka and Travis, 1990;Miller et al, 2001) and Walker Lane (Locke et al, 1940;Stewart, 1988;Oldow, 1992) has localized as much as 25% of the relative motion between the Pacific and North American plates (Eddington et al, 1987;McQuarrie and Wernicke, 2005;Argus and Gordon, 1991;Reheis and Sawyer, 1997;Dixon et al, 2000;Bennett et al, 2003;Oldow, 2003;Wesnousky, 2005a;Frankel et al, 2007aFrankel et al, , 2007bFrankel et al, , 2008Frankel et al, , 2011Ferranti et al, 2009;Lee et al, 2009;Ganev et al, 2010;Foy et al, 2012) as part of a major intraplate fault zone (Wesnousky, 2005b;Faulds et al, 2005). Within this tectonic belt, substantial deformation has been concentrated on the northern end of the Furnace Creek-Fish Lake Valley (FC-FLV) fault zone (Reheis and Sawyer, 1997;Reheis and Dixon, 1996;Oldow et al, 1994Oldow et al, , 2008, that marks the eastern boundary of the northern eastern California shear zone, where displacement is relayed north-northeast to the Walker Lane (Oldow, 1992(Oldow, , 2003Oldow et al, 1994Oldow et al, , 2008.…”

“…The discrepancy in cumulative displacement was attributed to the transfer of motion east to the central Walker Lane via the Silver Peak-Lone Mountain extensional complex (Oldow et al, 1994(Oldow et al, , 2008. The south to north reduction in Quaternary slip rate, however cannot be accommodated by the Silver Peak-Lone Mountain detachment, which ceased activity by 3-4 Ma, and requires displacement transfer on younger structures (Frankel et al, 2007a(Frankel et al, , 2007bFoy et al, 2012).…”

“…Expanding on the work of Foy et al (2012), our ongoing mapping and structural analysis in the northern part of the southern Walker Lane has identified a complex array of active high-angle faults that link the northern FC-FLV fault system with transcurrent faults of the central Walker Lane. The high-angle faults crosscut and postdate low-angle detachment structures in the region and transfer displacement east from the FC-FLV and north to the central Walker Lane (Fig.…”

“…Until the mid-Pliocene the displacement transfer was accomplished on a low-angle, northwest-dipping detachment fault system underlying the Silver Peak-Lone Mountain extensional complex (Oldow, 1992;Oldow et al, 1994Oldow et al, , 2008Oldow et al, , 2009). Since the mid-Pliocene, younger high-angle faults have crosscut the detachment and continue to carry motion from the FC-FLV fault system to the central Walker Lane (Oldow et al, 2008;Foy et al, 2012).…”

The unusual temporal and spatial slip history of the Wassuk Range normal fault, western Nevada (USA): Implications for seismic hazard and Walker Lane deformation

“…The advent of recent technological advances, such as terrestrial cosmogenic nuclide (TCN) geochronology, increasingly-accurate geodetic information, and improved geophysical modeling tools, has enhanced our ability to compare strain accumulation and release across fault zones over a more complete range of timescales (e.g., Gosse and Phillips, 2001;Bennett et al, 2003;Friedrich et al, 2003;Grosfils et al, 2003;Foy et al, 2012). These temporal and spatial data permit us to address how fault behavior varies in areas of active tectonic deformation.…”