Constraints on exhumation and extensional faulting in southwestern Nevada and eastern California, U.S.A., from zircon and apatite thermochronology

Abstract

Eastern California and southwestern Nevada represent an area of Tertiary and Quaternary extensional and dextral transtensional deformation. We used zircon and apatite fi ssion-track thermochronology to study the distribution and timing of tectonic exhumation resulting from extensional and transtensional detachment faulting in this area. Sampling efforts were focused on Paleozoic and Precambrian clastic sedimentary and metasedimentary rocks. Sixty-nine new apatite and zircon fi ssion-track cooling ages from 50 samples, analyzed in conjunction with published fi ssion-track data from the region, indicate a distinct population of young (Miocene) fi ssion-track ages and a population of irregularly distributed older (pre-Miocene) fi ssion-track ages. Miocene (young population) fi ssion-track ages become younger toward the west-indicating westward migration of the cooling front, consistent with well-documented Miocene extension of the Basin and Range Province. The younging pattern is also consistent with west-northwest displacement of the hanging wall of a crustal-scale extensional fault system and consequent progressive footwall exhumation. The active trailing edge of the hanging wall of this system generally coincides with Death Valley. Migration rates of the cooling front in the footwall of this system are on the order of 10-11 mm/yr. Based on the distribution of the Miocene fi ssion-track ages, we interpret that the crustal faults that defi ned the eastern edge of the detachment system originated as separate normal faults that were linked by the formation of a transfer fault. Extrapolation of apatite fi ssion-track closure ages from two transects across the eastern margin of the Death Valley region suggests that exhumation along the eastern margin of the system continues beneath Death Valley today.

Low-temperature thermochronology of the Black and Panamint mountains, Death Valley, California: Implications for geodynamic controls on Cenozoic intraplate strain

“…The new thermochronology data, when placed within the context of published fault timing data, demonstrate that the very eastern part of the Eastern California shear zone experienced a transition to dextral transtension that was coincident with and likely triggered by the plate-boundary kinematic change at 10-8 Ma, while areas to the west lagged this change by several million years. A westward progression in fault initiation is predicted by and may support a rolling hinge model for the structural development of the greater Death Valley area (e.g., Stewart, 1983;Wernicke et al, 1988;Snow and Wernicke, 2000;Niemi et al, 2001;Ferrill et al, 2012), but given the two-phase pattern of deformation documented by this and other studies (e.g., Stockli et al, 2003;Lee et al, 2009;Walker et al, 2014), such a model may be too simplistic. As an alternative, the westward progression of fault initiation could reflect changes in crustal strength that closely follow the locus of earlier extension and crustal thinning (Fridrich and Thompson, 2011).…”

“…Such a connection has been postulated and modeled by a number of authors (e.g., Jones et al, 2004;Oldow et al, 2008;Le Pourhiet et al, 2006;Saleeby et al, 2012), but major gaps in fault timing constraints have rendered the relationship between the two ambiguous. Data from this study, combined with published fault timing constraints Dokka, 1991, 1993;Hoisch and Simpson, 1993;Reheis and Sawyer, 1997;Snow and Lux, 1999;Niemi et al, 2001;Stockli et al, 2003;Lee et al, 2009;Mahan et al, 2009;Beyene, 2011;Ferrill et al, 2012;Walker et al, 2014), indicate that the initiation of dextral transtension occurred as a westward-migrating wave, with transtensional structures initiating in the east at ca. 11-8 Ma, in Death Valley and Fish Lake Valley at 6 Ma, and in areas west of Death Valley at 4-3 Ma.…”

“…Faults located east and north of the Black Mountains (e.g., Stateline fault, Boundary Canyon detachment, Furnace Creek fault, Northern Death Valley-Fish Lake Valley fault) initiated between 11-8 Ma, around the time of the plate-boundary change (Fig. 1; Holm and Dokka, 1991and Dokka, , 1993Hoisch and Simpson, 1993;Reheis and Sawyer, 1997;Snow and Lux, 1999;Niemi et al, 2001;Mahan et al, 2009;Beyene, 2011;Ferrill et al, 2012). It is unclear if these structures initiated at the onset of regional extension or dextral transtension, a problem that is compounded by the fact that some of the published data are maximum ages rather than well-defined fault initiation ages (e.g., Reheis and Sawyer, 1997;Snow and Lux, 1999;Niemi et al, 2001).…”

A diamictite dichotomy: Glacial conveyor belts and olistostromes in the Neoproterozoic of Death Valley, California, USA

“…In this paper, we resolve this controversy, with widespread implications for how rift-related and glacially related diamictites can be distinguished in the Cryogenian. The sections occur near the westward limit of the Basin and Range province and are cut through by a series of fault systems in multiple orientations that include Miocene extensional overprint of older fault zones (Ferrill et al, 2012). In spite of the rocks having locally reached amphibolite grade (Kupfer, 1960), delicate sedimentary textures are well preserved throughout the succession.…”

Observations on normal-fault scarp morphology and fault system evolution of the Bishop Tuff in the Volcanic Tableland, Owens Valley, California, U.S.A.

“…Timing of basin formation, fault activity, andesite-rhyolite volcanism, and the transition from diverse andesite-rhyolite volcanism to basaltic or bimodal volcanism all generally become younger from east to west across the Basin and Range Province (Stewart, 1998). Some of the most active deformation in the Basin and Range Province is occurring in eastern California in a region referred to as the Walker Lane belt-an area of interconnected normal and strike-slip faults that includes Miocene to present largemagnitude crustal extension and tectonic exhumation of the eastern Walker Lane (Stewart, 1983;Snow and Wernicke, 2000;Ferrill et al, 2012b). Owens Valley marks the western edge and most active portion of the Walker Lane belt along the eastern Sierra Nevada range (Dixon et al, 2000(Dixon et al, , 2003Oldow, 2003;Fig.…”