Two-stage formation of Death Valley Ian Norton* Jackson School of Geosciences, Institute for Geophysics, University of Texas at Austin, J.J. Pickle Research Campus, Bldg. 196, 10100 Burnet Road (R2200), Austin, Texas 78758-4445, USA ABSTRACT lar to the core complex at Tucki Mountain, (1966), on the basis of the morphology of the at the northern end of the range. The Basin valley and occurrence of strike-slip faults, sug- Extension in Death Valley is usually inter- and Range extensional detachment tracks gested that Death Valley was formed as a strike- preted as a combination of low-angle Basin over the top of the range, with extensional slip pull-apart basin, with the basin forming and Range–style extension and strike slip allochthons perched on the eastern fl anks of between the Northern Death Valley–Furnace associated with the developing Pacifi c-North the range. This modifi ed model for evolution Creek fault to the north and the Southern America plate boundary in western North of Death Valley suggests a strong link between Death Valley fault zone to the south (Fig. 2). America, with these two tectonic regimes timing and style of deformation in the basin This idea has been incorporated into several operating synchronously in Death Valley. with the developing Pacifi c-North America models for the structural evolution of Death Examination of structural, stratigraphic, plate boundary, particularly eastward propa- Valley. Miller and Pavlis (2005) divided these and timing relationships in the region sug- gation of this boundary. models into two categories, depending on how gests that this interpretation needs revision. strike-slip and low-angle detachment faulting Evolution of Death Valley is best described INTRODUCTION are combined. The fi rst category described by as a two-stage process. In the fi rst stage, last- Miller and Pavlis (2005) is the “Rolling Hinge” ing from ca. 18 to 5 Ma, low-angle Basin and Interpretations of the geology of Death Val- model as proposed by Stewart (1983), Hamil- Range extension transported allochthons ley have played an important role in the devel- ton (1988), Wernicke et al. (1988a), and Snow consisting of Late Proterozoic through Early opment of models of continental extension, and Wernicke (2000). In these models, the low- Paleozoic miogeoclinal section along detach- particularly for models that incorporate large- angle detachment faults are dominant, with the ment surfaces that, as extension continued, magnitude extension accommodated by low- Panamint Range moving 80 km west from an were exhumed from mid-lower crustal levels angle detachment faults (Wright and Troxel, original position east of the Black Mountains to the surface. Near the end of this extensional 1973; Hamilton, 1988; Wernicke et al., 1988a; and strike-slip faults as upper crustal edges of phase and lasting until ca. 3 Ma, deposition Snow and Wernicke, 2000; Hayman et al., the detachment system. In the second category, of a thick sequence of volcanics, clastics, and 2003). Detachment fault surfaces are exposed in based on the pull-apart model developed by some lacustrine carbonates signaled a period several places in the Death Valley region, with Burchfi el and Stewart (1966), strike-slip faults of relative tectonic quiescence, with sediments the best studied being the antiformal structures penetrate deeply into the crust and drive exten- in some areas covering the exhumed detach- known as turtlebacks in the Black Mountains sion between their terminations (Wright and ment surfaces. At ca. 3 Ma, initiation of the on the east side of the valley (Figs. 1 and 2; Troxel, 1984; Topping, 1993; Serpa and Pavlis, East California Shear Zone started develop- Miller and Pavlis, 2005). The detachment fault 1996; Miller and Prave, 2002). The low-angle ment of the present-day topographic depres- in the Black Mountains is known as the Amar- detachment surfaces in the latter category are sion of Death Valley, formed as a pull-apart gosa detachment (Wright et al., 1974). Another normal faults linking the strike-slip faults. The basin associated with this strike slip. Faulting important detachment surface is exposed at pull-apart concept has also been applied to the broke the older, inactive, Basin and Range Tucki Mountain, located at the north end of Panamint Valley, the basin on the west side detachment surfaces, with high-angle trans- the Panamint Range on the west side of Death of the Panamint Range, which links via the tensional faulting along the Black Mountains Valley (TM on Fig. 2; Hodges et al., 1987; Hunter Mountain strike-slip fault northwards front. The Black Mountains were elevated as Wernicke et al., 1988b). Stewart (1983) proposed into Saline Valley (Burchfi el et al., 1987; Lee a result of footwall uplift, with the well-known that the Panamint Range forms the hanging wall et al., 2009). In all current models, strike-slip turtleback structures being megamullions of an extensional system that transported the and low-angle extensional faults are regarded along these bounding faults. These mega- Panamint Range westward from on top or east as synchronous. mullions are similar to those seen at oceanic of the Black Mountains, with the latter form- To understand more about structural evolu- spreading centers. The Panamint Range has ing the footwall of this extensional system. In tion of Death Valley, it is useful to consider the previously been interpreted as an extensional this interpretation, motion was accommodated area’s position in relation to structural prov- allochthon, with the entire range transported along the Amargosa detachment fault. A predic- inces that have been defi ned in western North from on top of or east of the Black Moun- tion of this model is that there is a detachment America. Death Valley is located in three partly tains. A new interpretation presented here is fault underneath the Panamint Range; this will overlapping structural provinces (Fig. 1). It that the range is a large core complex simi- be addressed later in this paper. is located in the Basin and Range extensional Prior to recognition of low-angle extensional province (Sonder and Jones, 1999; Burchfi el *E-mail: [email protected] faulting in Death Valley, Burchfi el and Stewart et al., 1992), in the Walker Lane belt (Stewart, Geosphere; February 2011; v. 7; no. 1; p. 171–182; doi: 10.1130/GES00588.1; 11 fi gures; 1 table. For permission to copy, contact [email protected] 171 © 2011 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/7/1/171/3339711/171.pdf by guest on 28 September 2021 Norton 120°W 118°W 116°W Although the ECSZ today accommodates Owens Valley 25% of Pacifi c-North America relative motion, timing of initiation of this shear zone is poorly known. Dokka and Travis (1990b) favored an 38°N Sierra Nevada Basin and Range 38°N initiation age of 10–6 Ma for the Mojave por- WM tion of the ECSZ. In the White Mountains northwest of Death Valley, Stockli et al. (2003) found two main phases of tectonism. In the Walker San Joaquin Valley fi rst phase, up to 8 km of uplift of the White IR Lane Mountains (WM, Fig. 1) occurred in the Middle Miocene as a result of footwall uplift associated with east-west extension. In the second phase, Death transtensional faulting began east of the White Valley 36°N San Andreas Mountains at 6 Ma, followed at 3 Ma by initia- NV 36°N CA tion of strike slip in the Owens Valley (Fig. 1) on the west side of the White Mountains. The Inyo FaultEastern Mountains, south of the White Mountains, are California bounded to the east by the East Inyo fault zone, Garlock Shear which links via the Hunter Mountain fault to the Fault Zone Panamint Valley. Lee et al. (2009), in a detailed analysis of the Inyo Mountains, report a phase of normal faulting starting at 15.6 Ma and initia- tion of strike-slip faulting on the Hunter Moun- 34°N tain fault at 2.8 Ma. The Hunter Mountain fault SJFZ 34°N Elsinore FZ connects to strike-slip faults on the west side of the Panamint Range; Burchfi el et al. (1987) docu- Salton ment 8–10 km of offset on this fault system. Trough These recent studies indicate that strike-slip faulting and extension occurred in separate 120°W 118°W 116°W phases. In this paper, I suggest that Death Valley also formed in two phases, with low-angle Basin Figure 1. Regional topography of western North America, showing and Range–style extension in the Miocene fol- location of Death Valley and tectonic domains. WM—White Moun- lowed by pull-apart basin development during tains; IR—Inyo Range. Topography is gray-shaded with illumina- strike-slip deformation in the last three million tion from the north for areas above sea level. Areas below sea level years. This inference is based on a compilation are in blue. Data from Smith and Sandwell (1997). of age data for the Death Valley region, com- bined with a new interpretation of the geometry of detachment surfaces. In this new interpreta- 1988), and also in the Eastern California Shear of these domains, satellite geodesy (GPS) has tion, a detachment surface tracks over the crest Zone (ECSZ; Dokka and Travis, 1990a). The shown that the Walker Lane belt and ECSZ are of the Panamint Range, rather than underneath Basin and Range is characterized by block together accommodating ~25% of present-day the range, and the Black Mountains turtlebacks faulting and, in areas of large-magnitude exten- plate motion between the Pacifi c and North are megamullion structures formed as a result of sion like Death Valley, by exhumation of middle American plates (Miller et al., 2001; Hammond strike slip.