Middle Miocene to Recent Exhumation of the Slate Range, Eastern California, and Implications for the Timing of Extension and the Transition to Transtension

Middle Miocene to recent exhumation of the Slate Range, eastern California, and implications for the timing of extension and the transition to transtension J. Douglas Walker, Tandis S. Bidgoli, Brad D. Didericksen*, Daniel F. Stockli†, and Joseph E. Andrew Department of Geology, University of Kansas, Lawrence, Kansas 66045, USA ABSTRACT sional belt at the latitude of Las Vegas, Nevada, 2005) considered the Furnace Creek fault to be may have been stretched as much as 300% since active from ca. 9 to 5 Ma, and that this fault is a New mapping combined with fault-slip and ca. 16 Ma (e.g., Wernicke et al., 1988; Niemi component of the dextral regime (Fig. 1). Snow thermochronological data show that Middle et al., 2001). The earlier deformation resulted and Lux (1999) interpreted the change to dex- Miocene to recent extension and exhumation in primarily east-west extension across the tral deformation in Death Valley to have started of the Slate Range, eastern California, is pro- region (Wernicke et al., 1982, 1988), initiat- ca. 11 Ma (Fig. 1). Other studies that focus on duced by the active Searles Valley fault sys- ing ca. 15 Ma, as inferred by the ages of early different areas interpret younger ages for this tem and the Slate Range detachment, an older basin deposits of the Panuga (Snow and Lux, change to transtension. Hodges et al. (1989) Middle Miocene low-angle normal fault. Off- 1999) and Eagle Mountain formations (Niemi placed the transition as ca. 3.7 Ma in Pana- set Middle Miocene rocks record a combined et al., 2001) of the northern Death Valley area, mint Valley (Fig. 1). Monastero et al. (2002) ~9 km of west-directed extension over the and of the Panamint Valley volcanic sequence considered this transition to have occurred ca. past ~14 m.y. for the fault zones. (U-Th)/He in the Argus, Panamint, and Slate Range region 3–2 Ma in the Indian Wells Valley based on apatite cooling ages of samples from the (Fig. 1; Andrew and Walker, 2009). Peak exten- mostly subsurface stratigraphic data. Bellier and central and southern Slate Range indi- sion, however, probably occurred after 15 Ma Zoback (1995) considered the transition to have cate that footwall cooling began ca. 14 Ma; (Snow and Wernicke, 2000, p. 687) and lasted occurred in the past 300 k.y. using Holocene we interpret this as the age of initiation of until Late Miocene time; the locus of the major fault scarp slip data. In Stockli et al. (2003), a motion on the Slate Range detachment. This deformation is interpreted to be east of Pana- general westward migration of the transition timing is consistent with inferences made mint Valley. was reported, starting at 6 Ma and progressing using stratigraphic and structural criteria. Later deformation is primarily transtensional westward to 4 Ma, based on fault kinematic and Data from the northern Slate Range show in character, expressed as dextral-oblique nor- thermochronometric data from the Fish Lake that rapid fault slip began along the Searles mal faults and strike-slip faults active in the Valley–White Mountain area. Thus, the precise Valley fault ca. 4 Ma; data from the central region from the Spring Mountains to the eastern timing and associated spatial patterns of the and southern Slate Range can be interpreted fl ank of the Sierra Nevada. At this latitude, this onset of signifi cant dextral deformation remain as indicating cooling at 5–6 Ma. This tim- later deformation belt is variously referred to uncertain. The transition from east-west exten- ing correlates to the results of nearby stud- as the eastern California shear zone or Walker sion to northwest-directed oblique extension is ies, suggesting a strain transition in the sur- Lane belt, and affects the western half of the apparently complex in both timing and location. rounding area between ca. 6 and 3 Ma. The older Basin and Range extensional province. The resolution of this problem requires more data collected are most consistent with a Atwater and Stock (1998) interpreted a complete documentation of the age of transten- westward migration in the locus of transten- change in plate motions ca. 10 Ma, from a sional slip on specifi c structures. sional deformation, and show that the initia- more westward to a more northward motion This paper aims to more closely bracket the tion of that deformation commonly lags the of the Pacifi c plate relative to North America, initiation of extension and to better defi ne the timing predicted by plate reconstructions by and associated this change to the transition to age of the transition from extension to transten- a few million years. dextral-transtensional deformation. Geological sion for the Slate Range and adjacent Searles evidence indicates a more complex deforma- Valley, which are west of Panamint and Death INTRODUCTION tional history. Mahan et al. (2009) suggested Valleys (Fig. 1). To do this we present new initiation of dextral transtension along the State- structural interpretations tied to three thermo- The Miocene Basin and Range extensional line fault in southern Nevada ca. 5 Ma (Fig. 1). chronologic transects from the northern, cen- province and the latest Miocene to recent east- Wernicke et al. (1988; and subsequently Snow tral, and southern Slate Range. The northern ern California shear zone–Walker Lane transten- and Wernicke, 2000; McQuarrie and Wernicke, transect (approximately along cross-section *Present address: Platte River Associates Inc., Houston, Texas 77270, USA †Present address: Jackson School of Geosciences, University of Texas, Austin, Texas 78712, USA Geosphere; April 2014; v. 10; no. 2; p. 276–291; doi:10.1130/GES00947.1; 9 fi gures; 3 tables; 1 supplemental fi le. Received 13 May 2013 ♦ Revision received 24 August 2013 ♦ Accepted 12 February 2014 ♦ Published online 17 March 2014 276 For permission to copy, contact [email protected] © 2014 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/10/2/276/3332756/276.pdf by guest on 28 September 2021 Slate Range extension and transtension CM = Cottonwood Mountains Nevada EIF = Eastern Inyo Fault Test Site FCF = Furnace Creek fault Region GF = Garlock fault HMF = Hunter Mountain fault 118° W 118° OVF = Owens Valley fault 37° N NB = Nova Basin Inyo Mountains EIF NDVF NDVF = Northern Death Valley fault Nevada California SDVF = Southern Death Valley fault SLF = State Line fault SV CM OVF SNFF = Sierra Nevada Frontal fault SV = Saline Valley TPF = Towne Pass Fault HMF TPF FCF SLF Spring Mountains Panamint Valley NB Death Valley Panamint Range Argus Range Sierra Nevada SNFF 36° N SDVF Slate Range 116° W 116° Study Area (Figure 2) Kilometers GF 0255012.5 Figure 1. Digital elevation model of study area and surrounding region. Warm colors correspond to the mountain ranges and cool colors to the basins. Extensional and transtensional structures that are part of the eastern Cali- fornia shear zone are indicated. A–A′ in Fig. 2) trends east-west across the along the northern transect consist of 100 Ma lava fl ows, pumaceous epiclastic rocks, and northern Slate Range, near where the south- Stockwell diorite, 159 Ma Copper Queen andesitic to dacitic laharic deposits (Smith et al., west-striking Manly Pass fault joins the north- alaskite, and 166 Ma Isham Canyon granite 1968; Andrew and Walker, 2003, 2009; Dider- striking Searles Valley fault; the central transect (Moore, 1976; Dunne and Walker, 2004) con- icksen, 2005). A similar volcanic and sedimen- (along cross-section B–B′ in Fig. 2) crosses the taining pendants of Paleozoic and Mesozoic tary sequence is also found to the northwest in Slate Range just north of Tank Canyon; and the metasedimentary rocks. The central and south- the Argus Range (Moore, 1976; Andrew and southern transect (cross-section C–C′ in Fig. 2) ern transects cross Jurassic plutonic rocks that Walker, 2003, 2009), to the east in the Panamint parallels Layton Canyon. This work comple- contain pendants of Jurassic metavolcanic and Range (Johnson, 1957; Andrew and Walker, ments studies of late Cenozoic deformation in metaepiclastic rocks (Smith et al., 1968; Dunne 2009) and Owlshead Mountains (Davis, 1988; the southern and northern Slate Range (Walker and Walker, 2004). These assemblages repre- Davis and Fleck, 1977; Luckow et al., 2005), et al., 2005; Numelin et al., 2007; Andrew and sent portions of the Mesozoic Sierran magmatic and to the southeast in the Quail Mountains Walker, 2009). arc and the Paleozoic continental passive mar- (Muehlberger, 1954; Andrew, 2002), although gin. There is an ~85 m.y. time gap between the thicknesses vary greatly between the sections to GEOLOGIC SETTING youngest Cretaceous intrusive rock and Middle the east and south of the study area. Miocene sedimentary-volcanic units, marked The relatively uniform nature of the Mio- The Slate Range trends north-south and the by an extensive erosion surface (Moore, 1976; cene sections in the Slate Range and nearby southern two-thirds of the range is bound on Andrew and Walker, 2003, 2009). Miocene areas implies that the basal nonconformity was its western fl ank by a west-dipping, low- to rocks dip eastward, and comprise a ca. 14.5– relatively planar (Andrew and Walker, 2009), moderate-angle normal fault zone (Fig. 2; 12.5 Ma sequence consisting of basal sandstone although the thickness of the lowest Miocene Moore, 1976; Smith et al., 1968; Walker et al., and conglomerate with locally interbedded sedimentary deposits varies from 0 to 30 m. 2005; Numelin et al., 2007). Pre-Cenozoic rocks limestones overlain by basaltic rocks, rhyolite The thickest sections were deposited against Geosphere, April 2014 277 Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/10/2/276/3332756/276.pdf by guest on 28 September 2021 Walker et al.

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