Research Paper THEMED ISSUE: Origin and Evolution of the Sierra Nevada and Walker Lane GEOSPHERE New constraints on fault architecture, slip rates, and strain partitioning beneath Pyramid Lake, Nevada GEOSPHERE; v. 11; no. 3 Amy Kendra Eisses1, Annie Kell1, Graham Martin Kent1, Neal William Driscoll2, Robert LeRoy Baskin3, Ken Dent Smith1, Robert Ellis Karlin4, John 1 5 doi:10.1130/GES00821.1 Nikolai Louie , and Satish Kumar Pullammanappallil 1Nevada Seismological Laboratory, University of Nevada, Reno, 1664 North Virginia Street, MS0174, Reno, Nevada 89557-0174, USA 2Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive #0244, La Jolla, California 92093-0244, USA 13 figures; 1 table 3U.S. Geological Survey, 2222 West 2300 South, 2nd floor, Salt Lake City, Utah 84119 USA 4Department of Geological Sciences and Engineering, University of Nevada, Reno, Geological Sciences and Engineering (0172), 1664 North Virginia Street, Reno, Nevada 89557, USA CORRESPONDENCE: [email protected] 5Optim, Inc., 200 South Virginia Street, Suite 560, Reno, Nevada 89501, USA CITATION: Eisses, A.K., Kell, A., Kent, G.M., Driscoll, N.W., Baskin, R.L., Smith, K.D., Karlin, R.E., Louie, J.N., and Pullammanappallil, S.K., 2015, New con- ABSTRACT INTRODUCTION AND RATIONALE straints on fault architecture, slip rates, and strain par- titioning beneath Pyramid Lake, Nevada: Geosphere, A seismic compressed high-intensity radar pulse (CHIRP) survey of Pyr- Dextral shear is unevenly distributed along the western margin of North v. 11, no. 3, p. 683–704, doi:10.1130 /GES00821.1. amid Lake, Nevada, defines fault architecture and distribution within a key America, with ~75%–80% of the Pacific and North American plate motion Received 16 May 2012 sector of the northern Walker Lane belt. More than 500 line-kilometers of being accommodated by the San Andreas fault and other fault systems to Revision received 21 January 2015 high-resolution (decimeter) subsurface imagery, together with dated piston the west (Bennett et al., 1999; Dixon et al., 2000). The remaining deforma- Accepted 26 March 2015 and gravity cores, were used to produce the first comprehensive fault map tion occurs east toward the Basin and Range Province (e.g., Atwater, 1970; Published online 13 May 2015 and attendant slip rates beneath the lake. A reversal of fault polarity is ob- Atwater and Stock, 1998; McQuarrie and Wernicke, 2005). The structurally served beneath Pyramid Lake, where down-to-the-east slip on the dextral complex transition between the Sierra Nevada microplate and the Basin and Pyramid Lake fault to the south switches to down-to-the-west displacement Range (Fig. 1), known as the Walker Lane deformation belt to the north and on the Lake Range fault to the north. Extensional deformation within the the Eastern California shear zone to the south, is identified by seismic, geo- northern two thirds of the basin is bounded by the Lake Range fault, which detic, and geologic data (e.g., Locke et al., 1940; Stewart, 1988; Dokka and exhibits varying degrees of asymmetric tilting and stratal divergence due Travis, 1990; Argus and Gordon, 1991; Thatcher et al., 1999; Svarc et al., 2002; to along-strike segmentation. This structural configuration likely results Bennett et al., 2003; Unruh et al., 2003; Oldow, 2003; Hammond and Thatcher, from a combination of changes in slip rate along strike and the splaying of 2004; Wesnousky, 2005a, 2005b; Wesnousky et al., 2005). This ~100-km-wide fault segments onshore. The potential splaying of fault segments onshore belt of seismicity and active faulting accommodates up to 20%–25% or 8–13 tends to shift the focus of extension away from the lake. The combination of mm/yr of relative motion between the Sierra Nevada microplate and stable normal- and oblique-slip faults in the northern basin gives Pyramid Lake its North America plate (Thatcher et al., 1999; Thatcher, 2003; Bennett et al., 2003; distinctive “fanning open to the north” geometry. The oblique-slip faults in Hammond et al., 2011). Studies show that most of the deformation in the the northwestern region of the lake are short and discontinuous in nature, Walker Lane belt occurs along the eastern and western margins of the belt possibly representing a nascent shear zone. In contrast, the Lake Range fault (Hammond et al., 2011). Furthermore, seismicity is concentrated at the east- is long and well defined. Vertical slip rates measured across the Lake Range ern and western boundaries of the Basin and Range, with higher rates of and other faults provide new estimates on extension across the Pyramid strain localized on the western side within the Central Nevada seismic belt Lake basin. A minimum vertical slip rate of ~1.0 mm/yr is estimated along and the Walker Lane (Eddington et al., 1987). the Lake Range fault. When combined with fault length, slip rates yield a Pyramid Lake is located toward the eastern margin of the northern potential earthquake magnitude range between M6.4 and M7.0. Little to no Walker Lane belt in a transitional zone between two distinct geological re- offset on the Lake Range fault is observed in the sediment rapidly emplaced gions: the Walker Lane deformation belt and the Basin and Range Province at the end of Tioga glaciation (12.5–9.5 ka). In contrast, since 9.5 ka, CHIRP (Fig. 1). Within the Pyramid Lake region, transtension is accommodated imagery provides evidence for three or four major earthquakes, assuming a through a series of mainly dextral oblique strike-slip faults (Turner et al., characteristic offset of 2.5 m per event. Regionally, our CHIRP investigation 2008). Northwest of Pyramid Lake (e.g., Honey Lake fault zone; Fig.1), dex- helps to reveal how strain is partitioned along the boundary between the tral faults strike northwest, whereas toward the southwest, north-striking, For permission to copy, contact Copyright northeastern edge of the Walker Lane and the northwest Basin and Range normal fault–bounded basins predominate (e.g., Lake Tahoe Basin; Dingler Permissions, GSA, or [email protected]. Province proper. et al., 2009). South of Pyramid Lake, within the Carson domain (Stewart, © 2015 Geological Society of America GEOSPHERE | Volume 11 | Number 3 Eisses et al. | Constraints on fault architecture, slip rates, and strain partitioning beneath Pyramid Lake Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/3/683/3334425/683.pdf 683 by guest on 25 September 2021 Research Paper C N 40.75° N a e A ll ii v ff a Northern o d r n a ii a Walker Lane Honey Lake Pyramid Lake HLF NMF LR WB Basin and WSF F Range F Province MVFMV PL (44° N, 114° W) F F B OF CarsoCaCarrssoonn SSiSinkink Reno CL ruckee River T Sierra Nevada Lake Tahoe Pacific Ocean 50 km N (31° N, 125° W) 200 km N 38.75° N 121.25° W 119.0° W Figure 1. (A) Map of the northern Walker Lane deformation belt, northwest Basin and Range Province, and northern Sierra Nevada microplate. River and state boundary lines are dark gray, and faults are thin black lines. Pyramid Lake is shaded in light blue, and the Truckee River is dark blue. CL—Carson Lineament; HLF—Honey Lake fault; LRF—Lake Range fault; MVF—Mohawk Valley fault; NMF—Nightingale Mountains fault; OF—Olinghouse fault; PLF— Pyramid Lake fault; WB—Winnemucca Basin; WSF—Warm Springs Valley fault. (B) Regional map of the western United States; red box shows the enlarged map of the northern Walker Lane deformation belt shown in A. GEOSPHERE | Volume 11 | Number 3 Eisses et al. | Constraints on fault architecture, slip rates, and strain partitioning beneath Pyramid Lake Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/3/683/3334425/683.pdf 684 by guest on 25 September 2021 Research Paper 42° N 1988), a more complex pattern of deformation is observed (Fig. 2), char- acterized by significant amounts (>30°) of clockwise vertical-axis rotation Modoc Plateau bounded by ENE-striking sinistral faults (Cashman and Fontaine, 2000). DA Pyramid Lake is a remnant of Pleistocene lakes that once covered much VA CALIFORNIA NE of the Great Basin during the late Pleistocene. The two largest of these lakes were Lake Bonneville and Lake Lahontan (Gilbert, 1890; Adams et al., 1999). 41° N At its highstand, Lake Lahontan straddled the boundary between the Walker Lane region and the central Basin and Range Province (Adams et al., 1999). The deepest point of ancient Lake Lahontan is within the present-day Pyramid Lake Pyramid Lake basin (Benson and Mifflin, 1986). Domain The stratigraphy of Pyramid Lake provides a detailed record of the geologic HLF Basin and Range LRF and tectonic history of the basin. The low wave energy of the hydrologic sys- WSF Province 40° N Northern Walker tem preserves the stratigraphy and chronicles the tectonic deformation (e.g., PLF Lane Kent et al., 2005; Dong et al., 2014). The asymmetric (i.e., half-graben) geometry MVF GF OF CL Carson creates differential accommodation, which records and preserves the defor- Domain SNTF mation. Remnant sections of ancient Lake Lahontan (i.e., Pyramid Lake) pro- WL vide ideal opportunities to investigate the rapidly deforming northern Walker WTDPF SF Walker Lake Lane belt (Adams et al., 1999; Thatcher et al., 1999). Many remnant sections of GD 39° N MF BSF Domain CF WRF Lake Lahontan have been targets for extensive paleoclimate studies, includ- PSF AF ing cores used for chronostratigraphic analysis. Cores collected from Pyramid IH Lake highlight a nearly continuous record of sedimentation extending to 48 ka Central Walker RF Mina (Benson et al., 2013). Lane BF Great Sierra Nevada- Deflection The Pyramid Lake basin provides an ideal natural laboratory in which to CF CoF 38° N study transtensional deformation in the northern Walker Lane.