Research Paper GEOSPHERE Paleoseismic patterns of Quaternary tectonic and magmatic surface deformation in the eastern Basin and Range, USA 1 2 3 3 3 GEOSPHERE, v. 16, no. 1 T.A. Stahl , N.A. Niemi , M.P. Bunds , J. Andreini , and J.D. Wells 1School of Earth and Environment, University of Canterbury, Christchurch 8140, New Zealand 2Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA https://doi.org/10.1130/GES02156.1 3Department of Earth Science, Utah Valley University, Orem, Utah 84058, USA 12 figures; 3 tables; 1 supplemental file CORRESPONDENCE: [email protected]; volcanic centers, have events temporally clustered for instance, a segment dominated by crustal or [email protected] ABSTRACT around the timing of Pleistocene volcanism in at lithospheric extension on normal faults can become CITATION: Stahl, T.A., Niemi, N.A., Bunds, M.P., The competing contributions of tectonic and least one instance, and have accommodated exten- dominated by magma-assisted rifting as melt pro- Andreini, J., and Wells, J.D., 2020, Paleoseismic pat- magmatic processes in accommodating continen- sion ~2×–10× above geodetic and long-term geologic duction and availability evolve (e.g., Bursik and Sieh, terns of Quaternary tectonic and magmatic surface tal extension are commonly obscured by a lack of rates. We propose a model whereby Pliocene to 1989; Parsons and Thompson, 1991; Ebinger and deformation in the eastern Basin and Range, USA: Geosphere, v. 16, no. 1, p. 435–455, https://doi .org on-fault paleoseismic information. This is especially recent extension in the Sevier Desert is spatially Casey, 2001; Muirhead et al., 2015, 2016). Similarly, /10.1130 /GES02156.1. true of the Sevier Desert, located at the eastern mar- partitioned into an eastern magma-assisted rift- spatial variations in magma supply and lithospheric gin of the Basin and Range in central Utah (USA), ing domain, characterized by transient episodes structure can lead to along-strike segmentation of Science Editor: Andrea Hampel where surface-rupturing faults are spatially asso- of higher extension rates during volcanism, and a rifts, with adjacent segments dominated by either Associate Editor: Graham D.M. Andrews ciated with both regional detachment faults and western tectonic-dominated domain, characterized tectonic or magma-assisted extension (e.g., Hay- Quaternary volcanism. Here, we use high-resolution by slower-paced faulting in the Cricket Mountains ward and Ebinger, 1996). Extension can also be Received 21 May 2019 Revision received 28 September 2019 topographic surveys (terrestrial lidar scans and and House Range and more typical of the “Basin and partitioned between these processes within a sin- Accepted 25 November 2019 real-time kinematic GPS), terrestrial cosmogenic Range style” that continues westward into Nevada. gle basin (e.g., Bilham et al., 1999; Ebinger and nuclide (10Be and 3He) exposure dating, 40Ar/39Ar The Sevier Desert, with near-complete exposure and Casey, 2001; Ebinger, 2005; Keir et al., 2006; Ath- Published online 19 December 2019 geochronology, and new neotectonic mapping to the opportunity to utilize a range of geophysical ens et al., 2016; Muirhead et al., 2016), with border distinguish between modes of faulting and exten- instrumentation, provides a globally significant lab- faults typically accommodating tectonic extension sion in a transect across the Sevier Desert. In the oratory for understanding the different modes of and intrabasin faults accommodating both tectonic western Sevier Desert, the House Range and Cricket faulting in regions of continental extension. faulting and extension above shallow intrusions Mountains faults each have evidence of a single (Rowland et al., 2007; Ibs-von Seht et al., 2001; Cal- surface-rupturing earthquake in the last 20–30 k.y. ais et al., 2008; Athens et al., 2016). In all cases, the and have time-integrated slip and extension rates ■ INTRODUCTION characteristics of active faults at the surface provide of <0.1 and ~0.05 mm yr−1, respectively, since ca. clues that assist in evaluating modes of extension. 15–30 ka. These rates are similar to near- negligible Continental extensional provinces, or rifts, are In magma-assisted rifting, extension in the modern geodetic extension estimates. Despite rel- commonly partitioned into segments in which defor- upper crust is partly accommodated by dike injec- atively low geologic, paleoseismic, and modern mation is dominated by either magma-assisted or tion and secondary faulting around the intrusion extension rates, both faults show evidence of con- tectonic extension (e.g., Buck, 1991; Hayward and (e.g., Rubin and Pollard, 1988; Bursik and Sieh, 1989; tributing to the long-term growth of topographic Ebinger, 1996; Scholz and Contreras, 1998; Wright Wright et al., 2006; Rowland et al., 2007; Villamor relief and the structural development of the region. et al., 2006; Rowland et al., 2010; Muirhead et al., et al., 2011; Athens et al., 2016; Gómez-Vasconcelos In the eastern Sevier Desert, the intrabasin Tab- 2016). The underlying reasons for rift segmentation et al., 2017). The thinner effective elastic thickness ernacle, Pavant, and Deseret fault systems show comprise an interplay of modern strain rate, total of the crust in magma-assisted rifts means that markedly different surface expressions and behavior amount of cumulative strain, presence of inher- seismic strain release is localized on shallowly from the range-bounding normal faults farther west. ited structures, thermal and mechanical layering rooted (<5 km) faults associated with propagat- Pleistocene to Holocene extension rates on faults of the lithosphere, and melt availability (e.g., Buck, ing dikes. These faults do not usually accumulate in the eastern Sevier Desert are >10× higher than 1991; Brun, 1999; Corti et al., 2007; Nestola et al., elastic strain through a seismic cycle and do not This paper is published under the terms of the those on their western counterparts. Faults here 2015). Depending on these factors, the mode of typically produce Mw ≥6 earthquakes (Parsons and CC-BY-NC license. are co-located with Late Pleistocene to Holocene deformation within segments can vary with time; Thompson, 1991; Smith et al., 1996; Rowland et al., © 2019 The Authors GEOSPHERE | Volume 16 | Number 1 Stahl et al. | Paleoseismic patterns of Quaternary tectonic and magmatic surface deformation Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/16/1/435/4920116/435.pdf 435 by guest on 29 September 2021 Research Paper 2007). In tectonic rift segments, or during episodes of limited melt supply, upper-crustal extension can 114°W 113°W 112°W 111°W be accommodated entirely by tectonic faults that span the seismogenic portion of the crust (Rowland e ID WY n et al., 2010; Medynski et al., 2016). Surface rupturing o C Z A earthquakes of Mw 7 or greater occur regularly on NV UT Roc ky t tectonic normal faults, despite evidence for tem- Mts. l Basin and u poral variability in the length of the seismic cycle a Range F (e.g., Friedrich et al., 2003; Gómez-Vasconcelos and CO Wernicke, 2017). Given the disparity in maximum Colorado 40°N h magnitudes on dike-induced versus tectonic faults, Plateau c t distinguishing between the two is important for the AZ NM a s purposes of characterizing seismic hazard, espe- ORBT a cially if they are both present within the same rift W segment (Smith et al., 1996; Villamor et al., 2007; House Rowland et al., 2010; Villamor et al., 2011; Gómez- Range DM Sevier Fault Fig. 8 P106 Vasconcelos et al., 2017). Desert SPM Tectonic and magma-assisted rifting can be dis- HR FOOT TV SMEL CR tinguished based on the geometry, recurrence, and P103 P105 P082 GPS Transect Fig. 3 SPIC expression of active faults at the surface (Smith CnR et al., 1996; Rowland et al., 2007; Payne et al., 2009; Fig. 10 P104 Villamor et al., 2011; Gómez-Vasconcelos et al., lt 39°N SL u Lake a 2017; Stahl and Niemi, 2017). If magma-assisted F . Bonneville s rifting is accommodated by dike intrusion, faults BH t CM BRDVF Max. M t exhibit a spatial and temporal coincidence of fault- e Extent k c ri ing with volcanism, and are intermixed with mode (Bonnevile C I extensional fissures (cf. Smith et al., 1996; Payne Shoreline) ransition Zone et al., 2009). Compared to regions dominated by T Colorado Plateau tectonic faulting, there may also be discrepan- cies between geodetic and geologic extension estimates if some strain is accommodated aseis- mically (e.g., Smith et al., 2004; Wright et al., 2006). Elevation (m) 3000+ In contrast, the surface expressions of tectonic faults have displacement, length, and recurrence 38°N characteristics that roughly follow empirical scal- 1300 ing laws developed from catalogues of historical surface-rupturing earthquakes (e.g., Wells and Cop- Figure 1. Overview of the Sevier Desert region, study sites, and transect location at the eastern margin of the Basin and Range persmith, 1994; Wesnousky, 2008), and geological province (inset) in central Utah (USA). The locations of Figures 3, 8, and 10 are indicated. The Wasatch fault zone (red) is commonly extension or moment estimates may be expected designated as the boundary between eastern Basin and Range and the Basin and Range–Colorado Plateau transition zone. The maximum extent of Late Pleistocene Lake Bonneville is shown in blue. Lake Bonneville was divided after water levels fell below to more closely align with geodetic and seismo- the Old River Bed threshold (ORBT) separating the Great Salt Lake and Sevier sub-basins. Light red shaded areas in the eastern logical estimates. Sevier Desert are Pliocene to recent volcanic rocks within the Black Rock Desert volcanic field (BRDVF; dotted outline). Black The Basin and Range of the western United lines are Quaternary faults and folds included in the U.S. Geological Survey Quaternary faults database (U.S.