Crustal-scale tilting of the central Salton block, southern California

Dorsey, Rebecca J.; Langenheim, Victoria E.

doi:10.1130/ges01167.1

Cited by 15 publications

(56 citation statements)

References 108 publications

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“…1 and 2a). Their results require a northeast dip for the SAF and predict a northeast tilt of the Santa Rosa block; the latter hypothesis is supported by interpretations of geologic and gravity data (Dorsey and Langenheim, 2015).…”

Section: Geological and Geophysical Settingmentioning

confidence: 72%

“…6d and 7). Sedimentary rocks were chosen to have a density contrast with basement of ∼400 kg=m 3 , based on other modeling studies in southern California (e.g., Mabey, 1960;Dorsey and Langenheim, 2015). This contrast is consistent with the average density contrast predicted by the velocity structure within the basin using the relationship of Gardner et al (1974) to convert velocity to density.…”

Section: Ssip Linementioning

confidence: 99%

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Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Fuis¹,

Bauer²,

Goldman³

et al. 2017

Bulletin of the Seismological Society of America

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The San Andreas fault (SAF) is one of the most studied strike-slip faults in the world; yet its subsurface geometry is still uncertain in most locations. The Salton Seismic Imaging Project (SSIP) was undertaken to image the structure surrounding the SAF and also its subsurface geometry. We present SSIP studies at two locations in the Coachella Valley of the northern Salton trough. On our line 4, a fault-crossing profile just north of the Salton Sea, sedimentary basin depth reaches 4 km southwest of the SAF. On our line 6, a fault-crossing profile at the north end of the Coachella Valley, sedimentary basin depth is ∼2-3 km and centered on the central, most active trace of the SAF. Subsurface geometry of the SAF and nearby faults along these two lines is determined using a new method of seismic-reflection imaging, combined with potential-field studies and earthquakes. Below a 6-9 km depth range, the SAF dips ∼50°-60°NE, and above this depth range it dips more steeply. Nearby faults are also imaged in the upper 10 km, many of which dip steeply and project to mapped surface fault traces. These secondary faults may join the SAF at depths below about 10 km to form a flower-like structure. In Appendix D, we show that rupture on a northeast-dipping SAF, using a single plane that approximates the two dips seen in our study, produces shaking that differs from shaking calculated for the Great California ShakeOut, for which the southern SAF was modeled as vertical in most places: shorter-period (T < 1 s) shaking is increased locally by up to a factor of 2 on the hanging wall and is decreased locally by up to a factor of 2 on the footwall, compared to shaking calculated for a vertical fault.

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Section: Geological and Geophysical Settingmentioning

confidence: 72%

Section: Ssip Linementioning

confidence: 99%

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Fuis¹,

Bauer²,

Goldman³

et al. 2017

Bulletin of the Seismological Society of America

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“…8 Ma due to regional extension . Extension was accommodated via pull-apart basins within the SAF system as well as by the West Salton detachment fault in the Plio-Pleistocene (Axen and Fletcher, 1998;Dorsey et al, 2011;Dorsey and Langenheim, 2015;Mason et al, 2017). Many extensional structures shut off with the inception of the San Jacinto fault zone to the west at ca.…”

Section: ■ Tectonic Background Tectonic Evolution Of the Coachella Vamentioning

confidence: 99%

“…Individual fault strands integrate into flower structures that core the transpressional zones in the center of the valley (Mecca and Indio Hills), where local Quaternary transpression has resulted in near-field deformation and basin inversion. Transpressional loading along the southern SAF also results in broad northeastward tilting (8°) of the central Salton block, which underlies the Coachella Valley basin and lies between the SAF and San Jacinto fault zone to the west (Dorsey and Langenheim, 2015).…”

Section: ■ Tectonic Background Tectonic Evolution Of the Coachella Vamentioning

confidence: 99%

“…The kinematics of this Quaternary extensional tilting also match the expected broad uplift of the Salton block due to transpression along the SAF. The central Salton block is defined as the basement block between the SAF and San Jacinto fault that underlies Coachella Valley fill and includes the Santa Rosa Mountains, which appears to be tilted to the east based on geophysical and geomorphic evidence (Dorsey and Langenheim, 2015).…”

Section: 47mentioning

confidence: 99%

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Constraints on rock uplift in the eastern Transverse Ranges and northern Peninsular Ranges and implications for kinematics of the San Andreas fault in the Coachella Valley, California, USA

et al. 2020

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The nexus of plate-boundary deformation at the northern end of the Coachella Valley in southern California (USA) is complex on multiple levels, including rupture dynamics, slip transfer, and three-dimensional strain partitioning on nonvertical faults (including the San Andreas fault). We quantify uplift of mountain blocks in this region using geomorphology and low-temperature thermo chronometry to constrain the role of longterm vertical deformation in this tectonic system. New apatite (U-Th)/He (AHe) ages confirm that the rugged San Jacinto Mountains (SJM) do not exhibit a record of rapid Neogene exhumation. In contrast, in the Little San Bernardino Mountains (LSBM), rapid exhumation over the past 5 m.y. is apparent beneath a tilted AHe partial retention zone, based on new and previously published data. Both ranges tilt away from the Coachella Valley and have experienced minimal denudation from their upper surface, based on preservation of weathered granitic erosion surfaces. We interpret rapid exhumation at 5 Ma and the gentle tilt of the erosion surface and AHe isochrons in the LSBM to have resulted from rift shoulder uplift associated with extension prior to onset of transpression in the Coachella Valley. We hypothesize that the SJM have experienced similar rift shoulder uplift, but an additional mechanism must be called upon to explain the pinnacle-like form, rugged escarpment, and topographic disequilibrium of the northernmost SJM massif. We propose that this form stems from erosional resistance of the Peninsular Ranges batholith relative to more-erodible foliated metamorphic rocks that wrap around it. Our interpretations suggest that neither the LSBM nor SJM have been significantly uplifted under the present transpressive configuration of the San Andreas fault system, but instead represent relict highs due to previous tectonic and erosional forcing.GEOSPHERE GEOSPHERE, v. 16, no. 3

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Two‐Phase Exhumation of the Santa Rosa Mountains: Low‐ and High‐Angle Normal Faulting During Initiation and Evolution of the Southern San Andreas Fault System

et al. 2017

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Low‐angle detachment fault systems are important elements of oblique‐divergent plate boundaries, yet the role detachment faulting plays in the development of such boundaries is poorly understood. The West Salton Detachment Fault (WSDF) is a major low‐angle normal fault that formed coeval with localization of the Pacific‐North America plate boundary in the northern Salton Trough, CA. Apatite U‐Th/He thermochronometry (AHe; n = 29 samples) and thermal history modeling of samples from the Santa Rosa Mountains (SRM) reveal that initial exhumation along the WSDF began at circa 8 Ma, exhuming footwall material from depths of >2 to 3 km. An uplifted fossil (Miocene) helium partial retention zone is present in the eastern SRM, while a deeper crustal section has been exhumed along the Pleistocene high‐angle Santa Rosa Fault (SFR) to much higher elevations in the southwest SRM. Detachment‐related vertical exhumation rates in the SRM were ~0.15–0.36 km/Myr, with maximum fault slip rates of ~1.2–3.0 km/Myr. Miocene AHe isochrons across the SRM are consistent with northeast crustal tilting of the SRM block and suggest that the post‐WSDF vertical exhumation rate along the SRF was ~1.3 km/Myr. The timing of extension initiation in the Salton Trough suggests that clockwise rotation of relative plate motions that began at 8 Ma is associated with initiation of the southern San Andreas system. Pleistocene regional tectonic reorganization was contemporaneous with an abrupt transition from low‐ to high‐angle faulting and indicates that local fault geometry may at times exert a fundamental control on rock uplift rates along strike‐slip fault systems.

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Crustal-scale tilting of the central Salton block, southern California

Cited by 15 publications

References 108 publications

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Subsurface Geometry of the San Andreas Fault in Southern California: Results from the Salton Seismic Imaging Project (SSIP) and Strong Ground Motion Expectations

Constraints on rock uplift in the eastern Transverse Ranges and northern Peninsular Ranges and implications for kinematics of the San Andreas fault in the Coachella Valley, California, USA

Two‐Phase Exhumation of the Santa Rosa Mountains: Low‐ and High‐Angle Normal Faulting During Initiation and Evolution of the Southern San Andreas Fault System

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