Present‐day motion of the Sierra Nevada block and some tectonic implications for the Basin and Range province, North American Cordillera

Dixon, Timothy H.; Miller, M. Meghan; Farina, Frederic; Wang, Hongzhi; Johnson, Daniel J.

doi:10.1029/1998tc001088

Cited by 343 publications

(388 citation statements)

References 73 publications

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“…The direction of motion of the Pacific plate and Baja California relative to North America is similar, but Baja California moves at a rate that is ∼ 10% slower than the Pacific plate (Dixon et al, 2000;Plattner et al, 2007). Thus, Baja California behaves as a separate microplate, which is only partially coupled to the Pacific plate (Dixon et al, 2000;Plattner et al, 2007Plattner et al, , 2009). Dixon et al (2000) suggest that the relative movement between the Pacific plate and the Baja California microplate is accommodated by offshore slip along several active fault zones, collectively named the Baja California shear zone.…”

Section: Geology Of the Baja California Microplatementioning

confidence: 94%

“…1). The Baja California shear zone accommodates the relative movement between the Pacific plate and the Baja California microplate (e.g., Dixon et al, 2000;Plattner et al, 2009). Microstructures from the San Quintín lower-crustal and upper-mantle xenoliths allow us to investigate the active deformation mechanisms and viscosity structure of the lithosphere near an active strike-slip plate boundary.…”

Section: T Van Der Werf Et Al: Lower Crust Rheology In a Strike-slimentioning

confidence: 99%

“…Thus, Baja California behaves as a separate microplate, which is only partially coupled to the Pacific plate (Dixon et al, 2000;Plattner et al, 2007Plattner et al, , 2009). Dixon et al (2000) suggest that the relative movement between the Pacific plate and the Baja California microplate is accommodated by offshore slip along several active fault zones, collectively named the Baja California shear zone. The Baja California shear zone includes the San Clemente-San Isidro fault zone along northern Baja California (Legg et al, 1991) and may continue southward to the Tosco-Abreojos (Spencer and Normark, 1979), the Santa Margarita-San Lazaro , and/or the Todos Santos fault zones (Fletcher and Munguía, 2000) (Fig.…”

Section: Geology Of the Baja California Microplatementioning

confidence: 99%

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Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

et al. 2017

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Abstract. The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene–Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750–890 °C and pressures of 400–560 MPa, corresponding to 15–22 km depth. A hot crustal geotherm of 40 ° C km−1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12–33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12–17 MPa) in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1–1.3×1020 Pa ⋅ s for the high temperature conditions (890 °C) in the lower crust. Significantly lower viscosities in the range of 1016–1019 Pa ⋅ s, were estimated using flow laws for wet plagioclase. The shallow upper mantle has a low viscosity of 5.7×1019 Pa ⋅ s, which indicates the lack of an upper-mantle lid beneath northern Baja California. Our data show that during post-seismic transients, the upper mantle and the lower crust in the Pacific–Baja California plate boundary are characterized by similar and low differential stress. Transient viscosity of the lower crust is similar to the viscosity of the upper mantle.

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Section: Geology Of the Baja California Microplatementioning

confidence: 94%

Section: T Van Der Werf Et Al: Lower Crust Rheology In a Strike-slimentioning

confidence: 99%

Section: Geology Of the Baja California Microplatementioning

confidence: 99%

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Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

et al. 2017

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“…Active shear deformation along the SN-BR boundary [e.g., Surpless et al, 2002;Oldow, 2003] prevents the application of the flexural bending model toward the BR side; whereas the crustal coherency of the SN region toward the west [e.g., Dixon et al, 2000] makes this area suitable for flexural bending analysis. The problem can be envisioned as stretching an elastic band upward from one side (the location of maximum thermal expansion), and the force of gravity is acting externally on all sections of the band.…”

Section: Thermal Uplift and Flexural Bendingmentioning

confidence: 99%

Transient thermal regimes in the Sierra Nevada and Baja California extinct outer arcs following the cessation of Farallon subduction

Erkan

Blackwell

2009

J. Geophys. Res.

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[1] We examine the thermal relaxation of the Sierra Nevada and Baja California extinct outer arc blocks following the progressive cessation of Farallon subduction under western North America beginning at $30 Ma. Being parts of the same outer arc until the inland jump of the San Andreas transform fault at $5 Ma, these two regions show many similarities in their geology, geomorphology, rigid body behavior, and their relatively low seismicity. In the thermal model, we combine results of different geophysical and geophysical studies to constrain the thermal state and geometry of the outer arcs before the cessation of subduction and then model the postsubduction temperature responses in these regions using the results of the tectonic reconstructions. A well-constrained regional thermal model of these blocks using the results of many earlier studies in these regions confirms that the present low heat flow values in these regions are the remnants of the very cold outer arc thermal regime of the subduction zone even as long as 30 Ma after cessation of subduction. Thus the entire Pacific boundary of the North American plate is still in a transient thermal state. The calculated low lithospheric temperatures in the Sierra Nevada and Peninsular blocks correlate very well with their rigid body behavior obtained from geodetic studies, and seismogenic layer thicknesses obtained from seismological studies. This is in contrast with the fact that both regions are surrounded by intense deformation associated with the western North America intraplate and extraplate motions. These low-temperature islands play important roles in the present interaction of the North American and Pacific plates and contribute to the broad deformation of the transform boundary. The thermal relaxation of the extinct outer arcs includes both vertical heating from the underlying asthenosphere and the lateral heating from the extinct back arc (Basin and Range), which has remained as a high heat flow region after the cessation of the subduction. We suggest that the significant lateral heat transfer from the Basin and Range in the Sierra Nevada (and from the Gulf of California spreading center in the Peninsular block since $5 Ma) may be the main driving mechanism of the postsubduction volcanism/magmatism along the extinct volcanic arc and the recent tilted uplift of the Sierra Nevada block. The low lithospheric temperatures in Sierra Nevada region may also explain the observation of the high seismic velocities in the mantle beneath the southern Sierra Nevada where the downwelling of the mantle lithosphere proposed.

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“…Present day Walker Lane transtentional tectonics of western Nevada and eastern California, including prominent right-lateral strike slip faulting [Faulds and Henry, 2008] and extension along the eastern Sierra range front, has in turn evolved in conjunction with northward migration of the Mendocino Triple Junction (MTJ) [Furlong and Schwartz, 2004]. Within this setting, the Walker Lane has been characterized as an incipient transform [Faulds et al, 2005] with right-lateral shear deformation east of the Sierra resulting from the~13-14 mm/yr northwest translation and modern counterclockwise rotation of the stable Sierran block [Dixon et al, 2000;Argus and Gordon, 1991]. This motion accounts for~20-25% of the North American-Pacific plate boundary strain budget [Faulds et al, 2005;Bennett et al, 1999] and is the driving mechanism of Walker Lane deformation.…”

Section: Introductionmentioning

confidence: 99%

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

Smith

Kent

Seggern

et al. 2016

Geophysical Research Letters

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Lithospheric rifting most often initiates in continental extensional settings where “breaking of a plate” may or may not progress to sea floor spreading. Generally, the strength of the lithosphere is greater than the tectonic forces required for rupture (i.e., the “tectonic force paradox”), and it has been proposed that rifting requires basaltic magmatism (e.g., dike emplacement) to reduce the strength and cause failure, except for the case of a thin lithosphere (<30 km thick). Here we isolate two very similar and unprecedented observations of Moho‐lower crustal transition dike or fluid injection earthquake swarms under southern Sierra Valley (SV: 2011–2012) and North Lake Tahoe (LT: 2003–2004), California. These planar distributions of seismicity can be interpreted to define the end points, and cover ~25% of the length, of an implied ~56 km long structure, each striking N45°W and dipping ~50°NE. A single event at ~30 km depth that locates on the implied dipping feature between the two swarms is further evidence for a single Moho‐transition depth structure. We propose that basaltic or fluid emplacement at or near Moho depths weakens the upper mantle lid, facilitating lithospheric rupture of the Sierra Microplate. Similar to the LT sequence, the SV event is also associated with increased upper crustal seismicity. An 27 October 2011, Mw 4.7 earthquake occurred directly above the deep SV sequence at the base of the upper crustal seismogenic zone (~15 km depth).

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Present‐day motion of the Sierra Nevada block and some tectonic implications for the Basin and Range province, North American Cordillera

Cited by 343 publications

References 73 publications

Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

Transient thermal regimes in the Sierra Nevada and Baja California extinct outer arcs following the cessation of Farallon subduction

Evidence for Moho‐lower crustal transition depth diking and rifting of the Sierra Nevada microplate

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