scholarly journals Isolating non-subduction-driven tectonic processes in Cascadia

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
K. A. McKenzie ◽  
K. P. Furlong
Keyword(s):  
Sierra Nevada ◽  
Crustal Deformation ◽  
Crustal Shortening ◽  
Walker Lane ◽  
Eastern California Shear Zone ◽  
Tectonic Processes ◽  
Block Motion ◽  
Northward Propagation ◽  
Gps Velocity Field ◽  
Great Valley

AbstractSeveral tectonic processes combine to produce the crustal deformation observed across the Cascadia margin: (1) Cascadia subduction, (2) the northward propagation of the Mendocino Triple Junction (MTJ), (3) the translation of the Sierra Nevada–Great Valley (SNGV) block along the Eastern California Shear Zone–Walker Lane and, (3) extension in the northwestern Basin and Range, east of the Cascade Arc. The superposition of deformation associated with these processes produces the present-day GPS velocity field. North of ~ 45° N observed crustal displacements are consistent with inter-seismic subduction coupling. South of ~ 45° N, NNW-directed crustal shortening produced by the Mendocino crustal conveyor (MCC) and deformation associated with SNGV-block motion overprint the NE-directed Cascadia subduction coupling signal. Embedded in this overall pattern of crustal deformation is the rigid translation of the Klamath terrane, bounded on its north and west by localized zones of deformation. Since the MCC and SNGV processes migrate northward, their impact on the crustal deformation in southern Cascadia is a relatively recent phenomenon, since ~ 2 –3 Ma.

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
North America ◽  
Shear Zone ◽  
Reference Frame ◽  
Fault Zone ◽  
Sierra Nevada ◽  
Fault Slip ◽  
Owens Valley ◽  
Walker Lane ◽  
Eastern California Shear Zone ◽  
Gps Velocities

Figure 2. Layer A. Shaded relief map showing major Quaternary faults in central Walker Lane, Mina deflection, northern Eastern California shear zone, and western Basin and Range Province. Heavy black arrow in the northwest corner of the map shows the present-day azimuth of motion of the Sierra Nevada block with respect to the central Great Basin (SN-CBG) (Bennett et al., 2003). Fault abbreviations: APHF—Agai Pah Hills fault; BSF—Benton Spring fault; CF—Coaldale fault; CVF—Clayton Valley fault; EIFZ—Eastern Inyo fault zone; EPF—Emigrant Peak fault; FLVFCDV—Fish Lake Valley–Furnace Creek–Death Valley fault zone; GHF—Gumdrop Hills fault; HLF—Honey Lake fault; HMF—Hunter Mountain fault; IHF—Indian Head fault; MVF—Mohawk Valley fault; OF—Olinghouse fault; OVF—Owens Valley fault; PLF—Pyramid Lake fault; PSF—Petrified Spring fault; PVF—Panamint Valley fault; QVF—Queen Valley fault; SLF—Stateline fault; SNFF—Sierra Nevada frontal fault zone; WMF—White Mountains fault zone; WRF—Wassuk Range fault; WSF—Warm Springs fault. Layer B. Geographic names. Layer C. Tectonic domains. Semi-transparent brown shows the Walker Lane–northern Eastern California shear zone. Layer D. Yellow dashed polygon shows the location of the Gabbs Valley–Gillis Ranges (GVGR) field area (see Fig. 3). Layer E. Yellow stars show the locations of documented middle Miocene fault-slip initiation age. Numbers in the stars are tied to numbers in Table 3. Layer F. Thin blue arrows show GPS velocities relative to stable North America (ITRFNA2005 reference frame) from Lifton et al. (2013), and heavy multi-colored arrows show GPS velocities relative to stable North America (NA12 North America reference frame) from Bormann et al. (2016). GPS velocity scales are in the upper right corner of the map. Maps, labels, and data sets for this figure are organized in a series of layers that may be viewed separately or in combination using the capabilities of the Acrobat (PDF) layering function (click “Layers” icon along vertical bar on left side of window for display of available layers; turn layers on or off by clicking the box that encompasses the layer label located within the gray box in the lower left corner of the map).

scholarly journals Characterizing strain between rigid crustal blocks in the southern Cascadia forearc: Quaternary faults and folds of the northern Sacramento Valley, California

Geology ◽  
2020 ◽  
Author(s):  
Stephen Angster ◽  
Steven Wesnousky ◽  
Paula Figueiredo ◽  
Lewis A. Owen ◽  
Thomas Sawyer
Keyword(s):  
Sierra Nevada ◽  
Late Quaternary ◽  
Optically Stimulated Luminescence ◽  
Sacramento River ◽  
Southern Limit ◽  
Oregon Coast ◽  
Crustal Shortening ◽  
Sacramento Valley ◽  
Uplift Rates ◽  
Great Valley

Topographic profiles across late Quaternary surfaces in the northern Sacramento Valley (California, USA) show offset and progressive folding on series of active east- and northeast—trending faults and folds. Optically stimulated luminescence ages on deposits draping a warped late Pleistocene river terrace yielded differential incision rates along the Sacramento River and indicate tectonic uplift equal to 0.2 ± 0.1 and 0.6 ± 0.2 mm/yr above the anticline of the Inks Creek fold system and Red Bluff fault, respectively. Uplift rates correspond to a total of 1.3 ± 0.4 mm/yr of north-directed crustal shortening, accounting for all of the geodetically observed contractional strain in the northern Sacramento Valley, but only part of the far-field contraction between the Sierra Nevada–Great Valley and Oregon Coast blocks. These structures define the southern limit of the transpressional transition between the two blocks.

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
North America ◽  
Shear Zone ◽  
Reference Frame ◽  
Fault Zone ◽  
Sierra Nevada ◽  
Fault Slip ◽  
Owens Valley ◽  
Walker Lane ◽  
Eastern California Shear Zone ◽  
Gps Velocities

Figure 2. Layer A. Shaded relief map showing major Quaternary faults in central Walker Lane, Mina deflection, northern Eastern California shear zone, and western Basin and Range Province. Heavy black arrow in the northwest corner of the map shows the present-day azimuth of motion of the Sierra Nevada block with respect to the central Great Basin (SN-CBG) (Bennett et al., 2003). Fault abbreviations: APHF—Agai Pah Hills fault; BSF—Benton Spring fault; CF—Coaldale fault; CVF—Clayton Valley fault; EIFZ—Eastern Inyo fault zone; EPF—Emigrant Peak fault; FLVFCDV—Fish Lake Valley–Furnace Creek–Death Valley fault zone; GHF—Gumdrop Hills fault; HLF—Honey Lake fault; HMF—Hunter Mountain fault; IHF—Indian Head fault; MVF—Mohawk Valley fault; OF—Olinghouse fault; OVF—Owens Valley fault; PLF—Pyramid Lake fault; PSF—Petrified Spring fault; PVF—Panamint Valley fault; QVF—Queen Valley fault; SLF—Stateline fault; SNFF—Sierra Nevada frontal fault zone; WMF—White Mountains fault zone; WRF—Wassuk Range fault; WSF—Warm Springs fault. Layer B. Geographic names. Layer C. Tectonic domains. Semi-transparent brown shows the Walker Lane–northern Eastern California shear zone. Layer D. Yellow dashed polygon shows the location of the Gabbs Valley–Gillis Ranges (GVGR) field area (see Fig. 3). Layer E. Yellow stars show the locations of documented middle Miocene fault-slip initiation age. Numbers in the stars are tied to numbers in Table 3. Layer F. Thin blue arrows show GPS velocities relative to stable North America (ITRFNA2005 reference frame) from Lifton et al. (2013), and heavy multi-colored arrows show GPS velocities relative to stable North America (NA12 North America reference frame) from Bormann et al. (2016). GPS velocity scales are in the upper right corner of the map. Maps, labels, and data sets for this figure are organized in a series of layers that may be viewed separately or in combination using the capabilities of the Acrobat (PDF) layering function (click “Layers” icon along vertical bar on left side of window for display of available layers; turn layers on or off by clicking the box that encompasses the layer label located within the gray box in the lower left corner of the map).

scholarly journals Southward expanding plate coupling due to variation in sediment subduction as a cause of Andean growth

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jiashun Hu ◽  
Lijun Liu ◽  
Michael Gurnis
Keyword(s):  
Sediment Transport ◽  
Three Dimensional ◽  
Mountain Building ◽  
Crustal Shortening ◽  
First Order ◽  
The Andes ◽  
Tectonic Processes ◽  
History Of ◽  
Plate Coupling ◽  
Trench Sediments

AbstractGrowth of the Andes has been attributed to Cenozoic subduction. Although climatic and tectonic processes have been proposed to be first-order mechanisms, their interaction and respective contributions remain largely unclear. Here, we apply three-dimensional, fully-dynamic subduction models to investigate the effect of trench-axial sediment transport and subduction on Andean growth, a mechanism that involves both climatic and tectonic processes. We find that the thickness of trench-fill sediments, a proxy of plate coupling (with less sediments causing stronger coupling), exerts an important influence on the pattern of crustal shortening along the Andes. The southward migrating Juan Fernandez Ridge acts as a barrier to the northward flowing trench sediments, thus expanding the zone of plate coupling southward through time. Consequently, the predicted history of Andean shortening is consistent with observations. Southward expanding crustal shortening matches the kinematic history of inferred compression. These results demonstrate the importance of climate-tectonic interaction on mountain building.

scholarly journals A multicomponent Isabella anomaly: Resolving the physical state of the Sierra Nevada upper mantle from Vp/Vs anisotropy tomography

Geosphere ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 2018-2042 ◽  
Author(s):  
Melissa V. Bernardino ◽  
Craig H. Jones ◽  
William Levandowski ◽  
Ian Bastow ◽  
Thomas J. Owens ◽  
...  
Keyword(s):  
Sierra Nevada ◽  
Upper Mantle ◽  
Oceanic Lithosphere ◽  
P Wave ◽  
Wave Speeds ◽  
High Wave ◽  
The Core ◽  
High Speeds ◽  
Great Valley ◽  
Isabella Anomaly

Abstract The Isabella anomaly, a prominent upper-mantle high-speed P-wave anomaly located within the southern Great Valley and southwestern foothills of the Sierra Nevada, has been interpreted either as foundering sub-Sierran lithosphere or as remnant oceanic lithosphere. We used Vp/Vs anisotropy tomography to distinguish among the probable origins of the Isabella anomaly. S waveforms were rotated into the Sierran SKSFast and SKSSlow directions determined from SKS-splitting studies. Teleseismic P-, SFast-, SSlow-, SKSFast-, and SKSSlow-wave arrival times were then inverted to obtain three-dimensional (3-D) perturbations in Vp, Vp/VsMean, and percent azimuthal anisotropy using three surface wave 3-D starting models and one one-dimensional (1-D) model. We observed the highest Vp/Vs anomalies associated with slower velocities in regions marked by young volcanism, with the largest of these anomalies being the Mono anomaly under the Long Valley region, which extends to depths of at least 75 km. Peak Vp/Vs perturbations of +4% were found at 40 km depth. The low velocities and high Vp/Vs values of this anomaly could be related to partial melt. The high wave speeds of the Isabella anomaly coincide with low Vp/Vs values with peak perturbations of −2%, yet they do not covary spatially. The P-wave inversion imaged the Isabella anomaly as a unimodal eastward-plunging body. However, the volume of that Isabella anomaly contains three separate bodies as defined by varying Vp/Vs values. High speeds, regionally average Vp/Vs values (higher than the other two anomalies), and lower anisotropy characterize the core of the Isabella anomaly. The western and shallowest part has high wave speeds and lower Vp/Vs values than the surrounding mantle. The eastern and deepest part of the anomaly also contains high speeds and lower Vp/Vs values but exhibits higher anisotropy. We considered combinations of varying temperature, Mg content (melt depletion), or modal garnet to reproduce our observations. Our results suggest that the displaced garnet-rich mafic root of the Mesozoic Sierra Nevada batholith is found in the core of the Isabella anomaly. If remnant oceanic lithosphere exists within the Isabella anomaly, it most likely resides in the shallow, westernmost feature. Within the Sierra Nevada, the highest upper-mantle anisotropy is largely contained within the central portion of the range and the adjacent Great Valley. Anisotropy along the Sierra crest is shallow and confined to the lithosphere between 20 and 40 km depth. Directly below, there is a zone of low anisotropy (from 170 to 220 km depth), low velocities, and high Vp/Vs values. These features suggest the presence of vertically upwelling asthenosphere and consequent horizontal flow at shallower depths. High anisotropy beneath the adjacent western foothills and Great Valley is found at ∼120 km depth and could represent localized mantle deformation produced as asthenosphere filled in a slab gap.

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