Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America

Atwater, Tanya

doi:10.1130/0016-7606(1970)81[3513:ioptft]2.0.co;2

Cited by 1,856 publications

(995 citation statements)

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“…This behaviour is perhaps the case in the Great Basin where the Middle Miocene to present extensional phase with associated basaltic volcanism (e.g. [40,41]) was subsequent, and perhaps consequent, upon the annihilation of a Mid-Cenozoic subduction zone along this portion of the west coast [41,42]. The subduction of the very young oceanic lithosphere in the late stages presumably required large compressive stress (Table 2) which was released when subduction stopped.…”

Section: Applicationmentioning

confidence: 99%

“…The subduction of the very young oceanic lithosphere in the late stages presumably required large compressive stress (Table 2) which was released when subduction stopped. Tensional regimes could result from the reheating of subducted lithosphere, stresses involved in reorientating plate motions [42] or diapirism [43], but it would be misleading to classify these regimes with the back-arc spreading associated with subduction of old lithosphere.…”

Section: Applicationmentioning

confidence: 99%

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Some consequences of the subduction of young slabs

England

Wortel

1980

Earth and Planetary Science Letters

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The negative buoyancy force exerted by a subducting oceanic slab depends on its descent velocity, and strongly on its age. For lithosphere close to thermal equilibrium, this force dominates by a large margin the resisting forces arising from friction on the plate boundary and compositional buoyancy. This may result in oceanward migration of the trench, with associated back-arc spreading. However, the strong age dependence of this force, and of the ridge push mean that a horizontal compressive stress is required to continue subduction if changing plate geometry should bring young lithosphere to the trench. Estimates can be made of the slab age, as a function of descent velocity, at which the driving forces are no longer sufficient to overcome a given resisting force. The transition corresponding to a resisting force of 8 × 1012 N/m divides regions displaying back-arc extensional tectonics from those displaying compressional tectonics. This is in good agreement with other estimates of the forces resisting slab motion. It is suggested that an increase in the width of -or the shear stress on -the plate boundary, associated with the subduction of lithosphere to the buoyant side of this transition, can result in a compressional stress on the overriding plate which is great enough to account for cordilleran tectonics.The proposed reduction in the one of driving forces of plate motion is still consistent with observations, being compensated by the greater relative importance of the push from the ridges.

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Section: Applicationmentioning

confidence: 99%

Section: Applicationmentioning

confidence: 99%

Some consequences of the subduction of young slabs

England

Wortel

1980

Earth and Planetary Science Letters

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“…A transform fault with no bathymetric expression is assumed to offset the 40-krn-long northern trough about 20 krn from the 15-krn-long southern Lorson, 1972;Lomnitz eta/., 1970, Figure 3]. The inset in the upper right-band comer, which shows the distinctive magnetic lineations and anomaly numbers m the nonheastem Pac1fic, bas been taken from Atwater [1970]. The rectangular area outlined in the center shows the region covered by Figure 2. trough ( Figure 2).…”

Section: The Guaymas Basinmentioning

confidence: 99%

“…Owing to its position within a complex evolution of such plates (e.g., Atwater, 1970) the gulf is considered a transition region between normal sea floor ~preadtng on the East Pacific Rise to the south and transform motion along the San Andreas fault system to the north. A nf.…”

Section: Introductionmentioning

confidence: 99%

Heat flow at the spreading centers of the Guaymas Basin, Gulf of California

Williams¹,

Becker²,

Lawver³

et al. 1979

J. Geophys. Res.

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Fifi~·four new heat ~ow measure~ents_in the central troughs of the Guaymas basin support the hypothesis that they are sues of active antrus1on In the northern trough a diStinct pattern of hydrothermal cooling is revealed, wuh ventang along the western boundary fault of the trough. In the southern trough an analogous pattern is apparently superimposed upon a conductive cooling anomaly associated with a recent central intrusion. The discharge of thermal waters occurs along the boundary faults and through other faults associated w1tb a possible horst block located in the north central floor of the southern trough. The heat flow patterns suggest that the intrusions are ep1sod1c and do not occur Simultaneously along the length ( 15-40 km) of a spreading segment. A review of all available beat flow measurementS ~or ~he G uaymas basin suggests that most of the recharge for a pervasive regional hydrothermal system is hm1ted to the central depress1ons, wuh perhaps some contribution from pore water. The discharge of thermal waters occurs predominantly in the central depressions and possibly along the boundary transform faults and fracture zones. The reg1ons of the basin more than a few kilometers an distance from the spreading a. xis, although presumably underlain by a hydrothermal system, are probably not the location of numerous vents or recharge zones.

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“…Although the relative motions of these three plates through time can be reconstructed from magnetic anomalies of the ocean floor [Atwater, 1970[Atwater, , 1989 Range province has a northwest-southeast direction and thus also accommodates some right-lateral shear component of motion with respect to the more stable interior of North America [e.g., Wernicke and Snow, 1998]. …”

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Subduction‐induced strain in the upper mantle east of the Mendocino triple junction, California

Hartog¹,

Schwartz²

2000

J. Geophys. Res.

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Abstract. We observe splitting of teleseismic shear waves at five stations of the Berkeley Digital Seismic Network located east of the Mendocino triple junction in northeastern California that is dependent on the arrival direction of the seismic phases. The observed variations with back azimuth cannot be explained with laterally varying anisotropy with a horizontal symmetry axis and are attributed to the presence of fabric with an inclined symmetry axis. We assume that the anisotropy is caused by the preferred alignment of olivine crystals. A grid search over possible orientations of the olivine a axes reveals that south of the Mendocino triple junction they dip to the east, whereas north of the triple junction they dip to the northeast. On the basis of a comparison of the ray paths of our data to the spatial distribution of fast and slow P wave velocity anomalies in the upper mantle, we conclude that the anisotropy is located within seismically slow regions and that the directions are controlled by the geometry of a steeply dipping fast P wave velocity anomaly. Assuming that the fast P velocity anomaly represents subducted slab material, we conclude that the fabric beneath the stations north of the triple junction is most likely caused by the differential motion between this rigid, strong down going plate and the surrounding mantle. South of the triple junction the fabric may have developed while subduction of the Farallon plate was still ongoing in this region (prior to 6 Ma). However, we prefer to attribute the observations to more recent asthenospheric flow associated with the opening of a slabless window beneath the North American lithosphere. The flow is modulated by the presence of rigid lithosphere to the north and east.

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Implications of Plate Tectonics for the Cenozoic Tectonic Evolution of Western North America

Cited by 1,856 publications

References 0 publications

Some consequences of the subduction of young slabs

Some consequences of the subduction of young slabs

Heat flow at the spreading centers of the Guaymas Basin, Gulf of California

Subduction‐induced strain in the upper mantle east of the Mendocino triple junction, California

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