Influence of Sediment Input and Plate-Motion Obliquity on Basin Development Along an Active Oblique-Divergent Plate Boundary: Gulf of California and Salton Trough

2012 ◽  
pp. 209-225 ◽  
Author(s):  
Rebecca J. Dorsey ◽  
Paul J. Umhoefer
Keyword(s):  
Gulf Of California ◽  
Plate Boundary ◽  
Plate Motion ◽  
Basin Development ◽  
Salton Trough ◽  
Sediment Input

Redefining the age of the lower Colorado River, southwestern United States

Geology ◽  
2021 ◽  
Author(s):  
R.S. Crow ◽  
J. Schwing ◽  
K.E. Karlstrom ◽  
M. Heizler ◽  
P.A. Pearthree ◽  
...  
Keyword(s):  
United States ◽  
Gulf Of California ◽  
Colorado River ◽  
Grand Canyon ◽  
Plate Motion ◽  
Southwestern United States ◽  
Northern Mexico ◽  
Base Level ◽  
Salton Trough ◽  
Lower Colorado River

Sanidine dating and magnetostratigraphy constrain the timing of integration of the lower Colorado River (southwestern United States and northern Mexico) with the evolving Gulf of California. The Colorado River arrived at Cottonwood Valley (Nevada and Arizona) after 5.24 Ma (during or after the Thvera subchron). The river reached the proto–Gulf of California once between 4.80 and 4.63 Ma (during the C3n.2r subchron), not at 5.3 Ma and 5.0 Ma as previously proposed. Duplication of section across newly identified strands of the Earthquake Valley fault zone (California) probably explains the discrepancy. The data also imply the start of focused plate motion and basin development in the Salton Trough (California) at 6–6.5 Ma and relative tectonic stability of the southernmost part of the lower Colorado River corridor after its integration. After integration, the Colorado River quickly incised through sediment-filled basins and divides between them as it also likely excavated Grand Canyon (Arizona). The liberated sediment from throughout the system led to deposition of hundreds of meters of Bullhead Alluvium downstream of Grand Canyon after 4.6 Ma as the river adjusted to its lower base level.

scholarly journals Pattern of seismic deformation in the Western Mediterranean

1999 ◽  
Vol 42 (1) ◽  
Author(s):  
S. Pondrelli
Keyword(s):  
Moment Tensor ◽  
Plate Boundary ◽  
Eastern Alps ◽  
Western Mediterranean ◽  
Plate Motion ◽  
Moment Tensors ◽  
Motion Models ◽  
Strain Pattern ◽  
Seismological Data ◽  
Seismic Deformation

The seismic deformation of the Western Mediterranean was studied with the aim of defining the strain pattern that characterizes the Africa-Eurasia plate boundary in this area. Within different sections along the boundary the cumulative moment tensor was computed over 90 years of seismological data. The results were compared with NUVELlA plate motion model and geodetic data. A stable agreement was found along Northern Africa to Sicily, where only Africa and Eurasia plates are involved. In this zone it is evident that changes in the strike of the boundary correspond to variations in the prevailing geometry of deformation, tectonic features and in the percentage of seismic with respect to total expected deformation. The geometry of deformation of periadriatic sections (Central to Southern Apennines, Eastern Alps and the Eastern Adriatic area) agrees well with VLBI measurements and with regional geological features. Seismicity seems to account for low rates, from 3% to 31%, of total expected deformation. Only in the Sicily Strait, characterized by extensional to strike slip deformation, does the ratio reach a higher value (79%). If the amount of deformation deduced from seismicity seems low, because 90 years are probably not representative of the recurrence seismic cycle of the Western Mediterranean, the strain pattern we obtain from cumulative moment tensors is more representative of the kinematics of this area than global plate motion models and better identifies lower scale geodynamic features.

No signal of a plume push force in Indo-Atlantic plate speeds before, during, or after Deccan plume arrival

2021 ◽  
Author(s):  
Graeme Eagles ◽  
Lucía Pérez Díaz ◽  
Karin Sigloch
Keyword(s):  
Late Cretaceous ◽  
Upper Mantle ◽  
Plate Boundary ◽  
Plate Motion ◽  
Driving Mechanism ◽  
African Plate ◽  
Plate Motions ◽  
Driving Mechanisms ◽  
High Resolution Models ◽  
Spreading Rates

<p>Observations of the apparent links between plate speeds and the global distribution of plate boundary types have led to the suggestion that subduction may provide the largest component in the balance of torques maintaining plate motions. This would imply that plate speeds should not exceed the sinking rates of slabs into the upper mantle. Instances of this ‘speed limit’ having been broken may thus hint at the existence of driving mechanisms additional to those resulting from plate boundary forces. The arrival and emplacement of the Deccan-Réunion mantle plume beneath the Indian-African plate boundary in the 67-62 Ma period has been discussed in terms of one such additional driving mechanism, leading to the establishment of “plume-push” hypothesis, which in recent years has gained significant traction. We challenge the model-based observations that form the principal evidence in favour of plume-push: a late Cretaceous pulse of anticorrelating accelerations and decelerations in seafloor spreading rates around the African and Indian plates. Using existing and newly-calculated high-resolution models of plate motion, we instead document an increase in divergence rates at 67-64 Ma. Because of its ubiquity, we consider this increase to be the artefact of a timescale error affecting chrons 29-28. Corrected for this artefact, the evolution of plate speeds resembles a smooth continuation of pre-existing late Cretaceous trends, consistent with the idea that the arrival of the Réunion plume did not substantially affect the existing balance of plate boundary forces on the Indian and African plates. </p>

An analytical model concerning the possible initiation of subduction between the India and Africa plates, caused by the Morondova plume

2020 ◽  
Author(s):  
Bernhard Steinberger ◽  
Douwe van Hinsbergen
Keyword(s):  
Subduction Zones ◽  
Plate Tectonics ◽  
Eastern Mediterranean ◽  
Plate Boundary ◽  
Plate Motion ◽  
Mantle Flow ◽  
Plate Motions ◽  
Subduction Initiation ◽  
Euler Pole ◽  
Geodynamic Processes

<p>Identifying the geodynamic processes that trigger the formation of new subduction zones is key to understand what keeps the plate tectonic cycle going, and how plate tectonics once started. Here we discuss the possibility of plume-induced subduction initiation. Previously, our numerical modeling revealed that mantle upwelling and radial push induced by plume rise may trigger plate motion change, and plate divergence as much as 15-20 My prior to LIP eruption. Here we show that, depending on the geometry of plates, the distribution of cratonic keels and where the plume rises, it may also cause a plate rotation around a pole that is located close to the same plate boundary where the plume head impinges: If that occurs near one end of the plate boundary, an Euler pole of the rotation may form along that plate boundary, with extension on one side, and convergence on the other.  This concept is applied to the India-Africa plate boundary and the Morondova plume, which erupted around 90 Ma, but may have influenced plate motions as early as 105-110 Ma. If there is negligible friction, i.e. there is a pre-existing weak plate boundary, we estimate that the total amount of convergence generated in the northern part of the India-Africa plate boundary can exceed 100 km, which is widely thought to be sufficient to initiate forced, self-sustaining subduction. This may especially occur if the India continental craton acts like an “anchor” causing a comparatively southern location of the rotation pole of the India plate. Geology and paleomagnetism-based reconstructions of subduction initiation below ophiolites from Pakistan, through Oman, to the eastern Mediterranean reveal that E-W convergence around 105 Ma caused forced subduction initiation, and we tentatively postulate that this is triggered by Morondova plume head rise. Whether the timing of this convergence is appropriate to match observations on subduction initiation as early as 105 Ma depends on the timing of plume head arrival, which may predate eruption of the earliest volcanics. It also depends on whether a plume head already can exert substantial torque on the plate while it is still rising – for example, if the plate is coupled to the induced mantle flow by a thick craton.</p>

Geodetic and tectonic analyses along an active plate boundary: The central Gulf of California

Tectonics ◽  
1989 ◽  
Vol 8 (3) ◽  
pp. 429-441 ◽  
Author(s):  
L. Ortlieb ◽  
J. C. Ruegg ◽  
J. Angelier ◽  
B. Colletta ◽  
M. Kasser ◽  
...  
Keyword(s):  
Gulf Of California ◽  
Plate Boundary

Late Holocene Lacustrine Chronology and Archaeology of Ancient Lake Cahuilla, California

1983 ◽  
Vol 19 (3) ◽  
pp. 373-387 ◽  
Author(s):  
Michael R. Waters
Keyword(s):  
Gulf Of California ◽  
Late Holocene ◽  
Colorado River ◽  
Archaeological Sites ◽  
Ancient Lake ◽  
Freshwater Lakes ◽  
Radiocarbon Dates ◽  
California Water ◽  
Salton Trough ◽  
Lake Cahuilla

AbstractFreshwater lakes existed intermittently in the Salton Trough of southern California during the late Holocene. The lakes formed north of the subaerial Colorado River Delta whenever the Colorado River flowed west into the trough instead of south to the Gulf of California. Water filled the trough to a maximum altitude of 12 m. Stratigraphy, radiocarbon dates, and supplementary evidence document four lacustral intervals of Lake Cahuilla between A.D. 700 and 1580. Archaeological sites are associated with the 12-m shoreline and their occupation correlates with these lacustral intervals.

Sign in / Sign up

Export Citation Format

Share Document