scholarly journals Pacific-North America plate boundary reorganization in response to a change in relative plate motion: Offshore Canada

2010 ◽  
Vol 11 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
K. M. M. Rohr ◽  
A. J. Tryon
Keyword(s):  
North America ◽  
Plate Boundary ◽  
Plate Motion ◽  
Relative Plate Motion

scholarly journals Extreme Quaternary plate boundary exhumation and strike slip localized along the southern Fairweather fault, Alaska, USA

Geology ◽  
2021 ◽  
Vol 49 (5) ◽  
pp. 602-606 ◽  
Author(s):  
Richard O. Lease ◽  
Peter J. Haeussler ◽  
Robert C. Witter ◽  
Daniel F. Stockli ◽  
Adrian M. Bender ◽  
...  
Keyword(s):  
North America ◽  
Sedimentary Cover ◽  
Plate Boundary ◽  
Slip Rate ◽  
Strike Slip ◽  
Plate Motion ◽  
The North ◽  
Exhumation Rates ◽  
Restraining Bend

Abstract The Fairweather fault (southeastern Alaska, USA) is Earth’s fastest-slipping intracontinental strike-slip fault, but its long-term role in localizing Yakutat–(Pacific–)North America plate motion is poorly constrained. This plate boundary fault transitions northward from pure strike slip to transpression where it comes onshore and undergoes a <25°, 30-km-long restraining double bend. To the east, apatite (U-Th)/He (AHe) ages indicate that North America exhumation rates increase stepwise from ∼0.7 to 1.7 km/m.y. across the bend. In contrast, to the west, AHe age-depth data indicate that extremely rapid 5–10 km/m.y. Yakutat exhumation rates are localized within the bend. Further northwest, Yakutat AHe and zircon (U-Th)/He (ZHe) ages gradually increase from 0.3 to 2.6 Ma over 150 km and depict an interval of extremely rapid >6–8 km/m.y. exhumation rates that increases in age away from the bend. We interpret this migration of rapid, transient exhumation to reflect prolonged advection of the Cenozoic–Cretaceous sedimentary cover of the eastern Yakutat microplate through a stationary restraining bend along the edge of the North America plate. Yakutat cooling ages imply a long-term strike-slip rate (54 ± 6 km/m.y.) that mimics the millennial (53 ± 5 m/k.y.) and decadal (46 mm/yr) rates. Fairweather fault slip can account for all Pacific–North America relative plate motion throughout Quaternary time and indicates stability of highly localized plate boundary strike slip on a single fault where extreme rock uplift rates are persistently localized within a restraining bend.

scholarly journals The Wandel Hav Strike-Slip Mobile Belt – A Mesozoic plate boundary in North Greenland

2001 ◽  
Vol 48 ◽  
pp. 149-158
Author(s):  
E. Håkansson ◽  
S.A.S. Pedersen
Keyword(s):  
Plate Boundary ◽  
Strike Slip ◽  
Seafloor Spreading ◽  
Plate Motion ◽  
Mobile Belt ◽  
Eurasian Plate ◽  
Late Palaeozoic ◽  
Break Up ◽  
Relative Plate Motion ◽  
North Greenland

The historical ‘de Geer Line’ between Svalbard and Greenland is shown to have had a Mesozoic precursor now residing well within the continental Greenland plate, where it coincides with the Wandel Hav Strike-Slip Mobile Belt. Well-constrained phases in relative plate motion reflected in the mobile belt are discernible back to the mid Jurassic, with more obscure phases dating even further back. There is evidence that the Wandel Hav Strike-Slip Mobile Belt may have been formed already in Late Palaeozoic time during onset of Pangean break-up; evidence for strike-slip movements of this age is, however, largely circumstantial, due to severe overprinting during the later phases. Wrench tectonics along the ‘fossil’ plate boundary culminated around the Cretaceous – Palaeogene boundary in the major right-lateral, transpressional Kronprins Christian Land Orogeny. Thus, the Wandel Hav Strike-Slip Mobile Belt may constitute the geological/structural expression of the Mesozoic Laurentian – Eurasian plate boundary all the way up to initiation of actual seafloor spreading at chron 24 in Palaeogene time.

scholarly journals Geodynamic evolution of southwestern North America since the Late Eocene

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Alireza Bahadori ◽  
William E. Holt
Keyword(s):  
North America ◽  
Boundary Conditions ◽  
Plate Boundary ◽  
Late Eocene ◽  
Plate Motion ◽  
Minor Role ◽  
Mantle Flow ◽  
Body Forces ◽  
Slab Rollback ◽  
Deviatoric Stresses

AbstractSlab rollback, lithospheric body forces, or evolution of plate boundary conditions are strongly debated as possible lithospheric driving mechanisms for Cenozoic extension in southwestern North America. By incorporating paleo-topography, lithospheric structure, and paleo-boundary conditions, we develop a complete geodynamic model that quantifies lithospheric deviatoric stresses and predicts extension and shear history since Late Eocene. We show that lithospheric body forces together with influence of change-over from subduction to transtensional boundary conditions from Late Eocene to Early Miocene were the primary driving factors controlling direction and magnitude of extensional deviatoric stresses that produced topographic collapse. After paleo-highlands collapsed, influence of Pacific-North America plate motion and associated deformation style along the plate boundary became increasingly important from Middle Miocene to present. Smaller-scale convection stress effects from slab rollback and associated mantle flow played only a minor role. However, slab rollback guided deformation rate through introduction of melts and fluids that impacted rheology.

scholarly journals The Crustal Dynamics Project

1988 ◽  
Vol 129 ◽  
pp. 337-338
Author(s):  
Robert J. Coates
Keyword(s):  
North American ◽  
Plate Boundary ◽  
Plate Motion ◽  
The North ◽  
Long Baseline ◽  
Regional Deformation ◽  
Plate Stability ◽  
Crustal Dynamics ◽  
The Stability ◽  
Relative Plate Motion

The Crustal Dynamics Project has been developing, deploying, and operating very-long-baseline interferometry (VLBI) systems and satellite laser ranging (SLR) systems for highly accurate geodetic measurements of global plate motion, plate stability, regional crustal deformation, and earth rotation/polar motion. Over the past 10 years, the measurement accuracies of these systems have been improved by a factor of 10 to the cm level. Plans are to continue these developments to reach mm level accuracies. The present deployment of the VLBI systems is primarily in the Northern Hemisphere. This network has produced measurements of the relative plate motion between the North American, Eurasian, and Pacific plates; the stability of the same plates; and the regional deformation at the North American/Pacific plate boundary in California and Alaska.

Fault evolution and strain partitioning within deforming continents

2015 ◽  
Author(s):  
◽  
Jiyang Ye
Keyword(s):  
Southern California ◽  
Mainland China ◽  
Plate Boundary ◽  
Plate Motion ◽  
Fault System ◽  
Strain Rates ◽  
Strain Partitioning ◽  
Boundary Fault ◽  
Fault Evolution ◽  
Relative Plate Motion

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Diffuse deformation within continents and over broad plate boundary zones deviates from the prediction of plate tectonics theory. Some of the deforming continents are now well delineated by space geodetic measurements, but the cause of such diffuse deformation remains poorly understood. My Ph.D. research focuses on two regions: 1) Fault evolution and Strain partitioning in Southern California: High-precision GPS measurements have enabled kinematic modeling of the present-day strain partitioning between these faults, but the causes of such strain partitioning and fault evolution remain uncertain. Using a three-dimensional viscoelasto-plastic finite element model, I have explored how the plate boundary fault system evolves to accommodate the relative plate motion in Southern California. My results show that, when the plate boundary faults are not optimally orientated to accommodate the relative plate motion, new faults will be initiated. In particular, the Big Bend of the San Andreas Fault, which is the main plate boundary fault, impedes the relative plate motion, thus forces the development of a system of secondary faults. 2) Active strain rates of crustal deformation in mainland China: In the past decades Chinese scientists and international teams have measured GPS velocities at more than a thousand sites in mainland China, allowing calculation of detailed spatial distribution of the crustal strain rates. Using the latest GPS data, I have calculated strain rates in different tectonic provinces in China and compared them with neotectonic data. I have also calculated strain rates using earthquakes and geological fault slip rates. The differences of strain rates derived from different data sets show the time-scale dependence of strain rates. Comparing GPS strain rates with seismic moment release patterns illustrates the limitations of using earthquake catalog for earthquake hazard analysis.

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