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.

scholarly journals Distribution of Relative Plate Motion Along the Pacific-North American Plate Boundary Determined from Mobile VLBI Measurements

1988 ◽  
Vol 129 ◽  
pp. 365-366
Author(s):  
P. M. Kroger ◽  
G. A. Lyzenga ◽  
K. S. Wallace ◽  
J. M. Davidson
Keyword(s):  
North American ◽  
Plate Boundary ◽  
Temporal Distribution ◽  
North American Plate ◽  
Primary Sources ◽  
Plate Motion ◽  
Fault System ◽  
Pacific North American ◽  
The Pacific ◽  
San Andreas Fault System

The problem of understanding the deformation occurring along the Pacific-North American plate boundary in the western United States depends upon understanding the forces which drive the plates in this region. One of the primary sources of our knowledge concerning these forces lies in their manifestation as relative displacements which occur throughout the broad zone of deformation surrounding the San Andreas fault system. It is information concerning the spatial and temporal distribution of these motions which will be of greatest benefit in helping to determine which of several possible mechanisms is responsible for driving contemporary plate motions in this region.

scholarly journals Constraints on rock uplift in the eastern Transverse Ranges and northern Peninsular Ranges and implications for kinematics of the San Andreas fault in the Coachella Valley, California, USA

Geosphere ◽  
2020 ◽  
Vol 16 (3) ◽  
pp. 723-750
Author(s):  
James A. Spotila ◽  
Cody C. Mason ◽  
Joshua D. Valentino ◽  
William J. Cochran
Keyword(s):  
San Andreas Fault ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Fault System ◽  
Published Data ◽  
Strain Partitioning ◽  
San Bernardino Mountains ◽  
Coachella Valley ◽  
San Andreas ◽  
Peninsular Ranges

Abstract The nexus of plate-boundary deformation at the northern end of the Coachella Valley in southern California (USA) is complex on multiple levels, including rupture dynamics, slip transfer, and three-dimensional strain partitioning on nonvertical faults (including the San Andreas fault). We quantify uplift of mountain blocks in this region using geomorphology and low-temperature thermochronometry to constrain the role of long-term vertical deformation in this tectonic system. New apatite (U-Th)/He (AHe) ages confirm that the rugged San Jacinto Mountains (SJM) do not exhibit a record of rapid Neogene exhumation. In contrast, in the Little San Bernardino Mountains (LSBM), rapid exhumation over the past 5 m.y. is apparent beneath a tilted AHe partial retention zone, based on new and previously published data. Both ranges tilt away from the Coachella Valley and have experienced minimal denudation from their upper surface, based on preservation of weathered granitic erosion surfaces. We interpret rapid exhumation at 5 Ma and the gentle tilt of the erosion surface and AHe isochrons in the LSBM to have resulted from rift shoulder uplift associated with extension prior to onset of transpression in the Coachella Valley. We hypothesize that the SJM have experienced similar rift shoulder uplift, but an additional mechanism must be called upon to explain the pinnacle-like form, rugged escarpment, and topographic disequilibrium of the northernmost SJM massif. We propose that this form stems from erosional resistance of the Peninsular Ranges batholith relative to more-erodible foliated metamorphic rocks that wrap around it. Our interpretations suggest that neither the LSBM nor SJM have been significantly uplifted under the present transpressive configuration of the San Andreas fault system, but instead represent relict highs due to previous tectonic and erosional forcing.

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.

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