scholarly journals Possibility of recovery of slip deficit rate between the North American plate and the Pacific plate off Sanriku, northeast Japan

2007 ◽  
Vol 34 (20) ◽  
Author(s):  
Shinzaburo Ozawa ◽  
Hisashi Suito ◽  
Takuya Nishimura ◽  
Mikio Tobita ◽  
Hiroshi Munekane
Keyword(s):  
North American ◽  
Pacific Plate ◽  
North American Plate ◽  
The North ◽  
Slip Deficit ◽  
The Pacific ◽  
Off Sanriku

Uplift and exhumation in Haida Gwaii driven by terrane translation and transpression along the southern Queen Charlotte fault, Canada

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 908-912
Author(s):  
Philip Schoettle-Greene ◽  
Alison R. Duvall ◽  
Ann Blythe ◽  
Eric Morley ◽  
William Matthews ◽  
...  
Keyword(s):  
North America ◽  
North American ◽  
North American Plate ◽  
Cascadia Subduction Zone ◽  
Haida Gwaii ◽  
Crustal Shortening ◽  
Basin Inversion ◽  
Subduction Initiation ◽  
The North ◽  
The Pacific

Abstract The mountainous archipelago of Haida Gwaii abuts the transpressive Pacific–North American plate margin north of the Cascadia subduction zone (northwestern North America). Topography on Haida Gwaii has been attributed to either dynamic uplift supported by subduction initiation or crustal shortening driven by shear adjacent the plate-bounding Queen Charlotte fault. In order to resolve how intraplate strain is accommodated, we obtained thermochronometry data from 20 bedrock samples on Haida Gwaii, including zircon (U-Th)/He, apatite (U-Th-Sm)/He, and apatite fission-track dates. With dates ranging from 5 to 60 Ma, we interpret exhumation rates increasing in proximity to the Queen Charlotte fault and leading to a maximum of 6 km of exhumation since 20 Ma. The onset of exhumation significantly predates the purported initiation of subduction, precluding a direct relationship between subduction initiation and the development of topography in the archipelago. Instead, exhumation onset correlates with passage of the Yakutat terrane, suggesting that North America was deformed and Haida Gwaii uplifted during terrane translation. Steady or slightly decreasing exhumation rate since the Miocene is at odds with estimated increases to intraplate convergence over this time, ruling out crustal shortening in Haida Gwaii as the only response to transpression between North America and the Pacific. From this, we conclude that plate convergence is accommodated through basin inversion and internal shortening in the North American and Pacific plates as well as potential underthrusting of the Pacific plate beneath North America.

The Eocene–Oligocene magmatic hiatus in the south-central Canadian Cordillera: a capture of the Kula Plate by the Pacific Plate?

2008 ◽  
Vol 45 (1) ◽  
pp. 69-82 ◽  
Author(s):  
Jaroslav Dostal ◽  
J Duncan Keppie ◽  
B Neil Church ◽  
Peter H Reynolds ◽  
Cheryl R Reid
Keyword(s):  
Volcanic Rocks ◽  
Pacific Plate ◽  
North American Plate ◽  
Volcanic Complex ◽  
Canadian Cordillera ◽  
Continental Flood Basalts ◽  
The North ◽  
South Central ◽  
The Pacific ◽  
Back Arc

The Tertiary (Paleogene and Neogene) geological record in south-central Canadian Cordillera is dominated by the 350–400 km wide, lower Eocene volcanic arc and the overlying Miocene–Recent back-arc lavas that are separated by a hiatus in magmatic activity between 48 and 24 Ma. In the Black Dome area (~240 km north of Vancouver), the Eocene volcanic rocks are mainly continental margin calc-alkaline andesite and dacite, resulting from the melting of a juvenile mafic source at the base of the crust. In contrast, the Miocene volcanic rocks resemble continental flood basalts. Both Eocene and Miocene rocks from the Black Dome volcanic complex have high positive εNd values (+7.2 to +7.4 and +6.4 to +7.6, respectively) and low initial Sr isotopic ratios (0.702 516 – 0.703 528 and 0.703 376 – 0.703 392, respectively) comparable to modern oceanic basalts. The onset of the hiatus in magmatism at 48 Ma coincides with capture of the Kula Plate by the Pacific Plate resulting in a change in convergence direction with the North American Plate from orthogonal to margin-parallel. The margin-parallel motion is inferred to have removed a 50–100 km sliver of the Eocene forearc that formed the boundary between the Pacific and subducted Kula Plate. Reinitiation of arc magmatism at 24 Ma is related to subduction of the Farallon and associated plates and it superimposed back-arc tholeiitic magmatism on top of the Eocene arc.

scholarly journals Index of stress data for the North American and parts of the Pacific plate

1984 ◽  
Author(s):  
Mary Lou C. Zoback ◽  
Mark D. Zoback ◽  
Mara E. Schiltz
Keyword(s):  
North American ◽  
Pacific Plate ◽  
The North ◽  
The Pacific

Overview of Naturally Occurring Asbestos in California and Southwestern Nevada

2020 ◽  
Vol 26 (1) ◽  
pp. 9-14
Author(s):  
R. Mark Bailey
Keyword(s):  
Sierra Nevada ◽  
North American ◽  
Volcanic Belt ◽  
Island Arc ◽  
North American Plate ◽  
Mountain Range ◽  
The North ◽  
Rock Types ◽  
Naturally Occurring ◽  
Naturally Occurring Asbestos

ABSTRACT Naturally occurring asbestos (NOA) is being discovered in a widening array of geologic environments. The complex geology of the state of California is an excellent example of the variety of geologic environments and rock types that contain NOA. Notably, the majority of California rocks were emplaced during a continental collision of eastward-subducting oceanic and island arc terranes (Pacific and Farallon plates) with the westward continental margin of the North American plate between 65 and 150 MY BP. This collision and accompanying accretion of oceanic and island arc material from the Pacific plate onto the North American plate, as well as the thermal events caused by emplacement of the large volcanic belt that became today's Sierra Nevada mountain range, are the principal processes that produced the rocks where the majority of NOA-bearing units have been identified.

scholarly journals Constraints on North American-Pacific Plate Boundary Deformation in Central California from VLBI and Ground-Based Geodetic Data

1988 ◽  
Vol 129 ◽  
pp. 353-353
Author(s):  
Jeanne Sauber ◽  
Thomas H. Jordan ◽  
Gregory C. Beroza ◽  
Thomas A. Clark ◽  
Michael Lisowski
Keyword(s):  
North American ◽  
A Priori ◽  
Plate Boundary ◽  
Pacific Plate ◽  
Rate Of Change ◽  
Geodetic Data ◽  
Central California ◽  
The North ◽  
San Andreas ◽  
Plate Boundary Deformation

To accommodate the relative motion across the North American-Pacific plate boundary predicted by global plate solutions, significant deformation on faults other than the San Andreas is necessary. In central California, this deformation is thought to include distributed compression perpendicular to the San Andreas as well as right-lateral strike-slip motion parallel to the San Andreas on faults such as the San Gregorio/Hosgri system. A self-consistent set of VLBI observations from experiments beginning in October 1982 is used to determine the vector rate of change of station position at central California VLBI sites Ovro, Mojave, Vandenberg, Fort Ord, Presidio, and Point Reyes. To estimate VLBI station positions, a procedure is used that minimizes the uncertainties in defining a reference frame by including a priori geologic and geodetic information. The vector rate of change of station positions provides constraints on the integrated deformation rates between stations. Geologic and geophysical data suggest that the rate and mode of deformation varies on both local and regional scales. Thus, the VLBI derived results are interpreted in the context of an overall tectonic framework by examining geologic and ground-based geodetic data.

scholarly journals Intraseasonal and Interannual Variability in North American Storm Tracks and Its Relationship to Equatorial Pacific Variability

2013 ◽  
Vol 141 (10) ◽  
pp. 3610-3625 ◽  
Author(s):  
Kevin M. Grise ◽  
Seok-Woo Son ◽  
John R. Gyakum
Keyword(s):  
North America ◽  
Interannual Variability ◽  
North American ◽  
Southern Oscillation ◽  
Extratropical Cyclones ◽  
The North ◽  
The Pacific ◽  
Cyclone Tracks ◽  
Lagrangian Tracking ◽  
The North Atlantic Oscillation

Abstract Extratropical cyclones play a principal role in wintertime precipitation and severe weather over North America. On average, the greatest number of cyclones track 1) from the lee of the Rocky Mountains eastward across the Great Lakes and 2) over the Gulf Stream along the eastern coastline of North America. However, the cyclone tracks are highly variable within individual winters and between winter seasons. In this study, the authors apply a Lagrangian tracking algorithm to examine variability in extratropical cyclone tracks over North America during winter. A series of methodological criteria is used to isolate cyclone development and decay regions and to account for the elevated topography over western North America. The results confirm the signatures of four climate phenomena in the intraseasonal and interannual variability in North American cyclone tracks: the North Atlantic Oscillation (NAO), the El Niño–Southern Oscillation (ENSO), the Pacific–North American pattern (PNA), and the Madden–Julian oscillation (MJO). Similar signatures are found using Eulerian bandpass-filtered eddy variances. Variability in the number of extratropical cyclones at most locations in North America is linked to fluctuations in Rossby wave trains extending from the central tropical Pacific Ocean. Only over the far northeastern United States and northeastern Canada is cyclone variability strongly linked to the NAO. The results suggest that Pacific sector variability (ENSO, PNA, and MJO) is a key contributor to intraseasonal and interannual variability in the frequency of extratropical cyclones at most locations across North America.

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