Record Details

Diffuse deformation patterns along the North American plate boundary zone, offshore western United States

ScholarsArchive at Oregon State University

Field Value
Title Diffuse deformation patterns along the North American plate boundary zone, offshore western United States
Names Chaytor, Jason D. (creator)
Goldfinger, Chris (advisor)
Date Issued 2006-10-06T15:48:10Z (iso8601)
Internet Media Type application/pdf
Note Graduation date: 2007
Abstract Plate boundaries are commonly regions of complex, diffuse deformation with
the motion across the boundary accommodated by numerous structural systems, rather
than being narrow, discrete zones of deformation. One such boundary occurs where
the North American plate makes contact with Juan de Fuca, Gorda, and Pacific plates
along the west coast of the United States, forming a wide zone of deformation which
crosses the ocean-continent transition. Two offshore regions associated with this
boundary zone, the Gorda plate and California Continental Borderland, have
undergone significant deformation in order to accommodate the changing relative
tectonic motion across the boundary. The Gorda plate, seaward of the Cascadia
Subduction Zone is deforming as a modified, vertically-hinged flexural-slip buckle
that utilizes, via-reactivation, the relict spreading-fabric faults and newly-formed leftlateral
strike-slip faults that cut the original fabric. In this way, it appears that the
Gorda plate, as the youngest and weakest plate in the system, absorbs the motion of
the surrounding plates, essentially buffering the strain accumulation in other regions.
In southern California, the plate boundary is dominated by the San Andreas transform
system, but with deformation distributed over structures within a zone whose width
west of the main San Andreas fault exceeds 300 km. While much of this deforming
zone is onshore, a significant component is offshore within the California Borderland
and Western Transverse Ranges provinces. Deformation related to the growth of the
San Andreas fault system within the Borderland has been ongoing since the late
Oligocene, resulting in a poly-deformed terrane of distributed deformation, reflecting
the shift from subduction to a highly evolved transform system. Two areas within the
Borderland illuminate aspects of the regions complex history: the intersection of the
Santa Cruz-Catalina Ridge and northern Channel Islands platform which reflect the
current transpressional tectonic regime, and Dall Bank within the Outer Borderland
which contains evidence of earlier (Oligocene-Miocene) deformational phases.
Genre Thesis
Topic Plate tectonics

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