Tectonic core of a sedimentary drift: a potential ridge propagation feature beneath the Blake Outer Ridge |
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Authors: | Dayton Dove Steven C Jaume Erin Beutel |
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Institution: | (1) Department of Geology and Environmental Geosciences, College of Charleston, 66 George Street, Charleston, SC 29424, USA;(2) Present address: Department of Geology and Geophysics, University of Alaska Fairbanks, Natural Sciences Building, 900 Yukon Drive, P.O. Box 755780, Fairbanks, AK 99775-5780, USA |
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Abstract: | The Blake Outer Ridge is a 480–kilometer long linear sedimentary drift ridge striking perpendicular to the North American
coastline. By modeling free-air gravity anomalies we tested for the presence of a crustal feature that may control the location
and orientation of the Blake Outer Ridge. Most of our crustal density models that match observed gravity anomalies require
an increase in oceanic crustal thickness of 1–3 km on the southwest side of the Blake Outer Ridge relative to the northeast
side. Most of these models also require 1–4 km of crustal thinning in zone 20–30 km southwest of the crest of the Blake Outer
Ridge. Although these features are consistent with the structure of oceanic fracture zones, the Blake Outer Ridge is not parallel
to adjacent known fracture zones. Magnetic anomalies suggest that the ocean crust beneath this feature formed during a period
of mid-ocean ridge reorganization, and that the Blake Outer Ridge may be built upon the bathymetric expression of an oblique
extensional feature associated with ridge propagation. It is likely that the orientation of this trough acted as a catalyst
for sediment deposition with the start of the Western Boundary Undercurrent in the mid-Oligocene. |
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Keywords: | Blake Outer Ridge Crustal density model Gravity anomalies Magnetic anomalies Ridge propagation Sedimentary drift |
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