Marine Geophysical Researches

, Volume 28, Issue 1, pp 1–11 | Cite as

Tectonic core of a sedimentary drift: a potential ridge propagation feature beneath the Blake Outer Ridge

Original Paper


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.


Blake Outer Ridge Crustal density model Gravity anomalies Magnetic anomalies Ridge propagation Sedimentary drift 



Both the extraction of the bathymetry and gravity anomaly profiles, and the figures in this manuscript were created using the GMT software system (Wessel and Smith 1991). R. Lillie and an anonymous reviewer offered numerous suggestions on an earlier draft of this manuscript, and comments by editor P. Clift and 3 anonymous reviewers helped to greatly improve the final version. We thank G. Mountain and P. Tulchoke for discussions regarding their work on the Blake Outer Ridge and M. Katuna for references regarding the geologic history of the Gulf Stream. The gravity anomaly modeling was done using the GM-SYS® gravity and magnetics modeling software.


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Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Department of Geology and Environmental GeosciencesCollege of CharlestonCharlestonUSA
  2. 2.Department of Geology and GeophysicsUniversity of Alaska FairbanksFairbanksUSA

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