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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 60 (1976)

Issue: 7. (July)

First Page: 1078

Last Page: 1106

Title: Tectonics of Southwestern North Atlantic and Barbados Ridge Complex

Author(s): George Peter (2), Graham K. Westbrook (3)


More than 40,000 km of bathymetric, magnetic, and gravity data and 2,000 km of seismic-reflection data were obtained in 1971 and 1972 aboard the NOAA ships Researcher and Discoverer over the Barbados Ridge complex and the adjacent southwestern North Atlantic. Most of the tracklines were oriented east-west and spaced closely (20 km) to attempt correlation between adjacent lines. About a dozen long, north-south-trending tracklines provided control on the structural variations in that direction.

From bathymetric and magnetic data it was established that from the Late Cretaceous to Holocene the development of the Mid-Atlantic Ridge in this area is essentially the same as in the rest of the North Atlantic.

Indications for relatively recent tectonic activity were found on some seismic records along several east-west faults, some of which were in alignment with offset zones of the magnetic-anomaly lineations. The implicit suggestion is that intraplate tectonic activity is common, and that the western extension or "dead traces" of transform faults may provide avenues where the accumulated tectonic energy within the oceanic plate is released.

The influence of many of the major east-west faults extends westward from the Atlantic basin across the Barbados Ridge complex to the platform of the Lesser Antilles volcanic arc. Major topographic changes, as well as changes in the character of the geophysical anomalies and in the chemistry of the volcanic rocks across the fault lines suggest that the faults have played a significant role in the evolution of this area. As these faults apparently have affected the structure west of the shallow earthquake belt and the axis of the gravity minima, this area appears ideal to study possible anomalies in the subduction process or, perhaps, the applicability of the concept itself.

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