Geophysical survey of a mud volcano seaward of the Barbados Ridge Accretionary Complex.

Abstract

A detailed geophysical investigation that included multibeam bathymetry, 3.5kHz channel and single-channel seismic profiles, 20 heat flow measurements and 4 piston cores was made of a mud volcano located about 8km seaward of the toe of the Barbados Ridge Accretionary Complex in the N Guiana Basin. The material erupted from the volcano covers an oval area about 3 X 9km with its long axis oriented E-W, roughly perpendicular to the deformation front. Acoustic stratigraphy suggests that mud volcanism began at the site approx 200 000Ma. Heat flow on the active mound is 4 times that in the surrounding basin. 1-D modeling of this anomaly supports a low-level continuing flux of mud and water at rates of 2-5cm/yr. The mud volcanism appears to have arisen from the combined action of overpressured water that comes from beneath the accretionary prism and existing overpressures in the oceanic section. Large E-W trending basement escarpments underlie the 2 known mud volcanoes seaward of the Barbados Ridge Accretionary Complex, and they probably play an important role in developing vertical pathways for fluid to escape and in determining the location where mud volcanism starts.-from Authors