TY - JOUR

T1 - Tectonics and hydrogeology of the northern Barbados Ridge

T2 - Results from Ocean Drilling Program Leg 110

AU - Moore, J. Casey

AU - Mascle, Alain

AU - Taylor, Elliott

AU - Andreieff, Patrick

AU - Alvarez, Francis

AU - Barnes, Ross

AU - Beck, Christian

AU - Behrmann, Jan

AU - Blanc, Gerard

AU - Brown, Kevin

AU - Clark, Murlene

AU - Dolan, James

AU - Fisher, Andrew

AU - Gieskes, Joris

AU - Hounslow, Mark

AU - Mclellan, Patrick

AU - Moran, Kate

AU - Ogawa, Yujiro

AU - Sakai, Toyosaburo

AU - Schoonmaker, Jane

AU - Vrolijk, Peter

AU - Wilkens, Roy

AU - Williams, Colin

PY - 1988

Y1 - 1988

N2 - Drilling near the deformation front of the northern Barbados Ridge cored an accretionary prism consisting of imbricately thrusted Neogene hemipelagic sediments detached from little-deformed Oligocene to Campanian underthrust deposits by a décollement zone composed of lower Miocene to upper Oligocene, scaly radiolarian claystone. Biostrati-graphically defined age inversions define thrust faults in the accretionary prism that correlate between sites and are apparent on the seismic reflection sections. Two sites located 12 and 17 km west of the deformation front document continuing deformation of the accreted sediments during their uplift. Deformational features include both large- and small-scale folding and continued thrust faulting with the development of stratal disruption, cataclastic shear zones, and the proliferation of scaly fabrics. These features, resembling structures of accretionary complexes exposed on land, have developed in sediments never buried more than 400 m and retaining 40% to 50% porosity. A single oceanic reference site, located 6 km east of the deformation front, shows incipient deformation at the stratigraphic level of the décollement and pore-water chemistry anomalies both at the décollement level and in a subjacent permeable sand interval. Pore-water chemistry data from all sites define two fluid realms: one characterized by methane and chloride anomalies and located within and below the décollement zone and a second marked solely by chloride anomalies and occurring within the accretionary prism. The thermogenic methane in the décollement zone requires fluid transport many tens of kilometers arcward of the deformation front along the shallowly inclined décollement surface, with minimal leakage into the overlying accretionary prism. Chloride anomalies along faults and a permeable sand layer in the underthrust sequence may be caused by membrane filtration or smectite dewatering at depth. Low matrix permeability requires that fluid flow along faults occurs through fracture permeability. Temperature and geochemical data suggest that episodic fluid flow occurs along faults, probably as a result of deformational pumping.

AB - Drilling near the deformation front of the northern Barbados Ridge cored an accretionary prism consisting of imbricately thrusted Neogene hemipelagic sediments detached from little-deformed Oligocene to Campanian underthrust deposits by a décollement zone composed of lower Miocene to upper Oligocene, scaly radiolarian claystone. Biostrati-graphically defined age inversions define thrust faults in the accretionary prism that correlate between sites and are apparent on the seismic reflection sections. Two sites located 12 and 17 km west of the deformation front document continuing deformation of the accreted sediments during their uplift. Deformational features include both large- and small-scale folding and continued thrust faulting with the development of stratal disruption, cataclastic shear zones, and the proliferation of scaly fabrics. These features, resembling structures of accretionary complexes exposed on land, have developed in sediments never buried more than 400 m and retaining 40% to 50% porosity. A single oceanic reference site, located 6 km east of the deformation front, shows incipient deformation at the stratigraphic level of the décollement and pore-water chemistry anomalies both at the décollement level and in a subjacent permeable sand interval. Pore-water chemistry data from all sites define two fluid realms: one characterized by methane and chloride anomalies and located within and below the décollement zone and a second marked solely by chloride anomalies and occurring within the accretionary prism. The thermogenic methane in the décollement zone requires fluid transport many tens of kilometers arcward of the deformation front along the shallowly inclined décollement surface, with minimal leakage into the overlying accretionary prism. Chloride anomalies along faults and a permeable sand layer in the underthrust sequence may be caused by membrane filtration or smectite dewatering at depth. Low matrix permeability requires that fluid flow along faults occurs through fracture permeability. Temperature and geochemical data suggest that episodic fluid flow occurs along faults, probably as a result of deformational pumping.

U2 - 10.1130/0016-7606(1988)100<1578:TAHOTN>2.3.CO;2

DO - 10.1130/0016-7606(1988)100<1578:TAHOTN>2.3.CO;2

M3 - Journal article

AN - SCOPUS:0001302208

VL - 100

SP - 1578

EP - 1593

JO - Bulletin of the Geological Society of America

JF - Bulletin of the Geological Society of America

SN - 0016-7606

IS - 10

ER -