a decollement with varying permeability based on a relationship of bulk permeability -

vertical effective stress.

 Background

 The Barbados accretionary complex is located in the Caribbean where the

Atlantic Plate (Figure 4-1) is being subducted beneath the Caribbean Plate at a rate of 2

cm/yr in an east-west direction (DeMets et al., 1990). At Barbados, active accretion of

sediments takes place at the eastward end of the complex as the more stabilized portion

lies westward, where the complex is partially exposed above sea level at the Barbados

Island (Figure 4-1). The complex varies in thickness from 200 km south of Tiburon Rise

at 140N, to approximately 10 km north of Tiburon Rise at 160N (Bangs and Westbrook,

1991). The variation in thickness of the complex is related to the distance from the

terrigenous sediment source from South America (Underwood and Deng, 1997), as well

as the affect of local barriers such as the Tiburon Rise (Figure 4-1), which slows the

influx to the complex.

 The northern Barbados accretionary complex is rich in hemipelagic sediments

(Bekins et al., 1995), whereas the southern part is dominated by turbidites (Langseth et

al., 1990). The age of the sediments at the Barbados accretionary complex varies from

Late Eocene to Late Cretaceous (Underwood and Deng, 1997). Mud volcanoes and mud

diapirs, which indicate excess pore pressures, are abundant in the southern part of the

complex where the sediment sequence is thicker (Moore et al., 1982).

 Based on seismic reflection images the decollement was estimated to be -14 m

thick at the northern Barbados accretionary complex (Shipley et al., 1994). It was

inferred as a high-porosity zone with undercompacted sediments and high-fluid pressures