decollement (Langseth et al., 1990). In contrast, Fisher and Hounslow (1990) and Moore

et al. (1998) suggest possible lateral fluid flow along turbidites in the underthrust

sequence. Muller and Smith (1993) argued that the uniformly high background heat flow

in the ODP drilling area could be due to crustal thinning of the Tiburon Rise. Based on

both steady state and transient state models, fluid fluxes needed to explain the observed

heat flow anomaly are approximately one order of magnitude higher than the fluxes

needed to explain the low-chlorinity anomaly (Henry, 2000). Similarly several other

studies (Foucher et al., 1990; Saffer and Bekins 1999; Cutillo et al., 2003; Bekins and

Screaton, 2006) have noted that the outflow from the underthrust necessary to create a

thermal anomaly (greater than 60 mW m-2) seems excessive compare to the in flow thus,

suggesting that the hypothesis on crustal thinning under Tiburon Rise should be further

explored.

 In addition to low-chloride and heat flow anomalies, the presence of mineralized

veins supports the idea of transient fluid flow along the decollement. Mineral veins were

found in the upper part of the decollement (Labaume et al., 1997). The orientations of

the veins suggest that pore fluids around the fault zones is at near lithostatic pressure

during vein formation (Labaume et al., 1997). Veins that were formed during several

growth phases reflect the episodicity of fluid flow along the decollement (Labaume et al.,

1997).

 Bekins et al. (1995) used low chloride anomalies as constraints on a transient

model. In their model they raised permeabilities from 10-12 -10-15 m2 along the entire

decollement zone to match observed low-chloride anomalies. To justify this, they

hypothesized that pressures in the accretionary complex build until it reaches values that