Three‐dimensional numerical simulation of fluid flow and heat transport within the Barbados Ridge accretionary complex

Abstract

[1] The thickness of the Barbados accretionary prism varies along strike. The increased thickness of the prism to the south is believed to affect the transport of heat by fluids, resulting in anomalously high heat flow at the deformation front. We utilized a coupled three-dimensional numerical fluid flow and heat transport model to investigate the effect of variable accretionary prism thickness on fluid flow patterns and heat transport in the décollement zone. The variation in sediment thickness produced along-strike fluid flow in the more permeable décollement. Although surface heat flow is higher for simulations where flow occurs along both the décollement and underthrust sediments, the resultant advective heat transport was not sufficient to appreciably raise steady state surface heat flow at the latitude of the Ocean Drilling Program transect. Simulated temperatures in the décollement were consequently much lower than in situ borehole measurements, suggesting an additional source of warmer fluid. We then investigated the transient hydrologic and thermal response of the system to enhanced fault permeability. Model results provide insight into the degree to which episodic faulting may drive fluid flow and heat transport within subduction complexes. A transient scenario in which décollement permeability was increased two orders of magnitude with fluid flow along both the décollement and underthrust sediments caused the temperature gradient at the location of the drill sites to increase by a factor of two within 7100 years. The results of the threedimensional numerical simulations indicate that while both along-strike advective heat transport and transient fluid flow events should be considered in the heat flow distribution of the northern Barbados accretionary complex, the effects of episodic fluid flow are more significant.

Hydrostratigraphy as a control on subduction zone mechanics through its effects on drainage: an example from the Nankai Margin, SW Japan

“…2008). It is also consistent with existing 3D modeling studies, which show that large trench‐parallel driving forces can drive a component of along‐strike flow in high‐permeability horizons ( k = 10 −14 –10 −12 m 2 ), but the primary fluid flow direction is up‐dip toward the trench (e.g., Screaton & Ge 1997; Cutillo et al. 2003; Spinelli & Saffer 2007).…”

The impact of splay faults on fluid flow, solute transport, and pore pressure distribution in subduction zones: A case study offshore the Nicoya Peninsula, Costa Rica

“…The distribution of excess pore pressure, in combination with the hydraulic architecture of the forearc, defines fluid, heat, and solute flow paths and rates [e.g., Cutillo et al, 2003;Lauer and Saffer, 2012]. Fluids sampled at seafloor seep sites and in boreholes at convergent margins are commonly geochemically distinct from seawater and characterized by reaction products derived from deeper in the subduction zone [e.g., Kastner et al, 1991;Hensen et al, 2004;Sahling et al, 2008;Ranero et al, 2008].…”

Fluid budgets of subduction zone forearcs: The contribution of splay faults

“…However, previous modeling studies of subduction zone hydrogeology have generally considered only the décollement zone as a permeable pathway [e.g., Bekins et al , 1995; Spinelli et al , 2006]. Some studies have considered the effects of splay faults in local sediment dewatering [ Shi et al , 1989] and in transporting heat [ Cutillo et al , 2003] but have not systematically explored their role in forearc hydrogeology.…”