Yl. Shi et Cy. Wang, MODEL STUDIES OF ADVECTIVE HEAT-FLOW ASSOCIATED WITH COMPACTION AND DEHYDRATION IN ACCRETIONARY PRISMS, J GEO R-SOL, 99(B5), 1994, pp. 9319-9325
Surface heat flow across the deformation front of subduction zones sho
ws complex patterns, and fluid flow is often invoked to interpret thes
e patterns. Here we estimate the maximum possible amount of fluid flow
due to sediment compaction and dehydration in subduction zones, and c
ompare these estimates with the required fluid flow to produce signifi
cant thermal disturbances across faults and vents in two- and three-di
mensions. The results show that lateral heat loss becomes significant
for faults or vents with thickness or diameter less than about 1 km. F
or two-dimensional channel flow in fault zones or permeable strata, su
bduction-induced compaction alone can hardly provide enough steady sta
te flow to cause surface heat flow anomalies such as that observed in
the Barbados accretionary prism [Foucher et al., 1990; Langseth et al.
, 1990]. Fluid flow in three-dimensional pipes (vents or vent fields)
of a few hundred meters to approximately 1 km in diameter is efficient
in producing thermal disturbances; but steady state flow in small iso
lated pipes of a few meters in diameter is incapable of producing meas
urable heat flow anomalies. Small-scale heat flow anomalies which are
observed in some accretionary prisms are probably best explained by in
termittent, transient flow.