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Earlier studies of terrestrial heat flow in the North Slope Basin, Alaska, found that heat flow varies systematically in a trend perpendicular to the strike of basin strata and the neighboring Brooks Range. Heat flow (~+20%) increases from a low of 27 mW/m 2 in the foothills of the Brooks Range in the south to a high of 90 mW/m 2 on the coastal plain to the north. The thermal pattern can be explained by a regional-scale (-330 km) groundwater flow system which transports heat by advection from regions of high elevation in the Brooks Range and its foothills to lower elevations on the Arctic coastal plain. Permeability data from 2031 core measurements made parallel to bedding and 15 well tests were compiled for 10 geologic units. Arithmetic-mean permeabilities derived from measurements on core samples range from 2.2 x 10 -13 m 2 for sandstones of the Endicott Group to 1.1 x 10 -16 m 2 for limestones of the Lisburne Group. The arithmetic-mean permeability derived from all 2031 core measurements made parallel to bedding is 6.1 x 10 -14 m 2. A numerical model of coupled heat and fluid flow in the North Slope Basin was constructed and a series of model simulations were conducted. A model simulation incorporating permeability data obtained from core measurements resulted in a good match to observed heat flow data, apparently suggesting that permeability in the North Slol•. Basin does not increase significantly from the core scale (~10-2 -10-1 m) to the basin scale (~105 -106 m). This inference, however, is complicated by the possible effects of factors such as sample bias in measurements and choice of an appropriate averaging algorithm. A further series of model simulations were done in which the specified model permeability was homogeneous and anisotropic. Comparisons of heat flow predicted by these simulations with heat flow determined in field studies suggested that the effective basin-scale permeability parallel to bedding (kx) is in the range of 2.5 x 10-14 < kx < 2.5 x 10 -13 m 2 and permeability perpendicular to bedding (kz) is in the range of 1.0 x 1• -16 < kz < 5.0 x 10-16 m2. These constraints depend upon the explicit assumption that groundwater flow is the only mechanism responsible for heat flow variations across the North Slope Basin. migration of hydrocarbons [Hubbert, 1953; Toth, 1988; Garven, distances over which permeability can be directly measured. For 1989; Bethke eta/., 1991; Meissner, 1991]. Crustal fluids are also example, Garven [1989] showed that the formation of the giant involved in virtually all aspects of sedimentary diagenesis and oil sands deposits of Alberta may have been the result of oil play a critical role in the genesis of hydrothermal ore deposits transport by a gravity-driven flow system through the western 'Also at U.S. Geological Survey,

A moderately large data set of mostly sedimentary and metamorphic rocks compiled from the literature shows an inverse correlation between thermal conductivity anisotropy and thermal conductivity perpendicular to bedding. The empirical relationship can be represented by a simple two‐component end‐member mixing model. One end‐member is anisotropic (λx/λz ∼ 2.5) and has a relatively low thermal conductivity perpendicular to bedding (λz ∼ 1 W/m‐K); the other end‐member is isotropic and has a relatively high thermal conductivity perpendicular to bedding (γ ∼ 4 W/m‐K). The proposed model may be used to derive a correction for anisotropic effects observed during thermal conductivity measurements on mixtures of randomly oriented aggregates. Although the accuracy and reliability of a universal correction procedure remain to be determined, the proposed correction scheme should enhance our ability to estimate accurately heat flow in sedimentary basins where generally only borehole cuttings are available for thermal conductivity measurements.

The migration of abnormally warm, saline water through the Appalachian basin and North American midcontinent in Paleozoic time has been inferred from fluid inclusion studies, remagnetizations, and widespread potassic alteration. A time‐dependent numerical model of fluid, heat and solute transport is used to evaluate the viability of topographically driven recharge as a mechanism for brine migration. The model represents a wedge‐shaped sedimentary basin 400 km long by 6 km deep (maximum) with a basal aquifer 500 to 750 m thick overlain by a homogeneous aquitard. Temperature predicted by model simulations is found to be inconsistent with constraints inferred from fluid inclusion studies, unless average heat flow values greater than about 100 mW/m2 are used. Model simulations also lead to predictions of low heat flow and subsurface temperature in recharge zones that are generally not observed in modern orogenic zones. The initial solute content of pore waters in the model basin is flushed out by fresh water entering in the recharge zone before fluid velocities high enough to produce significant warming of the discharge zone can develop. Model simulations with source terms reveal that basin sediments can provide enough solute to maintain hot, hypersaline brine migration for about 1 m.y., at most. High fluid velocity in the basal aquifer is required to carry heat to the basin margins, but the higher the fluid velocity, the more quickly the basin's supply of solute is exhausted. Consideration of these constraints implies that topographically driven recharge may be an effective mechanism to explain regional brine migration only if flow is focused from regional scale recharge zones into more spatially restricted discharge zones.