--> ABSTRACT: Geothermal Gradient Estimates for Continental Margin North of Alaska, by Patrick D. Finley; #91022 (1989)

Datapages, Inc.Print this page

Geothermal Gradient Estimates for Continental Margin North of Alaska

Patrick D. Finley

Estimates of heat flow and geothermal gradients were obtained for the outer continental shelf, slope, and rise of the Alaskan Beaufort Sea. Well-developed seismic bottom simulating reflectors (BSRs) in the region indicate the base of the gas hydrate stability zone. The lateral distribution and subbottom depth of BSRs from all available single and multichannel seismic lines from the region were mapped. The subbottom depths of the BSRs are principally controlled by the pressure and temperature limits of methane hydrate stability. Using models derived from other regions, estimated geothermal gradients were obtained from measured water depths, water temperatures, and BSR depths.

Estimated geothermal gradients of the Beaufort continental margin range from 2.7° to 6.7°C/100 m with an average of 4.8°C/100 m. Mean gradients increase from 3.2°C/100 m beneath the outer continental shelf to a maximum of 5.2°C/100 m in the upper slope sediments. Gradients decrease from 4.7°C/100 m in the lower slope sediments to 3.4°C/100 m in continental rise sediments. The heat-flow pattern reflects sediment failure and slumping of the continental slope.

Mean geothermal gradients decrease eastward from Point Barrow to Camden Bay. Gradients then increase rapidly eastward toward the Mackenzie delta. Gradients over shale diapirs average 1.2°C/100 m higher than undisturbed sediments. The higher gradients over diapirs indicate that the slope is not thermally equilibrated and suggest that the diapirs are recently or presently active.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.