Bore-Hole Survey at Dye 3, South Greenland

Abstract

AbstractIn 1983 three directional surveys were made in the bore hole from which a deep ice core was obtained in the summers of 1979–81. The inclination and azimuth of the bore hole were measured on three surveys, temperature was included on two surveys, fluid pressure and hole diameter on one of the surveys. Fluid-pressure measurements show that the ice-overburden pressure was undercompensated in the upper few hundred meters and overcompensated at the bottom of the hole. Diameter measurements show closure in the upper portion and expansion near the bottom beginning at the transition from the Holocene to Wisconsin ice at 1784 m. The hole expansion and increase in inclination correlate with dust and silt content in the Wisconsin ice. Changes in azimuth are due to flow of the ice and are consistent with the direction of flow at the surface. Temperature measurements show that the hole is at or near equilibrium. The gradient of 0.012 K/m below 1400 m is less than the 0.018 K/m at Camp Century. There is a slight reduction in gradient near the bottom from internal friction in the silty ice.