Lake Bonneville - Constraints on lithospheric thickness and upper mantle viscosity from isostatic warping of Bonneville, Provo, and Gilbert stage shorelines

• Main Authors: Bills, Bruce G., May, Glenn M.
• Format: Other/Unknown Material
• Language: unknown
• Published: 1987
• Subjects: 46; Ice Sheet
• Online Access: http://ntrs.nasa.gov/search.jsp?R=19880029591

Data collected from three deformed shorelines of Lake Bonneville (the Bonneville, Provo, and Gilbert shorelines) are used to constrain the effective elastic lithospheric thickness to 23 + or - 2 km, the mantle viscosity to (1.2 + or - 0.2) x 10 to the 20th Pa sec, and the depth to a significant viscosity increase to no less than 300 km. A modification of the earth model of Nakiboglu and Lambeck (1982, 1983) is used for the calculations, and the water load is computed at each time step from a digital terrain model and a specified lake elevation. Differences noted between the observed and computed shoreline elevations indicate a regional tilt down to the NE of about 6 x 10 to the -5th, which is suggested to be due to collapse of the peripheral bulge formed by the Laurentide ice sheet.