GRAVITY STUDIES OVER THREE EVAPORITE PIERCEMENT DOMES IN THE CANADIAN ARCTIC

Abstract

Reconnaissance gravity surveys over three evaporite piercement domes in the Canadian Arctic Islands have been interpreted. Each dome was considered as a right‐vertical cylinder divided into two homogeneous regions, a high density anhydrite zone [Formula: see text] overlying a low density gypsum and/or rock salt zone [Formula: see text]. The cylinder is surrounded by a sedimentary sequence which has a uniform density of [Formula: see text]. Interpretation involved a least‐sum‐of‐squares approach to estimate the thickness of the anhydrite and gypsum‐rock salt zones. The three sets of estimates gave a range of 200 to 550 m for the anhydrite thickness and a range of 700 to 5500 m for the vertical extent of domes. In each case the depths were less than expected on the basis of estimates from seismic and geological data. Possible explanations for this are: (a) the cross‐sectional area of each dome decreases with depth; (b) the existence of a transition zone where a gradation occurs between the high and low density zones; and (c) the effective density contrast of the low density zone is less than [Formula: see text].