Uplift estimated from remanent magnetization: Munro area of Superior Province since 2150 Ma ago

Abstract

A method for determining depth of burial from remanent magnetization was applied to three igneous contacts of two different ages in Munro Township of the Superior Province of the Canadian Shield. Sampling profiles perpendicular to the contact of a 2150 Ma diabase dike, one collected in an older (2690 Ma) diabase dike and a second in gabbro country rock, yielded ambient temperatures for the present erosion surface at the time of dike emplacement of 219 ± 23 and 181 ± 7 °C, respectively. A third sampling profile perpendicular to a 2690 Ma dike failed to provide a usable magnetic contact zone.A secondary magnetic component with shallow inclination and easterly declination was detected in individual samples collected from both dikes as well as from the surrounding country rock. Converging remagnetization circles indicate that this component, acquired some time after emplacement of the younger (2150 Ma) dike, has the direction D = 70°, I = −39° and corresponding paleopole 39°E, 4°S.