An Early Proterozoic Vgp From an Oriented Drillcore Into the Precambrian Basement of Southern Alberta

Abstract

We report paleomagnetic results for 25 samples from a fully‐oriented PanCanadian Petroleum drillcore which penetrated the Precambrian basement of southern Alberta at a depth of 2550m. Samples were taken at approximately 1m intervals over a 7m section of core. Intensities of natural remanent magnetization (NRM) were 0.5‐14 Am‐1 over the section, which consists mainly of granodiorite, with one short granite interval. X‐ray and Curie temperature data indicated magnetite as the only important NRM carrier. Most of the NRM was an intense, steeply‐inclined drilling remanence, with coerrivities <20 mT and distributed low‐to‐intermediate unblocking temperatures. After magnetic cleaning, a weak but stable primary NRM with high coercivities and high unblocking temperatures was isolated, with D= 157°, I=+52° (k= 118, α95 =95, N, 20). the corresponding virtual geomagnetic pole (VGP) is 4°S, 93° (dp = 3°; dm= 4°), which falls on the North American apparent polar wanderpath around 1850 Ma. the basement of this part of Alberta is probably an extension of the Churchill Structural Province of the Laurentian Shield. Copyright © 1988, Wiley Blackwell. All rights reserved