T104 Pulse of the Earth: Geochronology and Paleomagnetism of Large Igneous Provinces, the Key to Reconstructing Precambrian Supercontinents

Monday, 29 October 2007
1:30 PM - 5:30 PM

A PALEOMAGNETIC RESTUDY OF THE KAMINAK DIKE SWARM, NUNAVUT, CANADA

Paper number: T104-2
Program: Technical Sessions
Time: 1:50 PM – 2:05 PM

Authors

Abstract

Recent paleomagnetic resampling of the Kaminak dike swarm of Laurentia's Hearne domain provides ample material to address outstanding concerns regarding the original pole by Christie et al (1). Featuring large, white feldspar megacrysts, Kaminak dikes are presumed coeval with the megacrystic Matachewan swarm on Superior craton since both swarms are dated ca. 2.45 Ga. Therefore, the Kaminak pole is commonly compared to the Matachewan pole in early Paleoproterozoic paleogeographic reconstructions, despite the dependence of the Kaminak pole on data from only three dikes. Our measurements of bulk susceptibility versus temperature suggest that pyrrhotite in coarse dike interiors might have complicated demagnetization in the original study.

We report combined AF and thermal demagnetization data from a new field collection of 14 dikes that were originally studied by Christie et al. (1), plus an additional 14 dikes in the least-metamorphosed zone near Kaminak Lake, that are being studied for the first time. This sample suite includes two baked contact tests with east-west trending dikes in different locations. One cross-cutting dike is a non-megacrystic diabase, possibly referable to the ca. 2.19 Ga Tulemalu suite, and the other is a biotite lamprophyre of possible ca. 1.83 Ga Hudson suite affinity. These additional field constraints shed new light on the position and age of the Kaminak paleopole.

1 Christie et al. (1975) Canadian Journal of Earth Sciences 12, 2048-2064.