Abstract

Studies of metamorphic rocks from the Daly Bay and Melville Peninsula areas of the Churchill Structural Province of the Canadian Shield have yielded two groups of directions. Group A directions (16 sites) from gneisses of basic and intermediate composition have the mean 196°, +55 °(N = 16, k = 39, α95 = 6.1°) with a corresponding pole at 12°N, 101°W (k = 27, α95 = 7°). These rocks are foliated and the average effect of anisotropy on the high coercive force (stable) components is small. Evidence is presented to show that agewise the pole falls within the range of 1250 to 2100 m.y. The pole lies on the apparent polar wander curve for the Canadian Shield in the time range 1425 to 1725 m.y. which defines its age within narrower limits. Since the mean K–Ar age is 1622 ± 30 m.y., the magnetization of Group A may reflect this age. This result shows that metamorphic rocks can be used to provide useful paleomagnetic data. The Group B magnetization, however, derived mainly from acidic gneisses and having a mean direction of 055°, +72 °(N = 8, k = 18, α95 = 13°) and a pole at 67°N, 009°W very close to the present pole, is probably of recent origin.

You do not currently have access to this article.