Multicomponent magnetization of the Pearson Formation (Great Slave Supergroup, N.W.T.) and the Coronation loop

Abstract

The Pearson Formation is the youngest unit of the Great Slave Supergroup of the Coronation Geosyncline. Study of samples from 22 locations shows that the dominant magnetization has a direction 329°, −08° (α₉₅ = 10°) and corresponding pole at 195°, 077°W (A₉₅ = 9°). This magnetization is considered to have been acquired at the time the rock was formed about −1800 Ma ago. In addition, there are two, possibly three, overprints. One of the two well-established overprints is attributed to uplift following deep burial at about −1600 Ma. The other has no known explanation. These results, together with others from the Coronation Geosyncline, are used to construct a polar loop (the Coronation loop) that is apparently the paleomagnetic signature of the orogeny that affected the geosyncline. The Coronation loop straddles the boundary between the Aphebian and Paleohelikian, and it is tentatively suggested that the physical boundary between these two eras could be placed between the Great Slave Supergroup and the overlying Et-Then Group.