Revisiting the paleomagnetism of the 1.476 Ga St. Francois Mountains igneous province, Missouri

igneous province in southeastern Missouri provides a key 1476 ± 16 Ma paleomagnetic pole for Laurentia. The pole (13.2S, 219.0E; dp = 4.7, dm = 8.0) is considered primary on the basis of positive conglomerate, inverse baked contact, and fold tests. An analysis of 1470–1430 Ma poles from Laurentia highlights key differences between poles obtained from the Belt Supergroup, Electra Lake gabbro, and cratonic North America. Paleolatitudes based on the Lower Belt Supergroup poles are enigmatic, as two previous studies yielded a difference of 10. Our new pole, combined with an analysis of previous results, favors the higher latitude interpretation for the Lower Belt Supergroup. Paleolatitudes from the younger Belt rocks indicate lower latitudes than coeval rocks from elsewhere in Laurentia for which there has been no adequate explanation. A comparison of the St. Francois Mountain pole with similar-age poles from Baltica, Siberia and Australia allow first-order tests of proposed continental configurations. Paleomagnetic data from Australia are compatible with proposed Rodinia reconstructions, whereas paleomagnetic data from Baltica are not. We are unable to rigorously test the alternative suggestion that places Siberia against the western margin of Laurentia due in part to large errors associated with Siberian paleomagnetic data. INDEX TERMS