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

Abstract

A paleomagnetic investigation of the St. Francois Mountains igneous province in southeastern Missouri provides a key 1476 ± 16 Ma paleomagnetic pole for Laurentia. The pole (13.2°S, 219.0°E; 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.

Paleomagnetism of the Ulkan massif (SE Siberian platform) and the apparent polar wander path for Siberia in late Paleoproterozoic–early Mesoproterozoic times

“…12) at (1) Halls and Heaman, 2000) and Cleaver dykes (Plat = 19, Plong = 277;Irving et al, 2004);and (3) 1590 Ma from dykes of Western Channel Diabase (WCD) (Plat = 9, Plong = 245; Irving et al, 2004;age by Hamilton and Buchan, 2010); and (4) 1470-1480 Ma from the St. Francois Mtn. (Plat = −13, Plong = 219; Meert and Stuckey, 2002). Usually normal polarity is attributed to these poles, that is, they are northern, which is consistent with the APWP for Laurentia constructed more than 20 years ago (Piper, 1982), although there are alternative opinions (Park, 1994).…”

The palaeomagnetically viable, long-lived and all-inclusive Rodinia supercontinent reconstruction

“…If a similar reconstruction emerges from several adjacent time slices, then a long-lived direct connection between the cratons can be considered viable. Examples of this method, called the 'closest approach' technique, are found in Buchan et al (2000Buchan et al ( , 2001, Meert & Stuckey (2002) and Pesonen et al (2003).…”

Paleo-position of the North China craton within the supercontinent Columbia: Constraints from new paleomagnetic results

“…In order to provide a more complete path, we use the following data reference points for Laurentia (see Table 5). For the period ∼1.5 Ga, the 1476 Ma St. Francois Mountains igneous province pole was used for comparison with the Yangzhuang Formation of the NCC (Meert and Stuckey, 2002). The slightly younger pole from Tobacco Root Mtns.…”