A primary paleomagnetic pole for ca. 606 Ma volcanics, Avalonian Newfoundland: implications for Ediacaran paleogeography and hypotheses of extreme true polar wander and weak anomalous magnetic fields

Ediacaran paleogeography is controversial due to complicated mid-Ediacaran paleomagnetic data that have been variously interpreted to reflect (1) magnetic overprinting, (2) rapid ∼90° true polar wander (TPW), (3) rapid tectonic plate motions, and (4) unusual magnetic field behaviour such as alternating axial and nonaxial dipole fields during times of very weak field intensity. A particular concern is the scarcity of demonstrably primary Ediacaran paleomagnetic poles from well-dated rock units. We establish a primary Ediacaran paleopole for mafic flows and conformably underlying felsic flows with a 606 +4/−3 Ma U–Pb zircon date from the Avalon Peninsula of Newfoundland, the type locality for West Avalonia. The dual polarity hematite remanence pre-dates Ediacaran folding and passes an intraformational conglomerate test. The tilt-corrected remanence direction is Ds = 237°, Is = 61° (α ₉₅ = 8°). Assuming an axial dipole field, this corresponds to a paleopole of 12°N, 267°E (A ₉₅ = 11°) and paleolatitude of 42° ± 10°. These data, combined with other primary paleomagnetic results from Avalonian Newfoundland at 592 and 580 Ma, are consistent with the terrane remaining in low/intermediate paleolatitudes through much of the Ediacaran. However, complicated mid-Ediacaran paleomagnetic data from other cratons require a more complex explanation. TPW or plate motion interpretations appear to be ruled out by data that require TPW or plate speeds greatly exceeding plausible speed limits. However, interpretations in which a very weak magnetic field alternated between an axial dipole and a nonaxial dipole (perhaps an equatorial dipole) remain feasible.