Paleomagnetic results from the 2.72-2.69 Ga Vermilion District of the Superior Craton, Minnesota

Paleomagnetism can reveal whether geologically-modern plate tectonic processes operated in deep-time. The Superior Craton of North America may preserve evidence of several such processes, as it was likely assembled from a series of imbricated arc terranes around 2.7 Ga. Paleomagnetic data from the Superior Craton during this interval can answer important questions about the paleogeography and plate tectonic style in the Neoarchean. To this end, we present newly acquired paleomagnetic data from greenstones in the 2.72-2.69 Ga Vermillion Belt, Superior Craton, Minnesota. The Vermillion Belt has experienced lower greenschist facies alteration in volcanic-hosted massive sulfide (VHMS) deposits on the Archean paleoseafloor as well as weak metamorphism from later reworking events. We identify a well-defined component of magnetization in samples of a range of emplacement ages and lithologies that unblocks between ~400-580°C. We constrain the age of magnetization with a fold test, two baked contact tests, and a conglomerate test. Micromagnetic imaging of ferromagnetic carrier phases using a Quantum Diamond Microscope (QDM) coupled with petrography contextualizes the mechanism of alteration and magnetization. Preliminary results based on the baked contact tests, an in-progress fold test, and micromagnetic imaging constrain the age of the magnetization to >2.1 Ga, and possibly to greater than circa 2.6 Ga.