Protracted High-Grade Metamorphism and Slow Cooling in the Adirondacks Recalibrate Neoproterozoic Global Paleogeography

The assembly and breakup of the supercontinent Rodinia set the stage for Earth system evolution through the Neoproterozoic Era. Laurentia, the central craton in Rodinia, lacks well-dated paleomagnetic poles between ca. 990 Ma and 780 Ma. In this study, we develop new U-Pb petrochronology and thermochronology data sets from zircon, garnet, titanite, rutile, and apatite from the Adirondack Highlands of the Grenville orogen. Data from zircon, garnet, and titanite show protracted high-grade metamorphism that lasted through ca. 996 Ma. Probabilistic thermal history modeling based on U-Pb cooling ages tightly constrains that the Adirondack Highlands slowly exhumed throughout the Neoproterozoic. The thermal history indicates that the paleomagnetic remanence records carried by titanomagnetite in Marcy massif anorthosite of the Adirondack Highlands were acquired ca. 887 (Formula presented.) 23 Ma—85 Myr later than previously estimated. In the context of existing late Mesoproterozoic and late Tonian apparent polar wander paths of Laurentia, our new data fill in a critical gap and imply that Rodinia was a slowly drifting supercontinent in the early to mid-Tonian.