Widespread magmatic provinces at the onset of the Sturtian snowball Earth

Abstract

The striking coincidence of the Franklin large igneous province (LIP) and the Sturtian glaciation onset ca. 717 million years ago (Ma) has inspired the hypothesis that either basaltic weathering or stratospheric sulfate aerosol injection of the Franklin LIP plunged Earth into global glaciation. The cool background climate just before the Sturtian has been commonly invoked by such initiation models. Difficulty in definitively linking these concepts with geological evidence has precluded complete demonstration of a snowball trigger mechanism. Here, we report that Franklin-aged magmatism was not only present in Laurentia and Siberia, but also in South China, where the Hubei–Shaanxi Magmatic Province formed at 720 Ma, revealing widespread magmatic provinces immediately preceding the onset of the Sturtian snowball Earth. Geochronological and geochemical data suggest that the geographically widespread magmatic provinces were emplaced over a short duration (ca. 720–717 Ma) and likely related to a mantle superplume beneath supercontinent Rodinia. We propose that low-to-mid-latitude volcanism prior to the Sturtian by a few million years enhanced global weatherability and created the background cool climate for the superimposed shock of stratospheric sulfate aerosol injection of the terminal Franklin eruption. Such widespread 720–717 Ma volcanism on different continents may have driven the Sturtian snowball initiation.