Large Igneous Provinces, Sulfur Aerosols, and Initiation of Snowball Earth

Abstract:

The events that led to the initiation of Snowball Earth remain poorly understood. Proposed scenarios include a methane addiction, a biological innovation that led to an increase in organic carbon burial and anaerobic remineralization, or an increase in global weatherability due to a paleogeography with a preponderance of low latitude continents, and the subareal implacement of large igneous provinces (LIPs) at the equator. The Franklin LIP was emplaced between 730 and 710 Ma and covers an area of over 2.25 Mkm² with lavas, sills, and dikes extending over much of northern Laurentia from Alaska through northern Canada to Greenland and potentially to Siberia. The most precise geochronological constraints on the Franklin LIP overlap with the onset of the Sturtian Snowball Earth glaciation, which began between 717 and 716 Ma and marked the first glaciation in over 1 billion years. The Franklin LIP is the largest preserved Neoproterozoic LIP and one of the largest in Earth History. Additionally, it was emplaced at equatorial latitudes with associated sills that invaded epicontinental sulfur evaporite basins, potentially maximizing environmental effects. Here we explore the hypothesis that the Sturtian Snowball Earth was initiated in part by an increase in planetary albedo from the conversion of volcanic SO₂/H₂S emissions to tropospheric and stratospheric sulfate aerosols through a combination of geochemical and modeling studies.