NEOPROTEROZOIC SEDIMENTATION IN THE LAURENTIAN MIDCONTINENT: DETRITAL ZIRCON PROVENANCE OF THE JACOBSVILLE SANDSTONE, LAKE SUPERIOR BASIN, USA AND CANADA

The Neoproterozoic Jacobsville Sandstone outcrops along the south and east shores of Lake Superior, USA. It records intraplate deformation after the ca. 1100 Ma Midcontinent Rift (MCR) failed, some during its deposition and some afterwards. Thus, its age and provenance give insight into regional tectonic and sedimentary history. Here we analyze 547 new detrital zircon ages from five sites, combined with prior data. Initially, local paleotopography controlled the source material, including the MCR-adjacent Penokean and Archean rocks. With time the percentage of distal sources increased, including the ca. 1300-980 Ma Grenville orogeny and 1480-1360 Ma Granite-Rhyolite Province. Sites near the Keweenaw fault contain a significant number of MCR-age zircons, presumably uplifted to the surface, indicating fault motion during deposition. Only a relatively small percentage of 1090-980 Ma Grenville-age zircons from collisions to the east are present, suggesting that they were not efficiently transported to the Lake Superior area.