DETRITAL ZIRCON U-PB GEOCHRONOLOGY OF THE NEOPROTEROZOIC JACOBSVILLE SANDSTONE ON THE EASTERN END OF LAKE SUPERIOR, ONTARIO, CANADA

Recent detrital zircon studies on the Neoproterozoic Jacobsville Sandstone in southern Ontario have revealed that the deposition of the Jacobsville Sandstone postdates volcanism associated with the Midcontinent Rift (MCR). Moreover, these data indicate that the provenance of the Jacobsville Sandstone was variable in space and time. The paper presents detrital zircon U-Pb age results for the Jacobsville Sandstone exposed on the eastern shore of Lake Superior. These exposures represent the easternmost occurrences of the Jacobsville. Samples were collected from 3 different areas; Echo Bay (n=101), Batchawana Bay (n=147), and Alona Bay (n=113). The detrital zircon age spectrum at Echo Bay ranged from 1068-1313 Ma with a peak at 1180 Ma (n=29) and 1404-1543 Ma with a peak at 1456 Ma (n=30). The detrital zircon spectrum at Batchawana Bay ranged from 1343-1545 Ma with a peak at 1456 Ma (n=29), 1065-1350 Ma with a peak at 1200 Ma (n=7), 1545-1775 Ma with a peak at 1675 Ma (n=5), and 2630-2740 Ma with a peak at 2700 (n=4). The detrital zircon age spectrum at Alona Bay ranged from 1000-1275 Ma with a peak at 1160 Ma (n=9), 1275-1375 Ma with a peak at 1323 Ma (n=5), 1375-1520 Ma with a peak at 1470 Ma (n=4), and 1520-1715 Ma with a peak at 1650 Ma (n=4). These data indicate that rocks of the Grenville orogen and Midcontinent Granite-Rhyolite terrane (possibly the Wolf River Batholith) were an important source of sediment at Echo Bay. The Batchawana Bay locality was mostly derived from the Midcontinent Granite-Rhyolite terrane. And Alona Bay had sediment source from rocks of the Grenville Orogeny, Wolf River Batholith, Yavapai-Mazatzal, and Archean Superior Province.