Discovery of distal ejecta from the 1850 Ma Sudbury Impact Event
MetadataShow full item record
A 25?70-cm-thick, laterally correlative layer near the contact between the Paleoproterozoic sedimentary Gunflint Iron Formation and overlying Rove Formation and between the Biwabik Iron Formation and overlying Virginia Formation, western Lake Superior region, contains shocked quartz and feldspar grains found within accretionary lapilli, accreted grain clusters, and spherule masses, demonstrating that the layer contains hypervelocity impact ejecta. Zircon geochronologic data from tuffaceous horizons bracketing the layer reveal that it formed between ca. 1878 Ma and 1836 Ma. The Sudbury impact event, which occurred 650?875 km to the east at 1850 1 Ma, is therefore the likely ejecta source, making these the oldest ejecta linked to a specific impact. Shock features, particularly planar deformation features, are remarkably well preserved in localized zones within the ejecta, whereas in other zones, mineral replacement, primarily carbonate, has significantly altered or destroyed ejecta features.
Showing items related by title, author, creator and subject.
A new ~3.46 Ga asteroid impact ejecta unit at Marble Bar, Pilbara Craton, Western Australia: A petrological, microprobe and laser ablation ICPMS studyGlikson, A.; Hickman, A.; Evans, Noreen; Kirkland, Chris; Park, J.; Rapp, R.; Romano, S. (2016)The Archean rock record contains seventeen asteroid impact ejecta units that represent the terrestrial vestiges of an extended late heavy bombardment (LHB). Correlated impact ejecta units include 3472–3470 Ma impact ...
Pidgeon, Robert; Merle, Renaud; Grange, M.; Nemchin, Alexander (2018)© The Meteoritical Society, 2018. Breccia boulders scattered around the 25 Ma Cone Crater near the Apollo 14 landing site provide a potential source of material ejected from the underlying Fra Mauro formation, which is ...
Thiessen, F.; Nemchin, Alexander; Snape, J.; Whitehouse, M.; Bellucci, J. (2017)Secondary ion mass spectrometry (SIMS) U-Pb ages of Ca-phosphates from four texturally distinct breccia samples (72255, 76055, 76015, 76215) collected at the Apollo 17 landing site were obtained in an attempt to identify ...