Geology and age of the Glikson impact structure, Western Australia

The Glikson structure is an aeromagnetic and structural anomaly located in the Little Sandy Desert of Western Australia (23°59′S, 121°34′E). Shatter cones and planar microstructures in quartz grains are present in a highly deformed central region, suggesting an impact origin. Circumferential shortening folds and chaotically disposed bedding define a 19 km-diameter area of deformation. Glikson is located in the northwestern Officer Basin in otherwise nearly flat-lying sandstone, siltstone and conglomerate of the Neoproterozoic Mundadjini Formation, intruded by dolerite sills. The structure would not have been detected if not for its strong ring-shaped aeromagnetic anomaly, which has a 10 km inner diameter and a 14 km outer diameter. We interpret the circular magnetic signature as the product of truncation and folding of mafic sills into a ring syncline. The sills most likely correlate with dolerites that intrude the Boondawari Formation ∼25 km to the north, for which we report a SHRIMP U-Pb baddeleyite and zircon age of 508 ± 5 Ma, providing a precise older limit for the impact event that formed the Glikson structure.