Geology and age of the Glikson impact structure,Western Australia |
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| Authors: | F A Macdonald M T D Wingate K Mitchell |
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| Institution: | 1. Division of Earth and Planetary Sciences , Harvard University , 20 Oxford Street, Cambridge, MA, 02138, USA;2. Tectonics Special Research Centre, School of Earth and Geographical Sciences , University of Western Australia , 35 Stirling Highway, Crawley, WA, 6009, Australia;3. 81 Fern St., Gerringong, NSW, 2534, Australia |
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| Abstract: | 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. |
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| Keywords: | aeromagnetic anomalies baddeleyite Boondawari Formation Glikson impact structures Kalkarindji Large Igneous Province Mundadjini Formation Officer Basin planar microstructures shatter cones SHRIMP uranium?–?lead dating |
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