The discovery of a 4km-diameter meteorite impact crater in Western Australia's Eastern Goldfields has sparked excitement and intrigue. Named the 'Ora Banda impact structure', this site is significant for several reasons. Firstly, it's one of the few impact craters on Earth whose target rocks are ancient greenstones, which are metamorphosed volcanic rocks like basalt. These greenstones are economically valuable in Australia due to their gold content in some areas. The impact was accidentally discovered during gold exploration drilling, highlighting the potential for hidden treasures beneath the surface. The scientific confirmation of the impact site involved the discovery of shatter cones, which are distinctive conical features in rocks that record the passage of the shock wave. These were found in both rubbly outcrops and drill cores, providing strong evidence of the impact. The drill cores also revealed a range of rock types, including clay-rich sediments and impact breccias. Breccia is a rock type that has been broken up into smaller fragments and has a matrix of smaller particles that 'glue' it all together. The Ora Banda breccias contained glassy melt particles, which hinted at the presence of molten material thrown up into the sky during the impact. This material turned to glass before landing back into the crater, resulting in a layer of suevite breccia. Additionally, the breccias contained small nuggets of gold, indicating that gold particles were raining back down onto the surface during the impact event. This discovery adds to the growing list of confirmed meteorite impact craters in Australia, which now stands at 34. These craters range in age from a few thousand years to the 2.2 billion-year-old Yarrabubba structure. The Ora Banda impact structure, with its unique geological setting and potential for gold, offers a fascinating glimpse into the planet's history and the hidden treasures that lie beneath our feet.
