Brenner Alec R, Cavosie Aaron J, Palma-Gomez Jasmine, Li Joanna, Kingsbury Lee Sophie-An, Fu Roger R
Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA, USA.
Space Science and Technology Centre, School of Earth and Planetary Science, Curtin University, Perth, WA, Australia.
Sci Adv. 2025 Jul 11;11(28):eadu5379. doi: 10.1126/sciadv.adu5379. Epub 2025 Jul 9.
North Pole Dome (Pilbara Craton, Western Australia) contains unique geological analogs to early Earth and Mars. Recently discovered shatter cones in 3.47-billion-year-old (Ga) rocks reveal that it is also the site of an ancient meteorite impact. Initial reports claimed that the impact occurred at 3.47 Ga and produced a ≥100-kilometer (km) crater; we show that these age and size estimates are inaccurate. Shatter cones are radially oriented over a 6.5-km-diameter area, defining a 16-km-wide structure. Shatter cones postdate regional structures and occur in younger overlying rocks, providing unambiguous evidence that the impact occurred after ~2.7 Ga. We also report the first shocked mineral from this site, the high-pressure TiO polymorph TiO-II (srilankite). We provisionally name this feature the Miralga impact structure. The 3.47 Ga hydrothermally altered basalts at Miralga are the oldest known shocked terrestrial rocks, highlighting the site's analog potential for impacts into biosignature-bearing Archean greenstones and the Martian surface.
北极穹顶（西澳大利亚皮尔巴拉克拉通）拥有与早期地球和火星独特的地质相似物。最近在34.7亿年前（Ga）的岩石中发现的撞击锥表明，它也是一个古代陨石撞击的地点。初步报告称，撞击发生在34.7亿年前，形成了一个直径≥100公里（km）的陨石坑；我们表明这些年龄和大小估计是不准确的。撞击锥在直径6.5公里的区域呈放射状排列，确定了一个宽16公里的结构。撞击锥形成于区域构造之后，出现在较年轻的上覆岩石中，提供了明确的证据表明撞击发生在约27亿年前之后。我们还报告了该地点的首个冲击矿物，即高压TiO多晶型物TiO-II（斯里兰卡矿）。我们暂时将这个特征命名为米拉加撞击构造。米拉加34.7亿年前的热液蚀变玄武岩是已知最古老的受冲击陆地岩石，突出了该地点对于撞击具有生物标志的太古代绿岩和火星表面的类比潜力。
