Corinto: A Young, Extensively Rayed Crater That Produced a Billion Secondaries on Mars

Corinto crater is a fresh, 13.9 km diameter impact crater in Elysium Planitia that produced one of the most extensive systems of thermally distinct rays and secondary craters on Mars, extending up to ∼2,000 km and covering a nearly 180° arc. It is the youngest crater of its size on Mars and impacted between 0.1 and 2.5 Ma into Early Amazonian basalt flows (∼1.7 Ga) that may have been water or ice rich at depth. The location of most rays and secondaries and the shape of the crater and the layered, continuous ejecta indicate it was produced by an oblique impact (20°–30°). Four facies of radial rays consisting of dense secondary craters, vary predominantly with distance from the crater. Thermal rays have low thermal inertia indicating surface materials dominated by fine sand. The total number of secondary craters >10 m diameter produced by Corinto is estimated to be ∼2 billion (∼10⁹ to 7 × 10¹⁰) from counts of the size-frequency distribution of secondaries. Four martian meteorites (basaltic Shergottites) have ejection and crystallization ages that most closely match the impact and protolith ages of Corinto, but their crystallization ages are 4–5 times younger than the Elysium basalts that Corinto impacted. Differences in thermal rays and secondary crater morphology and size with distance from Corinto suggest that material properties and/or composition of the impacting material, properties of the surface material being impacted, and the impact velocity and size/mass of the ejected material, are all important in determining the nature of the rays.