The Geology and Astrobiology of McLaughlin Crater, Mars: An Ancient Lacustrine Basin Containing Turbidites, Mudstones, and Serpentinites

McLaughlin crater is a 92-km diameter complex crater that formed on Mars ~4 billion years ago. The resulting basin was the site of a large (~3,000 km²), deep (~500 m), voluminous (~1,500 km³) Martian lake circa 3.8 Ga. While there is strong evidence that hundreds of lakes have existed on Mars at some point during the same time period, the geology of McLaughlin crater is extraordinary for a number of reasons. Detailed spectral analyses show that the deep-water sediments include detrital inputs of olivine and pyroxene, but the lake-floor sediments include lithologies with abundant Fe-rich, Mg-bearing smectite, serpentine-rich deposits, and ferrihydrite. For astrobiologists, this site provides a treasure trove of high-priority targets. Serpentinization reactions are thought to have played a key role in abiogenesis on Earth, and within McLaughlin crater, deposits of subterranean and probably sublacustrine serpentinites are well preserved. In addition, delta sequences are well exposed throughout the east side of the basin; such deposits are endorsed by some as the highest priority targets for preservation of organics on Mars. Yet deep-water turbidites, which might have flowed through hydrothermal environments, may be the most intriguing aspect of this geology. Such rapid sedimentation could have sequestered and preserved any potential organic materials for future exploration by a rover.