An ancient sandstorm recorded by supercritical climbing wind ripple strata in Gale crater, Mars

Direct evidence of isolated transient atmospheric events are rarely preserved in the geological record, yet when observed can provide valuable insight into ancient atmospheric and sediment transport processes. Climbing wind ripple strata (specifically termed supercritical climbing translatent strata) were identified for the first time on Mars by the Curiosity rover within a sequence of aeolian strata in Gale crater. Here, six interstratified packages of climbing and planar wind ripple strata are described and interpreted. They resulted from fluctuating wind speed that varied sediment transport rates, combined with flow separation and expansion associated with a leeward slope. These conditions caused rapid deposition of sediment onto migrating wind ripples, occasionally resulting in supercritical angles of climb, recording gusting winds that originated from the south. Interstratified packages of climbing wind ripple strata uniquely record a broader sustained event such as a sandstorm, potentially lasting several hours or more.