Gilles Dromart Dave Rubin Laticia Le Deit Nicolas Mangold Lauren A. Edgar Olivier Gasnault Kenneth E. Herkenhoff S. Lemouelic Ryan B. Anderson S. Maurice V. Fox B. L. Ehlmann J. L. Dickson R. C. Wiens William Rapin 2021 <p><span>The Curiosity rover is exploring Hesperian-aged stratigraphy in Gale crater, Mars, where a transition from clay-bearing units to a layered sulfate-bearing unit has been interpreted to represent a major environmental transition of unknown character. We present the first description of key facies in the sulfate-bearing unit, recently observed in the distance by the rover, and propose a model for changes in depositional environments. Our results indicate a transition from lacustrine mudstones into thick aeolian deposits, topped by a major deflation surface, above which strata show architectures likely diagnostic of a subaqueous environment. This model offers a reference example of a depositional sequence for layered sulfate-bearing strata, which have been identified from orbit in other locations globally. It differs from the idea of a monotonic Hesperian climate change into long-term aridity on Mars and instead implies a period characterized by multiple transitions between sustained drier and wetter climates.</span></p> application/pdf 10.1130/G48519.1 en Geological Society of America Alternating wet and dry depositional environments recorded in the stratigraphy of Mt Sharp at Gale Crater, Mars article