ARTICLE DOI: 10.1038/s41467-018-05291-5 OPEN The Medusae Fossae Formation as the single largest source of dust on Mars Lujendra Ojha1, Kevin Lewis1, Suniti Karunatillake 2 & Mariek Schmidt3 Transport of fine-grained dust is one of the most widespread sedimentary processes occurring on Mars today. In the present climate, eolian abrasion and deflation of rocks are likely the most pervasive and active dust-forming mechanism. Martian dust is globally 1234567890():,; enriched in S and Cl and has a distinct mean S:Cl ratio. Here we identify a potential source region for Martian dust based on analysis of elemental abundance data. We show that a large sedimentary unit called the Medusae Fossae Formation (MFF) has the highest abundance of S and Cl, and provides the best chemical match to surface measurements of Martian dust. Based on volume estimates of the eroded materials from the MFF, along with the enrichment of elemental S and Cl, and overall geochemical similarity, we propose that long-term deflation of the MFF has significantly contributed to the global Martian dust reservoir. 1 Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA. 2 Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, USA. 3 Department of Earth Sciences, Brock University, St. Catharines, ON L2S 3A1, Canada. Correspondence and requests for materials should be addressed to L.O. (email:
[email protected]) NATURE COMMUNICATIONS | (2018) 9:2867 | DOI: 10.1038/s41467-018-05291-5 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | DOI: 10.1038/s41467-018-05291-5 ust is ubiquitous on Mars and plays a key role in con- formation on Mars today is likely abrasion of mechanically weak temporary atmospheric and surface processes.