Late-stage formation of Martian chloride salts through ponding and evaporation

Research Article| September 01, 2015 Late-stage formation of Martian chloride salts through ponding and evaporation Brian M. Hynek; Brian M. Hynek 1Department of Geological Sciences, University of Colorado–Boulder, UCB399, Boulder, Colorado 80309, USA2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Mikki K. Osterloo; Mikki K. Osterloo 2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Kathryn S. Kierein-Young Kathryn S. Kierein-Young 2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Brian M. Hynek 1Department of Geological Sciences, University of Colorado–Boulder, UCB399, Boulder, Colorado 80309, USA2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Mikki K. Osterloo 2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Kathryn S. Kierein-Young 2Laboratory for Atmospheric and Space Physics, University of Colorado–Boulder, 3665 Discovery Drive, Boulder, Colorado 80303, USA Publisher: Geological Society of America Received: 14 Apr 2015 Revision Received: 21 Jun 2015 Accepted: 25 Jun 2015 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2015 Geological Society of America Geology (2015) 43 (9): 787–790. https://doi.org/10.1130/G36895.1 Article history Received: 14 Apr 2015 Revision Received: 21 Jun 2015 Accepted: 25 Jun 2015 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Brian M. Hynek, Mikki K. Osterloo, Kathryn S. Kierein-Young; Late-stage formation of Martian chloride salts through ponding and evaporation. Geology 2015;; 43 (9): 787–790. doi: https://doi.org/10.1130/G36895.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Small deposits of chloride salts have been documented at hundreds of locations on Mars through the use of multispectral orbital data. Given the small spatial extent of these deposits, their formation mechanisms, timing, and relation to other aqueous processes in Mars' history are presently poorly constrained. Here we detail one of the chloride deposits near Meridiani Planum, the location of the Opportunity rover. This chloride deposit likely formed from fluviolacustrine processes, implying an active hydrologic cycle. Late-stage activity led to valley incision in the surrounding highlands and ponding of water to form a lake in a local basin. The lake level eventually rose and breached the drainage divide, leading to significant outflow. The remaining water evaporated and eventually precipitated the chlorides at the lowest levels. Through digital terrain models, the lake and salt flat volumes were used to calculate the salinity of the lake, which at full lake extent was ∼8% of the salinity of Earth's oceans. Crater density measurements on the terrain cross-cut by the outlet valley constrain the maximum age to 3.60 Ga. This hydrological episode occurred after regional widespread fluvial incision and also post-dates formation of the sulfate bedrock being investigated by Opportunity. We conclude that this and other similar chloride deposits represent some of the last vestiges of habitable surface water on Mars as recorded in the mineralogical record. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.