Last summer, two interns worked with Drs. Janice Bishop and Lori Fenton to study the North Polar Gypsum Dunes on Mars, focusing on the Olympia Undae region. Our French colleague Yves Langevin first discovered the high gypsum levels here in 2005, shown in red above the white ice cap of the martian north pole.
Langevin Y., Poulet F., Bibring J.-P. & Gondet B. (2005) Sulfates in the north polar region of Mars detected by OMEGA/Mars Express. Science, 307, 1584-1586.
These dunes are intriguing due to their unique gypsum composition, proximity to the polar ice deposits, and seasonal variations. Bishop and Fenton had suspected that these dunes were more complex than previously realized and decided to characterize the morphology and mineralogy of the dunes with newly available images from the Mars Reconnaissance Orbiter.
Szynkiewicz A. & Bishop J. L. (2021) Assessment of sulfate sources under cold conditions as a geochemical proxy for the origin of sulfates in the circumpolar dunes on Mars. Minerals, 11, 507.
Intern Katya Yanez from California State University Northridge researched the morphology of the dunes using HiRISE images collected at different seasons and discovered that seasonal frost on the dunes acts strangely. In summer, the dunes appear dark compared to the bright patches underneath and between the dunes. However, the frost in winter creates the opposite illusion, where the dunes become lighter-toned than the interdune materials.
Katya also mapped out four different types of surface morphologies she identified in the interdune regions and noticed that the frequency of these changed across the Olympia Undae Sand Sea. We were particularly intrigued by the polygonally-cracked surfaces observed in interdune regions in parts of Olympia Undae.
View full presentation poster here.
Differences in the morphology and color of the interdune materials from east to west across Olympia Undae suggest that a dynamic system with changing processes produces these light-toned patches. Furthermore, variations between the morphology of the dunes and interdune regions imply a difference in composition.
Katya presented her results at the Geological Society of America meeting in Denver in October.
Katya presented a continuation of her project at the American Geophysical Meeting held virtually and in Chicago on December 13th. She has been characterizing variations in gypsum concentration in the dunes across Olympia Undae using CRISM images. Her analysis correlates the gypsum content of the dunes with the morphology and composition of the interdune regions to begin outlining hypotheses for modern processes occurring across the North Polar region of Mars.
Intern Markus Gruendler from Newark Memorial High School investigated CRISM images at Olympia Undae processed with a new calibration technique by collaborator Mario Parente, Professor of Engineering and Computer Science at the University of Massachusetts at Amherst. Markus collected spectra of multiple dunes and the associated brighter interdune regions and compared these martian spectra with lab spectra of minerals from the collection of Janice Bishop. His project focused on characterizing the composition of the bright regions between and underneath the gypsum-rich dunes. Our group discovered that different types of sulfates are present together with the gypsum. Further, the composition is associated with the morphologies of the interdune materials and the location at Olympia Undae.
Markus also presented his results at the Geological Society of America meeting in Denver in October.
