@article{830f3b1272424834a3a483654c9b4072,
title = "Buried Ice and Sand Caps at the North Pole of Mars: Revealing a Record of Climate Change in the Cavi Unit With SHARAD",
abstract = "The cavi unit at the north pole of Mars is a deposit of aeolian sand and water ice underlying the Late Amazonian north polar layered deposits. Its strata of Middle to Late Amazonian age record wind patterns and past climate. The Mars Reconnaissance Orbiter Shallow Radar (SHARAD) reveals extensive internal and basal layering within the cavi unit, allowing us to determine its general structure and relative permittivity. Assuming a basalt composition for the sand (ε′ = 8.8), results indicate that cavi contains an average ice fraction between 62% in Olympia Planum and 88% in its northern reaches beneath the north polar layered deposits and thus represents one of the largest water reservoirs on the planet. Internal reflectors indicate vertical variability in composition, likely in the form of alternating ice and sand layers. The ice layers may be remnants of former polar caps and thus represent a unique record of climate cycles predating the north polar layered deposits.",
keywords = "Cavi unit, Climate Record, Composition, Mars, Radar, Stratigraphy",
author = "S. Nerozzi and Holt, {J. W.}",
note = "Funding Information: This work was supported by the NASA Mars Data Analysis Program grant NNX15AM52G and by the Landmark Software and Services, a Halliburton Company. The data used in this work are available through PDS (https://pds.nasa.gov/). Processed data are attached as supporting information. SHARAD was provided to NASA's Mars Reconnaissance Orbiter mission by the Italian Space Agency (ASI). Ternary plot code is courtesy of Ulrich Theune, University of Alberta. We thank Daniel Lalich and one anonymous reviewer for their constructive contributions to this manuscript. Funding Information: This work was supported by the NASA Mars Data Analysis Program grant NNX15AM52G and by the Landmark Software and Services, a Halliburton Company. The data used in this work are available through PDS (https://pds. nasa.gov/). Processed data are attached as supporting information. SHARAD was provided to NASA's Mars Reconnaissance Orbiter mission by the Italian Space Agency (ASI). Ternary plot code is courtesy of Ulrich Theune, University of Alberta. We thank Daniel Lalich and one anonymous reviewer for their constructive contributions to this manuscript. Publisher Copyright: {\textcopyright}2019. The Authors.",
year = "2019",
month = jul,
day = "16",
doi = "10.1029/2019GL082114",
language = "English (US)",
volume = "46",
pages = "7278--7286",
journal = "Geophysical Research Letters",
issn = "0094-8276",
publisher = "American Geophysical Union",
number = "13",
}