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High Ice Purity of Martian Lobate Debris Aprons at the Regional Scale: Evidence From an Orbital Radar Sounding Survey in Deuteronilus and Protonilus Mensae
Author(s) -
Petersen Eric Ivan,
Holt John W.,
Levy Joseph S.
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl079759
Subject(s) - geology , martian , debris , glacier , landform , mars exploration program , depth sounding , geomorphology , astrobiology , oceanography , physics
Lobate Debris Aprons (LDA) are martian landforms with a strong morphologic resemblance to rock glaciers and debris‐covered glaciers. While the Shallow Radar (SHARAD) sounder has confirmed that a handful of LDA are composed of >80% water ice, viscous flow morphology can also be produced by as little as 30% ice. To distinguish between these endmembers, we conducted a comprehensive regional SHARAD survey of LDA, in Deuteronilus Mensae. We found that the majority of LDA are penetrated by SHARAD and determined that they are composed of a material with ε ′ = 3 and t a n δ ≈0.002 < 0.005. These LDA are thus consistently composed of >80% water ice, which constrains the regional sequestered ice budget to a minimum of 0.9 − 1.0 × 10 5 km 3 or a 62–69‐cm Global Equivalent Layer.