Using CRISM and THEMIS to characterize high thermal inertia terrains in the northern Hellas region of Mars

Abstract:

Previous analyses of Thermal Emission Imaging System (THEMIS) data indicate that high thermal inertia (TI) materials within the cratered highlands north of Hellas are in situ bedrock units enriched in olivine. The high TI materials occur in both ~3.5 Ga infilled, flat-floored craters as well as ~3.8-4.0 Ga expanses of intercrater plains. A spatial association of the intercrater plains units with the Hellas ring structures suggests that they may have resulted from magma ascension and eruption via crustal fractures. Infilled craters may have formed after individual impact events triggered decompressional melting and effusive volcanism. Here we examine the mineralogy of both the high TI intercrater plains materials and high TI crater floor materials to the north of Hellas (30°E to 85°E and 7°S to 27°S) using Vis/NIR spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM). We report on the spatial distribution and variability of observed mafic minerals (olivine, low-calcium pyroxene, and high-calcium pyroxene) to constrain whether the formation of these outcrops were caused or influenced by a single event (e.g., the Hellas impact), multiple individual events, or by some other means, and to provide overall insight into Noachian/Hesperian crustal evolution of Mars.