Extensive glaciation in the Erebus Montes region of Mars

Abstract

Lobate debris apron (LDA) in the Mars' mid-latitudes substantiate extensive glaciation during the Late Amazonian. Detailed investigation of these landforms is imperative because different areas distributed at different latitudes, distinct geologic settings and varied regional topography may have responded to climate in different ways. In this study, mapping of LDA deposits in Erebus Montes region in the flat, low-lying plains of the northern mid-latitudes has been undertaken and examined at a detail previously not attempted to infer new insights on the history of extensive glaciation. LDA deposits show convex-up, steep terminus profiles consistent with typical down-gradient flow characteristics, and integrated flow patterns akin to the glacial landforms reported along the dichotomy boundary. Evidence for a broad piedmont-like lobe, down-gradient flow within a possible oblique-impact crater, and infilled craters, suggest focused localized flow and glaciation. Lobate flows emanating from small alcoves and superposed on the main LDA are not observed, which likely suggests that there is a lack of multi-stage glaciation facilitated by the alcove microclimatic conditions in the region. Linear-curvilinear ridges on the LDA deposits could be the remnant of the internal flow lineations, and are most likely produced by the sublimation of debris-rich ice. Brain-terrain textures, polygonal cracks and ring-mold craters are ubiquitous on the upper surface of LDA deposits, which provides the morphological evidence for the past accumulation of LDM in the region. Hitherto, radar-based investigations do not provide substantial evidence for the presence of extant water ice beneath LDA deposits. We find that the LDA deposits examined here are more consistent with the cold-based glacial behavior - morphological observations supports existence of the sublimation process in the region. We suggest that the derived best-fit age of ~30 Ma for the LDA deposits indicates age of the debris apron that has been mantled and the mapped LDA deposits in our study should be better represented by a broad age range of ~10–100 Ma. Together, our findings add another well-documented case to support the rapidly accumulating evidences for widespread extensive debris-covered glacial landsystems in the northern mid-latitudes of Mars in the Late Amazonian geological history.