Layering and degradation of the Rupes Tenuis unit, Mars – a structural analysis south of Chasma Boreale
T. Kneissl, S. Van Gasselt, L. Wendt, C. Gross, G. Neukum, 2011. "Layering and degradation of the Rupes Tenuis unit, Mars – a structural analysis south of Chasma Boreale", Martian Geomorphology, M. R. Balme, A. S. Bargery, C. J. Gallagher, S. Gupta
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The circum north-polar Rupes Tenuis unit forms the polar-proximal basal stratigraphical and morphological units that delineate the north polar cap between 180° and 300°E. In the region of the mouth of the Chasma Boreale re-entrant, the Rupes Tenuis unit is likely to extend further southwards into the northern plains. This is suggested by the occurrence of isolated remnants that have been interpreted as basaltic shield volcanoes, maar craters or mud volcanoes in the past.
As key elements of this study, we assessed the quantitative characteristics of this unit using layer attitudes derived from high-resolution images and terrain-model data, and by performing cross-correlations of prominent layers whose outcrops are observed at eight cone-like remnants. The identification and unambiguous correlation of characteristic layers across the study area provided a reasonable basis for introducing at least three additional stratigraphical subunits of the Rupes Tenuis unit. Extrapolation of altitude data indicates a gentle southward dip of remnant layers, suggesting that the unit had a much larger areal extent in Martian history. The palaeo-layer contact between two subunits of the Rupes Tenuis unit correlates well with elevation values of the Hyperborea Lingula surface. Both results disagree with an interpretation of a volcanic origin for isolated mesas but underpin that they are erosional relicts of the Rupes Tenuis unit. Average erosion rates of 2.5×10−4±4×10−5 mm year−1 are relatively high when compared to Amazonian rates but are not exceptional for areas undergoing deflation. They also corroborate the idea of aeolian denudation of the Rupes Tenuis unit.
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The latest Mars missions are returning data of unprecedented fidelity in their representation of the martian surface. New data include images with spatial resolution better than 30 cm per pixel, stereo imaging-derived terrain models with one meter postings, high-resolution imaging spectroscopy, and RADAR data that reveal subsurface structure. This book reveals how this information is being used to understand the evolution of martian landscapes, and includes topics such as fluvial flooding, permafrost and periglacial landforms, debris flows, deposition and erosion of sedimentary material, and the origin of lineaments on Phobos, the larger martian moon. Contemporary remote sensing data of Mars, on a par with those of Earth, reveal landscapes strikingly similar to regions of our own planet, so this book will be of interest to Earth scientists and planetary scientists alike. An overview chapter summarising Mars’ climate, geology and exploration is included for the benefit of those new to Mars.