A comparative study of interior layered deposits on Mars
Interior layered deposits (ILDs) of the eastern Valles Marineris and adjacent chaos regions were analysed using high-resolution imagery, topography and spectral data in order to detect possible correlations. We find that ILDs are susceptible to erosion and weathering, as proven by their shapes (mesa, buttes), surface structures (pitted, fluted, yardangs), stair-stepped morphologies at different scales, and metre-sized boulders and talus. ILDs bear hydrated sulphates; consequently, we conclude that aqueous conditions dominated during their formation. Subhorizontal layering and parallel bedding of the ILDs could then indicate that deposition took place under low-energy aquatic conditions. Their superposition on chaotic terrain suggests that they are younger than chaotic terrain and, hence, younger than Late Hesperian. For the hydrated ILDs, which show polyhydrated on top of monohydrated sulphates, we think that formation within an evaporative body is not conceivable and we assume instead that a conversion of sulphates by post-formational humidity changes took place. As hydrated ILDs correlate well with rock fragmentation, we suppose that volume changes due to water content are responsible for rock fragmentation. Despite the different ILD settings, the basic conditions during sedimentation and erosion of ILDs could not have varied greatly because comparable mineralogies and morphologies are found among ILDs.
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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.