An Evaluation of the History of Aqueous Activity on Mars through a Survey of Select Hypothesized Martian Deltas and Paleolakes via the Analysis of Mineralogy, Morphology, and Thermophysical Properties

Aqueous deposits are an essential key to understanding the geologic/climatic history of water on Mars. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), High Resolution Imaging Science Experiment (HiRISE), and Thermal Emission Imaging System (THEMIS) have enabled studies of Martian fan deposits in unprecedented detail, including the identification of hydrated minerals (such as phyllosilicates, carbonates, and sulfates) and morphologies consistent with formation in an aqueous environment associated with Martian sedimentary deposits. In this study, twenty-six previously identified fan-shaped deposits (hypothesized as possible deltas) have been examined for hydrated minerals in the beds and distal regions of the deposits. Six deposits have newly been identified to bear phyllosilicates (primarily Fe/Mg-smectites) and are characterized herein with regards to mineralogy, morphology, and thermophysical properties. The results of these analyses suggest that at least four of these deposits are consistent with formation in a deltaic environment; though other possible formation environments, such as alluvial fans and alluvial fan-deltas, should not be altogether excluded, as some of the deposits also bear resemblances to terrestrial examples of such features. The results of this study are consistent with Mars once having hosted aqueous environments in which flowing and standing water was sustainable on the surface, allowing the formation of deltas on Mars.