Geology of quartz and hydrated silica‐bearing deposits near Antoniadi Crater, Mars

The only area on Mars where crystalline quartz has been identified from orbit is near Antoniadi Crater, on the northern edge of the Syrtis Major shield volcano. However, the method of quartz formation has remained unknown. In this study, we use high‐resolution satellite imagery as well as thermal and near‐infrared spectroscopy to construct a geologic history of these deposits and their local context. We find that the quartz‐bearing deposits are consistently co‐located with hydrated silica. This spatial coherence suggests that the quartz formed as a diagenetic product of amorphous silica, rather than as a primary igneous mineral. Diagenetic quartz is a mature alteration product of hydrated amorphous silica, and indicates more persistent water and/or higher temperatures at this site. Beneath the silica‐bearing rocks, we also find spectral evidence for smectites in the lowermost exposed Noachian‐aged breccia. A similar stratigraphic sequence — smectite‐bearing breccias beneath deposits containing minerals suggesting a greater degree of alteration — has also been found at nearby exposures at Nili Fossae and Toro Crater, suggesting a widespread sequence of alteration. By merging the mineral detections of thermal infrared (quartz, feldspar) and near‐infrared spectroscopy (hydrated silica, smectite clays) we are able to construct a more complete geologic history from orbit.