Age and evolution of the lower NW flank of the Hecates Tholus volcano, Mars, based on crater size-frequency distribution on CTX images

作者：de Pablo M A^*; Michael G G; Centeno J D

来源：Icarus, 2013, 226(1): 455-469.

DOI：10.1016/j.icarus.2013.05.012

• Mars, Surface
• Cratering
• Geological processes
• Volcanism
• Ices

We present results of crater size-frequency distribution (SFD) analysis of the lower NW flank of the Hecates Tholus volcano, Elysium volcanic province of Mars, by the use of images acquired by the Context (CTX) instrument on board of Mars Reconnaissance Orbiter (6 m/pixel in resolution). Previous similar works were focused on the caldera complex of the volcano and some sectors of the lower NW flank. In this study, we analyzed the complete crater population of the main geomorphological units characterizing this sector of the volcano (de Pablo, M.A., Centeno, J.D. [2012]. Journal of Maps 8(3), 208-2014), discarding areas with possible clustering to avoid erroneous results. In total, 16 areas corresponding to 10 geomorphological units were measured and absolute model ages were derived for them. The ages correspond to ages of origin as well as of the end of resurfacing events, depending on the analyzed sector, resulting in some cases in more than one age per area. %26lt;br%26gt;Our results are in general in agreement with previous works, and establish that the age of the origin of the Hecates Tholus volcano could be at least 3.8 Ga, with possible volcanic eruptions occurring until at least 335 Ma. Glacial events were also dated at 90 Ma, 30 Ma, 16 Ma, and 6 Ma, although it is possible to recognize ages which could also be related to the recent ice ages of Mars, between 2 and 0.4 Ma. Our results allowed us to determine that glacial processes could have been active as far back as 1.4 Ga, with possible events at intermediate ages. We deduced from the resulting ages and our observations on CTX images and the available geomorphological map of the area, that glacial-related processes played an important role in sculpting this flank of the volcano, and the possible level of the glacial sheet at the edge of the main depression of this flank was also deduced, with altitudes ranging between -2035 m and -2490 m, in agreement with the presence of smooth outcrops and roche moutonnees in the area. Finally, a possible evolution of this region of the Hecates Tholus volcano is proposed and discussed, establishing the sequence of the most important geological events which occurred in the area and their possible timings.

• 出版日期2013-10