Flank vents and graben as indicators of Late Amazonian volcanotectonic activity on Olympus Mons

Abstract

Previous studies have focused on large‐scale features on Olympus Mons, such as its flank terraces, the summit caldera complex, and the basal escarpment and aureole deposits. Here we identify and characterize previously unrecognized and unmapped small scale features to help further understand the volcanotectonic evolution of this enormous volcano. Using Context Camera, High Resolution Imaging Science Experiment, Thermal Emission Imaging System, High Resolution Stereo Camera Digital Terrain Model, and Mars Orbiter Laser Altimeter data, we identified and characterized the morphology and distribution of 60 flank vents and 84 grabens on Olympus Mons. We find that effusive eruptions have dominated volcanic activity on Olympus Mons in the Late Amazonian. Explosive eruptions were rare, implying volatile‐poor magmas and/or a lack of magma‐water interactions during the Late Amazonian. The distribution of flank vents suggests dike propagation of hundreds of kilometers and shallow magma storage. Small grabens, not previously observed in lower‐resolution data, occur primarily on the lower flanks of Olympus Mons and indicate late‐stage extensional tectonism. Based on superposition relationships, we have concluded two stages of development for Olympus Mons during the Late Amazonian: (1) primarily effusive resurfacing and formation of flank vents followed by (2) waning effusive volcanism and graben formation and/or reactivation. This developmental sequence resembles that proposed for Ascraeus Mons and other large Martian shields, suggesting a similar geologic evolution for these volcanoes.

Small Volcanic Vents of the Tharsis Volcanic Province, Mars

“…In a previous version of this catalog (Bleacher et al., 2010), additional potential vent features were included on the flanks of Olympus Mons that had a morphology consistent with the vent morphology definition. An alternative interpretation of these structures on the Olympus Mons flank is that low‐shield‐like volcanic rises are points along lava flows where lava broke out of a tube or channel structure at a break in slope (Bleacher, Greeley, Williams, Werner, et al., 2007; P. Mouginis‐Mark, 2018; Peters & Christensen, 2017). These structures would then be analogous to secondary vents seen on Etna lava flows (Calvari & Pinkerton, 1998).…”

“…An alternative interpretation of these structures on the Olympus Mons flank is that low-shield-like volcanic rises are points along lava flows where lava broke out of a tube or channel structure at a break in slope (Bleacher, Greeley, Williams, Werner, et al, 2007;P. Mouginis-Mark, 2018;Peters & Christensen, 2017). These structures would then be analogous to secondary vents seen on Etna lava flows (Calvari & Pinkerton, 1998).…”

“…Within the boundaries of Tharsis lie several previously described terrains with clusters of small volcanic vents, including the Tempe-Mareotis region (Tanaka et al, 2014), parasitic vents on the Tharsis Montes (Bleacher et al, 2009) and near Olympus Mons (Bleacher, Greeley, Williams, Werner, et al, 2007;Peters & Christensen, 2017), and Syria Planum (Richardson et al, 2013). Many of these terrains are denoted as volcanic field units in work by Tanaka et al (2014).…”

Lava Flow Eruption Conditions in the Tharsis Volcanic Province on Mars

“…Although construction of Olympus Mons and Ascraeus Mons is believed to have been largely completed by the Late Noachian or Early Hesperian (>3.6 Ga), their surfaces have been dated to ∼100–800 Ma based on crater count modeling (e.g., Neukum et al., 2004; Werner, 2009; Xiao et al., 2012). Some of the youngest features on Olympus Mons and Ascraeus Mons include lavas on the floors of the nested calderas (∼100–200 Ma), some flank lava flows (∼50 Ma), and small satellite vents and arcuate graben (e.g., Byrne et al., 2012; Neukum et al., 2004; Peters & Christensen, 2017; Tanaka et al., 2014; Werner, 2009).…”

Distribution of Eruptive Centers on Top of Large Shield Volcanoes in the Inner Solar System: General Classification and Glimpses of Their Subvolcanic Structure

“…It is a shield volcano of probable basaltic composition. The volcano presents structural features such as terraces and radial escarpments on the flanks (Peters & Christensen, 2017). The oldest age estimated is between 3.8 and 3 Ga (Musiol et al., 2016).…”