Scoria cones on Mars: Detailed investigation of morphometry based on high‐resolution digital elevation models

Abstract

We analyze the shapes of 28 hypothesized scoria cones in three regions on Mars, i.e., Ulysses and Hydraotes Colles and Coprates Chasma. Using available High-Resolution Imaging Science Experiment and Context Camera (CTX) digital elevation models, we determine the basic morphometric characteristics of the cones and estimate from ballistic modeling the physical parameters of volcanic eruptions that could have formed them. When compared to terrestrial scoria cones, most of the studied cones show larger volumes (up to 4.2 × 10 9 m 3 ), larger heights (up to 573 m), and smaller average slopes. The average slopes of the Ulysses, Hydraotes, and Coprates cones range between 7°and 25°, and the maximum slopes only rarely exceed 30°, which suggests only a minor role of scoria redistribution by avalanching. Ballistic analysis indicates that all cones were formed in a similar way, and their shapes are consistent with an ejection velocity about 2 times larger and a particle size about 20 times smaller than on Earth. Our results support the hypothesis that the investigated edifices were formed by low-energy Strombolian volcanic eruptions and hence are equivalent to terrestrial scoria cones. The cones in Hydraotes Colles and Coprates Chasma are on average smaller and steeper than the cones in Ulysses Colles, which is likely due to the difference in topographic elevation and the associated difference in atmospheric pressure. This study provides the expected morphometric characteristics of Martian scoria cones, which can be used to identify landforms consistent with this type of activity elsewhere on Mars and distinguish them from other conical edifices.

The Apparent Absence of Kilometer‐Sized Pyroclastic Volcanoes on Mercury: Are We Looking Right?

“…However, as shown in the example of putative Martian scoria cones by Brož et al (2014), it is difficult to achieve the angle of repose on a body with a low-density or absent atmosphere and with substantially lower surface gravity than on Earth. Martian analogues therefore show gentler flank slopes and larger basal diameters (Brož et al, 2015). As a consequence, on Mars the erupted volumes of pyroclasts are not large enough for the flank slopes to attain the angle of repose, in contrast with Earth where this is common (and hence can be attained with lower erupted volumes).…”

“…Their volcanic origin is also favored from their geological context; they are situated within the areas where volcanism almost certainly occurred in the past. Brož et al, 2015Brož et al, , 2017Brož & Hauber, 2012;Hauber et al, 2009). Nevertheless, regardless of the mechanism of their origin, the extreme scarcity of kilometer-sized constructional volcanic edifices is a surprising fact itself, as such features are frequent on other terrestrial bodies within the solar system where volcanism has taken place, such as Earth (Kereszturi & Németh, 2013), the Moon (e.g., Lawrence et al, 2013), and Mars (e.g.…”

Distribution, morphology, and morphometry of circular mounds in the elongated basin of northern Terra Sirenum, Mars

“…This is because under low gravity and low atmospheric pressures on Mars surface, larger cone diameters and lower cone heights than those on Earth are expected due to the wider ranges of scoria distribution by far-reaching ballistic emplacement (Wilson and Head 1994;Brož et al 2015). Actually, the morphometries of candidates of Martian scoria cones (Brož et al 2015) and Martian tuff rings/cones (Brož and Hauber 2013) are plotted in the larger diameters than the terrestrial equivalents, and they are plotted in different way from that of the observed mounds in this study (Fig. 8).…”

“…The inconsistency between the studied mounds and the other analog features are quite difficult to accurately Kirkham et al 2017), onshore mud volcanoes on Earth (Chigira and Tanaka 1997;Brož and Hauber 2013), potential tuff rings and cones on Mars (Brož and Hauber 2013), potential scoria cones on Mars (Brož et al 2015), terrestrial maars (Pike 1978), terrestrial lava domes (Pike 1978), terrestrial cinder/scoria cones (Pike 1978;Favalli et al 2009;Rodríguez et al 2010), terrestrial pingos (Cabrol et al 2000), terrestrial tuff rings/cones (Pike 1978), and terrestrial rootless cones (Pike 1978). Morphometric data of elongated (not circular) mounds is not used.…”

“…Proposed terrestrial analog features include impact craters, scoria cones, rootless cones, tuff cones/rings, pingos, and mud volcanoes (e.g., Farrand et al 2005;Meresse et al 2008;Burr et al 2009;de Pablo and Komatsu 2009;Oehler and Allen 2010;Brož et al 2015).…”