Hydrovolcanic tuff rings and cones as indicators for phreatomagmatic explosive eruptions on Mars

Abstract

[1] Hydrovolcanism is a common natural phenomenon on Earth and should be common on Mars, too, since its surface shows widespread evidence for volcanism and near-surface water. We investigate fields of pitted cones in the Nephentes/Amenthes region at the southern margin of the ancient impact basin, Utopia, which were previously interpreted as mud volcanoes. The cone fields contain pitted and breached cones with associated outgoing flow-like landforms. Based on stratigraphic relations, we determined a Hesperian or younger model age. We test the hypothesis of a (hydro)volcanic origin. Based on a detailed morphological and morphometrical analysis and an analysis of the regional context, an igneous volcanic origin of these cones as hydrovolcanic edifices produced by phreatomagmatic eruptions is plausible. Several lines of evidence suggest the existence of subsurface water ice. The pitted cones display well-developed wide central craters with floor elevations below the preeruptive surface. Their morphometry and the overall appearance are analogous to terrestrial tuff cones and tuff rings. Mounds that are also observed in the same region resemble terrestrial lava domes. The hydrovolcanic interaction between ascending magma and subsurface water and/or water ice may explain the formation of the pitted cones, although other scenarios such as mud volcanism cannot be ruled out. Together with the mounds, the cones might represent effusive and explosive edifices of a monogenetic volcanic field composed of lava domes, tuff rings, tuff cones, and possibly maars.

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

“…These terrestrial cones/rings and Martian tuff rings/ cones (Brož and Hauber 2013) have basal diameters one or more orders of magnitude larger than the mounds measured 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.…”

“…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).…”

Monitoring and Modeling the Rapid Evolution of Earth's Newest Volcanic Island: Hunga Tonga Hunga Ha'apai (Tonga) Using High Spatial Resolution Satellite Observations

“…Future studies of the predominant direction of swells to the south of the new island in association with the regional seafloor topography within the submarine Hunga Caldera (Figure 3, lower right) may further explain the survival modes of the primary tuff cone, especially if the near‐shore bathymetry can be measured within ~500 m of the southern coast. Finally, application of these results to other volcanic island settings on Earth and potentially to Mars, where evidence of ancient (~2–3 billion years ago) hydrovolcanic eruptions has been documented (e.g., Broz & Hauber, 2013), is a potentially exciting next step.…”

Determining volcanic eruption styles on Earth and Mars from crystallinity measurements

“…Despite the absence of a present-day liquid hydrosphere on Mars, magmawater driven (that is, phreatomagmatic) eruptions are also possible through interaction with ice or subsurface water 6 . Both direct and indirect observations of volcanic deposits on Mars are now possible, but unequivocally constraining Martian eruption styles remains challenging.…”