A swarm of small shield volcanoes on Syria Planum, Mars

Abstract

[1] This study focuses on the volcanism in Syria Planum, located at the center of the Tharsis bulge at an altitude of 6 to 8 km above Mars datum. Syria Planum was previously recognized as a center for the tectonic activity of Tharsis, but not as a major locus for volcanic activity, despite its centrality over the bulge. Using high-resolution images from the high resolution stereo camera on Mars Express combined with Mars Observer Laser Altimeter data, we have characterized a volcanic system that reveals a number of very interesting aspects of Mars volcanism. We identified a swarm of tens of coalesced shallow volcanic edifices, typically 10-30 km diameter, 0.1-0.2 km high, and with slopes around 0.5°. These characteristics are similar to those of small shield volcanoes found in Iceland. In addition, an intermediate-sized volcano, which is the source of lava flows that extend over >200 km, is observed west of this shield swarm. Our study characterizes a previously unrecognized volcanic assemblage on Mars which appears to be much more developed than was documented before, in terms of morphology, inferred origin, and periodicity of eruption. The estimated lava flux of the Syria Planum volcanoes is of the same order as the lava flux of Tharsis Montes. These characteristics suggest that Syria Planum experienced a very specific style of volcanism, which we dated to the Hesperian period.

Arecibo radar imagery of Mars: The major volcanic provinces

“…11) shows this region to be entirely radar-dark, unlike the low-shield fields near the Tharsis Montes. This might be consistent with a suggestion by Baptista et al (2008) that Syria Planum experienced a different and very specific style of volcanism, which is plausible given its greater (Hesperian) age and isolation from the main axis of Tharsis Montes.…”

“…Finally, in an unrelated note, we point to the region of Syria Planum between 255-265°E and 10-20°S, where spacecraft imagery has identified clusters of small shields, vents, and lava flows (Hodges and Moore, 1994;Baptista et al, 2008;Hauber et al, 2009;Richardson et al, 2010). Our imagery (Fig.…”

Shape, rheology and emplacement times of small martian shield volcanoes

“…It is bounded by faults such as Noctis Labyrinthus to the north, and Claritas Fossae to the west (Masson, 1980;Tanaka and Davis, 1988). The presence of shield volcanoes was first suspected from Viking images (Hodges and Moore, 1994) and confirmed by Baptista et al (2008). Their diameters range from 10 to 30 km, with heights b200 meters; effusion rates estimated from individual lava flows are of the same order as Tharsis Montes (up to several thousand m 3 /s (Baptista et al, 2008)).…”

“…Given that the topography of large volcanoes is potentially complicated by possible migration of the volcanic sources, deformation associated with flexure of the lithosphere and changes of eruptive style over time, we focus here on the topography of smaller features, a few tens of kilometers in diameter and a few hundred meters high. The Tharsis region on Mars contains many such structures, for example, those documented by Davis and Tanaka (1993) in Tempe Terra using Viking photoclinometric profiles, those on Syria Planum first recognized by Plescia and Saunders (1982) and characterized using Mars Orbiter Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC) data by Baptista et al (2008), or the numerous shield volcanoes and vents described south of Ascraeus Mons and Pavonis Mons, and within the caldera of Arsia Mons (Bleacher et al, 2007a). In addition to the Tharsis region, it is of note that 22 shield volcanoes have also been described in central Elysium Planitia (Tanaka et al, 2005;Vaucher et al, 2006Vaucher et al, , 2009 and these too are included in our analysis.…”

Volcanism and tectonism across the inner solar system: an overview

“…9b), vents and fissures located in summit calderas, on edifice flanks, at the periphery of large shield volcanoes or within fractured terrain have also been identified so far. Particularly noteworthy are two low-shield fields in Sinai Planum (Baptista et al 2008;Hauber et al 2011;Richardson et al 2013) and Tempe Terra (Davis & Tanaka 1993;Hauber et al 2011) (Fig. 8).…”