Geology of the Small Tharsis Volcanoes: Jovis Tholus, Ulysses Patera, BibIls Patera, Mars

doi:10.1006/icar.1994.1144

Icarus

Volume 111, Issue 1, September 1994, Pages 246-269

https://doi.org/10.1006/icar.1994.1144 Get rights and content

Abstract

Jovis Tholus, Ulysses Patera, and Biblis Patera, three small volcanoes in the Tharsis area of Mars, provide important insight into the evolution of volcanism on Mars. All three are interpreted to be shield volcanoes, indicating that shield volcanism was present from the outset in Tharsis. Jovis Tholus is the least complex with simple repeated outpouring of lavas and caldera-forming events. Ulysses Patera is dominated by a giant caldera within which is a line of cinder cones or domes suggesting terminal stages of volcanism in which the magma had either significant volatiles or increased `viscosity. Biblis Patera is characterized by nested calderas which have expanded by block faulting of the flank; it also exhibits lava flows erupted onto the flanks from events along concentric fractures. These shields are different from the younger Tharsis Montes shields only in terms of the volume of erupted material. The limited shield volume suggests that the magma source which fed the shields was rapidly depleted. The relatively large size of the calderas probably results from relatively large, shallow magma bodies rather than significant burial of the flanks by younger lavas. Eruption rates consistent with typical terrestrial basaltic eruption rates suggest that these volcanoes were probably built over time spans of 10⁴ to 10⁵ years. Stratigraphic ages range from Early to Upper Hesperian; absolute ages range from 1.9 to 3.4 Ga.

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Cited by (28)

An overview of explosive volcanism on Mars
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Citation Excerpt :
Despite these numerous observations, the evidence for explosive eruptions in association with Syrtis Major remains spatially and temporally limited, with the edifice being dominated by lava flows, which together with the general shape of the volcano suggest that explosive volcanism played only a minor role in the evolution of this volcano (Robbins et al., 2011). The presence of scoria cones (also called “cinder cones”) was first suggested for several regions of Mars based on Viking data (Carr et al., 1977; Frey and Jarosewich, 1982; Edgett, 1990; Hodges and Moore, 1994; Plescia, 1994), but the interpretations were ambiguous due to the low resolution of available images. However, the lack of certainty in interpretation did not prevent study of their possible shapes and the way the ejected material would be emplaced by theoretical and numerical studies (Wood, 1979a, 1979b; Dehn and Sheridan, 1990; Wilson and Head, 1994; Fagents and Wilson, 1996).
Decades of space exploration reveal that Mars has been reshaped by volcanism throughout its history. The range of observed volcanic landforms shows that effusive and explosive eruptions have occurred, albeit unevenly in time and space. Evidence for explosive volcanism—characterized as eruptions in which magma is disrupted by the expansion of dissolved gases or by an interaction of magma with external volatiles—is less common than evidence for effusive activity. Nonetheless, indications of explosive volcanism have been identified. Examples include, old, rimless depressions, termed paterae, often on the summits of broad topographic rises with very gentle flanks, are located mainly around the Hellas impact basin. Also, fields of kilometre-sized cones are interpreted as scoria cones, tuff rings and tuff cones, and extensive clusters of sub-kilometre pitted cones in the northern lowlands are proposed to be rootless cones, i.e. constructional features caused by accumulation of volcanic fragments. Finally, layered deposits widely spread in equatorial areas (e.g., the Medusae Fossae Formation), and layered stacks of ash and a putative volcanic bomb observed by rover, also point to a protracted history of explosive volcanism on Mars. Yet some of these interpretations remain a matter of scientific debate. The discovery of evidence for explosive volcanism on Mars triggered an interest in the theoretical aspects of such volcanism under gravitational and atmospheric conditions different from those on Earth. These studies indicate that explosive eruptions on Mars would behave differently from those on Earth. This is because a lower atmospheric pressure and gravity can affect all stages of the eruption including the ascent of magma, the process of degassing and magma fragmentation, the transport and deposition of the pyroclasts, and, in some cases, the formation of explosive volcanoes themselves. On Earth, explosive eruptions are responsible for the formation of most volcanoes on land, and so the relatively sparse occurrence of explosive volcanism on Mars is surprising, especially considering the martian environmental conditions as well as wide occurrence of external volatiles on Mars. This is because the lower atmospheric pressure than on Earth ought to favour magma fragmentation and hence the formation of pyroclasts and associated explosive volcanic edifices, even if lower volumes of dissolved gases were present in martian magma than is usual on Earth. The relative dearth of explosive activity on Mars therefore represents a gap in our understanding of martian volcanism, suggesting that there may be considerable compositional differences between Mars and Earth or that evidence of explosive volcanism on Mars manifests differently than on Earth. Understanding these differences is important, as explosive volcanism provides insight into the planet’s composition and plays a crucial role in the evolution of a planet’s atmosphere by the release of magmatic gases, which have the ability to affect geological and even biological processes operating on the surface of a planet. In this paper, we present an overview of explosive volcanism on Mars—from both observational and theoretical perspectives—and discuss the implications of explosive eruptions for the evolution of the Red Planet.
The Tharsis Province
2020, The Volcanoes of Mars
The Tharsis Province is the largest and youngest volcanic region of Mars, and includes the giant shield volcanoes Olympus Mons and the three Tharsis Montes (Arsia, Pavonis, and Ascraeus Montes). Extensive studies of the styles of volcanic activity within Tharsis have been conducted over the past 45 years, and have identified numerous lava flows in excess of 150 km long, multiple caldera collapse events, and the possibility that explosive volcanism (perhaps due to phreatomagmatic activity) took place. Glacial and tectonic events have also been described. By virtue of the apparent age of the lava flows found in this area, the Tharsis Province is the most likely source of Martian meteorites.
Long-lived volcanism within Argyre basin, Mars
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Citation Excerpt :
Robbins et al. (2011) identified seven distinct, nested calderas with modeled surface ages based on crater counts ranging from 400 Ma to over 2 Ga. The relatively large size of the caldera complex relative to the total shield diameter is interpreted by Plescia (1994) to results from relatively large magma chambers at shallow depth. Morphologically, Argyre Mons resembles other volcanic features elsewhere in the solar system.
The Argyre basin, one of the largest impact structures on Mars with a diameter >1200 km, formed in the Early Noachian ∼3.93 Ga. The basin has collected volatiles and other material through time, and experienced partial infilling with water evident from stratigraphic sequences, crater statistics, topography, and geomorphology. Although volcanism has not been previously associated with the Argyre basin, our study of the northwest portion of the basin floor has revealed landforms suggesting volcanic and tectonic activity occurred including Argyre Mons, a ∼50 km wide volcanic-structure formed ∼3 Ga. Giant polygons with a similar surface age are also identified on terrain adjacent to the base of Argyre Mons, indicating the structure may have formed in a water-rich environment. In addition to Argyre Mons, cones, vents, mounds, dikes, and cavi or hollows, many of which are associated with extensional tectonics, are observed in the region. Multiple features appear to disrupt icy (and largely uncratered) terrain indicating a relatively young, Late Amazonian, formation age for at least some of the volcanic and tectonic features. The discovery of Argyre Mons, along with additional endogenic modification of the basin floor, suggests that the region has experienced episodes of volcanism over a protracted period of time. This has implications for habitability as the basin floor has been a region of elevated heat flow coupled with liquid water, water ice, and accumulation of sediments of diverse provenance with ranging geochemistry, along with magma-water interactions.
Alignments of volcanic features in the southern hemisphere of Mars produced by migrating mantle plumes
2016, Journal of Volcanology and Geothermal Research
Mars shows alignments of volcanic landforms in its southern hemisphere, starting from the equatorial regions and converging towards the South Pole, and visible at global scale. These composite alignments of volcanoes, calderas, shields, vents, heads of valley networks and massifs between the equatorial regions and the southern polar region define twelve different lines, fitted by rhumb lines (loxodromes), that I propose to be the traces of mantle plumes. The morphology of the volcanic centres changes along some of the alignments suggesting different processes of magma emplacement and eruptive style. The diameters of the volcanic centres and of the volcanic provinces are largest at Tharsis and Elysium, directly proportional to the number of alignments starting from them. A minor presence of unaligned volcanic features is observed on the northern lowlands and on the highlands outside the 12 major alignments. The heads of channels commonly interpreted as fluvial valleys are aligned with the other volcanic centres; unaltered olivine is present along their bed-floors, raising severe doubts as to their aqueous origin. Several hypotheses have tried to explain the formation of Tharsis with the migration of a single mantle plume under the Martian lithosphere, but the discovery of twelve alignments, six starting from Tharsis, favours the hypothesis of several mantle plumes as predicted by the model of the Southern Polar Giant Impact (SPGI) and provides a new view on the formation of the volcanic provinces of Mars.
Arecibo radar imagery of Mars: The major volcanic provinces
2012, Icarus
Citation Excerpt :
These paterae are older than the major Tharsis shields (Hodges and Moore, 1994; Plescia, 1994), so their darkness may simply reflect a long-term accumulation of eolian dust or a blanketing by a pre-Stealth pyroclastic airfall. Ulysses Patera may even have produced its own pyroclastics (Plescia, 1994), although its neighbor Biblis Patera probably did not. Both shields appear to have been built up from low-viscosity lavas (Plescia, 1994), so a smoother lava surface texture could also have contributed to their radar-darkness.
We present Earth-based radar images of Mars obtained with the upgraded Arecibo S-band (λ = 12.6 cm) radar during the 2005–2012 oppositions. The imaging was done using the same long-code delay-Doppler technique as for the earlier (pre-upgrade) imaging but at a much higher resolution (∼3 km) and, for some regions, a more favorable sub-Earth latitude. This has enabled us to make a more detailed and complete mapping of depolarized radar reflectivity (a proxy for small-scale surface roughness) over the major volcanic provinces of Tharsis, Elysium, and Amazonis. We find that vast portions of these regions are covered by radar-bright lava flows exhibiting circular polarization ratios close to unity, a characteristic that is uncommon for terrestrial lavas and that is a likely indicator of multiple scattering from extremely blocky or otherwise highly disrupted flow surfaces. All of the major volcanoes have radar-bright features on their shields, although the brightness distribution on Olympus Mons is very patchy and the summit plateau of Pavonis Mons is entirely radar-dark. The older minor shields (paterae and tholi) are largely or entirely radar-dark, which is consistent with mantling by dust or pyroclastic material. Other prominent radar-dark features include: the “fan-shaped deposits”, possibly glacial, associated with the three major Tharsis Montes shields; various units of the Medusae Fossae Formation; a region south and west of Biblis Patera where “Stealth” deposits appear to obscure Tharsis flows; and a number of “dark-halo craters” with radar-absorbing ejecta blankets deposited atop surrounding bright flows. Several major bright features in Tharsis are associated with off-shield lava flows; these include the Olympus Mons basal plains, volcanic fields east and south of Pavonis Mons, the Daedalia Planum flows south of Arsia Mons, and a broad expanse of flows extending east from the Tharsis Montes to Echus Chasma. The radar-bright lava plains in Elysium are concentrated mainly in Cerberus and include the fluvio-volcanic channels of Athabasca Valles, Grjotá Valles, and Marte Valles, as well as an enigmatic region at the southern tip of the Cerberus basin. Some of the Cerberus bright features correspond to the distinctive “platy-ridged” flows identified in orbiter images. The radar-bright terrain in Amazonis Planitia comprises two distinct but contiguous sections: a northern section formed of lavas and sediments debouched from Marte Valles and a southern section whose volcanics may derive, in part, from local sources. This South Amazonis region shows perhaps the most complex radar-bright structure on Mars and includes features that correspond to platy-ridged flows similar to those in Cerberus.
A unique volcanic field in Tharsis, Mars: Pyroclastic cones as evidence for explosive eruptions
2012, Icarus
Citation Excerpt :
Pyroclastic cones, defined in this study as cinder, scoria, or tephra cones (Vespermann and Schmincke, 2000), are the most common type of terrestrial volcanoes (Wood, 1979a,b) and were suggested by several authors already decades ago to exist on Mars (e.g., Wood, 1979b; Dehn and Sheridan, 1990). However, only few Viking Orbiter-based studies reported their possible existence near the caldera of Pavonis Mons, on the flanks of Alba Patera, in the caldera of Ulysses Patera, and in the Cydonia and Acidalia regions (Carr et al., 1977; Wood, 1979a,b; Frey and Jarosewich, 1982; Edgett, 1990; Hodges and Moore, 1994; Plescia, 1994). It was recognized that this might have been an observational effect caused by the relatively low image resolution of the Viking Orbiter cameras (typically 60–100 m/pixel), and Zimbelman (2000) presumed that many small domes on Mars might have a volcanic origin.
Based on theoretical grounds, explosive basaltic volcanism should be common on Mars, yet the available morphological evidence is sparse. We test this hypothesis by investigating a unique unnamed volcanic field north of the shield volcanoes Biblis Patera and Ulysses Patera on Mars, where we observe several small conical edifices and associated lava flows. Twenty-nine volcanic cones are identified and the morphometry of many of these edifices is determined using established morphometric parameters such as basal width, crater width, height, slope, and their respective ratios. Their morphology, morphometry, and a comparison to terrestrial analogues suggest that they are martian equivalents of terrestrial pyroclastic cones, the most common volcanoes on Earth. The cones are tentatively interpreted as monogenetic volcanoes. According to absolute model age determinations, they formed in the Amazonian period. Our results indicate that these pyroclastic cones were formed by explosive activity. The cone field is superposed on an old, elevated window of fractured crust which survived flooding by younger lava flows. It seems possible that a more explosive eruption style was common in the past, and that wide-spread effusive plain-style volcanism in the Late Amazonian has buried much of its morphological evidence in Tharsis.

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Regular ArticleGeology of the Small Tharsis Volcanoes: Jovis Tholus, Ulysses Patera, BibIls Patera, Mars

Abstract

Regular Article
Geology of the Small Tharsis Volcanoes: Jovis Tholus, Ulysses Patera, BibIls Patera, Mars