Evidence for ancient lakes in the Hellas region

Wilson, Sharon A.; Moore, Jeffrey M.; Howard, A. D.; Wilhelms, D. E.

doi:10.1016/b978-0-444-52854-4.00007-6

Cited by 11 publications

(8 citation statements)

References 81 publications

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“…The present-day surface of the basin appears relatively smooth compared to the surrounding highlands, probably because of postimpact modification of the landscape through fluvial, volcanic and glacial processes [e.g., Leonard and Tanaka, 2001;Bernhardt et al, 2015]. Indeed, the occurrence of a wide network of channels ending in the northwest of Hellas and the presence of fan deposits [Moore and Howard, 2005;Wilson et al, 2010;De Blasio, 2014] suggest reworking by liquid water flows in this part of the basin. Additionally, the northern and eastern flanks of the basin host young (late Amazonian) small viscous flow features [e.g., Milliken et al, 2003;Berman et al, 2009;Head et al, 2005;Hubbard et al, 2011;Souness et al, 2012], and larger, older (Early Amazonian), lobate debris aprons that have been attributed to creep of ice-rich materials at the surface [e.g., Squyres, 1979;Mangold and Allemand, 2001;Berman et al, 2009Berman et al, , 2015Levy et al, 2014].…”

Section: Geologic Settingmentioning

confidence: 99%

An ice‐rich flow origin for the banded terrain in the Hellas basin, Mars

et al. 2015

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The interior of Hellas Basin displays a complex landscape and a variety of geomorphological domains. One of these domains, the enigmatic banded terrain covers much of the northwestern part of the basin. We use high-resolution (Context Camera and High-Resolution Imaging Science Experiment) Digital Terrain Models to show that most of the complex viscous flowing behavior exhibited by the banded terrain is controlled by topography and flow-like interactions between neighboring banded terrain. Furthermore, the interior of the basin hosts several landforms suggestive of the presence of near-surface ice, which include polygonal patterns with elongated pits, scalloped depressions, isolated mounds, and collapse structures. We suggest that thermal contraction cracking and sublimation of near-surface ice are responsible for the formation and the development of most of the ice-related landforms documented in Hellas. The relatively pristine form, lack of superposed craters, and strong association with the banded terrain, suggest an Amazonian (<3 Ga) age of formation for these landforms. Finally, relatively high surface pressures (above the triple point of water) expected in Hellas and summertime temperatures often exceeding the melting point of water ice suggest that the basin may have recorded relatively "temperate" climatic conditions compared to other places on Mars. Therefore, the potentially ice-rich banded terrain may have deformed with lower viscosity and stresses compared to other locations on Mars, which may account for its unique morphology.

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Section: Geologic Settingmentioning

confidence: 99%

An ice‐rich flow origin for the banded terrain in the Hellas basin, Mars

et al. 2015

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“…We have utilized mapping techniques used to characterize Martian landscapes [ Irwin and Howard , ; Moore and Wilhelms , , ; Howard et al , ; Wilson et al , , ] to evaluate the geologic history and process dominance on Titan.…”

Section: Prospectusmentioning

confidence: 99%

The landscape of Titan as witness to its climate evolution

2014

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We investigated the range of Titan climate evolution hypotheses regulated by the role, sources, and availability of methane. We analyzed all available image data (principally synthetic aperture radar (SAR)) of Titan's landscape through the T-86 encounter, starting with focused examinations of terrains that carry the markers of climate evolution. Traditional geologic and geomorphic landscape analysis was used to perform morphometric characterization, establish time-stratigraphic relationships, and interpret local and regional geologic process-oriented evolutionary histories. We then assayed the distribution of terrains we identified with respect to both their latitudinal and altimetric occurrence. Our analysis of the terrain types and distributions was used to evaluate and rank the various climate evolution scenarios. We favor progressive hypotheses, which include a relatively brief period in which precipitation was able to affect geomorphic change in low latitudes at scales perceivable in SAR data, with subsequent gradual decline of precipitation intensity coupled with an increasing poleward restriction.

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“…There is remarkably little fluvial dissection of a steeper (0.05 or 3°) slope into Hellas below about −3 km. Normally, rivers flowing from a gentle surface to a steeper one become more erosive, which should create a more heavily dissected surface that is not observed at low elevations within the basin [ Wilson et al , 2010]. However, the sparse occurrence of valley networks south of ∼20°S may be partly attributable to post‐Noachian terrain softening or mantling.…”

Section: Study Areasmentioning

confidence: 99%

Topographic influences on development of Martian valley networks

Irwin¹,

Craddock²,

Howard³

et al. 2011

J. Geophys. Res.

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[1] Some morphometric differences between terrestrial and Martian valley networks may reflect the precursor topography on Mars, particularly impact basins or tectonic slopes. To evaluate these possible influences, we mapped highland watersheds in nine study areas that sample a range of geographic and topographic settings. We collected data including latitude, longitude, watershed length, divide and terminal elevations, watershed relief and slope, slope orientation, and qualitative descriptors including whether a drainage basin was open or closed. The longest valley networks and most overflowed basins occur on preexisting intercrater slopes of 0.1-1°, particularly on north facing slopes associated with the crustal dichotomy. The control of watershed length by earlier Noachian topographic features, which the relict networks did not significantly modify, suggests that the Early to Middle Noachian geomorphic environment was nominally much drier than the later Noachian to Hesperian transition. The distribution of fluvial valleys and likely orographic effects created by the crustal dichotomy suggest that evaporation from the northern lowlands was an important source of atmospheric humidity over short time scales. Much of the highland plateau consists of smaller enclosed watersheds, which (along with cooler temperatures) detained surface water at high elevations, lengthening or impeding the global water cycle. Ponding and evaporation may have partly offset a continentality effect of the highland landmass. Prolonged modification of the intercrater geomorphic surface prior to incision of valley networks included substantial weathering, reduction of relief, and gravity-driven sediment transport, indicating a long-term role for surface water in a transport-limited, arid to hyperarid Noachian paleoclimate.

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Evidence for ancient lakes in the Hellas region

Cited by 11 publications

References 81 publications

An ice‐rich flow origin for the banded terrain in the Hellas basin, Mars

An ice‐rich flow origin for the banded terrain in the Hellas basin, Mars

The landscape of Titan as witness to its climate evolution

Topographic influences on development of Martian valley networks

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