Channels on Mars

Sharp, Robert P.; Malin, M. C.

doi:10.1130/0016-7606(1975)86<593:com>2.0.co;2

Cited by 301 publications

(204 citation statements)

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“…Large channel landforms in major outflow regions on Mars such as Kasei, Ares, Tiu, Simund, Maja, and Mangala Valles have been compared to the channeled scablands of the Pacific Northwest, leading to general acceptance that these valleys were carved by water during megaflooding events (e.g., McCauley et al, 1972;Baker and Milton, 1974;Sharp and Malin, 1975;Komar, 1979;Burr et al, 2009;Carr and Head, 2010). However, identification of volcanic deposits on the channel floors in some of these regions have led to an alternative hypothesis suggesting that large martian outflow regions such as Mangala Valles were instead carved by vast volumes of lava (Leverington, 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Pre-fluvial impact craters on fluvial surfaces are observed to have an eroded, rather than covered or filled appearance, with lower, subdued rims. The resemblance of deep longitudinal striae within the Ast unit to Channeled Scabland grooves is suggestive of bedrock erosion by longitudinal roller vortices in powerful floodwaters (McCauley et al, 1972;Baker, 1973;Sharp and Malin, 1975). We consider the features of Ats to be the result of fluvial erosion, and are likely channel terraces and partially eroded topographic highs derived from the same event or events as scoured terrain, since these landforms often grade smoothly down into another fluvial unit of matching flow ridge orientation.…”

Section: Evidence Of Fluvial Activitymentioning

confidence: 99%

“…In particular, there are challenges associated with generating the substantial volumes of water required to erode and transport material out of these systems, which has prompted a wide range of alternative formation hypotheses including aqueous flooding (e.g., Baker and Milton, 1974;Sharp and Malin, 1975), volcanism (e.g., Leverington, 2004), glacial erosion (e.g., Lucchitta, 1982), eolian erosion (e.g., Cutts and Blasius, 1981), debris flows (e.g., Nummedal and Prior, 1981), or a combination of these processes (e.g., Chapman et al, 2003Chapman et al, , 2010Warner et al, 2009;McEwen et al, 2012). While lack of terrestrial analogs of comparable scale and complexity renders geomorphic comparison of large landscape features in these regions difficult (Mars Channel Working Group, 1983), new high-resolution images allow us to identify smaller surface features that provide clues about the processes that have influenced their overall surface geomorphology, allowing for reconstruction of their activity history.…”

Section: Introductionmentioning

confidence: 99%

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Episodes of fluvial and volcanic activity in Mangala Valles, Mars

Keske

Hamilton

McEwen

et al. 2015

Icarus

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A new mapping-based study of the 900-km-long Mangala Valles outflow system was motivated by the availability of new high-resolution images and continued debates about the roles of water and lava in outflow channels on Mars. This study uses photogeologic analysis, geomorphic surface mapping, cratering statistics, and relative stratigraphy. Results show that Mangala Valles underwent at least two episodes of fluvial activity and at least three episodes of volcanic activity during the Late Amazonian. The occurrence of scoured bedrock at the base of the mapped stratigraphy, in addition to evidence provided by crater retention ages, suggests that fluvial activity preceded the deposition of two of the volcanic units. Crater counts performed at 30 locations throughout the area have allowed us to construct the following timeline: (1) formation of Noachian Highlands and possible initial flooding event(s) before ~1 Ga, (2) emplacement of Tharsis lava flows in the valley from ~700 to 1000 Ma, (3) a megaflooding event at ~700-800 Ma sourced from Mangala Fossa, (4) valley fill by a sequence of lava flows sourced from Mangala Fossa ~400-500 Ma, (5) another megaflooding event from ~400 Ma, (6) a final phase of volcanism sourced from Mangala Fossa ~300-350 Ma, and (7) emplacement of eolian sedimentary deposits in the northern portion of the valley ~300 Ma. These results are consistent with alternating episodes of aqueous flooding and volcanism in the valles. This pattern of geologic activity is similar to that of other outflow systems, such as Kasei Valles, suggesting that there is a recurring, and perhaps coupled, nature of these processes on Mars.

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Section: Discussionmentioning

confidence: 99%

Section: Evidence Of Fluvial Activitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Episodes of fluvial and volcanic activity in Mangala Valles, Mars

Keske

Hamilton

McEwen

et al. 2015

Icarus

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“…While the fluvial origin is generally accepted, controversy remains over the relative role of various formation processes including groundwater sapping [Sharp and Malin, 1975;Pieri, 1980 [Baker and Kochel, 1979;Gulick and Baker, 1990] and groundwater flow resulting in subsurface solution and erosion [Malin and Cart, 1999;Cart and Malin, 2000]. In addition, the role of liquid water in the formation of valley networks has led to the suggestion that Mars may have had a warmer and wetter climate in the past.…”

Section: Introductionmentioning

confidence: 99%

Morphometric measurements of martian valley networks from Mars Orbiter Laser Altimeter (MOLA) data

Williams¹,

Phillips²

2001

J. Geophys. Res.

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“…Analyses of Mangala extend back to the time of Mariner 9 (Milton, 1973;Sharp and Malin, 1975;Mutch and Morris, 1979), and since then they have been of great importance for those interested in deciphering the role water has played in the evolution of the martian landscape. While some authors have suggested that liquid CO 2 or CO 2 -H 2 O mixtures resulting from decomposition of clathrates could be responsible for the erosion of the martian outflow channels (Milton, 1974;Hoffman, 2000), thermodynamic arguments continue to support a water-related origin for the channels (Stewart and Nimmo, 2001).…”

Section: Introductionmentioning

confidence: 99%

Mangala Valles, Mars: Assessment of Early Stages of Flooding and Downstream Flood Evolution

2005

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Abstract. The Mangala Valles system is an~900 km fluvially carved channel system located southwest of the Tharsis rise and is unique among the martian outflow channels in that it heads at a linear fracture within the crust as opposed to a collapsed region of chaos as is the case with the circum-Chryse channels. Mangala Valles is confined within a broad, north-south trending depression, and begins as a single valley measuring up to 350 km wide that extends northward from a Memnonia Fossae graben, across the southern highlands toward the northern lowlands. Approximately 600 km downstream, this single valley branches into multiple channels, which ultimately lose their expression at the dichotomy boundary. Previous investigations of Mangala Vallis suggested that many of the units mapped interior to the valley were depositional, related to flooding, and that a minimum of two distinct periods of flooding separated by tens to hundreds of millions of years were required to explain the observed geology. We use infrared and visible images from the THermal EMission Imaging System (THEMIS), and topographic data from the Mars Orbiting Laser Altimeter (MOLA), to investigate the nature of the units mapped within Mangala Vallis. We find that the geomorphology of the units, as well as their topographic and geographic distribution, are consistent with most of them originating from a single assemblage of volcanic flow deposits, once continuous with volcanic flows to the south of the Memnonia Fossae source graben. These flows resurfaced the broad, north-south trending depression into which Mangala Vallis formed prior to any fluvial activity. Later flooding scoured and eroded this volcanic assemblage north of the Mangala source graben, resulting in the present distribution of the units within Mangala Vallis. Additionally, our observations suggest that a single period of catastrophic flooding, rather than multiple periods separated by tens to hundreds of millions of years, is consistent with and can plausibly explain the interior geology of Mangala Vallis. Further, we present a new scenario for the source and delivery of water to the Mangala source graben that models flow of groundwater through a subcryosphere aquifer and up a fracture that cracks the cryosphere and taps this aquifer. The results of our model indicate that the source graben, locally enlarged to a trough near the head region of Mangala, would have required less than several days to fill up prior to any spill-over of water to the north. Through estimates of the volume of material missing from Mangala (13,000-20,000 km 3 ), and calculation of mean discharge rates through the channel system (~5 · 10 6 m 3 s )1 ), we estimate that the total duration of fluvial activity through the Mangala Valles was 1-3 months. Notation:Parameter: Definition (Units); H:water head height in aquifer above base of cryosphere fracture (m); lateral length scale of aquifer (m); P atm : atmospheric pressure (500) (Pa);pressure at bottom of cryosphere fracture (Pa);pressure in unsaturated portion...

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Channels on Mars

Cited by 301 publications

References 0 publications

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

Episodes of fluvial and volcanic activity in Mangala Valles, Mars

Morphometric measurements of martian valley networks from Mars Orbiter Laser Altimeter (MOLA) data

Mangala Valles, Mars: Assessment of Early Stages of Flooding and Downstream Flood Evolution

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