Multiple surface wetting events in the greater Meridiani Planum region, Mars: Evidence from valley networks within ancient cratered highlands

Williams, R. M. E.; Chuang, F. C.; Berman, D. C.

doi:10.1002/2016gl072259

Cited by 9 publications

(8 citation statements)

References 62 publications

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“…They generally lack a flat top (with a few exceptions, such as Figure 7a), and commonly show a furrowed or pitted crest. There are also examples of negative relief channel‐like forms, some of which transition from elongated or collinear pits into furrows (as observed elsewhere in Arabia Terra; Williams et al, 2017). The positive relief forms are in general more common (we have mapped ~150 km of subsidiary ridges and ~50 km of subsidiary channel‐like forms) but are not usually capped by the resistant materials that define much of the main Aram Dorsum ridge.…”

Section: Mapping and Observationsmentioning

confidence: 84%

Aram Dorsum: An Extensive Mid‐Noachian Age Fluvial Depositional System in Arabia Terra, Mars

et al. 2020

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A major debate in Mars science is the nature of the early Mars climate, and the availability of precipitation and runoff. Observations of relict erosional valley networks have been proposed as evidence for extensive surface runoff around the Noachian-Hesperian boundary. However, these valley networks only provide a time-integrated record of landscape evolution, and thus, the timing, relative timescales and intensity of aqueous activity required to erode the valleys remain unknown. Here, we investigate an ancient fluvial sedimentary system in western Arabia Terra, now preserved in positive relief. This ridge, "Aram Dorsum," is flat-topped, branching,~85 km long, and particularly well preserved. We show that Aram Dorsum was an aggradational alluvial system and that the existing ridge was once a large river channel belt set in extensive flood plains, many of which are still preserved. Smaller, palaeochannel belts feed the main system; their setting and network pattern suggest a distributed source of water. The alluvial succession is up to 60 m thick, suggesting a formation time of 10 5 to 10 7 years by analogy to Earth. Our observations are consistent with Aram Dorsum having formed by long-lived flows of water, sourced both locally, and regionally as part of a wider alluvial system in Arabia Terra. This suggests frequent or seasonal precipitation as the source of water. Correlating our observations with previous regional-scale mapping shows that Aram Dorsum formed in the mid-Noachian. Aram Dorsum is one of the oldest fluvial systems described on Mars and indicates climatic conditions that sustained surface river flows on early Mars. Plain Language SummaryThe oldest regions of Mars contain ancient valleys, carved by running water, and sinuous ridges, often interpreted as the remnants of former riverbeds, left upstanding by erosion. These "inverted channel" systems provide insight into Mars's ancient climate and hydrologic cycle. We use high-resolution satellite images to investigate "Aram Dorsum," an 85 km long ridge system in the Arabia Terra region. Our observations show that Aram Dorsum is composed of sedimentary rocks, originally deposited in rivers or their adjacent floodplains. The Aram Dorsum sedimentary material is up to 60 m thick, which, by comparison with similar sedimentary deposits on Earth, suggests that the Aram Dorsum river system was active for between 10,000 and 10 million years. Our study also indicates that Aram Dorsum was formed around 3.9 billion years ago, an age consistent with other evidence for ancient rivers and lakes in this region. The water that flowed within the rivers at Aram Dorsum probably came from both locally and regionally generated rainfall or snowfall, rather than a single point source of water, such as large distant ice sheets. Our observations therefore point to an ancient Martian climate that supported precipitation and river flow for thousands or millions of years.

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Section: Mapping and Observationsmentioning

confidence: 84%

Aram Dorsum: An Extensive Mid‐Noachian Age Fluvial Depositional System in Arabia Terra, Mars

et al. 2020

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“…The morphology (singular and transitional types), drainage pattern, and network density of fine-scale valley networks differ markedly across the region ( Figure 5 ). The latter is simply the total length of all valley network segments divided by the area of the Nhc1 exposure (see Williams, Chuang, & Berman, 2017 ). The regional differences in valley network morphology are especially apparent when comparing locations of unit Nhc1 , where the majority of fine-scale valley networks in GMP are located.…”

Section: Resultsmentioning

confidence: 99%

“…The pits are often aligned and interconnected, forming chains in overall branching patterns. Williams et al (2017) interpreted the pits as dissolution features along relict buried stream courses. This area has a slightly lower network density of 0.042 km −1 .…”

Section: Resultsmentioning

confidence: 99%

“… Mars Channel Working Group, 1983 ). Recent studies have also recognized a range of preservation states for valley networks ( Williams, Irwin, Burr, Harrison, & McClelland, 2013 , 2017 ) including sinuous ridges formed by landscape inversion that demarcate former fluvial pathways (often termed ‘inverted channels’; e.g. Burr et al, 2009 ; Pain, Clarke, & Thomas, 2007 ).…”

Section: Introductionmentioning

confidence: 99%

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Valley network morphology in the greater Meridiani Planum region, Mars

Chuang

Williams

2018

Journal of Maps

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The Greater Meridiani Planum region on Mars is a key locale for a diverse range of fluvial landforms. Valley networks in this region have a range of geomorphologic styles that include negative relief, positive relief, or some combination of both along their lengths. Using highresolution ∼5-6 m/pixel orbital images in ArcGIS Desktop software, we mapped previously under-recognized fine-scale valley networks within the Greater Meridiani Planum region and recorded their geomorphic characteristics as feature attributes. The objectives in using the mapped features are to 1) document the full range of valley network morphologic types in the region, 2) document changes in morphologic types both on a regional scale and along the valley network segments, and 3) to use the mapped features along with other geologic information from previous studies to better understand landscape evolution in the Greater Meridiani Planum region.

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“…Both sites experience frequent and strong onshore winds that often bring marine fog. The strong winds clearly result in significant deflation of the regional landscape, creating features such as inverted stream channels, and in other areas (particularly around perennial shrubs and trees), sediment is deposited as coppice dunes (Williams et al, 2017).…”

Section: Methodsmentioning

confidence: 99%

A late Quaternary paleoenvironmental record in sand dunes of the northern Atacama Desert, Chile

et al. 2018

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This paper reports a previously unidentified paleoenvironmental record found in sand dunes of the Atacama Desert, Chile. Long-term aeolian deflation by prevailing onshore winds has resulted in the deposition of sand on the irregular surface of a Miocene-aged anhydrite outcrop. Two deposits ~25 km apart, along the prevailing wind trajectory, were hand excavated then analyzed for vertical (and temporal) changes in physical and chemical composition. Radiocarbon ages of organic matter embedded within the deposits show that rapid accumulation of sediment began at the last glacial maximum and slowed considerably after the Pacific Ocean attained its present post-glacial level. Over this time period, grain sizes are seen to increase while accumulation rates simultaneously decrease, suggesting greater wind speeds and/or a change or decrease in sediment supply. Changes in δ34S values of sulfate in the sediment beginning ~10 ka indicate an increase in marine sources. Similarly, δ2H values from palmitic acid show a steady increase at ~10 ka, likely resulting from aridification of the region during the Holocene. Due to the extreme aridity in the region, these sand dunes retain a well-preserved chemical record that reflects changes in elevation and coastal proximity after the last glacial maximum.

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Multiple surface wetting events in the greater Meridiani Planum region, Mars: Evidence from valley networks within ancient cratered highlands

Cited by 9 publications

References 62 publications

Aram Dorsum: An Extensive Mid‐Noachian Age Fluvial Depositional System in Arabia Terra, Mars

Aram Dorsum: An Extensive Mid‐Noachian Age Fluvial Depositional System in Arabia Terra, Mars

Valley network morphology in the greater Meridiani Planum region, Mars

A late Quaternary paleoenvironmental record in sand dunes of the northern Atacama Desert, Chile

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