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Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

Rodriguez JA, Kargel JS, Baker VR, Gulick VC, Berman DC, Fairén AG, Linares R, Zarroca M, Yan J, Miyamoto H, Glines N - Sci Rep (2015)

Bottom Line: Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected].Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region.Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

View Article: PubMed Central - PubMed

Affiliation: Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ 85719-2395, USA.

ABSTRACT
Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

No MeSH data available.


Related in: MedlinePlus

(a) Context topographic view of southern circum-Chryse and eastern Valles Marineris showing cited geographic features (MOLA DEM, 460 m/pixel centered at 3.18° S; 332.10° E). (b) Geomorphic map of southern circum-Chryse showing the distribution of Noachian fluvial canyons, subsided surfaces, chaotic terrains and outflow channels. Black arrows show the inferred directions of surface flows along the upland canyons. Dashed yellow line traces an equatorial belt of chaotic terrains. (c) Close-up view on panel b shows the most extensive zone of subsidence in southern circum-Chryse, including the distribution of fault systems (white lines) in the region. (d,e) Close-up views on a subsided valley that exhibit faulted slope breaks (white arrows). We produced the maps in this figure using Esri’s ArcGIS geographic information system.
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f1: (a) Context topographic view of southern circum-Chryse and eastern Valles Marineris showing cited geographic features (MOLA DEM, 460 m/pixel centered at 3.18° S; 332.10° E). (b) Geomorphic map of southern circum-Chryse showing the distribution of Noachian fluvial canyons, subsided surfaces, chaotic terrains and outflow channels. Black arrows show the inferred directions of surface flows along the upland canyons. Dashed yellow line traces an equatorial belt of chaotic terrains. (c) Close-up view on panel b shows the most extensive zone of subsidence in southern circum-Chryse, including the distribution of fault systems (white lines) in the region. (d,e) Close-up views on a subsided valley that exhibit faulted slope breaks (white arrows). We produced the maps in this figure using Esri’s ArcGIS geographic information system.

Mentions: In order to explain the relative localized occurrence45 of catastrophic-flood-formed Martian outflow channels, it was hypothesized that the causative flooding emanated from a compartmentalized global hydrosphere that was also contained within a planetwide megaregolith6. In this model, the existence of high elevation outflow channels in the circum-Chryse region78 can be explained by the presence of an aquifer system that extended from the Tharsis Montes to the outflow channel head source regions9. It was subsequently discovered that rather than possessing global megaregolith, much of the Martian upper crust appears to be dominated by Noachian sedimentary deposits of great stratigraphic thicknesses that both infill and bury numerous impact craters1011. Hence, it was proposed that, instead of a megaregolith-trapped hydrosphere126, significant portions of these outflow-channel-source (OFCS) aquifers might have consisted of water-ice contained within buried impact craters and impact-fractured rocks1213. However, because the sedimentary deposits are distributed globally on Mars, the unique conditions leading to the formation of the southern circum-Chryse outflow channel source regions are still poorly understood. Here, we propose a new geologic model linking the development of OFCS aquifers within the highlands of southern circum-Chryse (Fig. 1a) to a stage of Late Noachian large-scale regional marine sedimentation.


Martian outflow channels: How did their source aquifers form, and why did they drain so rapidly?

Rodriguez JA, Kargel JS, Baker VR, Gulick VC, Berman DC, Fairén AG, Linares R, Zarroca M, Yan J, Miyamoto H, Glines N - Sci Rep (2015)

(a) Context topographic view of southern circum-Chryse and eastern Valles Marineris showing cited geographic features (MOLA DEM, 460 m/pixel centered at 3.18° S; 332.10° E). (b) Geomorphic map of southern circum-Chryse showing the distribution of Noachian fluvial canyons, subsided surfaces, chaotic terrains and outflow channels. Black arrows show the inferred directions of surface flows along the upland canyons. Dashed yellow line traces an equatorial belt of chaotic terrains. (c) Close-up view on panel b shows the most extensive zone of subsidence in southern circum-Chryse, including the distribution of fault systems (white lines) in the region. (d,e) Close-up views on a subsided valley that exhibit faulted slope breaks (white arrows). We produced the maps in this figure using Esri’s ArcGIS geographic information system.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562069&req=5

f1: (a) Context topographic view of southern circum-Chryse and eastern Valles Marineris showing cited geographic features (MOLA DEM, 460 m/pixel centered at 3.18° S; 332.10° E). (b) Geomorphic map of southern circum-Chryse showing the distribution of Noachian fluvial canyons, subsided surfaces, chaotic terrains and outflow channels. Black arrows show the inferred directions of surface flows along the upland canyons. Dashed yellow line traces an equatorial belt of chaotic terrains. (c) Close-up view on panel b shows the most extensive zone of subsidence in southern circum-Chryse, including the distribution of fault systems (white lines) in the region. (d,e) Close-up views on a subsided valley that exhibit faulted slope breaks (white arrows). We produced the maps in this figure using Esri’s ArcGIS geographic information system.
Mentions: In order to explain the relative localized occurrence45 of catastrophic-flood-formed Martian outflow channels, it was hypothesized that the causative flooding emanated from a compartmentalized global hydrosphere that was also contained within a planetwide megaregolith6. In this model, the existence of high elevation outflow channels in the circum-Chryse region78 can be explained by the presence of an aquifer system that extended from the Tharsis Montes to the outflow channel head source regions9. It was subsequently discovered that rather than possessing global megaregolith, much of the Martian upper crust appears to be dominated by Noachian sedimentary deposits of great stratigraphic thicknesses that both infill and bury numerous impact craters1011. Hence, it was proposed that, instead of a megaregolith-trapped hydrosphere126, significant portions of these outflow-channel-source (OFCS) aquifers might have consisted of water-ice contained within buried impact craters and impact-fractured rocks1213. However, because the sedimentary deposits are distributed globally on Mars, the unique conditions leading to the formation of the southern circum-Chryse outflow channel source regions are still poorly understood. Here, we propose a new geologic model linking the development of OFCS aquifers within the highlands of southern circum-Chryse (Fig. 1a) to a stage of Late Noachian large-scale regional marine sedimentation.

Bottom Line: Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected].Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region.Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

View Article: PubMed Central - PubMed

Affiliation: Planetary Science Institute, 1700 East Fort Lowell Road, Suite 106, Tucson, AZ 85719-2395, USA.

ABSTRACT
Catastrophic floods generated ~3.2 Ga by rapid groundwater evacuation scoured the Solar System's most voluminous channels, the southern circum-Chryse outflow channels. Based on Viking Orbiter data analysis, it was hypothesized that these outflows emanated from a global Hesperian cryosphere-confined aquifer that was infused by south polar meltwater infiltration into the planet's upper crust. In this model, the outflow channels formed along zones of superlithostatic pressure generated by pronounced elevation differences around the Highland-Lowland Dichotomy Boundary. However, the restricted geographic location of the channels indicates that these conditions were not uniform. Furthermore, some outflow channel sources are too high to have been fed by south polar basal melting. Using more recent mission data, we argue that during the Late Noachian fluvial and glacial sediments were deposited into a clastic wedge within a paleo-basin located in the southern circum-Chryse region, which at the time was completely submerged under a primordial northern plains ocean [corrected]. Subsequent Late Hesperian outflow channels were sourced from within these geologic materials and formed by gigantic groundwater outbursts driven by an elevated hydraulic head from the Valles Marineris region. Thus, our findings link the formation of the southern circum-Chryse outflow channels to ancient marine, glacial, and fluvial erosion and sedimentation.

No MeSH data available.


Related in: MedlinePlus