Mars Reconnaissance Orbiter (MRO)
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PSP_003583_1425_RED_browse-02.jpgGullies near Gorgonum Chaos (edm - Natural Colors; credits: Dr M. Faccin)54 visitePSP_003583_1425 shows incredible details of an Unnamed Crater with Gullies that provides strong evidence for gully formation involving fluid flow.
Of note is the variety of gully morphologies along the crater walls. The North and West Walls have Gullies, while the South Wall has only Landslides.
"Mass Wasting" is the more general term geologists use to describe Landslides, slumps, and other movements of the ground in response to gravity. It usually occurs on steep slopes when the force of gravity causes weak or loose material to travel downslope. Mass Wasting produces structures that are sometimes similar to gully channels, but which can usually be distinguished by their occurrence on steep slopes.
The Gullies on the North Wall have eroded all the way to the Crater Rim. They appear older than other nearby Gullies because they have existed long enough to be modified by permafrost processes as evidenced by the polgyonal fractures found on some of the channel and inter-gully walls.
Another noticeable difference among the gullies is channel lengths. The Gullies on the North Wall and the group just to the left of these have much shorter channels than the Gullies on the North-Western Wall. It is possible that the Gullies with shorter channels had less fluid flow through their systems. The Gullies appear to originate around a sequence of rocky layers near the Crater Rim.
Many of the gully channels appear to have boulders littered throughout. This is suggestive of a fluid flowing in these channels; a fluid would preferentially transport smaller particles and leave behind the larger ones, such as the boulders seen here.
There are many overprinted small channels in each gully, as can be seen in this edm. These are indicative of multiple flow events such that some channels experience flow, then are abandoned.
The edm also shows several channels merging.
Particularly interesting is the channel flowing from the top of the scene. There are several intertwining channels that merge into one just to the right of the center of the subimage. However, the way some channels truncate others suggests that there were at least three episodes of flow through this area. (written by Kerry Kolb)MareKromium
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PSP_003595_2115_RED_browse.jpgOlympus' Aureole (False Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team) 111 visiteThis image samples the rugged central portion of the mysterious "aureole" that extends to the West and North of Olympus Mons.
While many ideas for its formation have been advanced over the decades, these days it is generally thought to be a giant landslide deposit. The scene here fits that model with kilometer-scale (mile-sized) rocky hummocks and blocks strewn about. The blocks themselves are now covered with dust that is slumping off in small landslides or avalanches. These leave dark streaks on the sides of the blocks.MareKromium
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PSP_003595_2115_RED_browse~0.jpgOlympus' Aureole (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)63 visiteThis image samples the rugged central portion of the mysterious "aureole" that extends to the West and North of Olympus Mons.
While many ideas for its formation have been advanced over the decades, these days it is generally thought to be a giant landslide deposit. The scene here fits that model with kilometer-scale (mile-sized) rocky hummocks and blocks strewn about. The blocks themselves are now covered with dust that is slumping off in small landslides or avalanches. These leave dark streaks on the sides of the blocks. MareKromium
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PSP_003597_1765_RED_abrowse-PCF-LXTT2.jpgPossible Smoke Emissions in Elysium Planitia (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)124 visiteCaption NASA:"This observation shows fractured Mounds on the Southern Edge of Elysium Planitia. The Mounds are typically a few Km in diameter and about 200 feet tall. The fractures that crisscross their Surfaces are dilational (extensional) in nature, suggesting that the Mounds formed by localized uplift (i.e., they were pushed up from below).
The Mounds are probably composed of solidified Lava. They are contiguous with, and texturally similar to, the flood Lavas that blanket much of Elysium Planitia, and, where dilation cracks provide cross-sectional exposure, the uplifted material is rocky.
Patches of mechanically weak and disrupted material overlie the rocky mound material. This is particularly conspicuous in the Northeast corner of the HiRISE image. These patches may be remnants of a layer that was once more continuous but has been extensively eroded. Smooth Lava Plains fill the low-lying areas between the Mounds. They are riddled with sinuous pressure ridges.
The entire area is covered by a relatively thin layer of Dust and Sand".
Nota Lunexit: l'elemento più suggestivo dell'intero frame, completamente tralasciato dal commento NASA "Ufficiale", attiene quelle che a noi sembrano delle (evidenti e, riteniamo, anche piuttosto recenti) "emissioni di fumi", ben visibili in corrispondenza di quasi tutti i maggiori punti di fratturazione. E' proprio il dato, confermato dalla NASA stessa, per cui l'intera area ripresa è coperta da un sottile strato di sabbia e polvere (la quale dovrebbe conferire un colore denso e, soprattutto, uniforme a tutto il paesaggio) che ci fa ritenere recenti (se non recentissime) le summenzionate zone più scure ("macchiate", di fatto) e, dunque, molto probabilmente interessate da eventuali e persistenti emissioni di fumi, vapori (sulfurei?) e ceneri vulcaniche.MareKromium
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PSP_003605_2015_RED_browse~0.jpgLandslides along the Walls of Bahram Vallis (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)56 visiteLandslides are one of the most spectacular mass wasting features on Mars in terms of their areal extent and volume. Some of the best preserved landslides are in the Valles Marineris canyon system, but that's not the only place we see evidence for landslides.
This image of Bahram Vallis, a valley along the edges of the circum-Chyrse Basin, has large mounds of material at the base of the valley floor. These deposits of material are different from those deposits seen at Valles Marineris. They do not have a "ribbed" surface of transverse ridges. They also do not have a semi-circular distal margin giving it a lobate appearance and they have not travelled for many kilometers away from their source region like most Valles Marineris landslides do.
These particular deposits have the characteristic shape of rotational landslides or slumps on Earth where material along the entire wall slumps down and piles debris at the base of the slope, much like a person who slumps down the back of a chair. Right at the cliff edge at the top of the slope, the shape of the area where the valley wall gave way to a landslide is not straight, but rather curved or semi-circular. This is typical of large landslides where the failure area has an arcuate "crown" shape. The fact that landslides have occurred here indicates that the valley walls are not stable and the materials respond to Martian gravity with mass movements.
Scientists studying landslides can use these images along with topographic data to model how the wall failed, which can give clues to the nature of the materials (type, strength, etc.) in this region. Another consequence of landslide activity in Bahram Vallis is that the overall width of the valley will increase over time. MareKromium
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PSP_003608_1510_RED_abrowse-00.jpgThe VERY Deep Zumba Crater (Natural Colors; credits: Lunar Explorer Italia)54 visiteThis image taken at a high Sun Angle (a.k.a. "Phase Angle") shows the relatively unshadowed pristine and youthful rayed crater Zumba.
The crater’s rim-to-rim diameter is approx. 3 Km (about 1,85 miles) with a depth of about 620 mt (approx. 0,4 miles), and its rim rises about 200 mt (656 feet) above the surrounding lava-filled plains of Daedalia Planum, just South-West of the great Tharsis Volcanoes. Zumba is approximately 25% deeper than the average Martian Crater of this size – just one of several attributes that suggests it is a very fresh crater.
One estimate of Zumba’s age, generally accomplished by counting smaller superimposed craters on Zumba itself, suggests it may be 5 MY old. Even if such an estimate is off by 2-4 times, this is still a young geologic feature by Mars standards. Because Zumba is so young and so fresh, it is a perfect example of a simple crater. On Mars, a simple crater is generally less than 6-9 Km (about 3,7-5,6 miles) in diameter with a “simple” conical-bowl shape, minimal wall collapse and lacking a well-developed central feature (exx.: a peak, large pit, or ring).
By impacting into such hard durable rocks, the impact that created Zumba scattered greater than 10 million ejecta blocks at high speeds resulting in far-reaching ray segments and an impressive field of secondary impact craters. This pattern is hard to see in visible-light images, but “lights-up” spectacularly in nighttime thermal InfraRed images taken by THEMIS onboard the Mars Odyssey 2001 Orbiter. Scientists believe that some of these high-speed rocks may have even been expelled from Mars and even traveled to Earth.
Zumba is of considerable interest to scientists, whether it’s a source of Martian meteorites or not, as it possesses interesting features that are typically buried or eroded away in other older Martian Craters, and even within the freshest terrestrial craters (including Meteor crater in Arizona). These preserved and newly recognized features observed at the scale of HiRISE may reveal aspects of the impact process unknown to scientists from previous studies of craters on the terrestrial planets.
What is particularly intriguing is the presence of a pitted deposit giving Zumba the appearance that it has a relatively flat floor despite the pits. These crater-fill deposits are typically composed of lightly to highly damaged rock fragments and impact melts formed from the high temperatures achieved from the energy released by the impact event (on the order several to tens of megatons). The pits in the crater-fill deposits have not been recognized within lunar or terrestrial craters and appear to be unique to crater-fill deposits in only the freshest and best-preserved Martian Craters.
These pits may represent the result of the interactions of the very hot crater-fill deposits with water and water-ice that may have been present in the subsurface prior to impact. It is not well understood whether these pits form explosively (similar to terrestrial volcanic pits/craters formed from the interaction of hot lava with wet sediments/deposits), or by collapse from the drainage of impact melts or volatiles. The presence of pitted deposits in only the freshest and well-preserved craters suggests that they are likely related to the impact process.MareKromium
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PSP_003608_1510_RED_abrowse-01.jpgProximities of Zumba Crater: Secondary Craters Field (Natural - but enhanced - Colors; credits: Lunar Explorer Italia)54 visitenessun commentoMareKromium
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PSP_003617_1835_RED_abrowse-PCF-LXTT-00.jpgFeatures of Aram Chaos (CTX Frame - Absolute Natural Colors; credits for the additional process. and color: Dr Paolo C. Fienga - Lunexit Team)221 visitenessun commentoMareKromium
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PSP_003617_1835_RED_abrowse-PCF-LXTT-01.jpgFeatures of Aram Chaos (EDM n.1 - Absolute Natural Colors; credits for the additional process. and color: Dr Paolo C. Fienga - Lunexit Team)190 visiteCaption NASA:"This image captures an enigmatic approximately 6 Km-wide area in central Aram Chaos, a Region that is about 1000 Km in diameter and it is located East of Valles Marineris and just North of the Equator. The image depicts the edge of a light-toned cap unit forming two large sheets in the middle of this Chaotic Terrain. This cap unit is heavily eroded forming the 'icing' texture and terminates with a sharp approximately 300 mt Cliff going diagonally across the area". MareKromium
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PSP_003617_1835_RED_abrowse-PCF-LXTT-02.jpgFeatures of Aram Chaos (EDM n.2 - Absolute Natural Colors; credits for the additional process. and color: Dr Paolo C. Fienga - Lunexit Team)200 visiteCaption NASA:"In the past, the entire Aram Chaos Region [may have] once been an ice-covered lake connected to a nearby Valley via an Outflow Channel and underwent several episodes of catastrophic flooding. Thus, the multiple cracked overlapping layers of the Chaotic Terrain [may have] formed in presence of transient water and ice. Nowadays, Aram Chaos [may contain] water-rich minerals (including Hematite Deposits identified by TES) and thus [may] provide an ideal site for exploration of water-related processes on present day Mars". MareKromium
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PSP_003618_1725_RED_abrowse-PCF-LXTT.jpgGanges Chasma (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)57 visitenessun commentoMareKromium
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PSP_003639_1345_RED_browse-00.jpgDebris Apron South of Euripus Mons (context image - possible natural colors; elab. Lunexit)53 visiteEuripus Mons is located to the east of Hellas impact basin in the southern mid-latitudes of Mars.
The overall wavy, curved surface pattern of this debris apron suggests that material flowed out from the isolated flat-top ridge. This mass movement of debris probably involved ice flow (possibly forming rock glaciers) and potentially liquid water.MareKromium
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