The Elysium Region
MC-15
The Elysium Region covers the area 180° to 225° west longitude and 0° to 30° north latitude on Mars. It contains the major volcanoes named Elysium Mons and Albor Tholus and river valleys--one of which, Athabasca Valles may be one of the youngest on Mars. On the east side is the interesting elongated depression called Orcus Patera.
Topographical Map of the Elysium Region
The Elysium quadrangle contains the volcanoes Elysium Mons and Albor Tholus. As a result much of this area is covered with lava flows, some can even be shown approaching, then stopping upon reaching higher ground. Sometimes when lava flows the top cools quickly into a solid crust. However, the lava below often still flows, this action breaks up the top layer making for very rough terrain.
Image of the Elysium Region
Some of the valleys in the Elysium quadrangle seem to start from grabens. Granicus Vallis and Tinjar Vallis begin at a graben that lies just to the west of Elysium Mons. Certain observations suggest that they may have been the location of lahars (mudflows). The graben may have formed because of volcanic dikes. Heat from the dikes would have melted a great deal of ice. Two valleys, Hephaestus Fossae and Hebrus Valles, have sections that join and branch at high angles. Starting at the northeast corner of the Elysium Region we come to a continuation of the Granicus Vallis.
Depression at Eastern end of Granicus Valles
The location as seen by HiRISE here is at 25°N 138°E.
Next we come to the Elysium Fossae. The Elysium Fossae are a group of large troughs in the Elysium Region of Mars at 24.8° north latitude and 133.7° east longitude. They are about 1,175 km long and are named after a classical albedo feature name. The Elysium Fossae begins where the Granicus Valles end.
Location where the Granicus Valles and Elysium Fossae Meet
The Elysium Fossae is a large trough in the Elysium Region of Mars at 24.8° north latitude and 213.7° west longitude. It is about 1,175 km long and is named after a classical albedo feature name. Elysium Fossae contains layers, also called strata. Many places on Mars show rocks arranged in layers. Sometimes the layers are of different colors. Light-toned rocks on Mars have been associated with hydrated minerals like sulfates. The Mars Rover Opportunity examined such layers close-up with several instruments. Some layers are probably made up of fine particles because they seem to break up into fine dust. Other layers break up into large boulders so they are probably much harder. Basalt, a volcanic rock, is thought to be in the layers that form boulders. Basalt has been identified on Mars in many places. Instruments on orbiting spacecraft have detected clay (also called phyllosilicates) in some layers. Scientists are excited about finding hydrated minerals such as sulfates and clays on Mars because they are usually formed in the presence of water. Places that contain clays and/or other hydrated minerals would be good places to look for evidence of life.
Craters and Valleys in Elysium Fossae
This HiRISE image covers a small portion of the Elysium Fossae fracture system extending to the northeast from the giant Elysium Mons volcano. The relative roles of tectonics (motion along faults), volcanism, and water remain puzzling. The large crater just north of the center of the HiRISE image appears to have formed by collapse, not by a meteorite impact. Had it been an impact crater, we would see a blanket of material (ejecta) that had been thrown out of the crater. In general, this image demonstrates that this area has a similar stack of materials as other parts of the giant volcanoes on Mars. The deepest exposed material appears to be a stack of lava flows that produce thick layers that shed boulders. Above is a layer of weak material, possibly wind blown dust. Interestingly, in some areas (especially in the northern part of this image) there are thin, harder layers, more resistant to erosion, within the generally weak and easily eroded surface layer. These resistant layers seem to be too thin to be lava flows, and may indicate that some other process has hardened or cemented (indurated) portions of the weak material.
As we head southward we pass the western lava fields that come from the Elysium Mons. Much of the terrain to the west of this giant volcano has been affected by its past activity. We come to an area that is crisscrossed with fissures and channels called the Hyblaeus Fossae that leads to the Hyblaeus Catena.
Knobs West of Hyblaeus Fossae
To the east is Hyblaeus Catena from there the Hyblaeus Chasma crosses Elysium Chasma.
Locations of all three areas mentioned above
The Hyblaeus Catena is located at 21.5°N 141°E and the Hyblaeus Chasma from 22-23°N by 141-142°E. The Elysium Chasma stretches from 21-25°N by141-143°E. At about 22.3 °N on this map on the other side of the Elysium Chasma we come to our next feature the Stura Vallis.
Stura Vallis, as seen by HiRISE. Location is 22.8 degrees north latitude and 142.8 degrees east longitude.
The Stura Vallis is an ancient river valley in the Elysium Region of Mars. It is 75 km long and was named after a classical river east of Rome, Italy.
Directly south of the Elysium Chasma is Eddie Crater.
Central Peak of Eddie Crater
Eddie Crater: is a crater in the Elysium Region of Mars at 12.3° north latitude and 142° East longitude. It is 89 km in diameter and was named after Lindsay Eddie, a South African astronomer (1845–1913).
South of Eddie Crater on the Equator is Aeolis Planum a plateau extending from the Region from south of the Equator, located at 5-0°N and 139-147.5°E.
Ridges in Aeolis Planum
Like the Utopia Planitia to the north the Elysium Planitia covers all of the southern parts of the Elysium Region Unlike Earth, Mars is no longer protected by a global magnetic field or thick atmosphere. As a result, the planet has been vulnerable to radiation from space for billions of years. "Even the hardiest cells we know of could not possibly survive the cosmic radiation near the surface of Mars for that long," said Lewis Dartnell of University College London. Dartnell and his lab developed a radiation dose model that calculates how much solar and galactic radiation Mars is subjected to. They tested three surface soil scenarios and calculated particle energies and radiation doses on the surface and at various depths underground. From this, they calculated the length of time that the hardiest known cells on Earth could survive. The team believes a good place to look for living cells on the red planet is in ice from a frozen sea recently discovered on the Elysium Planitia. Scientists think the sea formed only within the last five million years. "That's very, very recent, five million years ago is yesterday in terms of geology." The researchers estimate that life could survive for long periods of time about 8 yards (7.5 meters) beneath Elysium's ice. However, this is still beyond the range of any currently planned missions.. The only mission that will come close, Dartnell said, is ExoMars, a European rover slated for launch in 2013. ExoMars will be equipped with a drill that can dig about 6.5 feet (2 meters) for samples. However, this is something a manned mission would be able to do better. Methane has been detected in three areas on Mars; one of which is in the Elysium Region. This is exciting because one possible source of methane is from the metabolism of living bacteria. So all the outward positive evidence is present there.
Lave Flows on the Equator in the Elysium Region
Located a few km to the east at 149°E is the Aeolis Serpens a river bed located between the Aeolis Planum and the Zeyphria Planum. It originates south of the Elysium Region in the Aeolis Region to the south of the Equator.
Aeolis Serpens River bed in center of image
Going north from there we come to the Cerberus Palus. It is a plain in the Elysium Region of Mars, located at 5.8° North and 148.2° East. It is 480 km across and was named after a classical albedo feature. Terrain in this region has been shown to contain spiral-shaped geological features.
Blocks in Cerberus Palus, as seen by HiRISE. Location is 7.8 North and 149.4 East.
The Cerberus Palus Area
Going north from there we cross into the Elysium Fossae again and the Elysium Catena at 17°N 150°E just south of the Volcano Albor Tholus. Then we come to the Albor Fossae at the base of the Volcano.
The Elysium Fossae in The Elysium Region is home to large troughs (long narrow depressions) called fossae in the geographical language used for Mars. Troughs are created when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. Fossae/pit craters are common near volcanoes in the Tharsis and Elysium system of volcanoes. A trough often has two breaks with a middle section moving down, leaving steep cliffs along the sides; such a trough is called a graben.
Troughs to the east of Albor Tholus, as seen by HiRISE under the HI Wish program.
Albor Tholus and Recent Activity
Albor Tholus is an extinct volcano on Mars. It lies southeast of the neighboring large volcano Elysium Mons. Albor Tholus is 4.5 kilometers high and has a diameter of 160 km at its base. Its caldera has a diameter of 30 km and is 3 km deep, it can put inside a whole Mount Etna. Compared with terrestrial volcanoes the caldera is unusually deep, the elevation of the lowest level of the caldera being the same as the base of the volcano; however, the original lower slopes of Albor Tholus may have been covered by lava flows from its larger neighbor, Elysium Mons. Evaluations by the Mars probe Mars Express found that the volcanoes of the Elysium Region were active over long periods of time.
Topographical Map for Albor Tholus
Albor Tholus with THEMIS the location is 17.6 degrees north latitude and 150.3 degrees east longitude.
To the northeast of Albor Tholus is the Iberus Vallis/ Elysium Fossae.
Wide view of Iberus Vallis, as seen by HiRISE.
Iberus Vallis is a valley in the Elysium Region of Mars, located at 21.5° N and 151.8 E. It is 80.2 km long and was named after a classical name for the Ebro River in NE Spain Much of the area in this region is also called the Elysium Fossae. In wide view of Iberus Vallis, as seen by HiRISE, imagine taking a walk in these canyons and looking up at the layers.
Close-up details of Iberus Vallis
We now travel back westward at the base of the larger Volcano through the Elysium Fossae to the Zephyrus Fossae. Fissures and channels seem to surround the Elysium Mons Volcano and the Zephyrus Fossae surrounds it to the west.
Zephyrus Fossae
The trough wall has cut through and exposed layered bedrock, visible near the top of the wall. Talus covers the lower portions of the wall; this debris includes many automobile- and house-sized boulders---most of which are seen as dark dots at the base of the slope. Dust has coated and mantled much of this terrain, including some of the boulders. The dark streak near the center of the picture was formed by land-sliding (or avalanching) of some of the dust. Sunlight illuminates the scene from the lower left.
The Elysium Mons Volcano
The Elysium Mons is located in the Elysium Region, in the eastern hemisphere of Mars . This volcano is much smaller than the volcanoes of Tharsis . As with the Tharsis Montes, the Elysium Mons is located over a large surface bulge the result of massive flows of magma that escaped from inside the planet in the past.
Elysium Mons Topographical Map (note Albor Tholus in right corner)
Elysium Mons a volcano on Mars is located at 25.02°N 147.21°E, It stands about 13.9 km (46,000 ft) above the surrounding lava plains, and about 16 km (52,000 ft) above the Martian datum. Its diameter is about 240 km (150 mi), with a summit caldera about 14 km (8.7 mi) across. Elysium Mons was discovered in 1972 in images returned by the Mariner 9 orbiter.
To the northeast of the Elysium Mons is the Stygis Fossae. Like the Zephyrus Fossae it curves around the northeast side of the Volcano.
\
Stygis Fossae from Themis
From Here we head south and come to Ituxi Vallis, which is a valley in the Elysium Region of Mars.
Ituxi Vallis
Ituxi Vallis is located at 25.4° N and 153°E. It is 62 km long and 19.2 km wide. It was named after the Ituxi River in Brazil. Ituxi Vallis is a lava channel that lies east of Elysium Mons.
Just south of the Ituxi Vallis is the Patapsco Vallis.
Patapsco Vallis
Patapsco Vallis, as seen by HiRISE. Location is 23.9 North and 153.9 East. Patapsco Vallis is a valley in the Elysium Region of Mars. It is 153 km long and was named after a modern river in Maryland, USA.
After that out in the middle of the plains east of Albor Tholus we come to Thila Crater.
.
Thila Crater: is an impact crater in the Elysium quadrangle of Mars, located at 18.09° N and 155.5°E. It is 5.3 km in diameter and was named after Thila, Yemen.
The next major area of importance that we come to after that is the Cerberus Fossae, which are combination or troughs, pits, and hills. Pits are produced when material collapses into the void that results from stretching. Pit craters do not have rims or ejecta around them, like impact craters do. Studies have found that on Mars a fault may be as deep as 5 km, that is the break in the rock goes down to 5 km. Moreover, the crack or fault sometimes widens or dilates. This widening causes a void to form with a relatively high volume. When material slides into the void, a pit crater or a pit crater chain forms. On Mars, individual pit craters can join to form chains or even to form troughs that are sometimes scalloped. Other ideas have been suggested for the formation of fossae and pit craters. There is evidence that they are associated with dikes of magma. Magma might move along, under the surface, breaking the rock, and more importantly melting ice. The resulting action would cause a crack to form at the surface. Pit craters are not common on Earth. Sinkholes, where the ground falls into a hole (sometimes in the middle of a town) resemble pit craters on Mars. However, on the Earth these holes are caused by subsurface limestone being dissolved, thereby causing a void. The images of the Cerberus Fossae, the Elysium Fossae and other troughs, as seen by HiRISE are examples of fossae. Knowledge of the locations and formation mechanisms of pit craters and fossae is important for the future colonization of Mars because they may be reservoirs of water.
The Cerberus Fossae
Here are a series of semi-parallel fissures on Mars formed by faults which pulled the crust apart in the Cerberus region (9°N, 197°W). Ripples seen at the bottom of the fault are sand blown by the wind . The underlying cause for the faulting was magma pressure related to the formation of the Elysium Volcanic field, located to the northwest. The faults pass through pre-existing features such as hills, indicating that it is a younger feature. The formation of the fossae is suspected to have released pressurized underground water, previously confined by the cryosphere, leading to the creation of the Athabasca Valles.
Just southwest of the Cerberus Fossae is the the Athabasca Valles area an overflow region for water and probably lava too. It is located at about 9°N 155°E. The Athabasca Valles is an outflow channel on Mars, cut into its surface by catastrophic flooding. It is one of the youngest known of these structures, probably forming only in the geologically recent past of Mars. The flood produced distinctive "teardrop" landforms similar to those found in the Channeled Scablands on Earth. It is thought that these landforms were produced though depositional processes wherein the floodwaters dropped sediment behind resistant bedrock outcroppings and craters.
Athabasca Valles Source, Islands, and Overflow Channels
The source of water for the flood is thought to be Cerberus Fossae, at 10 N and 157 E. Groundwater may have been trapped under a cryosphere which was broken when the fossae was created. The very high spatial resolution images from the HiRISE camera on board the Mar Reconnaissance Orbiter have revealed that all the flood features are draped by lava flows.
Going southeast of Athabasca Valles through the Cerberus Tholi a region of hills and knobs we come to Tombaugh Crater.
Central Region of Tombaugh Crater
Tombaugh Crater is located at 3.6°N 162°E. It is 60.3 km in diameter and is named after Clyde Tombaugh an American astronomer (1906–1997).
Going northeast from there we come to Zunil Crater. Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually have a central peak. The peak is caused by a rebound of the crater floor following the impact. Sometimes craters will display layers. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed unto the surface. Hence, craters can show us what lies deep under the surface.
Zunil Crater
Research published in the journal Icarus has found pits in Zunil Crater that are caused by hot ejecta falling on ground containing ice. The pits are formed by heat forming steam that rushes out from groups of pits simultaneously, thereby blowing away from the pit ejecta. Zunil Crater is 10.4 km in diameter and is named after a place name in Guatemala.
From there heading north we enter the Tartarus Montes. This area is a long chain of mountains going northeast and then north into the Phlegra Dorsa. The Tartarus Montes are a mountain range on the planet Mars, stretching over 1070 km and located around the coordinates 15.46º N, 167.54º E, between Orcus Patera and the Elysium volcanic region. The Albedo was first identified from the contrast of bright and dark signals photographed by Eugène Antoniadi.
Topographical Map of the Tartarus Montes
The mountain range was named in 1885. It has been named after Greek god of the underworld, Tartarus, by the standard planetary nomenclature for Martian landforms. According to Greek myth, Tartarus is the lowest part of Hades. Zeus imprisoned the Titans in Tartarus. The second part of the name "Montes" means mountains.
Part of the Tartarus Montes
Photographs taken by the Mars Global Surveyor indicate that there are cones and volcanic rings near the Tartarus Montes. Narrow grabens and fractures are present around the regions of this mountain range. Both the hilly areas and the intervening plains are cut with similar marks. This implies that there is a widespread tensional fracture system associated with Cerberus Fossae. At one point, the Grojta’ Vallis, an outflow channel, crosses the bedrock ridge of the Tartarus Montes.
Separating the southern part of the Tartarus Montes from the northern part there is a gap in which the Grojta Vallis crosses the ridge at about 15.53°N 165.4°E. The Grojta Vallis is 370 km long and is named after a river in Iceland.
Cratered Cones in Grjota Valles
North of the Grjota Valles and the Tartarus Montes lies the Phlegra Dorsa. To the northwest near the northern border is Lockyer Crater.
Central Hills of Lockyer Crater
Lockyer Crater: is a crater in the Elysium Region of Mars, located at 28° North and 161°E.. It is 71 km in diameter and was named after Joseph N. Lockyer, a British astronomer (1836-1920). Lockyer is fairly easy to spot on Mars maps because it sits in the relatively young northern hemisphere, where there are few craters. It is close to Elysium Mons but to its northeast.
Layers exposed in Lockyer Crater
The northeast corner of the Elysium Region is occupied by the Phlegra Dorsa.
This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some dark slope streaks in the Phlegra Dorsa region of Mars. Of particular interest is the split streak near the center of the image, which diverted around a rounded hill as the material was sliding down the slope. Slope streaks occur in regions of Mars that are mantled by fine, bright dust. They do not occur on slopes that have no dust coating. They are therefore suspected to form by dry avalanching of the dust, despite their somewhat fluid appearance.
The Phlegra Dorsa Area
South of the Phlegra Dorsa is the Orcus Patera. The Orcus Patera is a unique region on the surface of the planet Mars. It is a depression about 380 km long, 140 km wide, and about 0.5 km (500 meters) deep but with a relatively smooth floor. It has a rim up to 1.8 km high. Orcus Patera is west of Mons Olympus and east of Elysium Mons. It is about half-way between those two volcanoes, and east and north of Gale crater. It has experienced Aeolian processes, and has some small craters and graben structures. However, it is not known how the Patera originally formed. Theories include volcanic, tectonic, or cratering events. The coordinates are 177°E and between 11-17.5°N. It is a huge elongated feature right on the border of two regions.
Topographical Map of Orcus Patera
Orcas Patera
The term ‘patera’ is used for deep, complex or irregularly shaped volcanic craters such as the Hadriaca Patera and Tyrrhena Patera at the north-eastern margin of the Hellas impact basin. However, despite its name and the fact that it is positioned near volcanoes, the actual origin of Orcus Patera remains unclear. Aside from volcanism, there are a number of other possible origins. Orcus Patera may be a large and originally round impact crater, subsequently deformed by compressional forces. Alternatively, it could have formed after the erosion of aligned impact craters. However, the most likely explanation is that it was made in an oblique impact, when a small body struck the surface at a very shallow angle, perhaps less than five degrees from the horizontal.
Orcas Patera Perspective view
The existence of tectonic forces at Orcus Patera is evident from the presence of the numerous ‘graben’, rift-valley-like structures that cut across its rim. Up to 2.5 km wide, these graben are oriented roughly east–west and are only visible on the rim and the nearby surroundings. Within the Orcus Patera depression itself, the large graben are not visible, probably having been covered by later deposits. But smaller graben are present, indicating that several tectonic events have occurred in this region and also suggesting that multiple episodes of deposition have taken place. The occurrence of ‘wrinkle ridges’ within the depression proves that not only extensional forces, as would be needed to create graben, but also compressive forces shaped this region. The dark shapes near the center of the depression were probably formed by wind-driven processes, where dark material excavated by small impact events in the depression has been redistributed.
Just south of the Orcus Patera is the Rahway Valles.
Rahway Valles
Rahway Valles is a valley in the Elysium quadrangle of Mars, located at 9.4° North and 175 °East. It is 500 km long and was named after a river in New Jersey, USA. Below that is the Marte Vallis an area we have explored earlier in the next region. With that we have covered the northern half of the planet from the North Pole all the way to the Equator.
No comments:
Post a Comment