Phoenicis Lacus Region
MC-17
The Phoenicis Lacus Region covers the area from 90° to 135° west longitude and 0° to 30° south latitude on Mars. The Tharsis rise, which was formed from lava flows, occupies part of area. The volcanoes Pavonis Mons and Arsia Mons are believed to have once had glaciers on them. Glaciers may still exist under a thin layer of rocks.
Topographical Map of the Phoenicis Lacus Region
The ice on Mars can be a source of water for the possible future colonization of the planet. One of the most prominent features of this quadrangle is a large intersecting set of canyons called Noctis Labyrinthus. Other interesting features are lava channels, Dark slope streaks, pit crater chains, and large troughs (called fossae). Research published in the journal Icarus has found pits in Zumba Crater 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.
Image of the Phoenicis Lacus Region
Starting in the northeast corner of the Phoenicis Lacus Region we encounter a crater cluster which lies near the equator 510 miles south of Olympus Mons, in a type of terrain called the Medusae Fossae formation. The formation is coated with dust and contains wind-carved ridges called yardangs. These yardangs have steep slopes thickly covered with dust, so when the sonic boom of the air blast arrived from the impacts caused by meteoritess, dust started to move down the slope. Using photos from Mars Global Surveyor and HiRISE camera on NASA’s Mars Reconnaissance Orbiter, scientists have found about 20 new impacts each year on Mars. Because the spacecraft have been imaging Mars almost continuously for a span of 14 years, newer images with suspected recent craters can be compared to older images to determine when the craters were formed. Since the craters were spotted in a HiRISE image from February 2006, but were not present in a Mars Global Surveyor image taken in May 2004, the impact occurred in that time frame.
This image indicates a crater cluster and curved lines formed by air blast from meteorites.
Meteorites caused the air blast which caused dust avalanches on steep slopes. Image is from HiRISE.
Close up of previous image along light/dark boundary. Dark line in middle of image shows border between light and dark area of curved lines.
Green arrows show high areas of ridges. Loose dust moved down steep slopes when it felt the air blast from meteorite strikes. Image is from HiRISE. Location is of this image is 0 latitude and 226.9 E
Going southeast of this location to 5°S 230°E we come to the Arisa Sulci.
Arisa Sulci as seen by Themis
Sulci is a term used for sub parallel furrows and ridges in Mars geography, it was given the name Arisa because of its close proximity to the volcano Arisa Mons.
By going southward at 230°E we enter the Daedalia Planum which continues from the last Region we were in to the west. The Daedalia Planum covers the southwest quarter of the Phoenicis Lacus Region.
Unusual Surface Structure in Daedalia Planum at 21°S 223°E
South of there at we come to Zumba Crater. Zumba Crater, as seen by HiRISE. The location is 28.7 South and 226.9 East.
Zumba Crater
Close up examination of Zumba Crater (Vis/Ani)
Zumba Crater is only 3.3 km in diameter and was named after a town in Ecuador. Zumba has a depth of about 620 meters, and its rim rises about 200 meters above the surrounding lava-filled plains of Daedalia Planum. Zumba is approximately 25% deeper than the average Martian crater of this size, this fact suggests it is a very fresh crater. Since Zumba is so young, it is a perfect example of a simple crater. On Mars, a simple crater is generally less than 6-9 km in diameter with a conical-bowl shape, little wall collapse, and it lacks a well-developed central feature, like a central peak. Zumba is of special interest to scientists, because 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 new aspects of the impact process. A pitted deposit giving Zumba the appearance that it has a relatively flat floor despite the pits is especially interesting. These crater-fill deposits are typically composed of lightly to highly damaged rock fragments and impact melts that were made by the high temperatures of the impact event. The pits in the crater-fill deposits have not been observed within lunar or terrestrial craters. They are unique to crater-fill deposits in only the freshest and best-preserved Martian craters. These pits may result from the interactions of 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. Since the pitted deposits occur only in the freshest and well-preserved craters suggests that they are likely related to the impact process.
Traveling back north we pass through the Daedalia Planum again.
Large Pit Crater in Daedalia Planum at 19.5°S 237°E.
At 11°S 234°E we come to Aganippe Fossa.
Aganippe Fossa Surface Texture Sample
Aganippe Fossa is a surface feature on Mars which runs from 4.1° to 13° south latitude and 233° to 235° east longitude. It is named after a classical albedo feature. Its name was approved by the IAU in 1976. There are dark streaks on the slopes of Aganippe Fossa. Such streaks are common on Mars. They occur on steep slopes of craters, troughs, and valleys. The streaks are dark at first. They get lighter with age. Sometimes they start in a tiny spot, then spread out and go for hundreds of meters. They have been seen to travel around obstacles, like boulders. It is believed that they are avalanches of bright dust that expose a darker underlying layer. However, several ideas have been advanced to explain them. Some involve water or even the growth of organisms. The streaks appear in areas covered with dust. Much of the Martian surface is covered with dust. Fine dust settles out of the atmosphere covering everything.
At about 3.6°S 233°E we come to a new impact crater directly north of the Aganippe Fossa.
New Impact crater formed between March 2000 and July 2003, as seen by HiRISE. Scale bar is 500 meters long.
On the northeastern side of Arisa Mons we come to the Arisa Chasmata.
Arsia Chasmata, as seen by HiRISE. Location is 7.8 degrees south latitude and 240.7 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE.
Arsia Chasmata: is a steep-sided depression in the Phoenicis Lacus Region on Mars, located at 7.6° S and 241° E. It is 81 km long and was named after an albedo name. It has pit craters that must have formed when a void is produced by a cracking of the surface caused by stretching. Also, lava may drain out of an underground chamber, thus leaving an empty space. When material slides into a void, a pit crater or a pit crater chain forms. Pit craters do not have rims or ejecta around them, like impact craters do. On Mars, individual pit craters can join to form chains or even to form troughs that are sometimes scalloped.
Next we come to the largest volcano in the Phoenicis Lacus Region the Arisa Mons.
Topographical Map of the Arisa Mons and surrounding area.
Arsia Mons is the southernmost of three volcanos (collectively known as Tharsis Montes) on the Tharsis bulge near the equator of the planet Mars. To its north is Pavonis Mons, and north of that is Ascraeus Mons. The tallest mountain in the solar system. Olympus Mons, is to its northwest. Its name comes from a corresponding albedo feature on a map by Giovanni Schiaparelli, which he named in turn after the legendary Roman forest of Arsia Silva.
The Arisa Mons (2 views)
The Location of Arisa Mons is 8.35°S 240.5°E. Arsia Mons is a shield volcano with a relatively low slope and a massive caldera at its summit. The southernmost of the three Tharsis Montes volcanoes, it is the only major Tharsis volcano south of the equator. The volcano is 435 kilometers (270 mi) in diameter, almost 20 kilometers (12 miles) high (more than 9 kilometers (5.6 mi) higher than the surrounding plains), and the summit caldera is 72 miles (approximately 110 km) wide. It experiences atmospheric pressure lower than 107 pascals at the summit. Except for Olympus Mons, it is the biggest volcano in volume. Arsia Mons has 30 times the volume of Mauna Loa in Hawaii, the largest volcano on the Earth.
Area Near Arisa Mons
South of Arisa Chasmata on the southern rim of Arisa Mons we come to Oti Fossae. Oti Fossae is a trough in the Phoenicis Lacus Region on Mars, located at 9.3° S and 242° E.
Close-up of Oti Fossae, parallel graben, as seen by Themis. Location is 8.1 S and 243.8 E. Image is 18.1 km wide.
Oti Fossae, as seen by THEMIS. has parallel graben found on the northeastern side of Arsia Mons; they are in line with the NE/SW trend of the three volcanoes in Tharsis.
THEMIS image of probable cave entrances on Arsia Mons. The pits have been informally named (A) Dena, (B) Chloe, (C) Wendy, (D) Annie, (E) Abby (left) and Nikki, and (F) Jeanne.
The Caves of Mars Program also studied designs for inflatable modules and other such structures that would aid the astronauts to build a livable environment for humans and earth creatures. As of 2007 seven putative cave entrances, have been identified in satellite imagery of the flanks of Arsia Mons. They have been informally dubbed Dena, Chloe, Wendy, Annie, Abbey, Nikki, and Jeanne and resemble "skylights" formed by the collapse of lava tube ceilings:
1’Dena (6.084°S 239.061°E)
2.Chloe (4.296°S 239.193°E)
3.Wendy (8.099°S 240.242°E)
4.Annie (6.267°S 240.005°E)
5 & 6 Abbey and Nikki (8.498°S 240.349°E)
7.Jeanne (5.636°S 241.259°E)
From day to night, temperatures of the circular features change only about one-third as much as the change in temperature of surrounding ground. While this is more variable than large caves on Earth, it is consistent with them being deep pits. However, due to the extreme altitude, it is unlikely, so some think, that they will be able to harbor any form of Martian life. A more recent photograph of one of the features shows sunlight illuminating a side wall, suggesting that it may simply be a vertical pit rather than an entrance to a larger underground space. Nonetheless, the darkness of this feature implies that it must be at least 178 meters deep, and that is deep enough to harbor life.
Possible cave entrance to ("Jeanne") on Arsia Mons
Dark pits on some of the Martian volcanoes have been speculated to be entrances into caves. A previous HiRISE image, looking essentially straight down, saw only darkness in this pit. This time the pit was imaged from the west. Since the picture was taken at about 2:30 p.m. local (Mars) time, the sun was also shining from the west. We can now see the eastern wall of the pit catching the sunlight. This confirms that this pit is essentially a vertical shaft cut through the lava flows on the flank of the volcano. Such pits form on similar volcanoes in Hawaii and are called "pit craters." They generally do not connect to long open caverns but are the result of deep underground collapse. From the shadow of the rim cast onto the wall of the pit we can calculate that the pit is at least 178 meters (584 feet) deep. The pit is 150 x 157 meters (492 x 515 feet) across.
A repeated weather phenomenon occurs each year near the start of southern winter over Arsia Mons. Just before southern winter begins, sunlight warms the air on the slopes of the volcanos. This air rises, bringing small amounts of dust with it. Eventually the rising air converges over the volcano's caldera and the fine sediment blown up from the volcano's slopes coalesces into a spiraling cloud of dust that is thick enough to observe from orbit. The spiral dust cloud over Arsia Mons repeats each year, but observations and computer calculations indicate it can only form during a short period of time each year. Similar spiral clouds have not been seen over the other large Tharsis volcanoes, but other types of clouds have been seen. The spiral dust cloud over Arsia Mons can tower 15 to 30 kilometers (9.3 to 19 mi) above the volcano.
Orographic water ice clouds hover over the volcanic peaks of the central Tharsis region in this color image mosaic from Mars Global Surveyor. Olympus Mons dominates at upper left. At center are the three Tharsis Montes: Arsia Mons at bottom, Pavonis Mons at center, and Ascraeus Mons at top. (Orographic: any cloud whose existence and form are largely controlled by the disturbed flow of air over and around mountains).
The volcanoes of the Tharsis region are highlighted by this color image mosaic obtained on a single Martian afternoon by the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft. Olympus Mons dominates the upper left corner -- it is one of the largest known volcanoes and is nearly 550 km (340 miles) wide. The gray scale image on the right shows the name of each volcano in the scene. The white or bluish-white features are clouds. Clouds are common over the larger Tharsis volcanoes in mid-afternoon. The four largest volcanoes are more than 15 km (9 mi) high. Viewed from Earth by telescope before any spacecraft had visited the planet, astronomers often described a "W"-shaped white cloud over the Tharsis region. This "W" was actually the result of seeing the combined effects of bright clouds hanging over the Ascraeus, Pavonis, Arsia, and Olympus volcanoes. The clouds result when warm air containing water vapor rises up the slopes of each volcano, cools at the higher altitude, and causes the water vapor to freeze and form a cloud of ice crystals. Pavonis Mons lies on the Martian equator, north is up, and sunlight is illuminating the scene from the left. The picture is a mosaic of red and blue filter images taken on three consecutive orbits. The slightly blurred appearance of the left side of Arsia Mons results from distortion toward the edges of the images used to make the mosaic. To remove the blur, an image obtained on another day would be added to the mosaic--however, this image would not match well because the cloud patterns will have changed by the next day. Mosaics such as the one shown here are used to monitor changes in Martian weather and to plan future observations.
Going to 2.5°S 246°E we come to the southern part of the Pavonis Mons volcano. Here too we find caves that are the result of lava tubes.
Lava Tubes of Pavonis Mons
Lava sometimes forms a tube as it moves away from the vent (opening from which lava flows from a volcano). The top of a stream of lava cools down, thereby forming a solid roof. Meanwhile, the lava continues moving in the tube. Often, when all the lava leaves the tube, the roof collapses, making a channel. These features are found on Mars. Some can be seen around Pavonis Mons, in the picture above. . Some people have suggested that future colonists on Mars could use lava tunnels as shelters. They would offer great protection from radiation, especially ultraviolet radiation. Lava Channels on the flank of the volcano Pavonis Mons are pictured below in a picture from Mars Odyssey THEMIS. Sometimes the lava tube remains intact for a time. Lava will break out along the tube to accumulate or flow away. Lava flows often have a lobate appearance at the edges. A good view of such a lava tubes is shown above.
Many of the volcanoes on Mars show strong evidence of past and possible present glacial activity. When glaciers melt and retreat, they leave behind material that was carried in and on the ice. Often the material is dropped in a ridge, called a moraine.
Ridges on side of Arsia Mons, a large volcano, may be moraines dropped by glacial activity.
Underground Habitat on Mars
Passing out of the Tharsis Montes area we go south and re-enter the Daedalia Planum.
Pit in Lava Flows in Daedalia Planum at 18°S 243°E
Then heading east we come Claritas Rupes area which is a mountain ridge running from south to north. Here we come across the Lenya and Tecolate Craters.
Lenya and Tecolate Craters
Lenya Crater is 15.5 km in diameter and is named after a Burma place name. Tecolate Crater is 51 km in diameter and is named after a place in New Mexico USA.
Claritas Rupes Area
Claritas Rupes is a scarp in the Phoenicis Lacus Region of Mars, located at 26° South and 255°East. It is 924 km long and was named after an albedo feature at 25°S, 250°E
After this we come to another long group of troughs and graben the Claritas Fossae. Claritas Fossae is a group of troughs in the Phoenicis Lacus and Thaumasia Regions of Mars, located at 31.5° S and 254°E.
Claritas Fossae Note the steep scarp.
Claritas Fossae: Note the steep scarp.
The structure is 2,050 km long and was named after a classical albedo feature name. Long narrow depressions on Mars are called fossae. This term is derived from Latin; therefore fossa is singular and fossae is plural. Troughs form 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 regions. 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.
As we head north we enter the Syria Planum. It covers a large area from 8-20°S and 250-260°E at its widest extent.
Syria Planum
In the center of Syria Planum is the Syria Mons at 256°E 12°S.
Identification of Syria Mons in Syria Planum by Themis
Syria Planum is found between 8°-20°S and 110°-95°W. It is bound by Noctis Labyrinthus to the north and to the south by Claritas Fossae and Solis Planum. Syria Planum has long been acknowledged as a volcanic and tectonic center within the Tharsis province. Data from Mars Orbiter Laser Altimeter (MOLA) showed that the plateau is composed of dozens of small, coalesced shield volcanoes. Recently a geologic history was proposed for Syria Planum including multiple volcanic and tectonic events. A theory was developed as a geologic history of Syria Planum including tectonic and volcanic events identified in the Plateau. First, Northwest trending Noachian aged graben formed in the existing basement rock. These were enclosed by Hesperian lavas from Syria Mons, located near the center of the plateau. The lavas from the volcano flowed up to 1000 km to the southeast, covering a very large aerial extent. Sparse northeast trending faults later altered the volcano. To the east of Syria Mons, a second volcanic episode produced dozens of Hesperian aged volcanic vents whose flows coalesced to form a monogenetic volcanic field. Each shield covers an aerial extent of <1500 km2. These volcanoes are unabated to the southwest where some of their lava flows encircled the older flows of Syria Mons to the west. Finally, possibly during the opening of Noctis Labyrinthus, large scale (10s of kilometers in length) collapse features with a wide range of orientations formed within both volcanic units. Images from the Thermal Emission Imaging System (THEMIS), the Context Imager (CTX), and the High Resolution Imaging Science Experiment (HiRISE) as well as MOLA altimetry data were used to identify locations where lava erupted onto the surface of Syria Planum, forming small (up to 10s km in diameter) volcanic vents.
The Noctis Labyrinthus is a large canyon system found in the Phoenicis Lacus Region just north of the Syria Planum. Its walls contain many layers of rocks. Research, described in December 2009, found a variety of minerals—including clays, sulfates, and hydrated silicas in some of the layers. Noctis Labyrinthus, "the labyrinth of the night", is a region of Mars between Valles Marineris and the Tharsis upland. It is located in the Phoenicis Lacus Region. The region is notable for its maze-like system of deep, steep-walled valleys. The valleys and canyons of this region formed by faulting and many show classic features of grabens, with the upland plain surface preserved on the valley floor. In some places the valley floors are rougher, disturbed by landslides, and there are places where the land appears to have sunk down into pit-like formations. It is thought that this faulting was triggered by volcanic activity in the Tharsis region. Research described in December 2009 found a variety of minerals, including clays, sulfates, and hydrated silicas, in some of the layers.
Mariner 9’s image of the eastern part of the Noctis Labyrinthus near the western end of the Valles Marineris on Mars.
Linear graben, grooves, and crater chains dominate this region, along with a number of flat-topped mesas. The image is roughly 400 km across, centered at 6° S, 255°E, at the edge of the Tharsis bulge. Layers in the walls of Noctis Labyrinthus were discovered with Mars Global Surveyor,under the MOC Public Targeting Program.
Newer Image of Noctis Labyrinthus Canyon System
Ground view of the Canyons of Noctis Labyrinthus
This video shows the Noctis Labyrinthus features in more detail taken by MRO and Themis.
To the north of Noctis Labyrinthus is the Noctis Fossae at 5°S 260°E. It stretches all the way to the northern border of the Phoenicis Lacus Region.
Trough in Noctis Fossae
Going to the southeast from there we come to the western edge of the Valles Marineris at 5°S 265°E. Valles Marineris (Latin for Mariner Valleys, named after the Mariner 9 Mars orbiter of 1971–72 which discovered it) is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km (2,500 mi) long, 200 km (120 mi) wide and up to 7 km (23,000 ft) deep, the Valles Marineris rift system is one of the larger canyons of the Solar System, surpassed only by the rift valleys of Earth and (in length only) by Baltis Vallis on Venus. Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge, and stretches for nearly a quarter of the planet’s circumference. The Valles Marineris system starts to it’s west with Noctis Labyrinthus.
Valles Marineris in mosaic of THEMIS infrared images from 2001 Mars Odyssey
The Noctis Labyrinthus, on the western edge of the Valles Marineris Rift System, north of the Syria Planum and east of Pavonis Mons, is a jumbled terrain composed of huge blocks which are heavily fractured. Also it contains canyons that run in different directions surrounding large blocks of older terrain. Most of the upper parts of the blocks are composed of younger fractured material thought to be of volcanic origin associated with the Tharsis bulge. The other tops are composed of older fractured material thought also to be volcanic in origin, but differentiated from the younger material by more ruggedness and more impact craters. The sides of the blocks are composed of undivided material thought to be basement rock. The space between the blocks is composed mainly of either rough or smooth floor material. The rough floor material tends to be in the eastern portion of the Noctis Labyrinthus and is thought to be debris from the walls or maybe Aeolian features covering rough topography and landslides. The smooth floor material is thought to be composed of fluvial material and/or Aeolian features covering an otherwise rough and jumbled terrain. Terrains such as Noctis Labyrinthus are commonly found at the head of outflow channels, like the one explored by the Pathfinder mission and its Sojourner rover. They are interpreted to be a place of downward block faulting associated with the removal of ground fluid in catastrophic flood sequences. The fluid could be either carbon-dioxide ice and gas or water. Water is the prevailing theory, but one scientist proposes carbon dioxide gas/liquid as an agent of flooding.
Both the Tithonium Chasma and Ius Chasma extend eastward from the Noctis Labyrinthus into the main area of the Valles Marineris Canyon.
Northwest Ius Chasma
Crossing the Ius Chasma to the southeast we come to Oudemans Crater at 10°S 268°E. Oudemans Crater is an example of very pristine morphology since small features in its ejecta and on its floor are preserved. Being young, it does not display water erosion on its rim. Unlike some craters, Oudemans Crater does not have alluvial fans on its floor. In places, its rim has a terrace.
Layers in Oudemans Crater Wall, as seen by HiRISE. You can see many fine layers in walls of this crater.
Its location puts it near the intersection of Noctis Labyrinthus and the Ius Chasma of the Valles Marineris rift system. It is approximately 90 km wide, indicating it was caused by a meteorite 4.5 km in diameter. Nick Hoffman proposes that this might be the trigger that caused the formation of the flow deposits on the east end of the Valles Marineris System. He proposes that the impact heated up subsurface carbon dioxide permafrost causing explosive decompression that flooded down the Valles Marineris into the Northern Plains of Mars. The central uplift of Oudemans Crater exposes layered rock that may be sedimentary. Layered rock exposed in the central uplifts are common in terrestrial impact structures, and there is abundant layering exposed in the nearby Valles Marineris canyon system suggesting that layered deposits extend throughout the region. Oudemans Crater was named after Jean Abraham Chrétien Oudemans (Amsterdam, December 16, 1827 - Utrecht, December 14, 1906) he was a Dutch astronomer. He was the director of the Utrecht Observatory from 1875 until 1898, when he retired.
Going south from there we enter the Sinai Planum at 9°S 267°E. It is a plateau region that covers 900 km in area.
Plains in Sinai Planum
The Syria Planum is shown to be a composite, asymmetric crater formed by impact of at least two bolides whereas Sinai Planum is interpreted to be a result of a chain of tightly-clustered impacts , perhaps partly the result of spelled projectiles. The impact complex is portrayed as having tectonic elements including a a circumferential crustal welt, compressional crustal wedging, and an extensional regime having embedded volcanic activity including Olympus Mons and Tharsis Montes. The craters lie in the center of the crustal welt having about 135 degree surface span. Syria Planum and Sinai Planum lie at the center of a complex crustal structure interpreted to be the result of a multiple, hypervelocity (>6km/sec) impact event on Mars. Syria Planum is shown to be a composite, asymmetric crater formed by impact of at least two bolides whereas Sinai Planum is interpreted to be a result of a chain of tightly-clustered impacts , perhaps partly the result of chipped or split projectiles. The impact complex is portrayed as having tectonic elements including a a circumferential crustal welt, compressional crustal wedging, and an extensional regime having embedded volcanic activity including Olympus Mons and Tharsis Montes.
Crater Wall in Solis Planum
This dramatic perspective view looks south-east along the wall of a large eroded impact crater in the Solis Planum, bordering the mountainous Thaumasia region of Mars. Stretching for about 50 kilometers into the scene, the crater wall is around 800 meters high. Located just south and west of the Red Planet's grand Valles Marineris, this area features mountains and fault lines that are seen as evidence of surface plate motions or plate tectonics. The process of plate tectonics has long been shaping the surface of planet Earth but is thought to have been only briefly active on Mars. The image was constructed using color image data from the High Resolution Stereo Camera onboard ESA's Mars Express spacecraft. The Solis Planum extends all the way to the southern border of the Phoenicis Lacus Region.
No comments:
Post a Comment