The Coprates Region
MC-18
To begin, this Phase will be written differently than any of the other Phases before it. This is due to the west-east orientation of the Valles Marineris. Therefore we will be going from east to west and come back from west to east until this Phase ends. Normally I write each Phase in a north-south and south-north orientation, but not this time for the reasons I have given above.
Topographical Map of Coprates Region
The Coprates Region goes from 45° to 90° west longitude and 0° to 30° south latitude on Mars. Coprates Region is famous for the "Grand Canyon of Mars" named the Valles Marineris Canyon System. Signs of water exist in this Region as ancient river valleys. Networks of stream channels showing up as inverted terrain, and there is evidence of the past presence of lakes inside of Valles Marineris. 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. The 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.
Image of Coprates Region
The Valles Marineris system starts in the west with Noctis Labyrinthus; proceeding eastward to the Tithonium and Ius Chasmata, then Melas, Candor and Ophir Chasmata, then Coprates Chasma, then Ganges, Capri and Eos Chasmata; finally it empties into an outflow channel region containing chaotic terrain that ends in the basin of Chryse Planitia. It has been recently suggested that Valles Marineris is a large tectonic "crack" in the Martian crust. Most researchers agree that this formed as the crust thickened in the Tharsis region to the west, and was subsequently widened by erosion. However, near the eastern flanks of the rift there appear to be some channels that may have been formed by water or carbon dioxide.
Valles Marineris with labels (with associated Chasma). Image was taken with the Mars Odyssey's THEMIS.
There are at least four theories concerning it’s formation: Scientists believe that there was liquid water flowing on the Martian surface in the past. (1) Valles Marineris may have been formed by flowing water at this time. (2)Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma. (3)Around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. (4)The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, later made bigger by erosion and collapsing of the rift walls.
Topographical Map of Valles Marineris and surrounding terrain (Tharsis Montes to the West and the Chryse Planitia to the East).
Because the Valles Marineris is thought to be a large rift valley, its formation is closely tied with the formation of the Tharsis Bulge (to the west). The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, in three stages. The first stage consisted of a combination of volcanism and isostatic (the state of balance, or the equilibrium of the Mar’s lithosphere) uplift; soon, however, the volcanism loaded the crust to a point at which the crust could no longer support the added weight of Tharsis, leading to widespread graben formation in the elevated regions of Tharsis. Stage two consisted of more volcanism and a loss of isostatic equilibrium; the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures, then the Valles Marineris, formed. Stage three mainly consisted of more volcanism and asteroid impacts. The crust, having already reached its failure point, just stayed in place and younger volcanoes formed. Tharsis volcanism involved very low viscosity magma, forming shield volcanoes similar to those of the Hawaiian Island chain, but, because there seems to be no minor or no current active plate tectonics on Mars, the hotspot activity led to very long histories of repeated volcanic eruptions at the same spots, creating some of the largest volcanoes in the solar system, including the biggest, Olympus Mons.
The canyon's depth suggests that this location may be the best site for a manned outpost as it would have the highest natural air pressure on Mars. Equatorial solar irradiation and access to water would enhance this option still further. The Valles Marineris, the "Grand Canyon" of Mars, is over 3,000 km long and averages 8 km deep. Atmospheric pressure at the bottom would be some 25% higher than the surface average, 0.9 kPa vs. 0.7 kPa.
Outpost in Valles Marineris
1. We begin our survey headed west between 0-5°S:
Tithonium Chasm is a large canyon in the Coprates Region of Mars at 4.6° south latitude and 90° east longitude. It is about 810 km long and was named after a classical albedo feature name.
Tithonium Chasma Layers, as seen by HiRISE. Location is 4.6 degrees south latitude and 270.4 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE
Next we come to the Tithonium Fossae. Tithonium Fossae is located just north of Tithonium Chasma at 3°S 278°E.
Tithonium Fossae
To the northeast is the Echus Chasma at 0°S 280°East.
Echus Chasma
Echus Chasma is a Chasma in the Lunae Planum high plateau north of the Valles Marineris canyon system of Mars. Clay has been found within it, meaning that water once sat there for a time.
Echus Chasma
Echus Chasma is approximately 100 km long and 10 km wide, with valleys ranging in depth from around 1 km to 4 km. It is the source region of the Kasei Valles outflow channel, which extends northward from it. It is situated just west of Hebes Chasma, to which it does not connect.
Going to the southeast from there we come to Perrotin Crater at 3°S 282°E.
Perrotin Crater
Perrotin Crater is 84 km in diameter and was named after Henri Joseph Anastase Perrotin (December 19, 1845 – February 29, 1904) who was a French astronomer.
Heading northeast from there we come to Hebes Chasma at 0° 283°E., right on the Equator and to it’s south. This video will give you an idea of how big these Chasma in the Valles Marineris can be.
Hebes Chasma
Hebes Chasma is a large enclosed valley in the northern part of the Coprates Region , it may have once held water. Hydrated minerals have been found there. It is thought that large-scale underground springs of groundwater at different times burst to the surface to form deposits called Light Toned Deposits (LTD's). Some suggest the presence of fossilized life forms may be found there because the deposits are relatively young.
The next area of interest we come to is Ophir Chasma to the southeast and is a part of the larger areas that make up the Valles Marineris. It is located at 4°S 287° E.
Aqueous Sulfate Mineralogy
Ophir Chasma is a canyon in the Coprates quadrangle of Mars at 4° south latitude and 287° east longitude. It is about 317 km long and was named after a classical albedo feature name.
Inside Ophir Chasma is the Ophir Mensa. It is a square shaped mesa inside the Chasma at 4.5°S 287°E.
Ophir Mensa
Just north of the Ophir Chasma is the Juventae Dorsa at 2.5°S 289°E.
East of the Juventae Dorsa we enter the Lunae Planum area. One of the first features we come to in southeast is the Ganges Catena at 3°S 290° E.
Ganges Catena Pit Crater Chain Cut by Wrinkle Ridge
Going south of the Ganges Catena we come to Ceti Chasma. One of the smallest Chasma thus far encountered. Ceti Chasma is located at 5° S 292° E.
Layers in Ceti Chasma
In about the center of Lunae Planum we find Dittaino Valles a channel probably originating in the Ganges Catena area whose outflow is to the north into the next Region.
Dittaino Valles at 1°S 293°E.
The western border of Lunae Planum in the Coprates Region can be said to be the Juventae Chasma whose center is at about 3° S 299° E.
Juventae Chasma
Juventae Chasma is an enormous box canyon (250 km × 100 km) on Mars which opens to the north and forms the outflow channel Maja Valles.
Image of Juventae Chasma DTM
Juventae Chasma is located north of Valles Marineris and cuts more than 5 km into the plains of Lunae Planum. The floor of Juventae Chasma is partly covered by sand dunes. There is also a 2.5 km high mountain inside Juventae, 59 km long and 23 km wide, that was confirmed by Mars Express to be composed of sulfate deposits. MRO discovered sulfates, hydrated sulfates, and iron oxides in Juventae Chasma.
To the north of Juventae Chasma is Baetis Chaos located at 1°S 300° E. It is 55 km in diameter.
Baetis Chaos Close Up
Continuing east from Baetis Chaos we enter the Xanthe Terra Area. It extends all the way to the eastern border of the Coprates Region. In it at about 305°E we come across the bottom half of the Mutch Crater on the Equator. This Crater is 211 km in diameter.
Central Uplift of Mutch Crater
In the northeast corner of the Coprates Regions lies Orson Wells Crater 0° 315° E.
Orson Welles Crater, as seen by HiRISE. Layered, light-toned rocks seem to be under a dark mantling material. Layers may be sandstone, volcanic ash, or lakebed deposits.
Orson Welles Crater: is an impact crater in the Coprates Region of Mars, located at 0.2° S and 315° E. It is 124.5 km in diameter and was named after Orson Welles, an American radio and motion picture actor and director (1915–1985). He is famous for, among other things, his radio broadcast of The War of the Worlds in which Martians invade Earth.
Now the Survey will head back west to the other side of the Coprates Region between 5-10 °S :
Ganges Chasma, as seen by Themis. The location is 6.4 degrees south latitude and 310.7 degrees east longitude. Image is about 18 km wide.
Ganges Chasma is a deep canyon at the eastern end of the vast Valles Marineris system on Mars, an offshoot of Capri Chasma. It is named after the River Ganges in South Asia. Ganges Chasma is thought to have formed through a series of catastrophic discharges of water and CO2 from chaos terrains such as that preserved in Ganges Chaos at its southern margin. Most of the evidence for these discharges and the ensuing collapses is believed to have been washed away. Prior to developing an outlet that joined it to Capri Chasma and the connected outflow channels to its east, Ganges Chasma may at some point in the Noachian period have contained a lake which drained northward through partially subsurface pathways into the Shalbatana Vallis.
Ganges Chasma Layers, as seen by HiRISE. Location is 8.1 degrees south latitude and 307.5 degrees east longitude. Image was taken by the Mars Reconnaissance Orbiter's HiRISE.
Images of rocks in the canyon walls almost always show layers. Some layers appear tougher than others. In the image of the Ganges Chasma Layers, as seen by HiRISE, one can see that the upper, light-toned deposits are eroding much faster than the lower darker layers. Some cliffs on Mars show a few darker layers standing out and often breaking into large pieces; these are thought to be hard volcanic rock instead of soft ash deposits. Because of its closeness to the Tharsis volcanic region, the rock layers may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions.
Close-up of layers in wall of Valles Marineri
It is likely the rock strata in the walls preserve a long geological history of Mars. Dark layers may be due to dark lava flows. The dark volcanic rock basalt is common on Mars. However, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates. Probably having been formed in water, sulfate deposits are of great interest to scientists because they may contain traces of ancient life.
Light Toned Mounds in Ganges Chasma DTM
The HiRISE DTMs are made from two images of the same area on the ground, taken from different look angles. Not all of these images have been made into DTMs due to the time-intensive process. Creating a DTM is complicated and involves sophisticated software and a lot of time, both computing time and human operator time. The great advantage of a HiRISE DTM is the high resolution of the source images.
Elaver Vallis and Vicinity
From the southern canyon of Ganges Chasma we come to the Elaver Vallis. This valley is 160 km long and named for the Allier River in France.
To the west is Morella Crater located 9.7°S 308°E. it is 79 km in diameter.
Morella Crater is the large crater in center of Picture
Morella crater is named after a place name in Spain. As we head back west we enter an area called the Ophir Planum, which forms the northern border of Valles Marineris Canyons and a central plateau area between Ganges Chasma in the east and the Valles Mariners Canyons to the west. Heading west between 5-10° S we come into the Ophir Catenae located at 9.5°S 300.6°E. It stretches all the way to Candor Chasma.
Fresh 5-Kilometer Diameter Crater Near Ophir Catenae
In planetary geology, a catena is a chain of similarly sized craters. On Mars, they are named after nearby classical albedo features as prescribed by the International Astronomical Union's rules for planetary nomenclature. While catenae on most bodies of the Solar System consist of mainly of impact craters, those on Mars consist primarily of collapse pits.
Just north of Ophir Catenae at 7° 298° E is Hydrae Chasma which is a small Chasma.
Bedrock in Hydrae Chasma
Hydrae Chasma is a deep, circular depression covering and area of about 50 kilometers.
Just southwest of Hydrae Chasma at 8° S 296 E. begins Candor Chasma.
Image: Ridges as Evidence of Fluid Alteration on the Planet Mars. Tectonic fractures within the Candor Chasma region of Valles Marineris, Mars, retain ridge-like shapes as the surrounding bedrock erodes away. This points to past episodes of fluid alteration along the fractures and reveals clues into past fluid flow and geochemical conditions below the surface.
Layers and Canyons in Candor Chasma
Candor Chasma is one of the largest canyons in the Valles Marineris canyon system on Mars. The feature is geographically divided into two halves: East and West Candor Chasmata, respectively. It is unclear how the canyon originally formed; one theory is that it was expanded and deepened by tectonic processes similar to a graben, while another suggests that it was formed by subsurface water erosion similar to a karst (a karst is a region, that includes underground streams, sinks, ravines, and gorges). MRO discovered sulfates, hydrated sulfates, and iron oxides in Candor Chasma.
Going a little more than halfway through Candor Chasma we come to the canyon wall of the Baetis Mensa at about 5.5°S 288 E.
Dark Spots on the West Side of Baetis Mensa
To the south of the Baetis Mensa we come to the Candor Mensa at 7°S 286.5 E.
The Candor Mensa
If one goes east at this point the Candor Chasma ends at 283°E. But if we continue south we pass through the Candor Chaos to enter the Melas Chasma. The Candor Chaos is located at 7°S 287 E.
Chaos on the Floor of Candor Chasma
Central and Western Melas Chasma
Melas Chasma is a canyon on Mars, the widest segment of the Valles Marineris canyon system, located east of Ius Chasma at 9.8°S, 283.6°E. It cuts through layered deposits that are thought to be sediments from an old lake that resulted from runoff of the valley networks to the west. Other theories include windblown sediment deposits and volcanic ash. Support for abundant, past water in Melas Chasma is the discovery by MRO of hydrated sulfates. In addition, sulfate and iron oxides were found by the same satellite on the floor of Melas Chasma is about 70% younger massive material that is thought to be volcanic ash whipped up by the wind into Aeolian features. It also contains rough floor material from the erosion of the canyon walls.
Ius Chasma is a large canyon in the Coprates Region of Mars at 7° south latitude and 85.8° west longitude. It is about 938 km long and was named after a classical albedo feature name.
Ius Chasma faults and floor
Ius Chasma is believed to have been shaped by a process called sapping when water seeped from the layers of the cliffs and evaporated before it reached the canyon floor. Ius Chasma also has several structural features such as east trending normal faults and grabens that deformed the canyons. Recent geomorphologic events include avalanches and minor sapping from gullies that continued to erode the canyon walls. Because of its closeness to the Tharsis volcanic region, the rock layers may be made of layer after layer of lava flows, probably mixed with deposits of volcanic ash that fell out of the air following big eruptions. Dark layers may be due to dark lava flows, however, light-toned deposits may have resulted from rivers, lakes, volcanic ash, or wind blown deposits of sand or dust. The Mars Rovers found light-toned rocks to contain sulfates.
To the south of Ius Chasma is a group of Valles called Louros Valles. These Valles are located between 274°E and 282°E and between 10-7°S.
Light-Toned Material in Western Louros Valles/Sinai Planum
The Louros Valles are 517 km in length and named after the Louros River in northwestern Greece.
At the western end of the Ius Chasma we come to the Calydon Fossa located at 270°E 7.5°S.
Calydon Fossa
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