Mare Tyrrhenum quadrangle

The Mare Tyrrhenum quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. This quadrangle is also referred to as MC-22 (Mars Chart-22). It contains parts of the regions Tyrrhena Terra, Hesperia Planum, and Terra Cimmeria.

The Mare Tyrrhenum quadrangle covers the area from 225° to 270° west longitude and 0° to 30° south latitude on Mars. Schiaparelli named the area after Earth's Tyrrhenian Sea, which lies between Italy and Sicily. The region was subsequently renamed to Mare Tyrrhena after spacecraft photos revealed that it is an old, cratered plain rather than a sea. It contains the large volcano Tyrrhenus Mons, one of the oldest, and perhaps the most complex volcanoes on Mars. Mare Tyrrhenum's largest crater is Herschel. Licus Vallis and the Ausonia Montes are other major features in the region.

Fossa on Mars

Large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. 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 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. Lake George, in northern New York State, is a lake that sits in a graben. 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. 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.Wyrick, D., D. Ferrill, D. Sims, and S. Colton. 2003. Distribution, Morphology and Structural Associations of Martian Pit Crater Chains. Lunar and Planetary Science XXXIV (2003) 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 limestone being dissolved thereby causing a void. Tyrrhenus Mons has some beautiful fossae and pit craters associated with it. These features are easily visible in the gallery image below, obtained by HiRISE.

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.

Craters

* Auki
* Briault
* Herschel
* Kinkora
* Müller
* Robert Sharp
* Resen

Importance of craters

The density of impact craters is used to determine the surface ages of Mars and other solar system bodies. The older the surface, the more craters present. Crater shapes can reveal the presence of ground ice.

The area around craters may be rich in minerals. On Mars, heat from the impact melts ice in the ground. Water from the melting ice dissolves minerals, and then deposits them in cracks or faults that were produced with the impact. This process, called hydrothermal alteration, is a major way in which ore deposits are produced. The area around Martian craters may be rich in useful ores for the future colonization of Mars.

Image:27097craterdepressionwide.jpg, Depression on crater floor, as seen by HiRISE under HiWish program. This scene is enlarged in the next two images.
Image:27097craterdepression.jpg, Close-up of depression on crater floor, as seen by HiRISE under HiWish program.
Image:27097slump.jpg, Close-up of west edge of crater depression, as seen by HiRISE under HiWish program.
Image:ESP 037844 1690dunes.jpg, Dunes in crater, as seen by HiRISE under HiWish program. Some of these dunes are Barchans.
Image:ESP 034956 1745dunescraters.jpg, Dunes among craters, as seen by HiRISE under HiWish program. Some of these dunes are Barchans. Research published in Icarus stated that the dunes in Hershel Crater moved 0.8 m in a time span of 3.7 Earth-years. Also, it was determined that dune ripple moved 1.1 m in that time period. Other dunes may exhibit a similar amount of movement.

Hydrothermal features in Auki

The crater Auki shows ridge networks that are believed to be evidence of hydrothermal processes that occurred after impact. Impacts fracture rock and create enormous amounts of heat. On Mars, this heat can cause ice to melt and then the resulting water to move through cracks that are generated during impact. This water will eventually deposit minerals. The mineral deposits may become evident when surrounding ground erodes. Deposits formed in this manner are more resistant to erosion.

Researchers have speculated that these hydrothermal effects should be common on Mars. Ridges found in and around the center of Auki are evidence. This crater contains ridges that may have been produced after fractures formed with an impact. Using instruments on the Mars Reconnaissance Orbiter they found the minerals smectite, silica, zeolite, serpentine, carbonate, and chlorite that are common in impact-induced hydrothermal systems on Earth. Other evidence of post-impact hydrothermal systems on Mars from other scientists who studied other Martian craters.

Topoauki.jpg, Topographical map showing location of Auki crater and other nearby features. Color shows elevation.
Aukicratercpx.jpg, Wide view of Auki, as seen by CTX
ESP 011458 1640auki.jpg, Close view of central portion of Auki, as seen by HiRISE Arrow indicates ridges. Sand dunes are present near the top of the image.
11458 1640ridgesauki.jpg, Close view of ridges from previous HiRISE image Arrow indicates an "X" shaped ridge.
11458 1640ridgesauki2.jpg, Close view of central section of Auki showing ridges with arrow Image is an enlargement of a previous HiRISE image.

Channels

There is enormous evidence that water once flowed in river valleys and channels on Mars. Images of curved channels have been seen in images from Mars spacecraft dating back to the early seventies with the Mariner 9 orbiter.
''Vallis'' (plural ''valles'') is the Latin word for ''valley''. It is used in planetary geology for the naming of landform features on other planets, including what could be old river valleys that were discovered on Mars, when probes were first sent to Mars. The Viking Orbiters caused a revolution in our ideas about water on Mars; huge river valleys were found in many areas. Space craft cameras showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. Some valles on Mars ( Mangala Vallis, Athabasca Vallis, Granicus Vallis, and Tinjar Valles) clearly begin at graben. On the other hand, some of the large outflow channels begin in rubble-filled low areas called chaos or chaotic terrain. It has been suggested that massive amounts of water were trapped under pressure beneath a thick cryosphere (layer of frozen ground), then the water was suddenly released, perhaps when the cryosphere was broken by a fault.

Image:24341channel.jpg, Small meandering channel in the stream bed of a larger channel. Water probably eroded the two channels at different times. Image from HiRISE under the HiWish program.
Image:25897ausoniachannel.jpg, Channel in Ausonia Mensa, as seen by HiRISE under the HiWish program.
Image:Licus Vallis.JPG, Licus Vallis, as seen by HiRISE
ESP 045848 1745channel.jpg, Channel, as seen by HiRISE under the HiWish program.

Linear ridge networks

Linear ridge networks are found in various places on Mars in and around craters. Ridges often appear as mostly straight segments that intersect in a lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind.
Since the ridges occur in locations with clay, these formations could serve as a marker for clay which requires water for its formation. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life.

ESP 036893 1765ridgesnepenthestop.jpg, Linear ridge network, as seen by HiRISE under HiWish program
ESP 045992 1780ridges.jpg, Wide view of several groups of linear ridges, as seen by HiRISE under HiWish program
45992 1780curvedridges.jpg, Close view of curved ridges, as seen by HiRISE under HiWish program Note: this is an enlargement of previous image.
45992 1780ridgeswide.jpg, Close view of ridges, from a previous image, as seen by HiRISE under HiWish program
45992 1780blocks.jpg, Close view of ridges, from a previous image, as seen by HiRISE under HiWish program Arrows indicate fractures in ridge
45992 1780roughblocks.jpg, Blocks probably formed after fracturing in ridges Image, as seen by HiRISE under HiWish program
ESP 046269 1770ridges.jpg, Wide view of ridge networks, as seen by HiRISE under HiWish program Parts of this are enlarged in next three images.
46269 1770ridgesclose.jpg, Close view of ridge networks, as seen by HiRISE under HiWish program
46269 1770ridgesclose2.jpg, Close view of ridge networks, as seen by HiRISE under HiWish program
46269 1770ridgesindepression.jpg, Close view of ridge networks, as seen by HiRISE under HiWish program Since some ridges are at the bottom of the depression, the ridges may be from a lower layer.

Dunes

Sand dunes have been found in many places on Mars. The presence of dunes shows that the planet has an atmosphere with wind, for dunes require wind to pile up the sand. Most dunes on Mars are black because of the weathering of the volcanic rock basalt. Black sand can be found on Earth on Hawaii and on some tropical South Pacific islands.
Sand is common on Mars due to the old age of the surface that has allowed rocks to erode into sand. Dunes on Mars have been observed to move many meters.
Some dunes move along. In this process, sand moves up the windward side and then falls down the leeward side of the dune, thus caused the dune to go toward the leeward side (or slip face).
When images are enlarged, some dunes on Mars display ripples on their surfaces. These are caused by sand grains rolling and bouncing up the windward surface of a dune. The bouncing grains tend to land on the windward side of each ripple. The grains do not bounce very high so it does not take much to stop them.

ESP 045822 1680dunes.jpg, Dunes, as seen by HiRISE under HiWish program
45822 1680dunesclose.jpg, Close view of dunes, as seen by HiRISE under HiWish program
45822 1680color.jpg, Close, color view of dunes as seen by HiRISE under HiWish program Ripples are visible on dune surface.

ESP 052639 1680dunes.jpg, Dunes, as seen by HiRISE under HiWish program
52639 1680dunes.jpg, Close view of dunes, as seen by HiRISE under HiWish program
File:ESP 054774 1700dunes.jpg, Wide view of dunes among small craters, as seen by HiRISE under HiWish program
File:54774 1700dune.jpg, Close view of a dune, as seen by HiRISE under HiWish program

Layers

Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers.

ESP 047838 1780layers.jpg, Wide view of layered features, as seen by HiRISE under HiWish program
47838 1780layeredridge.jpg, Layered features, as seen by HiRISE under HiWish program

47838 1780layers2.jpg, Layered features, as seen by HiRISE under HiWish program Arrows show where some layers are.

47838 1780layersshadows.jpg, Layered features, as seen by HiRISE under HiWish program

ESP 050397 1735craterwalllayers.jpg, Layers in crater wall, as seen by HiRISE under HiWish program

52308 1765layers.jpg, Layers, as seen by HiRISE under HiWish program

Columnar Jointing

Lava flows sometimes cool to form large groups of more-or-less equally sized columns. These joints have been seen on Mars.McEwen, A. et al. 2017. Mars The Pristine Beauty of the Red Planet. University of Arizona Press. Tucson.

ESP 014016 1945columnarjointing.jpg, Wide view of crater that has columnar jointing that is visible in enlarged images that follow Picture taken with HiRISE.
14016 1945columnarjointingwide.jpg, Crater wall with columnar jointing in the location of the box Columnar joints are easily seen in the enlarged image that follows. Picture taken with HiRISE.

14016 1945columnarjointing.jpg, Close view of crater wall with columnar jointing labeled Picture taken with HiRISE.

Image:Parana traps.JPG, Columnar jointing on the Earth.
Image:Sounkyo 01 a.jpg, Columnar jointing on the Earth.
Image:Columnar Jointing in Yellowstone.JPG, Columnar Jointing in Yellowstone National Park.

Other views in Mare Tyrrhenum quadrangle

Image:Mare Tyrrhenum map.JPG, Map of Mare Tyrrhenum quadrangle. Tyrrhenus Mons is a major volcano.
Image:Ausonia Montes.JPG, The Ausonia Montes in Mare Tyrrhenum as seen by CTX.
Image:Tyrrhena Patera.JPG, Tyrrhenus Mons, as seen by HiRISE and suggested by Ehsan Sanaei's high school astronomy club in Yazd, Iran. Click on image to see excellent view of pit crater chains and concentric features around a volcano.


ESP 047337 1760curvedridges.jpg, Wide view of ridges that are mostly curved. Picture taken with HiRISE under HiWish program
47337 1760curvedridgesbottom.jpg, Mostly curved ridges Picture taken with HiRISE under HiWish program
47337 1760smallridgesclose.jpg, Ridges of different sizes, some indicated by arrows are straight. Picture taken with HiRISE under HiWish program
47337curvedridges.jpg, Mostly curved ridges Picture taken with HiRISE under HiWish program
47337curvedridgeslayersclose.jpg, Ridges, some of which seem to have layers Picture taken with HiRISE under HiWish program

ESP 049712 1525whiteridges.jpg, Wide view of linear features, as seen by HiRISE under HiWish program
49712 1525parallelridges.jpg, Close view of linear features, as seen by HiRISE under HiWish program

ESP 049712 1525ridgesclosecolor.jpg, Close, color view of linear features, as seen by HiRISE under HiWish program
File:ESP 055026 1590landslide.jpg, Landslide, as seen by HiRISE under HiWish program
File:ESP 055105 1530crater.jpg, Crater, as seen by HiRISE under HiWish program The floor appears to have dropped some.
File:ESP 056726 1695ejectalobes.jpg, Ejecta lobes in a crater, as seen by HiRISE under HiWish program

File:ESP 057584 1730fractures.jpg, Fractured crater floor, as seen by HiRISE under HiWish program

Other Mars quadrangles

Interactive Mars map

See also

* Barchan
* Columnar jointing
* Dunes
* Fossa (geology)
* Geology of Mars
* HiWish program
* HiRISE
* Impact crater
* Linear ridge networks
* List of quadrangles on Mars
* Vallis

References

Further reading

* Lorenz, R. 2014. The Dune Whisperers. The Planetary Report: 34, 1, 8-14
* Lorenz, R., J. Zimbelman. 2014. Dune Worlds: How Windblown Sand Shapes Planetary Landscapes. Springer Praxis Books / Geophysical Sciences.

External links

High resolution video
by Seán Doran of overflight of part of north central Mare Tyrrhenum quadrangle, including Tinto Vallis and Amenthes Planum (continues across the equator into Amenthes quadrangle)

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