View source for Mare Tyrrhenum quadrangle

{{Mars atlas}}
{| class="wikitable sortable"
|MC-22
|Mare Tyrrhenum
|0–30° S
|90–135° E
|[[Mars Quadrangles|Quadrangles]]
|[[Mars Atlas|Atlas]]
|}
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The Mare Tyrrhenum quadrangle contains a rich variety of features that include one of the planet’s oldest volcanoes, and many of the usual beautiful landscapes on the planet such as columnar jointing, craters, dunes, ridge networks, and even a landslide. In this article, some of the best pictures from a number of spacecraft will show what the landscape looks like in this region. The origins and significance of all features will be explained as they are currently understood.

==Geography and origin of name==

Most of the region contains heavily cratered highlands. The central part contains Tyrrhena Patera (a very old volcano).  The Mare Tyrrhenum quadrangle encompasses parts of the regions Tyrrhena Terra, Hesperia Planum, and Terra Cimmeria.  Mare Tyrrhenum's largest crater is Herschel. Licus Vallis and the Ausonia Montes are other major features in the region.
The Mare Tyrrhenum quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS). This quadrangle is also referred to as MC-22 (Mars Chart-22).<ref>Davies, M.E.; Batson, R.M.; Wu, S.S.C. “Geodesy and Cartography” in Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; Matthews, M.S., Eds. ''Mars.'' University of Arizona Press: Tucson, 1992.</ref>  
This quadrangle covers the area from 0° to 30° south latitude and 225° to 270° west longitude (135-90 E).  Giovanni 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.<ref>Hartmann, W. 2003. A Traveler's Guide to Mars. Workman Publishing. NY NY.</ref> <ref>Carr, M.  2007.  The surface of Mars.  Cambridge University Press.  New York. </ref> 

==Importance of craters==

The density of impact craters is used to determine the surface ages of Mars and other solar system bodies.<ref>http://www.lpi.usra.edu/publications/slidesets/stones/</ref>   The older the surface, the more craters present.  The floors of many craters have dunes.  Dunes form in them because wind on Mars is not strong enough to lift sand grains all the way out of a crater.  The Mare Tyrrhenum quadrangle lies in the southern hemisphere—an old region with many craters.
The area around craters may be rich in minerals.  On Mars, heat from an 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.  Perhaps this process will have made the  area around Martian craters rich in useful ores for the future colonization of Mars.<ref>http://www.indiana.edu/~sierra/papers/2003/Patterson.html.</ref>

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Image:27097craterdepressionwide.jpg|Depression on crater floor 

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[[File: 27097craterdepression.jpg|600pxr|Close-up of depression on crater floor  Rectangle represents the size of a football field.]]
Close-up of depression on crater floor, as seen by HiRISE under [[HiWish program]].  Rectangle represents the size of a football field.


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Image:ESP 037844 1690dunes.jpg|Dunes in crater

Image:ESP 034956 1745dunescraters.jpg|Dunes among craters  Some of these dunes are Barchans
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==Hydrothermal features in Auki==

The crater Auki shows ridge networks that some researchers believe 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 force the resulting water to move through cracks that were generated during impact.  This water will eventually deposit minerals.  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.<ref>Osinski, G., et al.  2013.  Impact-generated hydrothermal systems on Earth and Mars.  Icarus: 224, 347-363.</ref>  Ridges found in and around the center of Auki are evidence of hydrothermal processes. This crater contains ridges that may have been produced after fractures formed as a result of an impact.  Using instruments on the [[Mars Reconnaissance Orbiter]] they found the minerals smectite (clay), silica, zeolite, serpentine, carbonate, and chlorite that are common in impact-induced hydrothermal systems on Earth.<ref>Carrozzo, F. et al.  2017.  Geology and mineralogy of the Auki Crater, Tyrrhena Terra, Mars: A possible post impact-induced hydrothermal system.  281: 228-239</ref> <ref>Loizeau, D. et al.  2012.  Characterization of hydrated silicate-bearing outcrops in tyrrhena Terra, Mars: implications to the alteration history of Mars.  Icarus:  219, 476-497.</ref> <ref>Naumov, M.  2005.  Principal features of impact-generated hydrothermal circulation systems: mineralogical and geochemical evidence.  Geofluids: 5, 165-184.</ref> <ref>Ehlmann, B., et al.  2011. Evidence for low-grade metamorphism, hydrothermal alteration, and diagenesis on Mars from phyllosilicate mineral assemblages.  Clays Clay Miner: 59, 359-377.</ref> <ref>Osinski, G. et al.  2013.  Impact-generated hydrothermal systems on Earth and Mars.  Icarus: 224, 347-363.</ref> <ref>Schwenzer, S., D. Kring.  2013.  Alteration minerals in impact-generated hydrothermal systems – Exploring host rock variability.  Icarus:  226, 487-496.</ref>   Evidence of other hydrothermal systems around craters other than Auki has been found by different groups of scientists.<ref>Marzo, G., et al.  2010.   Evidence for hesperian impact-induced hydrothermalism on Mars.  Icarus: 667-683.</ref> <ref>Mangold, N., et al.  2012.  Hydrothermal alteration in a late hesperian impact crater on Mars.   43rd Lunar and Planetary Science.  #1209.</ref> <ref>Tornabene, L., et al.  2009. Parautochthonous megabreccias and possible evidence of impact-induced hydrothermal alteration in holden crater, Mars.   40th LPSC.  #1766.</ref>

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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


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[[File: ESP 011458 1640auki.jpg|600pxr|Close view of central portion of Auki, as seen by HiRISE  Arrow indicates ridges.  Sand dunes are present near the top of the image.]]
Close view of central portion of Auki, as seen by HiRISE  Arrow indicates ridges.  Sand dunes are present near the top of the image.


[[File: 11458 1640ridgesauki.jpg|600pxr|Close view of ridges from previous image  Arrow indicates an "X" shaped ridge.]]
Close view of ridges from previous image  Arrow indicates an "X" shaped ridge.

==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 70's with the Mariner 9 orbiter.<ref>Baker, V.  1982.  The Channels of Mars. Univ. of Tex. Press, Austin, TX</ref> <ref>Baker, V., R. Strom, R., V. Gulick, J. Kargel, G. Komatsu, V. Kale.  1991.  Ancient oceans, ice sheets and the hydrological cycle on Mars. Nature 352, 589–594.</ref> <ref>Carr, M.  1979.  Formation of Martian flood features by release of water from confined aquifers. J. Geophys. Res. 84, 2995–300.</ref> <ref>Komar, P.  1979. Comparisons of the hydraulics of water flows in Martian outflow channels with flows of similar scale on Earth. Icarus 37, 156–181.</ref> 
Vallis (plural ''valles'') is the Latin word for 'valley. It is used in planetary geology for the naming of 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;  river valleys were found in many areas.  Spacecraft cameras showed that floods of water broke through dams, carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers.<ref>Kieffer|title=Mars|url=https://books.google.com/books?id=NoDvAAAAMAAJ|accessdate=7 March 2011|date=1992|publisher=University of Arizona Press|</ref> <ref>Raeburn, P.  1998.  Uncovering the Secrets of the Red Planet Mars.  National Geographic Society.  Washington D.C.</ref> <ref>Moore, P. et al.  1990.  The Atlas of the Solar System. Mitchell Beazley Publishers NY, NY.</ref>

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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.

ESP 045848 1745channel.jpg|Channel

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==Linear ridge networks==

Linear ridge networks are found in various places on Mars in and around craters.<ref>Head, J., J. Mustard.  2006.  Breccia dikes and crater-related faults in impact craters on Mars: Erosion and exposure on the floor of a crater 75 km in diameter at the dichotomy boundary, Meteorit. Planet Science: 41, 1675-1690.</ref>   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.  Scientists are not totally sure what caused these ridges, but one popular idea is that impacts created fractures in the surface, these fractures later acted as channels for fluids.  Fluids hardened.  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 past water because clay requires water to be produced.<ref>Mangold et al.  2007.    Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 2. Aqueous alteration of the crust.  J. Geophys. Res., 112, doi:10.1029/2006JE002835.</ref> <ref>Mustard et al., 2007.  Mineralogy of the Nili Fossae region with OMEGA/Mars Express data: 1. Ancient impact melt in the Isidis Basin and implications for the transition from the Noachian to Hesperian, J. Geophys. Res., 112.</ref> <ref>Mustard et al.,  2009.  Composition, Morphology, and Stratigraphy of Noachian Crust around the Isidis Basin, J. Geophys. Res., 114, doi:10.1029/2009JE003349.</ref>  Water here could have supported past life in these locations.  Clay near these structures could preserve fossils or other traces of past life.

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ESP 045992 1780ridges.jpg|Wide view of several groups of linear ridges

45992 1780ridgeswide.jpg|Close view of ridges

45992 1780blocks.jpg|Close view of ridges  Arrows indicate fractures in ridge

45992 1780roughblocks.jpg|Blocks probably formed after fracturing in ridges Image, as seen by HiRISE under [[HiWish program]]


46269 1770ridgesclose.jpg|Close view of ridge networks


46269 1770ridgesindepression.jpg|Close view of ridge networks  Since some ridges are at the bottom of the depression, the ridges may be from a lower and therefore older layer.

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==Dunes==


[[File:45822 1688duneirb.jpg|600pxr|Close, color view of dunes  Ripples are visible on dune surface.]]
                           Close, color view of dunes  Ripples are visible on dune surface.

Sand dunes have been found in many places on Mars.  They are usually in low spots—like crater floors.  In HiRISE images they can appear in a variety of pretty colors.  The colors are somewhat artificial.  NASA modifies colors to determine mineral composition.  The presence of dunes shows that the planet has an atmosphere with wind, for dunes require wind to pile up the sand.  Although Mars has strong winds at times, we must remember that the Martian atmosphere is only about 1 % as dense as the Earth's.  Hence, a wind speed of a 60-mph storm on Mars would feel more like 6 mph (9.6 km/hr).<ref> https://www.space.com/30663-the-martian-dust-storms-a-breeze.html</ref>  Most dunes on Mars are black because of the weathering of the volcanic rock basalt.<ref>http://hirise.lpl.arizona.edu/ESP_016459_1830</ref> <ref name>Michael H. Carr|title=The surface of Mars|url=https://books.google.com/books?id=uLHlJ6sjohwC|accessdate=21 March 2011|year=2006|publisher=Cambridge University Press|</ref>   Black sand can be found on Earth on Hawaii and on some tropical South Pacific islands.<ref>https://www.desertusa.com/desert-activity/sand-dune-wind1.html</ref>  
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.<ref>https://www.youtube.com/watch?v=ur_TeOs3S64</ref> <ref>https://uanews.arizona.edu/story/the-flowing-sands-of-mars</ref> <ref>Cardinale, M., S. Silvestro,  D. Vazd, T.  Michaels, M. Bourke, G. Komatsu, L.  Marinangeli.  2016.  Present-day aeolian activity in Herschel Crater, Mars.  Icarus: 265, 139-148.</ref>
For a dune to move, 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).<ref>Namowitz, S., Stone, D.  1975.  earth science the world we live in.  American Book Company.  New York.</ref>  When iimages are enlarged, some dunes on Mars display ripples on their surfaces.<ref>https://www.jpl.nasa.gov/news/news.php?feature=6551</ref>

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ESP 045822 1680dunes.jpg|Dunes
45822 1680dunesclose.jpg|Close view of dunes

ESP 052639 1680dunes.jpg|Dunes
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
File:54774 1700dune.jpg|Close view of a dune

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==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.<ref>http://hirise.lpl.arizona.edu?PSP_008437_1750 |title=HiRISE &#124; High Resolution Imaging Science Experiment |publisher=Hirise.lpl.arizona.edu?psp_008437_1750 |date= |</ref>

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47838 1780layers2.jpg|Layered features, as seen by HiRISE under [[HiWish program]]  Arrows show location of some layers.

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[[File: 47838 1780layersshadows.jpg|600pxr|Layered features]]
                            Layered features


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ESP 050397 1735craterwalllayers.jpg|Layers in crater wall
 
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==Columnar Jointing==

Lava flows sometimes cool to form large groups of more-or-less equally sized columns.<ref>http://volcano.oregonstate.edu/columnar-jointing</ref> <ref>Bates, R. and J. Jackson (eds.)  1976.  Dictionary of Geological Terms.  Doubleday, New York.</ref>   These joints have been seen on Mars.<ref>McEwen, A. et al.  2017.  Mars  The Pristine Beauty of the Red Planet.  University of Arizona Press.  Tucson.</ref>

 
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ESP 014016 1945columnarjointing.jpg|Wide view of crater that has columnar jointing that is visible in enlarged images that follow.  

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.   

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[[File: 14016 1945columnarjointing.jpg|600pxr|Close view of crater wall with columnar jointing labeled]]
                     Close view of crater wall with columnar jointing labeled  

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Image:Parana traps.JPG|Columnar jointing on the Earth

Image:Sounkyo 01 a.jpg|Columnar jointing on the Earth along highway

Image:Columnar Jointing in Yellowstone.JPG|Columnar Jointing in Yellowstone National Park.

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==Other views in Mare Tyrrhenum quadrangle==

[[File: Mare Tyrrhenum map.JPG|600pxr|Viking map of Mare Tyrrhenum quadrangle showing some major features. The small colored rectangles represent areas imaged in high resolution with camera on [[Mars Global Surveyor]].]]  

Viking map of Mare Tyrrhenum quadrangle showing some major features. The small colored rectangles represent areas imaged in high resolution with camera on [[Mars Global Surveyor]].  


[[File: Tyrrhena Patera.JPG|600pxr|Tyrrhenus Mons, as seen by HiRISE and suggested by Ehsan Sanaei's high school astronomy club in Yazd, Iran.  it is great that NASA allows amateurs, especially kids to help explore Mars.]]



Tyrrhenus Mons, as seen by HiRISE and suggested by Ehsan Sanaei's high school astronomy club in Yazd, Iran.  it is great that NASA allows amateurs, especially kids to help explore Mars.


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Image:Tyrrhena Patera.JPG|Tyrrhenus Mons, as seen by HiRISE and suggested by Ehsan Sanaei's high school astronomy club in Yazd, Iran. 
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47337curvedridges.jpg|Mostly curved ridges 

47337curvedridgeslayersclose.jpg|Ridges, some of which seem to have layers  Picture taken with HiRISE under HiWish program


File:ESP 055026 1590landslide.jpg|Landslide

File:ESP 057584 1730fractures.jpg|Fractured crater floor
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[[File: ESP 056726 1695ejectalobes.jpg|Ejecta lobes indicated with arrows in a crater]]
                       Ejecta lobes indicated with arrows in a crater

==See also==

*[[Geography of Mars]]
* [[HiWish program]]
*[[High Resolution Imaging Science Experiment (HiRISE)]]
*[[How are features on Mars Named?]]
*[[Layers on Mars]]
*[[Mars Global Surveyor]]
*[[Rivers on Mars]]

== 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 ==

* [https://www.flickr.com/photos/136797589@N04/34264306316/ 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]])