Memnonia quadrangle

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Memnonia quadrangle
USGS-Mars-MC-16-MemnoniaRegion-mola.png
Map of Memnonia quadrangle from Mars Orbiter Laser Altimeter (MOLA) data. The highest elevations are red and the lowest are blue.
Coordinates 15°00′S 157°30′W / 15°S 157.5°W / -15; -157.5Coordinates: 15°00′S 157°30′W / 15°S 157.5°W / -15; -157.5
Image of the Memnonia Quadrangle (MC-16). The south includes heavily cratered highlands intersected, in the northeastern part, by Mangala Vallis. The north contains undulating wind-eroded deposits and the east contains lava flows from the Tharsis region.

The Memnonia quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Memnonia quadrangle is also referred to as MC-16 (Mars Chart-16).[1]

The quadrangle is a region of Mars that covers latitude -30° to 0° and longitude 135° to 180°.[2] The western part of Memnonia is a highly cratered highland region that exhibits a large range of crater degradation.

Memnonia includes these topographical regions of Mars (listed North to South):

Recently, evidence of water was found in the area. Layered sedimentary rocks were found in the wall and floor of Columbus Crater. These rocks could have been deposited by water or by wind. Hydrated minerals were found in some of the layers, so water may have been involved.[3]

Many ancient river valleys Vallis including Mangala Vallis, have been found in the Memnonia quadrangle. Mangala appears to have begun with the formation of a graben, a set of faults that may have exposed an aquifer.[4] Dark slope streaks and troughts (fossae) are present in this quadrangle.

Layers[edit]

Columbus Crater 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 find dust. Other layers break up into large boulders so they are probably much harder. Basalt, a volcanic rock, is thought to in the layers that form boulders. Basalt has been identified on Mars in many places. Instruments on orbiting spacecraft have detected clay (also called phyllosilicate) in some layers. Recent research with an orbiting near-infrared spectrometer, which reveals the types of minerals present based on the wavelengths of light they absorb, found evidence of layers of both clay and sulfates in Columbus crater.[5] This is exactly what would appear if a large lake had slowly evaporated.[6] Moreover, because some layers contained gypsum, a sulfate which forms in relatively fresh water, life could have formed in the crater.[7]

Scientists are excited about finding hydrated minerals such as sulfates and clays on Mars because they are usually formed in the presence of water.[8] Places that contain clays and/or other hydrated minerals would be good places to look for evidence of life.[9]

Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers.[10]

Mangala Vallis[edit]

Mangala Vallis is a major channel system that contains several basins which filled, then the overflow went through a series of spillways.[11][12] One source of waters for the system was Memonia Fossae, but water also probably came from a large basin centered at 40 degrees S.[13][14]

Craters[edit]

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.[15] The peak is caused by a rebound of the crater floor following the impact.[16] 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. At times, bright rays surround craters because the impact has gone down to a bright layer of rocks, then thrown out the bright rocks on the darker surface. An image below from Mars Global Surveyor shows this.

Dark slope streaks[edit]

Many places on Mars show dark slope streaks on steep slopes like crater walls. It seems that the youngest streaks are dark; they become lighter with age.[17] Often they begin as a small narrow spot then widen and extend downhill for hundreds of meters. Several ideas have been advanced to explain the streaks. Some involve water.[18] or even the growth of organisms.[19][20] 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. We know a lot about this dust because the solar panels of Mars Rovers get covered with dust. The power of the Rovers has been saved many times by the wind, in the form of dust devils, that have cleared the panels and boosted the power. From these observations with the Rovers, we know that the process of dust coming out of the atmosphere then returning happens over and over.[21]

It is most generally accepted that the streaks represent avalanches of dust.[22] The streaks appear in areas covered with dust. When a thin layer of dust is removed, the underlying surface is dark. Much of the Martian surface is covered with dust. Dust storms are frequent, especially when the spring season begins in the southern hemisphere. At that time, Mars is 40% closer to the sun. The orbit of Mars is much more elliptical then the Earth's. That is the difference between the farthest point from the sun and the closest point to the sun is very great for Mars, but only slight for the Earth. Also, every few years, the entire planet is engulfed in a global dust storm. When NASA's Mariner 9 craft arrived there, nothing could be seen through the dust storm.[16][23] Other global dust storms have also been observed, since that time. Dark streaks can be seen in the image below taken with HiRISE of the central mound in Nicholson Crater. At least one streak in the image splits into two when encountering an obstacle.

Research, published in January 2012 in Icarus, found that dark streaks were initiated by airblasts from meteorites traveling at supersonic speeds. The team of scientists was led by Kaylan Burleigh, an undergraduate at the University of Arizona. After counting some 65,000 dark streaks around the impact site of a group of 5 new craters, patterns emerged. The number of streaks was greatest closer to the impact site. So, the impact somehow probably caused the streaks. Also, the distribution of the streaks formed a pattern with two wings extending from the impact site. The curved wings resembled scimitars, curved knives. This pattern suggests that an interaction of airblasts from the group of meteorites shook dust loose enough to start dust avalanches that formed the many dark streaks. At first it was thought that the shaking of the ground from the impact caused the dust avalanches, but if that was the case the dark streaks would have been arranged symmetrically around the impacts, rather than being concentrated into curved shapes.[24][25]

Fossa on Mars[edit]

Large troughs (long narrow depressions) are called fossae in the geographical language used for Mars. This term is derived from Latin; therefore fossa is singular and fossae is plural.[26] Troughs form when the crust is stretched until it breaks. The stretching can be due to the large weight of a nearby volcano. 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.[27] Lake George, in northern New York State, is a lake that sits in a graben.

Other ideas have been suggested for the formation of fossae. 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. Dikes caused both by tectonic stretching (extension) and by dikes are found in Iceland.[28] An example of a graben caused by a dike is shown below in the image Memnonia Fossae, as seen by HiRISE.

It appears that the water started coming out of the surface to form Mangala Vallis when a graben was formed.[4][29]

Valles[edit]

See also[edit]

References[edit]

  1. ^ 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.
  2. ^ USGS Astrogeology: Planetary Map Listing
  3. ^ "HiRISE | Sedimentary Layers in Columbus Crater (PSP_010281_1510)". Hirise.lpl.arizona.edu. Retrieved 2012-08-04. 
  4. ^ a b "Mars Channels and Valleys". Msss.com. Retrieved 2012-08-04. 
  5. ^ Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier.NY.
  6. ^ Wray, J. et al. 2009. Columbus Crater and other possible plaelakes in Terra Sirenum, Mars. Lunar and Planetary Science Conference. 40: 1896.
  7. ^ "Martian "Lake Michigan" Filled Crater, Minerals Hint". News.nationalgeographic.com. 2010-10-28. Retrieved 2012-08-04. 
  8. ^ "Target Zone: Nilosyrtis? | Mars Odyssey Mission THEMIS". Themis.asu.edu. Retrieved 2012-08-04. 
  9. ^ "HiRISE | Craters and Valleys in the Elysium Fossae (PSP_004046_2080)". Hirise.lpl.arizona.edu. Retrieved 2012-08-04. 
  10. ^ "HiRISE | High Resolution Imaging Science Experiment". Hirise.lpl.arizona.edu?psp_008437_1750. Retrieved 2012-08-04. 
  11. ^ Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY.
  12. ^ Emrick, C. and R. De Hon. 1999. Flood discharge through Labou Vallis, Mars. Lunar Planet. Sci. Conf. XXX: Abstract #1893.
  13. ^ Zimbelman, J. et al. 1992. Volatile history of Mangala Valles, Mars. J. Geophys. Res. 97: 18309-18317
  14. ^ De Hon, R. 1994. Lacustrine sedimentation in lower Mangals Valles. Mars Lunar Planet. Sci. Conf. XXVII: 295-296
  15. ^ "Stones, Wind, and Ice: A Guide to Martian Impact Craters". Lpi.usra.edu. Retrieved 2012-08-04. 
  16. ^ a b Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 978-0-8165-1257-7. Retrieved 7 March 2011. 
  17. ^ Schorghofer, N, et al. 2007. Three decades of slope streak activity on Mars. Icarus. 191:132-140.
  18. ^ [1][dead link]
  19. ^ [2][dead link]
  20. ^ [3][dead link]
  21. ^ "Mars Spirit Rover Gets Energy Boost From Cleaner Solar Panels". Sciencedaily.com. 2009-02-19. Retrieved 2012-08-04. 
  22. ^ Ferris, J. C.; Dohm, J.M.; Baker, V.R.; Maddock III, T. (2002). Dark Slope Streaks on Mars: Are Aqueous Processes Involved? Geophys. Res. Lett., 29(10), 1490, doi:10.1029/2002GL014936
  23. ^ ISBN 0-517-00192-6
  24. ^ Kaylan J. Burleigh, Henry J. Melosh, Livio L. Tornabene, Boris Ivanov, Alfred S. McEwen, Ingrid J. Daubar. Impact air blast triggers dust avalanches on Mars. Icarus, 2012; 217 (1): 194 doi:10.1016/j.icarus.2011.10.026
  25. ^ "Red Planet Report | What's up with Mars". Redplanet.asu.edu. Retrieved 2012-08-04. 
  26. ^ "Mars Art Gallery Martian Feature Name Nomenclature". Marsartgallery.com. Retrieved 2012-08-04. 
  27. ^ "HiRISE | Craters and Pit Crater Chains in Chryse Planitia (PSP_008641_2105)". Hirise.lpl.arizona.edu. Retrieved 2012-08-04. 
  28. ^ "HiRISE | Graben in Memnonia Fossae (PSP_005376_1575)". Hirise.lpl.arizona.edu. Retrieved 2012-08-04. 
  29. ^ Michael H. Carr (2006). The surface of Mars. Cambridge University Press. ISBN 978-0-521-87201-0. Retrieved 21 March 2011. 

External links[edit]

Mars Quad Map
About this image
MC-16
Memnonia