User:Nicki Button/Class: Development of the Terrestrial Planets
Chloride Deposits on Mars (Class Wiki Page)
Across the southern highlands of Mars, approximately 640 sites of chloride deposits have been identified using the Thermal Emission Imaging System (THEMIS). These isolated patches (average size = 24 +/- 76 km2). [1] They have been dated to the older geologic periods on Mars: Noachian (4.5 – 3.5 billion years ago) and Hesperian (3.5 – 2.9 billion years ago) periods. Chlorides on Earth form through aqueous processes. The importance of finding these features on Mars is that it provides further evidence for the presence of surface or subsurface water in ancient Mars. [2]
Importance of Chlorides
Chlorides contain the anion Cl- and are soluble in water, meaning they provide evidence of past aqueous processes, which helps to constrain the type of environment at a particular region. On Earth, two main processes form chlorides: efflorescence and precipitation. Whereas on Earth these minerals are formed in more alkaline environments, the minerals on Mars form from more acidic fluids and the processes are connected to basaltic weathering. [3] The key similarity between the formation of chlorides on the two planets is the presence of water. This is important because water is essential to life on Earth, and therefore drives the search for evidence of life on other planets. Chlorides are of particular interest because of their potential to preserve a biological signature through chemical sedimentation.[2]
Methods for Identification
The chloride salts were identified using THEMIS on board the 2001 Mars Odyssey orbiter. The spectrum from THEMIS shows a featureless slope from wavenumber (~672 to 1475 cm-1).[1] Few things describe this spectrally distinct feature, and thus has been concluded to be chloride-bearing deposits.[2] One such supporting terrestrial example is the identification of halite in Death Valley by instruments in the same wavelength as THEMIS.[2] Further investigation of these deposits using the High Resolution Imaging Science Experiment (HiRISE) on Mars Reconnaissance Orbiter (MRO) showed the features to be light-toned and irregularly-shaped fractures overlying small, degraded craters.[2]
Terra Sirenum
Terra Sirenum is located at approximately at 38.8°S, 221°E and is of interest because of its higher brightness as compared to the typical background soils. [4]
References
- ^ a b c d Osterloo, M. M. (2010). "Geologic context of proposed chloride-bearing materials on Mars". Journal of Geophysical Research. 115. doi:10.1029/2010JE003613.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d e Osterloo, M. M. (2008). "Chloride-Bearing Materials in the Southern Highlands of Mars". Science. 319. doi:10.1126/science.1150690.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Goodall, T. (2000). "Surface and subsurface sedimentary structures produced by salt crusts". Sedimentology. 47. doi:10.1046/j.1365-3091.2000.00279.x.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b Glotch, T. D. (2010). "Distribution and formation of chlorides and phyllosilicates in Terra Sirenum, Mars". Geophysical Reserach Letters. 37. doi:10.1029/2010GL044557.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)
Wikipedia Start-Up Homework (Due: Jan. 31, 2014)
1. Planetary Geology Wikipedia Pages
1. Volcanology on Mars a) https://en.wikipedia.org/wiki/Volcanism_on_Mars b) This page is useful because it explains in depth each region of volcanic activity on Mars, specifically compared to the 3 sentence section "Volcanoes" in the Wikipedia article of "Mars." c) A useful addition would be a more detailed comparison of the size of Olympus Mons to volcanoes on Earth, such as through a diagram and citing the sources that explain why on Earth volcanoes cannot become this large. d) A successful part of the written communication has a section for each region of volcanism on Mars. The page could be improved by expanding on some of the written sections about specific locations, such as Syrtis Major and Arabia Terra. e) A successful part of the visual communication is the diversity of instruments from which these images were taken. This page could be improved by including a map of Mars and indicating on that map where these regions of volcanism are.
2. Olympus Mons a) https://en.wikipedia.org/wiki/Olympus_Mons b) This page is useful because it describes the tallest volcano in our solar system, Olympus Mons. c) A useful alteration would be making the first two paragraphs more captivating in order to show the impressiveness of Olympus Mons. d) A successful part of the written communication is the diversity of details from pressure at different elevations to the geologic setting of surrounding regions. This page could be improved by dividing up the sections of "General Description" and "Geology" into more specific sections. e) A successful part of the visual communication is the row of 5 images between "General Description" and "Geology" sections. This page could be improved by including a vertical profile of Olympus Mons.
3. Shield volcano a) https://en.wikipedia.org/wiki/Shield_volcano b) This page is useful because it describes what shield volcanoes are and gives specific examples, both terrestrial and extraterrestrial. c) A useful addition would be expanding the dangers section because that is directly relevant to people's safety (even if shield volcanoes pose a low threat to humans). This could be improved by showing before and after pictures of destroyed structures in Hawaii. d) A successful part of the written communication is providing a lot of detail about the shield volcanoes in Hawaii, Galapagos Islands, Iceland, and East Africa. This page could be improved by describing more of the mineralogical features/rock type. e) A successful part of the visual communication is the diversity of images: model of a shield volcano, terrestrial volcano, and Martian (Olympus Mons) volcano. This helps the reader to fully understand what a shield volcano is. This page could be improved by including images of other extraterrestrial shield volcanoes that are less familiar than Olympus Mons.
2. Potential Wikipedia Pages
1. Volcanism Across Our Solar System a) Outline 1. Types of volcanoes 2. List of major volcanoes/regions found on each planet/satellite 2.1 What are these types of volcanoes? And why do these types of volcanoes occur on these planets/satellites? 2.2 Size 2.3 When did these eruptions occur? 2.4 Possibilities for future eruptions b) This page would be valuable because there isn't something exactly like this on Wikipedia. A similar page is "List of tallest mountains in the Solar System." However, this page doesn't explain the different types of volcanoes and why each type would occur on a given planet/satellite. My page would be a more in depth description, similar to the pages listed above, but everything would be on one page. This would reach the wider audience that is seeking to be educated on general information about volcanoes in our solar system, while providing an extensive list for the specialized audience that would want to learn more in depth. c) I would structure this page by beginning with basic geology knowledge of the types of volcanoes in order to provide a background for the audience. I would then make a section for each planet/satellite in order to describe its volcanism. I would name its major volcanoes, while providing an overview about all volcanoes on it. I would try to include a map for each planet/satellite, pending it doesn't overwhelm the page. My original figure would be a vertical profile showing the differences in height/size between the volcanoes on different planetary bodies because I have not seen it included on other Wikipedia pages and I think it would be a great visual for the audience to understand the scale of some of these volcanoes (ex. Olympus Mons).
2. Volcanic regions on Mars as compared to other regions a) Outline 1. Major areas on Mars 2. Martian timeline (Noachian, Hesperian, Amazonian) 3. Difference between the Northern and Southern latitudes b) This page would be valuable because it would describe the differences in geology across Mars (including time of formation), but the emphasis would be on the volcanic regions since everything would be compared back to them. The wider audience would learn something new about the geology of Mars, while the specialized audience would see the geologic comparison from a different angle. c) I would structure this page by beginning with explanations of the different regions on Mars, including a map. I would then describe the different geologic times of Mars since this is important to the dichotomy of the planet. My original figure would show the differences in volcanic activity in each of the geologic periods.