 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
|
 |
 |
 |
|
 |
 |
 |
|
 |
|
 |
|
 |
|
 |
|
|
Green Mineral Indicates Red Planet is Dry
The presence of a common green mineral on Mars suggests that the Red Planet could have been cold and dry since the mineral has been exposed, which may have been more than a billion years ago, according to new research appearing in the Oct. 24 edition of Science. Todd Hoefen, a Denver-based U.S. Geological Survey (USGS) geophysicist, led a team of researchers from USGS, Arizona State University and NASA, that found abundant quantities of olivine on Mars at least locally. They based their conclusions on data obtained from a Thermal Emission Spectrometer (TES) carried by NASA's Mars Global Surveyor (MGS) spacecraft. Olivine, a transparent, green-colored mineral found in many rocks containing magnesium and iron (mafic igneous rocks), is highly susceptible to chemical weathering and readily alters to other minerals in the presence of liquid water (minerals such as iddingsite, goethite, serpentine, chlorite, smectite, maghemite and hematite). Except for trace amounts of hematite, which gives Mars its red color, none of these other weathering products have been detected at kilometer scales on Mars. The team detected a 30,000 square kilometer (18,720 square mile) area rich in olivine, in the Nili Fossae region of Mars, which makes up ~ 0.02 % of the planet by area. Nili Fossae has been interpreted as a complex of grabens (long depressions between geologic faults) and fractures related to the formation of the Isidis impact basin, where post-impact faulting most plausibly exposed the locally abundant olivine. They have also found smaller deposits of olivine all over the planet, all indicating a surface at least regionally dominated by volcanic processes. For the complete article on environmental conditions on Mars, go to: http://www.gsfc.nasa.gov/topstory/2003/1022olivine.html
|
||||||
|
|
||||||
