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Phyllosilicates in Nili Fossae
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Phyllosilicates in Nili Fossae

Acquired Date: January 23, 2008
Release Date: December 20, 2013
Latitude: 22.05 N
Longitude: 74.62 E
Keywords: Crater Interior/Rim/Ejecta, Fracture/Faults, Hydrated Mineral, Layered Mineral, Phyllosilicate minerals, Dichotomy Boundary
Parameters: BD1900R/BD1950 (H2O), BD2210 (Al-OH minerals), BD2290 (Mg/Fe-OH minerals)

This image shows a site near Nili Fossae, a group of long, narrow tectonic depressions called graben. Here we see layers of clay and clay-like minerals called phyllosilicates that are found in many of the oldest rocks on Mars. Aluminum-rich phyllosilicates (shown in green) overly a layer of iron/magnesium-rich phyllosilicates (shown in magenta). In this image, faulting exposes the underlying iron-magnesium phyllosilicates in the wall of the graben. Another region of Mars exhibiting this layering surrounds the Mawrth Vallis outflow channel.



This image shows a site near Nili Fossae, a group of long, narrow tectonic depressions called graben. Here we see layers of clay and clay-like minerals called phyllosilicates that are found in many of the oldest rocks on Mars. Aluminum-rich phyllosilicates (shown in green) overly a layer of iron/magnesium-rich phyllosilicates (shown in magenta). In this image, faulting exposes the underlying iron-magnesium phyllosilicates in the wall of the graben. Another region of Mars exhibiting this layering surrounds the Mawrth Vallis outflow channel.

The recurring pattern of aluminum-phyllosilicates overlying iron/magnesium-phyllosilicates is something that we see on Earth as well. It suggests a pedogenic (soil-forming) process may have been responsible for the clay mineralís formation. This layering of minerals may imply that more soluble elements (like iron and magnesium) were leached from overlying rocks, creating a residue of aluminum-phyllosilicates overlying less-leached iron-magnesium phyllosilicates.

Link to further description of the spectral parameters shown in this image

Disclaimer: Colors shown here represent indicators of mineralogy and are not what the human eye would see.

Acknowledgements: THEMIS, MOLA, CRISM, Google Earth.

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of six science instruments on NASA's Mars Reconnaissance Orbiter. Led by The Johns Hopkins University Applied Physics Laboratory, the CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad.

CRISM's mission: Find the spectral fingerprints of aqueous and hydrothermal deposits and map the geology, composition and stratigraphy of surface features. The instrument also tracks seasonal variations in dust and ice aerosols in the Martian atmosphere, and water content in surface materials — leading to new understanding of the climate.

Credit: NASA/JPL/JHUAPL

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