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Olivine, Carbonate, and Phyllosilicates in Nili Fossae
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Olivine, Carbonate, and Phyllosilicates in Nili Fossae

Acquired Date: January 13, 2007
Release Date: September 13, 2013
Latitude: 22.26 N
Longitude: 77.07 E
Keywords: Fracture/Faults, Volcanic Feature, Carbonate Mineral, Mafic minerals, Phyllosilicate minerals, Dichotomy Boundary
Parameters: BD2500H2 (Mg-carbonates), D2300 (Fe-Mg phyllosilicates), OLINDEX3 (Olivine)

This image shows a site near Nili Fossae, a group of long, narrow tectonic depressions called grabens. This CRISM image displays olivine-rich rocks in red, rocks rich in iron/magnesium-containing clay-like minerals called phyllosilicates in green, and small exposures of carbonate minerals in light yellow or white. Olivine is present in most places on Mars and reflects the volcanic nature of most crustal materials. Phyllosilicates, in contrast, show where water was present at least at one point in time. Carbonate minerals were first found on Mars using CRISM data in 2008. Before then, it was thought that martian carbonate was as a sink for an ancient atmosphere. CRISM data suggest that there is too little carbonate in the crust to hold a thick, ancient atmosphere.



This image shows a site near Nili Fossae, a group of long, narrow tectonic depressions called grabens. This CRISM image displays olivine-rich rocks in red, rocks rich in iron/magnesium-containing clay-like minerals called phyllosilicates in green, and small exposures of carbonate minerals in light yellow or white. Olivine is present in most places on Mars and reflects the volcanic nature of most crustal materials. Phyllosilicates, in contrast, show where water was present at least at one point in time. Carbonate minerals were first found on Mars using CRISM data in 2008. Before then, it was thought that martian carbonate was as a sink for an ancient atmosphere. CRISM data suggest that there is too little carbonate in the crust to hold a thick, ancient atmosphere.

The geology of the Nili Fossae region is dominated by the Isidis impact basin just to the east, visible in the global view as a light blue circle. The olivine-rich unit occurs throughout Nili Fossae and may be either volcanic lava or olivine-rich impact melt that was splashed into this location during the formation of Isidis. The grabens are concentric to the basin and may have formed from stresses around the impact site. The carbonates present may be a product of interaction of olivine with groundwater on ancient Mars, or it may have formed in springs or lakes. Carbonate, olivine, and clay-bearing rocks are exposed where an overlying layer of volcanic rock (shown in dark/black color) was removed by erosion.

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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