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Prehnite and Chlorite near Arnus Vallis
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Prehnite and Chlorite near Arnus Vallis

Acquired Date: March 30, 2007
Release Date: October 25, 2013
Latitude: 15.03 N
Longitude: 72.13 E
Keywords: Channel, Crater Interior/Rim/Ejecta, Volcanic Feature, Hydrated Mineral, Phyllosilicate minerals, Dichotomy Boundary
Parameters: BD1900R/BD1950 (H2O), BD2290 (Mg/Fe-OH minerals), BD2355 (Chlorite/Prehnite/Pumpellyite/Illite)

This image shows occurrence of the minerals prehnite (cyan/blue) and chlorite (red) around the Arnus Vallis rille, a long narrow depression resembling a channel. Prehnite is found on Earth in the veins and cavities of basaltic rock deriving from volcanoes. Chlorite is a type of phyllosilicate, a family of clay-like minerals, and is formed from altered clay-rich rocks or pyroxenes. These two minerals are found in combination on Mars mostly near the Hellas impact basin, one of the largest impact craters on the planet. The location shown here is near Isidis, another large impact basin.



This image shows occurrence of the minerals prehnite (cyan/blue) and chlorite (red) around the Arnus Vallis rille, a long narrow depression resembling a channel. Prehnite is found on Earth in the veins and cavities of basaltic rock deriving from volcanoes. Chlorite is a type of phyllosilicate, a family of clay-like minerals, and is formed from altered clay-rich rocks or pyroxenes. These two minerals are found in combination on Mars mostly near the Hellas impact basin, one of the largest impact craters on the planet. The location shown here is near Isidis, another large impact basin.

Arnus Vallis is believed to have formed as an open lava channel on the flank of the the Syrtis Major volcano. This CRISM image is just east of the Arnus Vallis and covers the wall of two craters. One large, older crater has been filled in with sediments, and another central peak crater is more well preserved. Prehnite is an important discovery on Mars because it forms only at elevated temperatures, and provided the first proof that much of Marsí ancient Noachian crust consists of metamorphic rock.

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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