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Mafic minerals and phyllosilicates in Elorza crater’s central pit
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Mafic minerals and phyllosilicates in Elorza crater’s central pit

Acquired Date: October 10, 2007
Release Date: July 20, 2020
Latitude: 8.74 S
Longitude: -55.20 E
Keywords: Crater Interior/Rim/Ejecta, Hydrated Mineral, Mafic minerals, Phyllosilicate minerals, Valles Marineris
Parameters: HCPINDEX2 (High-Calcium Pyroxene), LCPINDEX2 (Low-Calcium Pyroxene), OLINDEX3 (Olivine)

Elorza crater is a central pit crater (CPC) located to the north of Coprates Chasma and west of Ganges Chasma in Valles Marineris. CPCs are a type of complex crater that display central depressions on their floors instead of (or on top of) central peaks. The presence of a pit on the central peak of Elorza suggests that there was a volatile-rich material present before the crater formed, as CPCs are thought to form due to a release of volatiles during impact or a drainage of subsurface volatiles after the impact event.



Elorza crater is a central pit crater (CPC) located to the north of Coprates Chasma and west of Ganges Chasma in Valles Marineris. CPCs are a type of complex crater that display central depressions on their floors instead of (or on top of) central peaks. The presence of a pit on the central peak of Elorza suggests that there was a volatile-rich material present before the crater formed, as CPCs are thought to form due to a release of volatiles during impact or a drainage of subsurface volatiles after the impact event.

The CRISM image highlights the mineralogy surrounding the crater’s central pit/peak complex. Low-calcium pyroxene is displayed in cyan/green and and high-Ca pyroxene in blue. Pyroxenes are a mineral that form in volcanic rocks as lava cools. Iron/magnesium phyllosilicates, and possibly olivine, are displayed as red. Olivines are the product of magma crystallization, and also form in volcanic rocks. The distribution of the mafic minerals olive and pyroxene in the image corresponds with the rim of the central pit, which can indicate that they were uplifted from beneath the surface.

Additionally, olivines are frequently the first minerals to experience weathering, easily converting to Fe/Mg-phyllosilicates in the presence of water. The phyllosilicates around the crater’s central peak/pit complex could have formed because impact-generated hydrothermal alteration (the interaction between aqueous fluids heated by the impact and igneous rock) altered the composition of the target rock.

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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