Meteorite history exposed


Rebecca Pool

Wednesday, June 5, 2019 - 09:00
Cross-polarized light microscopy image of a thin section of the meteorite NWA 7325 with a width of field of 5 mm [Irving et al]
A recent study from US- and Germany-based researchers has revealed new details about a meteorite discovered in the deserts of southwestern Morocco in 2012.
Researchers from the Universities of Münster, Maryland and Washington examined fragments from the achondrite, Northwest Africa (NWA) 7325.
These stony meteorites do not contain spheroidal mineral grains known as chondrules.
Researchers examined the abundances of highly siderophile, or ‘iron-loving', elements and 187Re‐187Os isotopic systematics for two meteorite fragments.
To understand how NWA 7235 could have ended up with the observed siderophile abundances, the team constructed a model of the meteorite’s formation.
Results indicate that the parent body of NWA 7325 underwent complex planetary processes, and was large enough to form a core, mantle, and crust.
One of the fragments used in the study appears to be a sample of the object’s crust.
The team believes that a second fragment is likely material from the parent body mixed with chondritic material that was delivered to the object by surface impacts.
Based on their model, the researchers believe that the parent body of NWA 7325 underwent multiple episodes of low‐pressure, metal‐silicate equilibration, followed by limited late accretion and mantle homogenization.
The results help paint a picture of the history of NWA 7235, which can ultimately provide clues about the evolution of the Solar System.
Research is published in Meteoritics and Planetary Science.
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