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Project Progress

Carbonaceous chondrite meteorites contain abundant evidence of aqueous alteration that occurred on the asteroidal parent body. We have been investigating several components of these meteorites in order to better understand aqueous alteration and the formation of these components.

1) Amoeboid olivine aggregates effectively document parent body alteration. With an REU student, we have been imaging and analyzing the chemical composition of these aggregates in order to constrain the alteration history of 9 CO₃ chondrites which have not been extensively studied before. This will increase the number CO₃ chondrites with known alteration level to 22. We will be able to better understand the distribution of the different alteration levels on the parent asteroid which should yield insights into the mechanisms and dynamics of asteroidal alteration.

2) Refractory inclusions are thought to have formed 2-3 Ma before chondrules (mm-sized igneous spherioles). These objects have fine-grained accretionary rims around them in CO₃ chondrites. We have been analyzing the chemical composition of these rims in order to determine if these rims document any chemical evolution of the solar nebula. Our preliminary data shows that the rims are identical regardless of which object they surround. This implies that the rims formed at the same time and therefore, the chondrules and inclusions must have been brought together before rim accretion. This has implications for dynamic models of solar system evolution.

3) The fine-grained materials in carbonaceous chondrites contain a significant amount of amorphous material. In order to test the hypothesis that these materials could have accreted in an amorphous state, we have set up experiments to aqueously alter artificially produced amorphous smokes and will analyze their resultant textures and mineralogy. We will react the smokes to cold water (5° C), warm ice (ice + ethanol: -10° C) and cold ice (CO₂ + ethanol: -78.5° C).