The Nininger Meteorite Award recognizes outstanding student achievement in the meteoritical sciences as embodied by an original research paper. Papers must cover original research conducted by the student and must have been written, submitted, or published between January 1, 2019 and December 31, 2019.
Applicants must have been studying at an educational institution in the United States at the time the paper was written, submitted, or published.
The student must be first author of the paper, but does not have to be the sole author.
Paper must cover original research conducted by the student, and have been written, submitted or published between January 1, 2019 and December 31, 2019.
Jonathan’s paper “Chondrule porosity in the L4 chondrite Saratov: Dissolution, chemical transport, and fluid flow” (coauthored by Rhian Jones and Serafina Garcea) takes a close look at chondrule porosity to understand the chemical and physical effects of fluids present during thermal metamorphism.
Ordinary chondrite parent bodies were subjected to internal heating from the energetic decay of short-lived radioisotopes soon after their formation. As a result, ordinary chondrite meteorites exhibit increasing textural and chemical equilibration with increasing degrees of thermal metamorphism. While the presence of fluids during thermal metamorphism has been inferred from a variety of chemical and mineralogical signatures, the degree to which fluids facilitate the equilibration process is still under investigation. Because chondrules are not expected to form with significant porosity, chondrule pores can be used to understand parent body processes, particularly processes that involve the transport of fluids.
In this paper, the authors use X-ray microtomography in combination with scanning and transmission electron microscopy and X-ray chemical maps to investigate the role of fluids in developing and utilizing the porosity found within chondrules. The results indicate that chondrule pores in the L4 chondrite Saratov formed by fluid dissolution of mesostasis glass and that fluids subsequently infiltrated the pore network altering the mineralogy, mineral chemistry, and depositing new phases.
This is important because it shows that chemical equilibration in ordinary chondrites is not strictly a solid-state diffusional process resulting from thermal metamorphism, but rather a more complex process involving fluid-mediated chemical exchange between chondrules and matrix through pore networks.
Zachary's paper "Titanium isotope signatures of calcium-aluminum-rich inclusions from CV and CK chondrites: Implications for early Solar System reservoirs and mixing", investigates whether the isotope compositions of previously analyzed calcium-aluminum-rich inclusions (CAIs) are representative of CAIs from other chondrites and chondrite groups and, by extension, the broader CAI-forming region in the solar nebula.
CAIs are the oldest dated solids formed in our Solar System and therefore can provide us with important information about the initial isotopic composition of the Solar protoplanetary disk. However, most previous isotopic studies of CAIs have been limited to inclusions from the Allende CV chondrite and a few CAIs from other CV, CO, CM, and ordinary chondrites.
In this study, the authors analyze the mass-independant Ti isotopic compositions of 23 CAIs of different petrologic and geochemical types, including 11 CAIs from the Allende CV meteorite as well as 12 CAIs from 7 different CV and CK chondrites. These include the first reported measurements of the Ti isotope compositions of CAIs from CK chondrites.
The authors found that the mass-independent Ti isotopic compositions of CAIs from CV and CK chondrites define a single population (consistent with previously reported Ti isotope data for CAIs from other CV, CO, CM, and ordinary chondrites), indicative of a common CAI-forming region in the early Solar System. They further observed resolvable variation within this population, which indicates that some isotopic variability was present in the CAI-forming region.
This data, when taken in the context of previous studies, suggest that the isotopic reservoir from which CAIs formed was in the final stages of isotopic homogenization.