UC Davis

Meteorites are ancient records of early Solar System processes. Much can be learned about our Solar System’s evolution from the protoplanetary disk to its current architecture by studying meteorites’ geochemistry, minerology, and petrography. In the last two decades, a new analytical tool has emerged in the form of nucleosynthetic isotope anomalies, which are isotopes that were distributed heterogeneously within the protoplanetary disk when asteroids and planets were forming. Present-day meteorites retain the signature of their source reservoir through these isotopic anomalies, making them a powerful tracer of origin. In this work, I leverage the isotope anomaly observed in 54Cr, paired with oxygen measurements, to uncover the genetic identity of a suite of meteorites. With this method, I investigate the origin of three different types of meteoritic material: (1) chondritic, (2) achondritic, and (3) tektitic.Chondrites are the most primitive variety of meteorites. In this work, I employ ε54Cr-Δ17O systematics to determine the origins of the chondrite Almahata Sitta (AhS) clast 202, a unique stone which originated from a large, previously unknown parent body. I find that AhS 202 originates from the carbonaceous chondrite (CC) reservoir, which is linked to the outer Solar System, and may have ties to a growing number of thermally processed, NWA 3100-like chondrites and achondrites. Achondrites are meteorites that have experienced extensive metamorphism (thermally and/or shock induced) and/or melting on their parent bodies. In this work, I investigate the origins of the newly-fallen achondrites Jeminay, Tin-Essako 001, and Qiquanhu. I find that Jeminay, an ungrouped iron meteorite with silicate inclusions, bears the isotopic signature of the outer Solar System (Carbonaceous Chondrite reservoir) and may represent the core of another differentiated body in the outer Solar System. I find that TE 001 is a ureilite, despite possessing a minerology that does not align with the ureilite group. TE 001 joins the pallasite Choteau as a plagioclase-bearing, metal- and olivine-rich sample from the ureilite group, and may have been impact-generated. I find that Qiquanhu shares an isotopic signature with the Howardite-Eucrite-Diogenite (HED) clan, widely thought to have originated from Vesta, reaffirming its identity as a eucrite, and is likely not one of the known ‘anomalous’ eucrites (which are of non-Vestan origin). Tektites are terrestrial rocks which have formed through a meteoritic or asteroidal impact. In this work, I present the origins of the impactor which formed the enigmatic Libyan Desert Glass (LDG). I use combined ε53Cr-ε54Cr systematics and a binary mixing calculation to show the LDG impactor was likely carbonaceous (CC) in origin and may have incorporated ~1% of a Tagish Lake-type impactor. In addition to these genetic studies, chromium has chronologic utility as well. The extinct 53Mn-53Cr isochron system is used to date some of the earliest-formed Solar System materials. In this work, I present a 53Mn-53Cr isochron of the ultramafic HED-type achondrites NWA 12217, NWA 12319, and NWA 12562. I find that these achondrites have an age of 3.13 ± 0.58 Ma after the formation of Calcium-Aluminum Rich Inclusions (CAI), which mark the starting age of the Solar System. This age aligns with previous chronologic ages of basaltic eucrites, and may provide evidence that these dunite and lherzolite cumulates formed in Vestan subsurface magma chambers contemporaneously with basaltic eruptions at the Vestan surface.