Date of Award
Master of Science
Dr. Gordon R. Osinski
Dr. Desmond Moser
Lunar granulites are believed to be metamorphosed polymict impact breccias that have the potential to yield new information on the origin and evolution of the lunar crust and its impact history. A major challenge in studying these rocks is to elucidate the metamorphic environment and processes that gave rise to the enigmatic granulitic textures. Presented here is the first comparison of the metamorphic characteristics of lunar meteorite NWA 3163 with shock-metamorphosed and heated anorthosites at the Mistastin Lake impact structure of northern Labrador. The Mistastin Lake impact structure is a 36 ± 4 Ma, 28 km diameter feature situated at the north-eastern end of the Mesoproterozoic Mistastin Batholith composed of anorthosites, granites and lesser amounts of gabbro. Petrographic observations suggest that the majority of the feldspar within samples from the central uplift has been transformed to diaplectic glass (maskelynite). Samples from clasts within impact melt rock appear to have undergone some degree of devitrification, most likely because of thermal metamorphism due to the heat of the impact melt. A comparison of these shock features, maskelynite distribution and grain boundary characteristics as shown with Backscatter Imaging (BSE), colour Cathodoluminesence (CL) and Energy Dispersive X-Ray Spectrometry (EDS) spectra with those of NWA 3163 have determined that no samples retrieved from Mistastin exhibit textures similar to those found in lunar granulites. This result was unexpected and warrants additional studies of lunar granulites. Using CL to identify metamorphic textures, NWA 3163 has been found to be a poikiolitic granoblastic granulite.
Dammeier, Rod, "INVESTIGATION OF LUNAR METEORITE NWA 3163 AND COMPARISONS WITH SHOCKED ANORTHOSITES FROM THE MISTASTIN LAKE IMPACT STRUCTURE, LABRADOR" (2011). Digitized Theses. 3426.