Petrology and geochronology from basement core of the Paleoproterozoic Red Earth granulite domain, north-central Alberta

This thesis reports new petrological and geochronological data from Precambrian drill core samples from the Red Earth area of north-central Alberta. Quantitative pressure-temperature estimates for pelitic gneisses are 6--8 kilobars and at least 740--800°C and up to 905°C. Still higher (>925°C) and likely magmatic temperatures are recorded in some charnockite samples. Age dating of monazite by electron microprobe and monazite and zircon by isotope dilution thermal ionization mass spectrometry reveal three main clusters of ages: (1) 2020--1980 Ma---charnockitic and granitic magmatism and granulite-grade metamorphism; (2) 1960--1910 Ma---upper amphibolite---or possibly granulite-facies metamorphism and deformation; and (3) 1910--1865 Ma---late-stage fluid influx and retrogression. These data can be used to evaluate tectonic models for this part of the Canadian Shield. The Buffalo Head domain, which encompasses the Red Earth area, was originally distinguished from the adjacent Taltson magmatic zone by the absence of magmatic and high-grade metamorphic ages younger than 1.99 Ga. Geochronology and P-T constraints obtained in this study indicate the Red Earth area experienced at least upper amphibolite-facies metamorphic conditions between 1960--1910 Ma. This finding supports a growing body of evidence that the Buffalo Head domain and the Taltson magmatic zone are part of a single lithotectonic block rather than two formerly separate blocks that were juxtaposed between ca. 2.0 and 1.9 Ga by closure of intervening ocean basins.