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The Centralian Superbasin is a concept connecting Neoproterozoic successions that presently occur in separate structural basins in central Australia into a once-continuous depositional system. The superbasin is thought to have been initiated ∼830 Ma, coevally with the breakup of Rodinia, by a mantle plume centred under the central Adelaide Geosyncline, South Australia. The superbasin is thought to deepen towards the south with the basal sediments mainly sourced from the Arunta Region in the north, and blanketing the crystalline Musgrave Block to the south. Our results suggest that deposition in the Amadeus Basin, the most studied of these intraplate basins that made up the superbasin, began ∼1040 Ma ago (assembly of Rodinia; about 200 Ma earlier than previously suggested) in association with a mantle plume that formed the Warakurna large igneous province. Moreover, we argue for a two stage opening of the Amadeus Basin, one starting at ∼1040 and the other at ∼800 Ma, and a long stratigraphic break(s) within Supersequence 1. The basal units of Supersequence 1 in the southern Amadeus Basin yield detrital zircon U–Pb age populations consistent with derivation from the Musgrave Block, which must have been emergent at the time. Our data support the correlation between the basal Neoproterozoic units of the Amadeus Basin (Heavitree Quartzite and Bitter Springs Formation) and the Succession B in western North America, consistent with paleogeographical reconstructions placing Australia to the west of North America after the assembly of Rodinia and before its breakup. Furthermore, our study brings into question the existence of the Centralian Superbasin because Supersequence 1 sedimentary rocks do not belong to a single depositional system.

Important geochemical and tectonic events in the Paleoproterozoic Era lay the foundation for the status and operation of the modern Earth, including the initial rise of atmospheric oxygen paving the path for animal evolution, and the emergence of modern plate tectonic processes leading to the amalgamation of the Canadian Shield (Laurentia). Rudimentary geological and geochronological documentation of Paleoproterozoic sedimentary basins is the foundation from which we can ask larger questions about geochemical changes or plate tectonic events on the evolving Earth, since those questions are largely answered by analyzing the sedimentary record. This thesis outlines the stratigraphy, detrital zircon U-Pb geochronology, elemental and isotopic geochemistry, and basin evolution of the Paleoproterozoic Penrhyn and Piling basins on the Rae craton in Arctic Canada, which record important tectonic and geochemical events on both a regional and global scale. The concentration of the redox-sensitive trace element, U, in seawater has not been constant throughout geologic time and is linked to changes in oceanic and atmospheric oxygen content. Secular variations in the record of U contents of shales and iron formations indicate that the redox state of the atmosphere-ocean system after the Great Oxidation Event (GOE) was more dynamic than previously thought. Trends towards lower oxygen content recorded after ~2.05 Ga in the middle Proterozoic suggest that oxygen level decreased. This is contrary to traditional models assuming unidirectional atmospheric oxygen rise throughout the Proterozoic. The data demonstrate the earliest signal of oxidative U cycling, manifested in 2.47 - 2.43 Ga iron formations, and show that oxygenation was a protracted process initiated shortly after the end of the Archean. It has been proposed that a global and long-lived magmatic and tectonic shutdown event from ~2.45 to 2.22 Ga played a causal role in the GOE, since it overlaps the time interval in which

The effects of planar defects and composition on Ar mobility in trioctahedral micas have been investigated in samples from a small marble outcrop (~500m 2) in the Frontenac Terrane, Grenville Province, Ontario. These micas crystallized during amphibolite-facies metamorphism at ~1170Ma and experienced a thermal pulse ~100Ma later at shallow crustal levels associated with the emplacement of plutons. 87Rb/ 86Sr ages of the phlogopites range from ~950 to ~1050Ma, consistent with resetting during the later thermal event. The same phlogopites however, give 40Ar/ 39Ar ages between ~950 and 1160Ma, spanning the age range of the two thermal events. This result is intriguing because these micas have undergone the same thermal history and were not deformed after peak metamorphic conditions. In order to understand this phenomenon, the chemical, crystallographical, and microstructural nature of four mica samples has been characterized in detail using a wide range of analytical techniques. The scanning electron microscope (SEM), electron microprobe (EMP), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) data show that the micas are chemically homogeneous (with the exception of Ba) and similar in composition. The Fourier transform infrared spectroscopy and Mossbauer results show that the M sites for three of the micas are dominated by divalent cations and the Fe 3+/(Fe 2++Fe 3+) ratio for all four phlogopites ranges from 0.10 to 0.25. The stable-isotopic data for calcite indicate that this outcrop was not affected by hydrothermal fluids after peak metamorphism. No correlation between chemical composition and 87Rb/ 86Sr and 40Ar/ 39Ar age or between crystal size and 40Ar/ 39Ar age is observed. The only major difference among all of the micas was revealed through transmitted electron microscope (TEM), which shows that the older 1M micas contain significantly more layer stacking defects, associated with crystallization, than the younger micas. We propose th