Nanoscale relationships between uranium and carbonaceous material in alteration halos around unconformity-related uranium deposits of the Kiggavik camp, Paleoproterozoic Thelon Basin, Nunavut, Canada

• Published in: Ore Geology Reviews
• Main Authors: Riegler, Thomas, Beaufort, Marie-France, Allard, Thierry, Pierson-Wickmann, Anne-Catherine, Beaufort, Daniel
• Other Authors: Institut de Chimie des Milieux et Matériaux de Poitiers (IC2MP), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers-Institut de Chimie du CNRS (INC), Institut Pprime (PPRIME), ENSMA-Centre National de la Recherche Scientifique (CNRS)-Université de Poitiers, Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Géosciences Rennes (GR), Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Hydrothermal; Proterozoic; Carbonaceous material (CM); Unconformity uranium (U) deposits; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; Canada; Nunavut
• Online Access: https://hal-insu.archives-ouvertes.fr/insu-01312853; https://hal-insu.archives-ouvertes.fr/insu-01312853/document; https://hal-insu.archives-ouvertes.fr/insu-01312853/file/Riegler-2016.pdf; https://doi.org/10.1016/j.oregeorev.2016.04.018

International audience Concentrations of 7% U and 1% Cu were identified in massive, brecciated, and amorphous carbonaceous materials (CM) characterized by strongly negative values of carbon stable isotopes (δ13C = − 39.1‰ relative to PDB). The anomalies are restricted to clay alteration halos developed in Neoarchean Woodburn Lake group metagreywacke that is the predominant host of unconformity-related uranium (U) deposits in the Kiggavik exploration camp. Petrographic and microstructural analyses by SEM, X-Ray Diffraction, HR-TEM and RAMAN spectroscopy identified carbon veils, best described as graphene-like carbon, upon which nano-scale uraninite crystals are distributed. CM are common in U systems such as the classic Cretaceous roll-front deposits and the world-class Paleoproterozoic unconformity-related deposits. However, the unusual spatial and textural association of U minerals and CM described herein raises questions on mechanisms that may have been responsible for the precipitation of the CM followed by crystallization of U oxides on its surfaces. Based on the characteristics presented herein, the CMs at Kiggavik are interpreted as hydrothermal in origin. Furthermore, the nanoscale organization and properties of these graphene-like layers that host U oxide crystallites clearly localized U oxide nucleation and growth.