| The Deadhorse Creek 'Diatreme' is a Proterozoic vent breccia that probably formed in response to early mid-continent rifting. Following emplacement of the breccia, the western subcomplex experienced three alteration events, producing the complex mineralogy observed in the main mineralized zone. Each event has produced a unique mineral paragenesis and the timing of each has been deduced from both textural and compositional evidence. While independent, these events made use of the same pre-existing fracture system along which the western subcomplex is situated. In order, these events were: intrusion of granitic fluids, alkaline metasomatism, and thermal metamorphism due to the emplacement of the Coldwell alkaline complex. Following the alteration events, and presumably a result of denudation, oxidization and leaching of the main mineralized zone has produced a supergene paragenesis of calcite, tyuyamunite, hollandite and barite. The main mineralized zone was enriched in first- and second-row transition metals, rare-earth elements, beryllium, Th and U. (Abstract shortened by UMI.)... |
