| dc.description.abstract | 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 o f each
has been deduced from both textural and compositional evidence. While
independent, these events made use o f the same pre-existing fracture system
along which the western subcomplex is situated. In order, these events were:
intrusion o f granitic fluids, alkaline metasomatism, and thermal metamorphism
due to the emplacement o f the Coldwell alkaline complex. Following the
alteration events, and presumably a result o f denudation, oxidization and
leaching o f 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. The mineralization is represented by the presence of:
aegirine-jervisite, aegirine-natalyite, barite, baryhte, hollandite, coffinite,
hematite, Umenorutile, magnetite, monazite-(Ce), phenakite, pyrite, rutile,
thorite, thorogummite, thortveitite, tyuyamunite, uraninite, V-crichtonite,
xenotime-(Y), zircon, zircon-thorite-coffinite solid solutions and a few
unnamed mineral species. The resulting mineralogy is both unique and
complex, with several rare minerals and new compositional extremes reported
(i.e., Nb-V-rutile, aegirine-jervisite, aegifine-natalyite, zircon-thorite-coffinite
solid solutions, Dy-xenotdme-(Y), thortveitite, baotite, barylite and Vcrichtonite).
In addition, unique parageneses are reported, giving further insight
into the geochemistry o f Be, Ba, Sc, V, N b, Ti and Cr and conditions of
formation of phenakite, baryhte, thortveitite, crichtonite, ilmenorutile, barian
feldspars and zircon-thorite-coffinite solid solutions. | |
