An integrated geochemical, petrologic, geochronological, and metallogenic study of the Powder Horn Intrusive Suite and the associated Lodestar Prospect: A magmatic-hydrothermal auriferous breccia zone that links epithermal and porphyry systems, Northern Burin Peninsula, Newfoundland.

摘要

The Lodestar Prospect is associated with the Powder Horn Intrusive Suite and comprises auriferous sulphide-oxide mineralized polylithic breccias which have a magmatic-hydrothermal or phreatomagmatic origin. The best grades obtained by exploration companies from chip-channel sampling of the breccia were 4.98 g/t Au and 14.8 g/t Ag over 15.9 m, along with one area that returned an assay of approximately 2.0% Zn. Earlier assays derived values of 6.13 g/t Au over 4.7 m and 4.91 g/t Au over 3 m. More recent channel samples 5.6 g/t Au over 8.5 m including 12.6 g/t Au over 1m.;The Powder Horn Intrusive Suite is a multi-phase intrusive suite, with both pre- and post-brecciation (mineralization) phases. Pre-mineralization rocks consist of (1) the late Neoproterozoic Musgravetown Group sedimentary rocks, which are hornfelsed close to the intrusion, (2) medium grained gabbro/diorite, and (3) minor felsic material; the gabbro phase has been U-Pb zircon dated at 603+/− 2 Ma. Post-mineralization phases include (1) fine grained gabbro/diorite, (2) felsic phases, and (3) diabase dykes; a felsic dyke has been U-Pb zircon dated at 605+/− 5 Ma. (Abstract shortened by UMI.).