The formation and preservation of orogenic gold deposits are associated with a predictable set of magmatic, structural, and tectonic processes that have recurred throughout Earth's history. In world-class Archean gold districts, such as in the Superior Province of the Canadian Shield and the Yilgarn Craton of the West Australian Shield, the main gold-mineralized fault zones are characterized by early imbrication, lithospheric extension, synorogenic magmatism and sedimentation, thick-skinned re-imbrication, and late-stage strike-slip. Such an evolution results in the occurrence of gold-mineralized, upper crustal sequences of synorogenic magmatic and sedimentary rocks above terranes of granitoid rocks and/or older poly-deformed volcanic rocks. Targeted exploration for orogenic gold mineralization relies on remnant panels of synorogenic rocks (e.g. polymict conglomerate and bimodal magmatic rocks) as first-order field indicators of structurally controlled gold preservation along prospective crustal-scale fault zones. Paleozoic crustal-scale fault zones in central Newfoundland have been known to host significant gold mineralization and recent major discoveries (e.g. Valentine Lake gold deposit) and associated exploration suggest the emergence of a new district centred on the footwall rocks of the Victoria Lake shear zone. Fieldwork, combined with structural analysis and high-precision U-Pb geochronology throughout central Newfoundland, demonstrates that the structurally controlled Paleozoic gold district is remarkably similar to the much older Archean Abitibi gold district in scale, geological setting, structural architecture, synorogenic magmatism and sedimentation, style of mineralization, tectonic evolution, and process rates. In central Newfoundland, orogenic gold occurs within footwall blocks of an overall northwest-directed fault system that juxtaposed and deformed Neoproterozoic basement granitoid rocks and Late Silurian to Early Devonian synorogenic rocks during the Acadian Orogeny. Preliminary high-precision U-Pb zircon and rutile geochronology demonstrates that the key tectonic interval driving gold mineralization and synorogenic sedimentation and magmatism, including syenogranite and monzonite intrusions, occurred between 424 and 407 Ma, approximately the same relative time interval (15-20 million years) as the Abitibi greenstone belt. The similarities between the gold systems of central Newfoundland and the Abitibi imply that a common predictable set of structural and tectonic processes throughout Earth's history, and thus independent of time, have led to the deposition and preservation of orogenic gold mineralization.

Crustal-scale fault zones in central Newfoundland are being recognized as significant gold-mineralized structures. In particular, a northeast-trending structural corridor in the eastern Dunnage Zone (Exploits subzone), delineated by the Rogerson Lake Conglomerate, contains highly prospective vein-hosted gold deposits. Such mineralized vein systems, exposed near Valentine Lake (Marathon Gold Corp.) and Wilding Lake (Antler Gold Inc.), are products of progressive Paleozoic deformation and fluid-pressure cycling along crustal-scale faults that cut the Late Silurian to Early Devonian Rogerson Lake Conglomerate and underlying Neoproterozoic basement rocks. Well exposed, gold-bearing quartz-vein systems in the Wilding Lake area reveal a kinematic history that involved a main phase of reverse sinistral shearing and subsequent transient phases of horizontal extension, oblique compression, and, at least locally, components of late dextral strike-slip. High-grade gold mineralization is associated with siderite-ankerite-sericite alteration of the host rocks, structurally controlled quartz-vein emplacement, and supergene alteration of pyrite and chalcopyrite. Gold-bearing vein sets contain quartz, pyrite, chalcopyrite, tourmaline, native gold, Ag-poor electrum, bismuth-silver-gold tellurides, rutile, and secondary goethite, malachite, and acanthite. Prospective gold exploration targets in the Wilding Lake area are Late Silurian feldspar porphyry and felsic volcanic rocks overlying the Rogerson Lake Conglomerate, as well as, rheologically favourable Neoproterozoic basement granitoids that may provide a setting similar to that at Valentine Lake.

This report summarizes mineralization associated with the Nipissing Diabase sills in the broader Sudbury area and evaluates the geochemical link between these sills and potential feeder dykes that are part of the broader ca. 2.2 Ga Ungava large igneous province. New whole-rock major and trace element data are presented for the Nipissing sills and these are combined with previously published data. Sm-Nd isotope data are presented for the Maguire, Senneterre and Klotz dykes, and the Triangle Mountain sill, providing key constraints on their magmatic sources and history of crustal assimilation. To help constrain the temporal evolution of the magmatic system, a new U-Pb baddeleyite age has been determined for the Triangle Mountain sill at 2216.5 ± 2.1 Ma. We also report a previously obtained, precise, U-Pb zircon age for the Ni-Cu-PGE mineralized Shakespeare intrusion at 2217.0 +1.7/-1.5 Ma. Together, whole-rock major and trace elements, Sm-Nd isotopes, and U-Pb geochronology are used to gain a more complete picture of how the mineralized components of the ca. 2.2 Ga Ungava large igneous province were generated.

A brief report is presented on the early stages of our study of the ca. 1.1 Ga Mid-continent Rift system, which hosts a diverse range of intrusions, many of which are mineralized and are being actively explored. Key questions to be ad-dressed by this study are the localization of the mineralized intrusions, and whether we can resolve, through addition-al and more precise U-Pb geochronology, clear temporal, spatial, and tectonic patterns that link the various intrusions to the overall evolution of the rift system, and to specific stages of the flood basalt sequence. An initial compilation is presented of all known intrusions and their associated questions.

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