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TitleSetting and process evolution of the central Newfoundland gold belt
AuthorHonsberger, I WORCID logo; Bleeker, WORCID logo; Kamo, S L; Sandeman, H A I; Evans, D T W; Rogers, N; van Staal, C RORCID logo; Dunning, G R
SourceAbstracts GAC-MAC-IAH-CNC- CSPG 2022 Halifax; Geological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Abstracts Volume vol. 45, 2022 p. 125-126, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220654
PublisherThe Geological Association of Canada
Mediapaper; digital; on-line
File formatpdf
ProvinceNewfoundland and Labrador
NTS2D; 12A
Lat/Long WENS -58.0000 -54.0000 49.0000 48.0000
Subjectsmineralogy; gold; quartz veins; veins; Victoria Lake Shear Zone; Valentine Lake Intrusion; Ganderia; Devonian
ProgramTargeted Geoscience Initiative (TGI-6) Ore systems
Released2022 07 19
AbstractThe eastern Dunnage Zone of the central Newfoundland Appalachians hosts Early Devonian (ca. 410 Ma) orogenic gold mineralization along a major northeast trending fault corridor that is delineated by latest Silurian syntectonic magmatic and clastic sedimentary rocks. The orogenic gold system is characterized by structurally controlled, polyphase, quartz vein sets that form offshoots within a triangle zone-like structural domain that is defined by southeast- and northwest-dipping thrust faults. The southeast-dipping fault system includes the Victoria Lake Shear Zone, which uplifts metamorphic rocks of Ganderia and buries gold-mineralized, latest Silurian syntectonic magmatic and sedimentary rocks. The northwest-dipping fault system includes the Valentine Lake Shear Zone, which hosts an approximately five million ounce (5 Moz) orogenic gold deposit within generally shallow dipping quartz-tourmaline-pyrite±gold veins that cut uplifted Neoproterozoic granitoid rocks. High-precision CA-ID-TIMS U-Pb zircon geochronology defines a ca. 422-420 Ma syntectonic magmatic pulse along the length of the orogenic gold-mineralized fault corridor throughout central Newfoundland. These magmatic rocks are slightly older than the associated syntectonic, basal, clastic sedimentary rock sequence (Rogerson Lake Conglomerate); however, they structurally overlie the Rogerson Lake Conglomerate in some areas. Latest Silurian syntectonic bimodal magmatism and immature clastic sedimentation along the central Newfoundland gold belt are attributed to a transient phase of lithospheric extension or transtension resulting from asthenospheric and crustal melting related to slab break-off that marked the end of the Salinic orogenic cycle. In north-central Newfoundland, extension began earlier in the Silurian (ca. 429 Ma) than along the Rogerson Lake Conglomerate belt because the normal fault system did not propagate across- and along-strike until ca. 424-418 Ma. A latest Silurian (Ludlow to Pridoli), southeast-dipping, listric normal fault system in central Newfoundland may have provided structural surfaces for subsequent northwest-directed thrust reactivation and, as well, increased heat and fluid flow in the crust leading to orogenic gold mineralization. Hydrothermal rutile from structurally controlled, gold-mineralized quartz veins of the Leprechaun Pond deposit (Valentine Lake) and Wilding Lake prospect yielded ID-TIMS ages of ca. 410 Ma. These are consistent with Early Devonian quartz vein emplacement and orogenic gold mineralization in central Newfoundland during thick-skinned thrusting, backthrusting, and hydrothermal fluid-pressure cycling along the Acadian deformation front of Ganderia (see Honsberger et al., 2022, GSA Bulletin). Ultimately, the setting and process evolution of the central Newfoundland gold district are strikingly similar to world-class Archean orogenic gold systems of the Canadian Shield.
Summary(Plain Language Summary, not published)
This contribution presents a comprehensive model for orogenic gold mineralization in central Newfoundland.

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