Late neoproterozoic epithermal-style Au mineralization of the Burin Peninsula, Newfoundland: U-Pb geochronology and deposit characteristics

• Main Author: Ferguson, Sarah Anne
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2017
• Subjects: Long Harbour; Newfoundland
• Online Access: https://research.library.mun.ca/12913/; https://research.library.mun.ca/12913/1/thesis.pdf

The Burin Peninsula lies within the western portion of the Avalon Zone in Newfoundland. The Avalon Zone constitutes the eastern extent of the northern Appalachian orogen and includes extensive late Neoproterozoic magmatic arc-related volcanic, plutonic and epiclastic sedimentary rocks. The stratigraphy of the Burin Peninsula region is primarily composed of the Marystown, Musgravetown and Long Harbour Groups, all of which are host to high- and/or low-sulphidation epithermal precious metal mineralization, including the Hickey’s Pond, Tower, Stewart (and Forty Creek), Heritage, Big Easy and Long Harbour prospects. A 580-573 Ma plutonic suite, now recognized as the source to extensive hydrothermal activity in the region, runs along the length of the peninsula, intruding roughly coeval volcaniclastic rocks of the Marystown Group. New U-Pb (CA-TIMS) ages for volcanic host rocks within the Marystown Group constrain the timing of high-sulphidation mineralization to a maximum age of 584 ± 3 Ma at Hickey’s Pond and 576.7 ± 2.5 Ma (‘Caribou Tuff’) at Stewart. A previous host rock age of 572.5 ± 1.5 Ma at Hickey’s Pond is re-interpreted as a hydrothermal zircon age, which provides a more explicit age for the high-sulphidation mineralization at the prospect. New U/Pb zircon ages for the Marystown Group stratigraphy of the Stewart prospect also include 575.2 ± 2.1 Ma (‘Stewart Tuff’), 575.9 ± 2 Ma and 575.6 ± 1.7 Ma for other volcanic rocks, and 576.0 ± 2.7 Ma for the ‘Bat Zone’ granite (part of the ‘Burin Knee Intrusive Suite’). In conjunction with field observations, these ages confirm a northwest younging direction within the local Marystown Group stratigraphy at Stewart. The tightly overlapping ages also further link the 580-573 Ma regional plutonism to the volcaniclastic stratigraphy and to the regional high-sulphidation mineralization. A new age of 573.3 ± 2.7 Ma for rhyolite from the Musgravetown Group, proximal to the lowsulphidation Big Easy prospect, demonstrates contemporaneity with the Marystown Group. The ...