U-Pb and 40Ar/39Ar chronology of hydrothermal zircon, garnet, rutile and muscovite, Big Bell gold deposit, Yilgarn Craton, Western Australia

Andreas Gerhard Mueller, Neal Jesse McNaughton, Fred Jourdan

Research output: Chapter in Book/Conference paperConference paper

Abstract

The Hemlo-type Big Bell deposit (75 t Au) occurs in a narrow mafic-ultramafic greenstone belt bounded to the southeast by granodiorite-tonalite (2740-2700 Ma) and to the northwest by granite batholiths (2625 Ma). The steeply dipping greenstones are intruded parallel to bedding by granodiorite porphyry, both lineated and metamorphosed at 670±50°C during emplacement of the southeast border pluton at 2700±7 Ma. The calcic-potassic Big Bell alteration zone, centred on amphibolite-granodiorite dyke contacts, contains two scheelite-bearing ore bodies: almandine-cummingtonite-hornblende skarn (1-3 g/t Au, 1700 g/t As) dated at 2662±5 Ma (almandine U-Pb), and the muscovite-microcline gneiss of the Main Lode (3-5 g/t Au, 580 g/t Sb). Garnet-cordierite-biotite schist borders the lode and the skarn. Fe-Mg thermometry constrains P-T conditions during mineralization to 540-600°C and 300-400 MPa. The northwest granite and late Sn-Ta-Nb granite-pegmatite dykes intruded at 2625-2610 Ma. They are associated with auriferous andradite-diopside and barren epidote skarn veins. Zircons intergrown with andradite are dated at 2612±7 and 2609±10 Ma. Granite-pegmatite magmatic and hydrothermal activity did not cause recrystallization in the Main Lode but the thermal anomaly (about 450°C) reset rutile and muscovite in the microcline gneiss to 2614±4 Ma and 2603±8 Ma, respectively.
Original languageEnglish
Title of host publicationMineral Resources to Discover
Subtitle of host publicationProceedings of the 14th SGA Biennial Meeting 2017
EditorsP Mercier-Langevin
Place of PublicationQuebec City
PublisherSociety for Geology Applied to Mineral Deposits
ChapterS07
Pages1001-1004
Number of pages4
Volume3
ISBN (Print)9782981689801
Publication statusPublished - 2017
Event14th SGA Biennial Meeting : Mineral Resources to Discover - Québec City Convention Centre, Québec City , Canada
Duration: 20 Aug 201723 Aug 2017
Conference number: 14
http://sga2017.ca/

Publication series

NameProceedings SGA Biennial Meetings
PublisherSociety for Geology Applied to Mineral Deposits
Number3
Volume14

Conference

Conference14th SGA Biennial Meeting
CountryCanada
CityQuébec City
Period20/08/1723/08/17
Internet address

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