Geology - Master's Theses

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Browsing Geology - Master's Theses by Subject "alteration"

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    Characterization of alteration and mineralization at the Archean Grey Fox and Hislop magmatic-hydrothermal gold deposits, Matheson, Ontario
    (2021-06-30) Kelly, Christopher Hugh
    The Abitibi Greenstone belt (AGB) is host to some of the world’s largest gold deposits and their study has led to various gold deposit models and classifications. The latter includes a syenite- associated deposit type, which was first recognized in the early 2000s. This type of mineralization is present at the Grey Fox and Hislop deposits, which are located 80 km east of Timmins, Ontario. A study of their geologic setting, alteration, mineralogy, mineral chemistry, veining styles, and metal associations, suggest that these deposits, as well as others in the area, developed in different zones of a larger magmatic-hydrothermal system associated with alkalic intrusions of probable Timiskaming age (i.e., <2680 Ma). As such, they formed relatively early in the deformation history of the belt and predate the formation of the more common orogenic or greenstone-hosted quartz- carbonate vein deposits, such as the nearby Black Fox, which make up much of the gold budget in the AGB. A strong host-rock control is present at both deposits and their complex alteration histories provide insights on the formation of multiple mineralization styles within a single system. These different mineralization styles are described here to provide guidelines for mineral exploration for this deposit type in the Abitibi greenstone belt, as well as in other greenstone belts globally.
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    Chemostratigraphy and structural framework for gold mineralization at the Goliath Deposit, Western Wabigoon Subprovince, Ontario
    (2022-05-15) McRae, Mattea
    The Goliath deposit (32 Mt at 1.09 g/t Au and 3.42 g/t Ag) is one of the larger gold deposits within the western Wabigoon subprovince, 20 km east of Dryden, Ontario. The economic potential of the Goliath deposit makes it important to understand its geological setting to improve exploration models for such significant targets. Felsic volcanic sedimentary rocks (maximum age of ~ 2703 Ma) host the mineralization, were sericitized, and metamorphosed into the muscovite- sericite schist and biotite-muscovite schist. This package is enclosed within a similarly aged turbidite sequence (maximum age of ~2701 Ma). The mineralization consists of base metal sulphides with gold and silver hosted in As-rich pyrite and remobilized along pyrite fractures. The mineralization is likely pre-deformation as the regional compressional D1 deformation and transpressional D2 deformation reoriented the grade shells to be subparallel to the S1 foliation (075°/78°), and higher-grade shells subparallel to the intersection lineation of S1 and S2 fabric (52°/218°), and subparallel to the F1 fold axial plane (28°/81°). The Goliath gold deposit is thus interpreted to have formed in a synvolcanic, pre-orogenic environment.