LE3 .A278 2019

2019

Stanley, Cliff
Morelli, Ryan

Acadia University

Master of Science

Masters

Geology

Earth & Environmental Sciences

The Hanson Lake Assemblage (HLA) is an economically important succession as it hosts a number of volcanic-hosted massive sulphide (VHMS) deposits and has potential for new discoveries. Gaps in understanding the stratigraphy of the rocks hosting these deposits arise from facies changes in the volcanic stratigraphy and the effects of hydrothermal alteration, metamorphism and deformation. As a consequence, efforts to explore for base metal mineralization are hindered. In this study, lithogeochemical samples were collected from all major rock types in the stratigraphic succession for lithogeochemical characterization, to identify differences between rock types, and to assess the compositional effects of hydrothermal alteration. Rock types were classified using conserved element ratio (CER) procedures, affirmed by petrographic observations. Molar element ratios (MERs) were used to understand the igneous and hydrothermal processes responsible for compositional variation, and to identify and quantify the effects of hydrothermal alteration in rocks that host prospective VHMS deposits. Results illustrate that almost 50 % more units were resolved using CER procedures, and important observations include: (i) the lithogeochemical characterization of three rhyolite compositions that are all prospective hosts for VHMS mineralization, and (ii) identification of a new dacite volcanic unit high in the stratigraphy that is genetically related to a large, isotopically dated hypabyssal intrusion of the same composition, providing important temporal constraints. MER ratios used to quantify alteration illustrate a number of sites hosted by rhyolitic volcanic rocks exhibit strong muscovite or weak chlorite alteration and these have highest potential for hosting mineralization in the study area.

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https://scholar.acadiau.ca/islandora/object/theses:3352