LE3 .A278 2005

2005

Barr, Sandra
Stanley, Cliff

Acadia University

Master of Science

Masters

Geology

Earth & Environmental Sciences

The Mechanic Settlement pluton, southern New Brunswick, is a high-level mafic-ultramafic pluton of Late Neoproterozoic age (557 Ma), and contains eighteen lithologies, combined into six lithologic assemblages. Cumulate textures are present in many rocks, and several rock types contain interstitial hydrous silicate minerals, indicating a wet parent magma. The general crystallization order is olivine and chromite, plagioclase, clinopyroxene, orthopyroxene, and hydrous silicate (phlogopite or hornblende). Lithologic units are not continuous between drill holes, and no statistically significant pattern in the stratigraphic succession can be established. Variation in the chemistry and mineralogy of the rocks is controlled by fractionation of olivine and plagioclase. The Mechanic Settlement pluton, and comagmatic Coldbrook Group basalt (560-550 Ma), is probably of calc-alkaline affinity. Several platinum group element bearing horizons associated with minor sulphide mineralization (pyrrhotite-chalcopyrite-pentlandite) occur in peridotitic rocks, which may have formed during or following magma influx. Based on similarities to the Lac des Iles complex, Ontario, further potential for contact-type mineralization exists in the western portion of the pluton.

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https://scholar.acadiau.ca/islandora/object/theses:2751