Appalachians Project
The TGI-3 Appalachians Project research is focused on upgrading the geoscience knowledge base in central Newfoundland (primarily the Buchans - Robert's Arm belt, Victoria Lake Supergroup and Baie Verte Peninsula) and the Bathurst Mining Camp, New Brunswick. The Bathurst Mining Camp (BMC) and Central Mobile Belt, Newfoundland, represent two of Canada's most important base metal regions. However the potential of discovering new major deposits is hampered by the geological complexity and lack of surface expression. Basic geological studies, combined with the application of new techniques and technologies, are key to increasing exploration and discovery rates.
The bedrock geology of the BMC is well constrained at surface, but poorly understood at depth. Improved understanding of the 3D geological structure will enhance the ability to vector in on mineralised horizons, even in hitherto unprospective areas, e.g., beneath Carboniferous cover. New strategic geophysical surveys, combined with extensive existing data will allow us to model the regional 3D structure of the BMC and better project the surface geology to depth.
A new ground-based, gravity survey based on a nominal 1 km grid (modified in relation to access constraints), which is being combined with some with high resolution gravity surveys over specific structures. Although the resulting Bouguer gravity map illustrates many of the major geological features of the BMC such as the Nine Mile Synform, "blueschist nappe" and Pabineau Granite, it does not obviously delineate the internal structure of the main felsic pile within which the majority of the VMS mineralisation occurs. However the first vertical derivative map does illustrate a remarkable correlation between VMS prospective areas and high values. Massive sulphide horizons are too small to have been consistently registered at this resolution of survey, thus it is believed that the effect is linked to the metasomatic alteration associated with the VMS producing fluid systems.
The gravity data is being combined with existing geophysical and rock properties data to form a 3D geophysical model. In turn this will aide in the production of a series of transects across major structural and/or economically significant parts of the BMC. A 3D GIS will be developed to incorporate the geology from the transects along with inversions from the geophysical modelling to give a 3D structural model of the whole of the Bathurst Mining Camp.
In the Central Mobile Belt of Newfoundland, detailed geological knowledge of the local and regional structure, stratigraphy and tectonic setting is vital for base metal exploration. The Buchans - Robert's Arm belt is host to a number base metal past producers and a major area of current exploration, and yet remains largely geologically undefined beyond the immediate vicinity of the mines. Strategic geochemistry, geochronology and geophysics, in combination with detailed bedrock mapping is enabling extrapolation from the well constrained sequences across the belt and thus offers the potential of providing a focus for future exploration.
The Buchans Group is characterized by calc-alkaline arc basalt, rhyolite and granodiorite at its lowest stratigraphic levels. These are overlain by a sequence of calc-alkaline basalt and rhyolite which contain a key stratigraphic horizon characterized by a volcanogenic and granitoid boulder conglomerate and significant VMS mineralization. In contrast, the coeval Red Indian Lake Group is characterized by a tholeiitic, back-arc basin-like basalt sequence at its base overlain by a volcanogenic breccia-conglomerate and calc-alkaline bimodal arc sequence. The differences in Sm/Nd isotopic characteristics, zircon inheritance, and stratigraphic relationships suggest that the Buchans and Red Indian Lake groups formed upon distinctly different peri-Laurentian basement sequences; however the tectonic history of the groups inferred from these and geochemical data suggest kinematically complimentary development. We propose that the Red Indian Lake and Buchans groups were originally along strike equivalents. The reconstruction of original relationships between the arc systems has important implications for the development of the Laurentian margin and for the prospectivity of terranes and distribution of mineral deposits.
The Baie Verte Peninsula is underlain by Cambro-Ordovician rocks of the Laurentian continental margin and lower Ordovician ophiolites, locally hosting VMS mineralization, which were thrust onto the margin during the Taconian orogeny. The ophiolites are covered by a lower Ordovician mafic-felsic volcanic sequence. Uplift and erosion of the accretionary continental margin and its cover was followed by lower Silurian continental volcanism prior to the onset of the Salinic orogen and younger strike-slip deformation.
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