麻豆传媒

B. Sc. Honours Thesis

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In recent years there has been considerable interest in manganiferous sediments of the oceans. This interest is due to the special environment required to form manganiferous sediments, the association with other metals, and their occurrence as geochemical halos around hydrothermal deposits. In the Meguma Group of Nova Scotia finely laminated manganiferous beds are present at many localities near the Goldenville - Halifax Transition Zone (GHT) where deposits of Au, W, Pb, and Zn are known to occur (Zentilli et. al., 1984). These manganiferous beds may be interpreted as regionally metamorphosed equivalents of manganiferous sediments of marine origin.

The manganiferous bed at Lake Charlotte occurs in a 750m wide slate belt that forms the core of a tightly folded syncline and has been metamorphosed to chlorite and biotite grades. The manganiferous bed appears to occur across much of the width of the slate belt and is characterised by layers of carbonate that are commonly tightly folded or contorted. Its total thickness is uncertain but it could be up to 300m thick. The bed extends at least 11km along strike from the east shore of Ship Harbour to the village of Lake Charlotte in the west. Beyond these areas no mapping was done except along the east shore of Jeddore Harbour 7km west of Lake Charlotte. Samples taken in the 1950's from the north limb of the fold near the village of Lake Charlotte yielded 5.3% to 12.3% MnO₂ concentrations on core lengths of 160m to 1.5m, respectively.

This thesis describes the local geology and mineralogy of the manganiferous bed at Lake Charlotte. The Mn bed at Lake Charlotte is similar to other Mn beds in the Meguma Group and coticule beds found elsewhere in the world. Because of this similarity to coticule beds and the low degree of metamorphism the Mn bed at Lake Charlotte is considered a "proto - coticule". The Mn is concentrated in a Mn carbonate that is of diagenetic origin.

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Pages: 72
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