The East Kemptville tin deposit, Yarmouth County, southwestern Nova Scotia: a lithogeochemical study of the wallrock metasedimentary rocks

Authors

  • Daniel J. Kontak Nova Scotia Department of Natural Resources, P.O. Box 698, Halifax, Nova Scotia B3J 279, Canada
  • Jarda Dostal Department of Geology, St. Mary's University, Halifax, Nova Scotia B3H 3C3, Canada

DOI:

https://doi.org/10.4138/1851

Abstract

The results of a petrographic and lithogeochemical study of metasedimentary rocks (Lower Paleozoic Meguma Group) surrounding the northern part of the East Kemptville tin deposit, southwestern Nova Scotia are presented. The metasedimentary rocks, including interbedded psammites and pelites, are fine-grained and highly indurated. Pelitic horizons contain homfelsic textures (i.e., <5 mm cordierite grains) near the granite; sparse veining includes some cassiterite and sulphides. Hydrolhermal alteration is manifested by disseminated, fine-grained, secondary muscovite and/or muscovite and chlorite infilling and lining microfractures with bleached haloes and associated cassiterite, sulphides, tourmaline, fluorite and carbonate. The major and trace element chemistry, including the rare-earth elements, of the metasedimentary rocks are compared to different data bases that comprise: (1) averages for pelites and psammitcs of Phanerozic age, (2) nonmineralized Meguma Group rocks, and (3) fields in discriminant binary clement diagrams. For most of the major and trace elements analyzed an apparently unaltered, normal chemistry is indicated, except for some LILE (e.g., Li, Rb, U) and ore-forming elements (e.g., Sn, Zn, Bi) where enrichment is considered to reflect infiltration of mineralizing fluids from the proximal granite/greisen of the main deposit area. The data indicate that infiltration of fluids was minimal and that, for the most part, the metasedimentary rocks acted as an impermeable cap to the ore-forming solutions. RÉSUMÉ Les résultats d'une étude pétrographique et lithogéochimique des roches métasédimentaires (Groupe de Meguma du Paléozoique inférieur) entourant la partie nord du gisement d'étain de East Kemptville, dans le sud-ouest de la Nouvelle-Écosse, sont présentés. Les roches métasédimentaires, comprenant des grès et des pelites, sont à grain fin et fortement induces. Les horizons pélitiques montrent des textures de corndennes (i.e. des grains de cordidrite <5 mm) près du granite; des veines éparses contiennent de la cassitérite et des sulfures. L'altération hydrothermale se manifeste par de la muscovite secondaire à grain fin dissémindée ou par de la muscovite et de la chlorite en remplissage et en tapis sage de microfractures aux épontes lessivées et associées à de la cassitérite, des sulfures, de la tourmaline, de la fluorite et des carbonates. La composition en éléments majeurs et traces, incluant les terres rares, des roches métasédimentaires sont companies à diverses bases de données, incluant: (1) les composition moyennes des pélites et des grès d'âge Phanérozoique, (2) les roches non minéralisdes du Groupe de Meguma et (3) les champs des diagrammes de discrimination binaires. Les teneurs de la plupart des éléments majeurs et traces analyses indiquent une composition normale, apparamment inaltérée, à part pour certains éléments à grand rayon ionique (e.g., Li, Rb, U) et certains éléments économiques (e.g., Sn, Zn, Bi) ou l’enrichissement est considéré comme représentant l’inftitration de fluides minéralisateurs provenant du greisen proximal de la région du gisement principal. Les données indiquent que l’infiltration des fluides était minimale et que les roches métasédimentaires ont agi principalement comme une enveloppe imperméable pour les solutions minéralisatrices. [Traduit par le journal]

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Published

1992-03-01

How to Cite

Kontak, D. J., & Dostal, J. (1992). The East Kemptville tin deposit, Yarmouth County, southwestern Nova Scotia: a lithogeochemical study of the wallrock metasedimentary rocks. Atlantic Geoscience, 28(1). https://doi.org/10.4138/1851

Issue

Vol. 28 No. 1 (1992)

Section

Articles

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