Geologic, Fluid Inclusion and Stable Isotope Study of a Carbonate-Hosted Lead Deposit at Pembroke (Glenbervie), Colchester County, Nova Scotia

Abstract

The Pembroke (also Glenbervie) prospect is a carbonate-hosted lead deposit located at 45o17'05" North Latitude and 62o56'15" West Longitude in Colchester County, Nova Scotia. The deposit is stratabound within the Macdonald Road Formation limestone of the Lower Carboniferous Windsor Group, a sequence of cyclic marine carbonates, evaporites and red-beds. Coarse-grained galena occurs in calcite veinlets as well as filling interskeletal and intraskeletal pores created by abundant fossil brachiopods.

Homogenization temperatures obtained from fluid inclusions in mineralized calcite indicate that the minimum temperature of crystallization was 214.8oC.

Oxygen and carbon isotope data for mineralized calcite indicate mean values of +19.08SMOW and +1.38PDB respectively. Mineralization resulted in isotopic exchange, lowering the original 18O and 13C values of the host limestone.

The mineralizing event probably occurred during the Maritime Disturbance (Pennsylvanian) when high geothermal gradients accompanied the dewatering of evaporites, the resulting brines leaching the underlying Ordovician metasediments and transporting metals to favourable sites of deposition along the Horton-Windsor contact.

Keywords: Pages: 73 Supervisors: Marcos Zentilli