Controls on Barite Mineralization in a Major Intracontinental Shear Zone: Carboniferous of the Cobequid Highlands, Nova Scotia

Georgia Pe-Piper,David Piper

doi:10.3390/min11121413

Abstract

Prominent veins of late Carboniferous barite, associated with fluorite and calcite, outcrop close to older granite plutons along an intracontinental shear zone that was active throughout the Carboniferous in southeastern Canada. Some barite is stratigraphically constrained to younger than 315 Ma and final mineralization is constrained by a published Rb–Sr isochron of 300 ± 6 Ma. Barite occurrences in the Carboniferous basins of central Nova Scotia, 50 km to the south, are synchronous with or post-date ankerite-siderite-magnetite-pyrolusite and Pb-Zn mineralization, which was facilitated by fluid interaction with thick evaporites. This study aims to determine controls on the distribution of barite in the shear zone, from field relationships, vein petrography and isotope geochemistry of minerals. The isotope chemistry of shear zone barite is similar to that occurring in Pb-Zn-Mn-Ba mineralization to the south, suggesting a common origin. Veins of barite, associated with fluorite, represent the youngest and regionally coolest phase of a 70 Ma history of Carboniferous mineralized veins along the Minas Fault Zone. Their prominence close to granite plutons reflects brittle deformation of the deeply-rooted granites in a complexly deforming fault zone, but the origin of abundant F remains uncertain.

Highlights

IntroductionThe barite occurs together with specularite, other iron minerals (e.g., goethite, ankerite, siderite, and pyrite), or fluorite and less commonly with chalcopyrite, sphalerite, galena or manganese minerals
The barite occurs together with specularite, other iron minerals, or fluorite and less commonly with chalcopyrite, sphalerite, galena or manganese minerals. This complex fault system was initiated in the Late Devonian following collision of the outboard peri-Gondwanan Appalachian terranes with Laurentia [5], with the local component of the fault system known as the Cobequid Shear Zone, with dextral slip on ENE-trending faults
A 1 m in width breccia zone located in this area is partially cemented with medium-grained, tabular, white barite

Summary

Introduction

The barite occurs together with specularite, other iron minerals (e.g., goethite, ankerite, siderite, and pyrite), or fluorite and less commonly with chalcopyrite, sphalerite, galena or manganese minerals. This complex fault system was initiated in the Late Devonian following collision of the outboard peri-Gondwanan Appalachian terranes with Laurentia [5], with the local component of the fault system known as the Cobequid Shear Zone, with dextral slip on ENE-trending faults.

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