Abstract
The Cobequid Highlands of northern Nova Scotia lie at the intersection of two major dextral intra-continental shear zones which developed during closure of the Rheic Ocean and formation of Pangea. The Cobequid Shear Zone was an ENE–WSW transfer zone in a NE–SW-trending, orogen-parallel, shear system in the late Devonian–early Carboniferous (Neo-Acadian phase), in which syntectonic granite–gabbro plutons and volcanic strata <4 km thick were progressively deformed along multiple faults. In the Late Carboniferous–Permian, the Alleghanian collision of Africa with Laurentia formed the east–west-trending Minas Fault Zone, reactivating parts of the Cobequid Shear Zone. This deformation was mostly taken up on the master Cobequid–Chedabucto Fault. Deformation chronology is well constrained by the biostratigraphy of syntectonic sedimentary rocks, and by radiometrically dated igneous rocks and minerals in faults and veins. Early strike-slip faults were lubricated by magmatic heating, leading to dyke-to-pluton construction along multiple faults. During cooling, rooted gabbro was more resistant than ductile granite, thereby deflecting solid-state deformation. Neo-Acadian strike-slip displacement across the shear zone is estimated as >50 km. The location of Alleghanian deformation was influenced by the paucity of magmatism and the resistance offered by older stitching plutons.
- © 2020 Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources. Published by The Geological Society of London. All rights reserved
Please note that if you are logged into the Lyell Collection and attempt to access content that is outside of your subscription entitlement you will be presented with a new login screen. You have the option to pay to view this content if you choose. Please see the relevant links below for further assistance.