Anatomy of a terrane boundary: an integrated structural, geographic information system, and remote sensing study of the late Paleozoic Avalon-Meguma terrane boundary, mainland Nova Scotia, Canada

Abstract

Remote sensing and geographic information system analysis complimented by geological mapping have resulted in a new interpretation of the Late Carboniferous evolution of the Avalon-Meguma terrane boundary (known as the Minas Fault Zone) in the Canadian Appalachian Orogen. Various images, including optical, radar, and shaded-relief elevation, have been integrated with magnetic and gravity data to compliment mapping in the vicinity of the exposed terrane boundary in mainland Nova Scotia. Throughout much of the region, the style of deformation is typical of dextral motion along the east-west Chedabucto Fault, the most prominent structure in the Minas Fault Zone. Lineament analysis of the shaded-relief elevation and radar images has identified an important lineament trending east-northeast which corresponds to the axial trace of folds that rotate clockwise into parallelism with the Chedabucto Fault. However, in eastern mainland Nova Scotia, the shaded-relief and geophysical images, together with field data, suggest that the Chedabucto Fault was offset by sinistral motion along the north-northwest-trending Country Harbour Fault. Following this event, the region in the vicinity of this offset became a restraining bend during renewed dextral motion along the Chedabucto Fault, resulting in the formation of a positive flower structure represented by the exposure of Early Devonian volcanic and sedimentary rocks in the Guysborough block. The processes described are probably typical of recurrent motions along terrane boundaries.