Toward 3D Structural Constraints from Magnetic Models: An Example from the Montresor Belt, Nunavut, Canada

Abstract

New geophysical and geological results shed light on the tectonic history of the Montresor belt, located on the Rae craton of northern Canada — an Archean terrane that has been reworked by four Proterozoic orogenies. In this contribution we use forward modelling of high-resolution aeromagnetic data to explore the 3D geometry and structural history of the Montresor belt, part of the Rae cover sequence. Previously thought to be a simple syncline, our re-analysis of the aeromagnetic data has outlined a set of earlier structures that provide new insight on the deformation history of the belt. Five cross-sections model discrete magnetic-lithologic units truncated by a series of low-angle faults. Reconstruction of the magnetic map features and forward models reveals a pre-fold geometry analogous to foreland fold and thrust belts, produced by D1 deformation during the Trans-Hudson orogeny, bracketed by available geochronology between 1.94 and 1.864 Ga. The Montresor belt rocks have potential for a variety of mineral deposit types, including precious metals in hydrothermal settings, and are under study as part of the Geo-mapping for Energy and Minerals program in Canada.