Abstract

Lithoprobe aided and will continue to guide diamond exploration in Canada via a number of diverse ways and at scales from cratons to individual ore bodies. Specific transects outlined the domainal nature, geometry, and age relations of crust, subjacent mantle, and diamond-bearing roots in unusually rich detail for cratonic settings such as those of the Superior and Slave cratons, as well as pericratonic (shield) settings such as those of the Sask craton and Buffalo Hills terrane. The Superior and Slave examples of craton construction by multiple underthrust layers, as inferred from structural geometries observed in Lithoprobe seismic and magnetotelluric surveys, remain the clearest resolved to date. The first definition of the Sask craton occurred 10–15 years ago and helped fuel the diamond industry’s ongoing revision of Clifford’s Rule for exploration so as to include targets in Proterozoic shield settings. Main Lithoprobe transect results and supporting geoscience studies have helped to demonstrate the very different settings for paragenesis of both peridotitic and eclogitic types of diamonds found across Canada. Seismic methods have delineated many of the the oldest, typically depleted cratonic mantle blocks, as well as Archean and Proterozoic sutures, where larger percentages of eclogite might occur. Development of geophysical methods related to Lithoprobe data acquisition has led to metre-scale, high-resolution mapping of diamondiferous kimberlite pipes and shallow-dipping dykes, thus allowing more accurate estimates of their volume and more efficient mining of these diamond deposits.

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