The building and stabilization of an Archean Craton in the Superior Province, Canada, from a heat flow perspective

• Published in: Journal of geophysical research. Solid earth 2014-12, Vol.119 (12), p.9130-9155
• Main Authors: Jaupart, C., Mareschal, J.-C., Bouquerel, H., Phaneuf, C.
• Format: Article
• Language: English
• Subjects: Amalgamation; Anisotropy; Archean; Belts; Boreholes; Buildings; Canadian Shield; Concretions; Construction; craton; Cratons; Crusts; Differentiation; Docking; Earthquake construction; Enrichment; Fluctuations; Flux; Fragmentation; Fragments; Geophysics; Heat; Heat flow; Heat flux; Heat flux measurements; Heat transfer; Heat transmission; Lithosphere; Magma; Mantle; Mantle convection; Mathematical models; Mechanical properties; Perturbations; Sciences of the Universe; Stability; Stabilization; Strength; Stresses; Temperature; Temperature distribution; Temperature effects; Thermal analysis; Thermal models; Variability
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1002/2014JB011018

How continental lithosphere responds to tectonic stresses and mantle convective processes is determined in large part by its mechanical strength and temperature distribution, which depend on crustal heat production. In order to establish reliable crustal and thermal models for the Superior Craton, Canadian Shield, new measurements of heat flux and heat production in 28 deep boreholes at 16 sites are combined with a larger set of older data. The Superior Province was assembled by the docking of volcanic/plutonic and metasedimentary terranes and continental fragments to the southern margin of an older core around 2.7 Ga. The average heat flux is much lower in the craton core than in the accreted terranes, 31 versus 43 mW m−2. The major accreted volcanic/plutonic belts share the same heat production characteristics, testifying to the remarkable uniformity of crust‐building mechanisms. The marked difference between the crusts of the core and the accreted belts supports the operation of two different crust‐forming processes. The crust of the craton core has an enriched upper layer, in contrast to that of the younger belts which lack marked internal differentiation. At the end of amalgamation, the lithosphere of the craton core was colder and mechanically stronger than the lithosphere beneath newly accreted material. Surrounding the craton core with weaker belts may have ensured its stability against tectonic and mantle convection perturbations. This large strength contrast accounts for the lack of lithospheric imbrication at the edge of the craton core as well as for the different characteristics of seismic anisotropy in the lithospheres of the craton core and the younger terranes. Key PointsTwo different crust building processes in Archean recorded in heat fluxHeat production in craton core lower than in younger belts of Superior ProvinceStability achieved by core being colder and stiffer than surrounding belts