Name
Thermochemical state of the lithosphere beneath the Superior Craton region from multi-observable probabilistic inversion
Date & Time
Monday, May 8, 2023, 11:00 AM - 11:15 AM
Description
The Superior Craton comprises the nucleus of the Canadian Shield and has seen modification from localized ductile reworking at its northeastern and northwestern margins, hotspot passage, impingement of the midcontinent rift, and orogenesis along its margins. Here, we present a thermochemical model of the Superior Craton region by jointly inverting surface wave dispersion data, body wave data, geoid height, surface heat flow, and absolute elevation with a multi-observable probabilistic inversion method. Our model reveals a thick (~250-300 km) and chemically-depleted lithosphere (Mg#>90) beneath the eastern and western Superior arms and the Archean Rae and Hearne Cratons, consistent with independent results from mantle xenoliths.In contrast, beneath the Grenville Front, the Appalachian Front, and the North Quebec Orogen, we observe a chemically-fertile (87
Location Name
Aspen
Full Address
Banff Park Lodge Resort Hotel & Conference Centre
201 Lynx St
Banff AB T1L 1K5
Canada
Abstract
The Superior Craton comprises the nucleus of the Canadian Shield and has seen modification from localized ductile reworking at its northeastern and northwestern margins, hotspot passage, impingement of the midcontinent rift, and orogenesis along its margins. Here, we present a thermochemical model of the Superior Craton region by jointly inverting surface wave dispersion data, body wave data, geoid height, surface heat flow, and absolute elevation with a multi-observable probabilistic inversion method. Our model reveals a thick (~250-300 km) and chemically-depleted lithosphere (Mg#>90) beneath the eastern and western Superior arms and the Archean Rae and Hearne Cratons, consistent with independent results from mantle xenoliths.In contrast, beneath the Grenville Front, the Appalachian Front, and the North Quebec Orogen, we observe a chemically-fertile (87<Mg#<90) lithosphere, indicating extensive lithospheric modification and refertilization events resulting in mechanical erosion at multiple scales in these areas.The chemically-fertile mantle of the Trans-Hudson Orogen at shallower depths transitions to a less-depleted Proterozoic signature at deeper depths between the depleted cores of the Archean Superior and Churchill Cratons. This result supports the theory of a modern-style plate-tectonic collision between these cratons during the Trans-Hudson orogeny, resulting in the entrapment of juvenile Proterozoic material. Midcontinent rift and Hudson Strait region are imaged with a moderately-fertile mantle lithosphere along with a shallow lithospheric keel (< 200 km). The present-day thermochemical structure in the region is a result of a complex interaction between the compositionally-distinct and refractory Archean cratonic regions and the more fertile, modern mantle beneath the Proterozoic terranes.
Session Type
Breakout Session