Effects of rapid plate motion on the Mid-Continental Rift and mantle plume interactions under Pre-Cambrian mantle conditions

The Mid-Continent Rift System (MCRS) is a 3000-km long failed rift system that formed within the Precambrian continent of Laurentia, nearly splitting North America apart about 1.1 billion years ago. The MCRS can also be classified as a Large Igneous Province (LIP), made up of two distinct magmatic phases (Stein et al., 2015). The first phase, large-scale magmatism, is characterized by a large volume of flood basalt that filled a fault-controlled basin. The second phase, post-rift, consists of volcanics and sediment that were deposited in a thermally subsiding basin after faulting ended. The flood basalt-filled rift geometry is a special characteristic of the MCRS that is not observed in other presently active or ancient rifts. Hence, the MCRS's unusual nature likely reflects the combined effects of rifting and a mantle plume. We investigate this hypothesis with a 2D geodynamic model by fully exploring the parameter space for a range of mantle potential and plume excess temperatures under different extension scenarios and lithospheric/plume structure. Here we also explore the effect of rapid plate motion (up to 20^o latitude in 12 Myr) during the main rifting stage as suggested by Fairchild et al (2017) by modeling the translation of the rift relative to the mantle.

Stein, C.A. et al., North America's Midcontinent Rift: When rift met LIP. Geosphere, 11 (5): 1607-1616.

Fairchildm L.M. et al., The end of Midcontinent Rift magmatism and the paleogeography of Laurentia. Lithosphere, 9 (1): 117-133.