Impact and Crystallization Modeling of the Sudbury Basin and Its Implications for a Hadean Crust

Abstract

The 1.85 Ga Sudbury Structure hosts Earth's largest and best‐preserved impact‐induced melt sheet, the Sudbury Igneous Complex (SIC), which crystallized into distinct noritic, gabbroic, and granophyric layers. We conduct impact simulations with iSALE‐2D and crystallization modeling using alphaMELTS 2 to track the formation and evolution of the SIC. Our MELTS simulations indicate that the SIC bulk composition is best reproduced by a mixture of ∼65% Archean Levack Gneiss Complex material and ∼35% lower crust material. iSALE simulations identify an optimal impact scenario involving a 20 km impactor, represented in the model with granite as a practical proxy for a carbonaceous‐chondrite‐like body, striking the target at 15 km/s, consisting of sedimentary cover over granitic upper and gabbroic lower crust. This configuration produces a melt sheet ( k) consistent with previous estimates and dominantly sourced from upper and lower crust in a ∼2:1 ratio, with mantle‐derived contributions not required by the model results. We also revise previous melt scaling laws to more accurately predict melt volumes and contributions from each target layer for large impacts. Our models show that impact‐induced melt sheets derived primarily from crustal material can differentiate into stratified igneous units resembling the Sudbury crust. While developed for the Sudbury Basin, this approach can be used to explore how impact‐generated melt sheets may have contributed to the reworking, modification, or possible generation of early crust during the Hadean, although differences in lithosphere rheology and mantle temperature at that time introduce additional uncertainties.