TIMING CONSTRAINTS ON DEFORMATION HISTORY OF THE SUDBURY IMPACT STRUCTURE

Herein, we present new high-resolution seismic images of the Sudbury I mpact Structure, acquired across the Sudbury Igneous Complex and its e nvirons, which provide evidence for the relative timing of the deforma tion events that reshaped the initial Sudbury Structure. The seismic i mages show that the lower unit of the Sudbury basinal fill sediments, the Onwatin argillite, is penetrated by a set of blind, imbricated thr usts, whereas the overlying Chelmsford turbidites are unaffected by fa ulting. We interpret this observation to mean that the deposition of t he Chelmsford sediments postdates the latest major deformation of the Sudbury Structure, suggesting that the uniform paleocurrent trends obs erved in the Chelmsford turbidites are not related to the initial shap e of the Sudbury Structure.