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Abstract:

The ca. 1.85 Ga Sudbury impact structure straddles the Paleoproterozoic Southern Province to the south and the Archean Superior Province to the north. Structures in the Southern Province formed during several deformation events that occurred both before and after the Sudbury meteoritic impact event. D1 structures are characterized by a strong S1 fabric that predates the formation of Sudbury breccia in the ca. 2420 Creighton granite. D1 formed as a result of north-south crustal shortening and deformation of the Southern Province during the pre-impact Blezardian Orogeny. Sudbury breccia along the syn-sedimentary ENE-trending Murray fault is overprinted by a strong foliation (S2) and down-dip lineation (L2), which formed during post-impact reverse dip-slip reactivation of the fault (D2). S2 is cut by olivine diabase dikes of the Sudbury dike swarm, indicating a pre-1238 Ma, Mazatzal or Penokean age for this deformation. Southern Province was further deformed during the Grenvillian Orogeny. Two Grenvillian thrusting events D3 and D4 postdate D2 and produced S3 and S4 mylonitic foliations that cut across the ca. 1.47 Ga Chief Lake Complex along the Grenville Front. S3 and S4 are characterized by strong down-dip mineral lineations with rotated feldspar wings consistent with NW-directed thrusting. D4 produced the most prominent fabrics along the Grenville Front. In the Creighton pluton, approximately 14 km northwest of the Grenville Front, NW-SE compression during D4 was accommodated by the formation of conjugate dextral east-striking transcurrent shear zones and by sinistral transcurrent shear zones that locally follow north-striking Sudbury breccia dikes.

Notes:

GeoRef, Copyright 2018, American Geological Institute.<br/>2016-004031<br/>Blezardian Orogeny<br/>Murray Fault