Timing and kinematics of post-Timiskaming deformation within the Larder Lake - Cadillac deformation rone, southwest Abitibi greenstone belt, Ontario,Canada

The Larder Lake - Cadillac deformation zone is one of several anastomosing zones of high strain within the Abitibi greenstone belt. In the Kirkland La ke area, Ontario, the Larder Lake - Cadillac deformation zone is characteri zed by extensive carbonate and chlorite alteration, strong south-dipping fo liations, and steep lineations. These features formed during two ductile de formation increments, D-2 and D-3 that occurred after deposition of Timiska ming assemblage sediments. D-2 Strain accumulation and greenschist facies m etamorphism and alteration were localized within the deformation zone, faci litated by channelling of hydrothermal fluids within a preexisting structur e, possibly formed during early D-1 terrane accretion. During D-2 north-sou th shortening, east-west-trending sectors of the deformation zone accumulat ed bulk coaxial strains, while southeast- and northeast-trending sectors ex perienced, respectively, dextral and sinistral transpressive deformations. Preservation of Timiskaming assemblage sediments in the footwall of the def ormation zone indicates a component of south-over-north (reverse) displacem ent that is not recorded by D-2 fabrics. Northwest-southeast D-3 compressio n resulted in the formation of a regional, northeast-striking cleavage form ed under regional greenschist facies conditions, and local dextral reactiva tion of suitably oriented sections of the Larder Lake - Cadillac deformatio n zone. The Murdoch Creek and Lebel stocks abut the Larder Lake - Cadillac deformation zone. Their internal structure and emplacement are interpreted to be a consequence of D-2 north-south shortening. Magmatic zircon and tita nite in the Murdoch Creek and Lebel stocks yield U-Pb geochronology ages of 2672 +/- 2 and 2673 +/- 2 Ma, providing a maximum age for D-2 deformation. Hydrothermal titantite associated with S-3 foliation in the Murdoch Creek stock gives an U-Pb age of 2665 +/- 4 Ma, the maximum age of D-3 deformatio n. Pluton emplacement, deformation, and coincident metamorphism occurred ov er a span of 1 Ma (from 2670 to 2669 Ma) to over 14 Ma (from 2675 to 2661 M a), during a regime of north-south, followed by northwest-southeast, region al shortening.