DEFORMATION HISTORY OF THE KENOGAMISSI BATHOLITH AND THE EASTERN SWAYZE GREENSTONE BELT

The Swayze Greenstone Belt is the southwestern extension of the Abitibi Greenstone Belt (Superior Province, Canada) as they are connected by narrow corridors of volcanic and sedimentary rocks wrapping around the north and south margins of the Kenogamissi Batholith. The Ramsay-Algoma granitoid complex marks the southern boundary of the Swayze Greenstone Belt, while the Nat-River granitoid complex represents its northern boundary. In the West, the Swayze Greenstone Belt is truncated by the Kapuskasing Structure, a late Archean uplift exposing lower to middle continental crust.

Two major deformation events have been documented: an early N-S folding event followed by E-W oriented folding. The second event is more easily recognized in two regional scale folds: i) the Brett Lake Syncline, which infolds supracrustal rocks into the west-central part of the Kenogamissi Batholith and ii) the Woman River Anticline, extending from the supracrustal rocks into the southwestern lobe of the Batholith. They are subparallel with a general E-W strike, the Woman River Anticline hinge plunges to the W. N-S trending fold axes from the first folding event have been observed in the strain shadow west of the Kenogamissi Batholith.

The Kenogamissi Batholith consists of three main units, hornblende diorite, hornblende tonalite and biotite tonalite (from oldest to youngest). The two older units have been folded and the youngest is a sheet-like, syn-tectonic intrusion. The outcrop pattern and internal structure of the Kenogamissi Batholith resembles that of a W-plunging fold with N-S trending structures from the first deformational event preserved in the core of the fold (in the hornblende diorite).

Our interpretation is that the dome-and-basin-structure of the eastern Swayze Greenstone Belt and the Kenogamissi Batholith is the result of cross-folding during two different deformational events.