Antonio mine during January 2001 to asses the structural controls on gold mineralization for

application to mining and exploration. The mine is hosted by the San Antonio mine unit

(SAM unit), a 50-600 foot thick differentiated, layered sill-like gabbroic intrusion that

intrudes 2629-2631 Ma age northeast dipping felsic metavolcanic rocks of the western Rice

Lake greenstone belt. At least three phases of penetrative deformation affect the area, the

dominant of which, D2, produced ubiquitous regional north to northeast dipping foliation (S2)

and tight folds in metasedimentary rocks west of the mine, and a east-northeast plunging

elongation lineation (L2) at the intersection of S2 with older foliation (S1) and bedding.

Regional dextral shear zones that bound the Rice Lake belt were active during D2.

Within the SAM unit, D2 strain is inhomogeneous. Although large portions of the unit are

unfoliated in upper mine levels, strain increases with depth and in the current area of mining,

much of the gabbro is penetratively foliated. S2 foliation refracts from northeast dipping

outside the gabbro to steep north dipping within it. Minor, steep north dipping syn-D2 shear

zones with sinistral displacements are developed throughout the SAM unit and manifested as

discrete zones of increased foliation intensity and frequently, sericite-carbonate alteration.

Gold-bearing quartz vein systems occur in the SAM unit in a 1000-2000 foot wide area with

an east-northeast plunge that has been mined to depths of 5000 feet. This area is on the

northern margins of a 400-600 foot thick, east-northeast plunging, thick lobe of the SAM unit

in places where the unit is 200-400 feet thick.