We present data on the kinematics and geometry of a western segment of the San Juan Fault, which strikes east-west near the southern tip of Vancouver Island, British Columbia, Canada. This fault delineates the boundary between metamorphosed volcanic and plutonic rocks of the Wrangellia terrane, specifically West Coast Crystalline island intrusions, to the north from the altered Pandora Peak unit and Leech River Complex of the Pacific Rim terrane to the south. Detailed geologic mapping of the study area suggests the San Juan Fault is not a discrete fault, but rather a ~2400-meter fault zone, herein named the San Juan Fault Zone (SJFZ). The San Juan Fault is conjectured to be a left-lateral slip based on displacement of West Coast Crystalline rocks, yet kinematic support is lacking. Fault kinematic indicators from six locations, including a total of 203 slickenlines and shear-sense fractures, suggest left-lateral slip with a minor component of oblique thrust motion. Secondary faults predominantly trend northeast-southwest or northwest-southeast at about 30°-60° to the mapped SJFZ. These secondary faults likely formed in response to continued accretion of the Pacific Rim and Crescent terranes leading to increased strain on the transpressional strike-slip system. The San Juan fault begins to branch and splay towards its western extent. Thus, the San Juan fault is an east-west trending, left-lateral high angle strike-slip fault with a minor oblique thrust component.
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