Abstract

Ultramafic rocks of the Hozameen, Bridge River, and Cache Creek ophiolite assemblages show much variety. The Coquihalla belt of the Hozameen ophiolite assemblage, almost completely serpentinized, is elongate, narrow, and lies along a major fault. Three ultramafic bodies from the Bridge River ophiolite differ markedly from each other. (1) The Pioneer peridotite is a relatively small lens (4 km by 2 km), unaltered, well layered, and fault bounded. (2) The Shulaps body, one of the largest in British Columbia, is bounded on the northeast by a major fault and shows a wide mélange zone on the southwest. (3) A serpentinite body at Lillooet appears to be a steeply dipping slab in the Fraser River fault zone. At Cache Creek, serpentinite bodies are small and appear to be fragments in a mélange. Layers, transgressive sheets, and pods in the Pioneer and Shulaps bodies originated in the mantle, probably by one or several processes: metamorphic differentiation, metasomatism, and mechanical injection. Some ultramafic bodies were emplaced onto the crust by obduction but others, strongly serpentinized, that lie in fault zones may have been squeezed into their present positions.

You do not currently have access to this article.