Final answer:
The metamorphic facies fitting the conditions of high pressure and low temperature typical at accretionary prisms of convergent plate boundaries is blue schist, identified by minerals that form under such environments.
Step-by-step explanation:
The metamorphic facies that would develop at high pressures and low temperatures, such as in the accretionary prism at a convergent plate boundary, is blue schist. Metamorphic facies are sets of mineral assemblages that are formed under similar pressures and temperatures; they are linked to specific tectonic settings.
Both the blue schist facies and the eclogite facies are indicative of high-pressure, low-temperature conditions that are typical in subduction zones, where rocks are subjected to intense pressure due to tectonic collisions but are relatively cool because they are far from the heat of the Earth's mantle. Blue schist, characterized by the presence of glaucophane (a blue amphibole), forms under somewhat lower pressures than eclogite. In an accretionary prism, oceanic sediments and rocks are scraped off the downgoing plate and piled up against the leading edge of the overriding plate, which corresponds to this facies' development environment.