Santo Domingo Formation (Spanish: Formación Santo Domingo) is a mainly marine Miocene sedimentary formation located in south–central Chile. The formation was defined by R. Martínez Pardo and Mario Pino in 1979 and named after the roadcut locality they studied about 19 kilometres (12 mi) southeast of Valdivia. Sediments of the formation accumulated in and Osorno–Llanquihue Basin.