A 200 mWm (super -2) (5 HFU) thermal anomaly over the San Sebastian Field. The anomaly appears to be of subsurface origin and caused by a localized discharge of deep ground water. A single published heat flow value and deep bottom hole temperature data for the area suggest a regional heat flow that is at least 20 mWm (super -2) (0.5 HFU) higher than the world average for similar tectonic provinces. Considerable lateral migration (at least 100 km) of hydrocarbons from deeper in the Magellan Basin. Ground water moving from deeper in the Magellan Basin might simultaneously transport hydrocarbons and heat to the area.--Modified journal abstract.