The volcanic arc runs along the borders between Bolivia and Argentina with Chile, and behind the volcanic arc lies a chain of silicic volcanoes, of which Galán is a southern member. The whole region has been subject to substantial ignimbrite-forming volcanism with many eruptions producing volumes of rock larger than , although the actual vents often are only visible from space imagery. Many vents cluster in an area known as the Altiplano-Puna volcanic complex which occupies a surface of about approximately north of Galán, and which includes the large calderas of La Pacana, Cerro Guacha, Pastos Grandes and Cerro Panizos as well as more recent geothermal systems. This volcanism appears to be a surface expression of a pluton, and at depths of beneath the Altiplano-Puna volcanic complex electrical, gravity and seismic tomography data have localized a structure of partially molten rock called the Altiplano Puna Magma Body. Volcanism in this back region may not be directly related to subduction processes despite the region itself being close to a subducting margin.