Puritama Hot Springs
After leaving El Tatio geysers and hot springs, the excursion made a stop at the Puritama hot spring for some relaxation in the bathing pools. Bathing suits were provided to those that didn't have one. I, on the other hand, was not interested in soaking in some hot water, and instead went on a short hike out of the canyon to explore the surrounding area and look at the rocks.
The Puritama hot spring are located northeast of San Pedro de Atacama, at approximately 22°42' S Latitude and 67°55' W Longitude. The hot spring is located in the bottom of the canyon of the Rio Puritama. The canyon of the Rio Puritama is cut into the Puripicar Ignimbrite. The ignimbrite is described as a Pliocene-aged (4.2-4.5 million years old), pink colored, dacitic composition deposit of ash, mineral crystals and pumice. Ignimbrites are erupted as clouds of ash, that then often blankets large areas as ash flows and solidifies or compacts into solid rock.
After the formation of the Rio Puritama canyon, a Quaternary-aged lava flow of andesite erupted, followed the path of the Rio Puritama, and partially filled the canyon. This andesite is a gray colored, block lava flow.
The hot spring emerges from the base of the andesite lava flow, forming a series of pools that decrease in temperature as distance increases from the lava flow. This indicates that the probable source of heat for the hot spring is the cooling of the andesite lava flow.
Parts of the information above have been summarized from the following source: Marinovic, N. and A. Lahsen, 1984, Hoja Calama, Region de Antofagasta, Carta geologica de Chile No. 58, 1:250,000. Servicio Nacional de Geologia y Mineria, ISSN 0716-0194.