34. Dacite Domes and Ignimbrites, Sud Lipez, Bolivia

The Central Andean volcanic province contains many hundreds of major volcanos, active and inactive, and contains a higher density of volcanos than almost any other place on Earth. Every feature visible in this photograph is of volcanic origin. The area concerned is in the Sud Lipez province of southwest Bolivia, a remote region more than 4000 meters (13,120 feet) high that has only rarely been visited by geologists. From the top, the most important volcanic features are: (1) The resurgent center of a large caldera (this is the snow-capped mountain southwest of the playa lake), exhibiting an excellent apical graben. The caldera is probably 4 million years old. (2) A large dacite dome (immediately adjacent to a playa lake of similar size). This dome was probably erupted along the ring fractures of the same caldera. (3) The pink-brown colored areas are all ignimbrite sheets, pumiceous pyroclastic flows erupted during the formation of the caldera. Some of these sheets can be traced for exceptional distances, up to 150 kilometers (90 miles) from the caldera. (4) Several major andesite composite conical volcanos. These show up in dark tones (capped by snow) and are generally younger than the ignimbrites.

The brownish red lake at bottom is the Laguna Colorada. Rich in salts and salt resistant crustacea and other organisms, it is famous as the breeding ground of thousands of flamingoes, including the rare James flamingo.

STS-51A, November 1984. Picture #19-35-106.

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