16. Granitic Intrusion, Chanaral, Chile
The light-toned circular area at the right center of the photograph is a Paleozoic granodiorite exposed near the Pacific coast of Chile at Chanaral. The Humboldt current flowing northward along the coast gives rise to cool onshore breezes. As these move overland, they warm up, and are capable of carrying more water vapor; thus they have a very drying effect and are responsible for the long thin Atacama Desert, which extends all the way along the coast of South America from Central Chile to Ecuador. The desert is one of the driest in the world, and the absence of soil or vegetation makes it ideal for investigation using satellite remote sensing techniques.
The pale tones of the intrusion contrast sharply with the darker tones of the metamorphic basement, enabling rapid mapping. A swarm of mafic dikes cuts the intrusion, and some of the larger dikes, with northeast trend, are just visible. The valley just south of the intrusion contains a stream draining from the large porphyry copper mine at El Salvador. The stream and the beach at Chanaral on which it debouches are grossly polluted with mineral residues.
STS-8, August-September 1983. Picture #8-50-1798.