Payun Volcanic Field
Situated in the southern Andes Mountains, the Payún volcanic field of Argentina is a complex landscape that formed over hundreds of thousands of years. Sprawling over 5,200 square kilometres (2,000 square miles), Payún is a massive shield volcano-a broad formation resembling an ancient warrior shield.
This false-colour image is a composite of observations acquired on 07 February and 20 March 2001 by the Enhanced Thematic Mapper Plus on the Landsat 7 satellite. It was made from a combination of visible and infrared light, where green indicates vegetation, black indicates lava flows, and orange is bare rock rich in iron oxides.
Part of the back-arc volcanism of the Andes, Payún lies about 530 kilometres (330 miles) east from where the Nazca plate subducts below the South America plate. Not surprisingly, a volcanic zone extends over some 1,000 kilometres (600 miles) north-to-south in this region. According to a study published in 2010, the regional geology and chemical composition of the rocks indicate that the volcanic field likely formed within the past 300,000 years.
The dominant feature of the volcanic field is Payún Matru, an elliptical caldera measuring roughly 9 by 7 kilometres (6 by 4 miles). Geologists surmise that the caldera formed after the old magma chamber emptied and the summit collapsed. Southwest of the caldera is a stratovolcano composed of alternating layers of compacted ash, hardened lava, and rocks ejected during previous eruptions. This stratovolcano, Payún, rises to 3,680 metres (12,073 feet) above sea level. (The entire volcanic field sits at 2,000 metres, or 6,600 feet.)
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Credit: NASA Earth Observatory - Image courtesy Michael P. Taylor, Landsat Data Continuity Mission Project Office, NASA Goddard Space Flight Center