Casa Colorada is a dacitic volcanic dome complex erupted 17 million years ago. It has a volume of 1.5 cubic kilometres (0.36 cu mi). The complex formed in three stages, involving a tuff ring, lava domes and dacitic lava flows. It is constructed on red beds and a basement of Ordovician age. The main dome is dated 17.3 mya by potassium–argon dating. The main minerals are biotite, hornblende, feldspar and quartz; oxide minerals are also present.
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Casa Colorada (volcano) Wikipedia(Text) CC BY-SA