Magmatism in the western United States

Animation of magmatism in the western United States over the past 65 million years. Dots are color-coded by general compositional category. Points start to appear 1 million years before the age listed in the database, grow to maximum size at the listed age, and then shrink to zero radius for the next 2 million years. Plate boundaries are taken from Tanya Atwater's reconstructions; red lines are oceanic plate boundaries, the dashed magenta line is the Pacific-Farallon trench, and the solid magenta line is the developing San Andreas transform. Note that the plate elements are palinspastically restores whereas the North American base map and igneous points are not; the subduction zone and transform swing northwest as the Basin and Range opens.

Several magmatic patterns are apparent in this animation, including migration of silicic volcanism from Montana to Nevada, a clockwise sweep of magmatism around the southern edge of the Colorado Plateau, a burst of magmatism in northern Nevada around 17 million years ago (the Yellowstone event), and the general "basaltification" of magmatism throughout the Cenozoic.

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• magmatism
• western
• United
• States
• pacific
• Farallon
• plate
• San
• Andreas
• fault
• Noth
• American
• Basin
• and
• Range
• magmatic
• silicic
• volcanism
• Yellowstone
• basaltic
• Cenozoic
• intrusive
• rock