Distinguishing lower and upper crustal processes in magmas erupted during the buildup to the 7.7 ka climactic eruption of Mount Mazama, Crater Lake, Oregon, using 238U–230Th disequilibria

• Published in: Contributions to mineralogy and petrology Vol. 166; no. 2; pp. 563 - 585
• Main Authors: Ankney, Meagan E., Johnson, Clark M., Bacon, Charles R., Beard, Brian L., Jicha, Brian R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2013
• Subjects: Earth and Environmental Science; Earth Sciences; Geology; Mineral Resources; Mineralogy; Original Paper; Uranium-series isotopes; Crater Lake; Mount Mazama; Cascade arc; Crustal interaction

Uranium-series isotope ratios determined for 35 volcanic rocks and 4 glass separates erupted from ~36 to 4.8 ka at Mt. Mazama, Crater Lake, Oregon, identify both 230 Th-excess and 238 U-excess components. U–Th isotope compositions cover a wide range, exceeding those previously measured for the Casca...