|
|||||
|
|
Time-scales of Differentiation from Mafic Parents to Rhyolite in North American Continental Arcs |
|
| Authors: | REAGAN M K; SIMS K W W; ERICH J; THOMAS R B; CHENG H; EDWARDS R L; LAYNE G; BALL L |
| Institution: | 1 DEPARTMENT OF GEOSCIENCE, UNIVERSITY OF IOWA, IOWA CITY, IA 52242, USA 2 DEPARTMENT OF GEOLOGY AND GEOPHYSICS, WOODS HOLE OCEANOGRAPHIC INSTITUTION, WOODS HOLE, MA 02543, USA 3 EXXON-MOBIL, 800 BELL STREET, HOUSTON, TX 77002, USA 4 MINNESOTA ISOTOPE LABORATORY, DEPARTMENT OF GEOLOGY AND GEOPHYSICS, UNIVERSITY OF MINNESOTA, MINNEAPOLIS, MN 55455, USA |
| Abstract: | Young rhyolites and associated lavas and magmatic enclaves fromthe Katmai–Novarupta volcanic system (Alaskan Peninsula),and the Crater Lake and Medicine Lake volcanic system (Cascades)were analyzed for U and Th isotope abundances, as well as majorand trace element concentrations, to investigate the time-scalesof the processes that lead to rhyolite generation in continentalarcs. Basalts and basaltic andesites typically migrate fromthe mantle to the surface within several thousand years. Variationsin (230Th)/(232Th) and (238U)/(232Th) ratios with SiO2 concentrationsin intermediate lavas appear to result from crystal fractionationcombined with assimilation of recently crystallized magmas.These data also suggest that |
| Keywords: | |
| 本文献已被 Oxford 等数据库收录！ | |