HR: 09:45h
AN: V31H-08    [Abstracts]
TI: The Complicated Life of a Little Monogenetic Volcano in Mexico: Volcan El Jorullo
AU: * Rubin, K H
EM: krubin@hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96822, United States
AU: Jurado-Chichay, Z
EM: zinzuni@hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96822, United States
AU: Zellmer, G
EM: gzellmer@earth.sinica.edu.tw
AF: Dept. of Geology and Geophysics, SOEST, Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96822, United States
AU: Zellmer, G
EM: gzellmer@earth.sinica.edu.tw
AF: Academia Sinica Institute of Earth Sciences, 128 Academia Rd, Sec. 2, Taipei, 11529, Taiwan
AU: Moran-Zenteno, D
EM: dantez@servidor.unam.mx
AF: Insituto de Geologia, UNAM, Mexico City, DF 04510, Mexico
AU: Pyle, D
EM: pyled@hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96822, United States
AU: Rowland, S
EM: scott@hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, Univ. Hawaii, 1680 East-West Rd., Honolulu, HI 96822, United States
AB: Volcan El Jorullo was produced from 1759 to 1774 and represents one of two historical eruptions within the Michoacan-Guanajuato Volcanic field in the western Trans Mexican Volcanic Belt. Inspired by the results of an early detailed geological, petrological and geochemical study by Luhr and Carmichael (CMP 90, 1985), and the dearth of subsequent research, our group began a detailed assessment of spatial and temporal compositional variations within volcanic products of this eruption in the early 1990s. Collectively the studies have uncovered a complex (and non-linear) sequence of melting, ascent, differentiation, assimilation and eruption that betray a much larger spatial and temporal variability in magma storage and migration conditions than one might anticipate for a one-time volcanic event in a volcanic field fed sufficiently with magma to have produced nearly 1000 similar volcanic cones in the Holocene and Pleistocene. These complexities at Jorullo offer a rare opportunity to study mafic magma generation at a near arc volcano, a prospect that excited Jim Luhr and made him an engaged collaborator until his untimely passing. This presentation will summarize our data (mapping, major and trace element, Sr-Nd-Pb and U-series isotopic data) and synthesize it with those of the seminal Luhr and Carmichael study. We show that high to moderate MgO melts supplied to Jorullo were a mixture of those generated from an arc-fluid fluxed mantle and the lower crust and that magmas carry a signature of two distinct assimilation events (one deep, one probably shallow) that are distributed differently within the Jorullo compound lava flow field. Further, conditions of magma accumulation, differentiation, storage and transport were sufficiently heterogeneous to produce other spatial and temporal variations in lava compositions erupted in at least 8 distinct effusive events during this monogenetic activity. We suggest that there are direct feedbacks between what, where and how various magma compositions were erupted at Jorullo and contrast these conditions to those at Paricutin, at which an outwardly similar but ultimately simpler sequence of events prevailed (e.g., McBirney et al CMP 95, 1987).
DE: 1043 Fluid and melt inclusion geochemistry
DE: 3619 Magma genesis and partial melting (1037)
DE: 3640 Igneous petrology
DE: 8413 Subduction zone processes (1031, 3060, 3613, 8170)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting