HR: 0800h
AN: V51A-05 INVITED     [Abstracts]
TI: Not so Simple Monogenetic Volcanism at Volcan El Jorullo
AU: * Rubin, K H
EM: krubin@hawaii.edu
AF: Geology and Geophys., U. Hawaii, Honolulu, HI 96822, United States
AU: Jurado-Chichay, Z
EM: zinzuni@hawaii.edu
AF: Geology and Geophys., U. Hawaii, Honolulu, HI 96822, United States
AU: Zellmer, G F
EM: gzellmer@earth.sinica.edu.tw
AF: Geology and Geophys., U. Hawaii, Honolulu, HI 96822, United States
AU: Zellmer, G F
EM: gzellmer@earth.sinica.edu.tw
AF: Inst. Earth Sciences, Academia Sinica, 128 Academia Road, 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: Geology and Geophys., U. Hawaii, Honolulu, HI 96822, United States
AU: Feineman, M D
EM: mdf12@psu.edu
AF: Dept. of Geosciences, Penn State U. , University Park, PA 16802, United States
AU: Rowland, S
EM: scott@hawaii.edu
AF: Geology and Geophys., U. Hawaii, Honolulu, HI 96822, United States
AB: Volcan El Jorullo (1759 to 1774) was produced in one of two historical eruptions within the Michoacan- Guanajuato Volcanic field (MGVF) in the western Trans Mexican Volcanic Belt. Although direct observations of the eruption were sparse compared to the nearby 20th century Paricutin eruption, detailed geological, petrological and geochemical studies begun by Luhr and Carmichael (CMP 90, 1985) and continued by ourselves and others have uncovered a complex (and non-linear) sequence of melting, ascent, differentiation, assimilation and eruption. Collectively these 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. This presentation will summarize primarily ongoing geochemical work (mostly in the past decade) since the seminal Luhr and Carmichael study. We show that 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). Further, conditions of magma accumulation, differentiation, storage and transport were sufficiently heterogeneous to produce spatial and temporal variations in lava compositions erupted in at least 8 distinct effusive events that collectively formed the compound Jorullo flow field. 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 apparently simpler sequence of events prevailed (e.g., McBirney et al CMP 95, 1987)
DE: 1040 Radiogenic isotope geochemistry
DE: 1065 Major and trace element geochemistry
DE: 3618 Magma chamber processes (1036)
DE: 3641 Extrusive structures and rocks
DE: 8486 Field relationships (1090, 3690)
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly