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The Lower Toluca Pumice; a ca. 21,700 yr B. P. Plinian eruption of Nevado de Toluca Volcano, Mexico

Lucia Capra, Lia Maria Carreras, Jose Luis Arce and Jose Luis Macias
The Lower Toluca Pumice; a ca. 21,700 yr B. P. Plinian eruption of Nevado de Toluca Volcano, Mexico (in Neogene-Quaternary continental margin volcanism; a perspective from Mexico, Claus Siebe (editor), Jose Luis Macias (editor) and Gerardo J. Aguirre-Diaz (editor))
Special Paper - Geological Society of America (2006) 402: 155-173

Abstract

Approximately 21,700 yr B.P., after a period of quiescence of approximately 4800 yr, Nevado de Toluca volcano erupted, producing the Lower Toluca Pumice deposit. The activity generated a 24-km-high Plinian column that lasted approximately 11-13 h and dispersed 2.3 km (super 3) (0.8 km (super 3) dense rock equivalent) of tephra toward the NE, blanketing the Lerma basin, an area occupied today by the city of Toluca, with up to 5 cm of ash. Subsequent eruptive pulses were sub-Plinian in style, accompanied by phreatomagmatic explosions that emplaced surge deposits. Finally, the column collapsed toward the NE with the emplacement of a pumice flow deposit. The high vesicularity of the pumice from the basal Plinian layer, up to 83% by volume, indicates that exsolution was dominantly magmatic, and that pressurization of the magma chamber was probably due to a magma mixing process. Evidence for this includes the compositional range of juvenile products (61-65 wt% SiO (sub 2) ), as well as the presence of two types of plagioclase, one in equilibrium and the other one with disequilibrium textures and reverse zoning. This suggests input of an andesitic liquid into the dacitic magma chamber. Based on the eruptive record, the most likely future eruptive activity at Nevado de Toluca volcano will be Plinian. Although quiet for more than 3250 yr, Plinian activity could occur after a long period of quiescence, and it could represent a hazard for the entire Toluca basin, where more than one million people live today.


ISSN: 0072-1077
EISSN: 2331-219X
Coden: GSAPAZ
Serial Title: Special Paper - Geological Society of America
Serial Volume: 402
Title: The Lower Toluca Pumice; a ca. 21,700 yr B. P. Plinian eruption of Nevado de Toluca Volcano, Mexico
Title: Neogene-Quaternary continental margin volcanism; a perspective from Mexico
Author(s): Capra, LuciaCarreras, Lia MariaArce, Jose LuisMacias, Jose Luis
Author(s): Siebe, Clauseditor
Author(s): Macias, Jose Luiseditor
Author(s): Aguirre-Diaz, Gerardo J.editor
Affiliation: Universidad Nacional Autonoma de Mexico, Instituto de Geografia, Mexico City, Mexico
Affiliation: Universidad Nacional Autonoma de Mexico, Departamento de Vulcanologia, Mexico City, Mexico
Pages: 155-173
Published: 2006
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
Meeting name: Penrose conference on Neogene-Quaternary continental margin volcanism; a perspective from Mexico
Meeting location: Metepec, MEX, Mexico
Meeting date: 20040112Jan. 12-16, 2004
References: 33
Accession Number: 2006-067798
Categories: Quaternary geologyEnvironmental geology
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. 7 tables, sketch maps
N19°08'60" - N19°08'60", W99°45'00" - W99°45'00"
Secondary Affiliation: Universidad Nacional Autonoma de Mexico, Juriquilla Campus, MEX, Mexico
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200639
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