HR: 0800h
AN: V41D-0791 [Abstracts]
TI: The Massive Compound Cofre de Perote Shield Volcano: a Volcanological Oddity in the Eastern Mexican Volcanic Belt
AU: * Siebert, L
EM: siebertl@si.edu
AF: Smithsonian Institution, Global Volcanism Program, NMNH NHB-119, Washington, DC
20013-7012, United States
AU: Carrasco-Nunez, G
EM: gerardoc@geociencias.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Centro de Geociencias, Campus UNAM
Juriquilla, Carr. 15.5 Qro.-SLP, Queretaro, QRO 76230, Mexico
AU: Diaz-Castellon, R
EM: rdiaz@geociencias.unam.mx
AF: Universidad Nacional Autonoma de Mexico, Centro de Geociencias, Campus UNAM
Juriquilla, Carr. 15.5 Qro.-SLP, Queretaro, QRO 76230, Mexico
AU: Rodriguez, J L
EM: joseluisrv@hotmail.com
AF: Universidad Nacional Autonoma de Mexico, Centro de Geociencias, Campus UNAM
Juriquilla, Carr. 15.5 Qro.-SLP, Queretaro, QRO 76230, Mexico
AB:
Cofre de Perote volcano anchors the northern end of the easternmost of several volcanic chains orthogonal to the
E-W trend of the Mexican Volcanic Belt (MVB). Its structure, geochemistry, and volcanic history diverge
significantly from that of the large dominantly andesitic stratovolcanoes that have been the major focus of
research efforts in the MVB. Andesitic-trachyandesitic to dacitic-trachydacitic effusive activity has predominated at
Cofre de Perote, forming a massive low-angle compound shield volcano that dwarfs the more typical smaller
shield volcanoes of the central and western MVB. The 4282-m-high volcano overlooking Xalapa, the capital city of
the State of Veracruz, has a diameter of about 30 km and rises more than 3000 m above the coastal plain to the
east. Repeated edifice collapse has left massive horseshoe-shaped scarps that truncate the eastern side of the
edifice. Five major evolutionary stages characterize the growth of this compound volcano: 1) emplacement of a
multiple-vent dome complex forming the basal structure of Cofre de Perote around 1.9-1.3 Ma; 2) construction of
the basal part of the compound shield volcano from at least two main upper-edifice vents at about 400 ka; 3)
effusion of the summit dome-like lavas through multiple vents at ca. 240 ka; 4) eruption of a large number of
geochemically diverse, alkaline and calc-alkaline Pleistocene-to-Holocene monogenetic cones (likely related to
regional volcanism) through the flanks of the Cofre de Perote edifice; 5) late-stage, large-volume edifice collapse
on at least two occasions (ca. 40 ka and ca. 10 ka), producing long-runout debris avalanches that traveled to the
east. An undated tephra layer from Cofre de Perote overlies deposits likely of the youngest collapse. Cofre de
Perote is one of several volcanoes in the roughly N-S-trending chain that has undergone major edifice collapse.
As with Citlaltepetl (Pico de Orizaba) and Las Cumbres volcanoes, Cofre de Perote was constructed at the
eastern margin of the Altiplano, with pronounced differential relief and sloping substrate promoting failures
toward the Gulf of Mexico coastal plain.
DE: 8404 Volcanoclastic deposits
DE: 8425 Effusive volcanism
DE: 8486 Field relationships (1090, 3690)
DE: 8488 Volcanic hazards and risks
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting