Show simple item record

Mainly explosive Holocene eruptions of the Planchón volcano, southern Andes (35°15'S).

dc.contributoren-US
dc.contributores-ES
dc.creatorNaranjo, Jose A.
dc.creatorHaller, Miguel J.
dc.date2010-06-29
dc.identifierhttp://www.andeangeology.cl/index.php/revista1/article/view/V29n1-a06
dc.identifier10.5027/andgeoV29n1-a06
dc.descriptionLa reducida actividad eruptiva holocena del Planchon se ha desarrollado a traves de 5 crateres, en su mayoria de explosion, fuente de los depositos piroclasticos distribuidos sobre el sector oriental. La primera erupcion registrada consto de tres etapas sucesivas cuyas facies son representativas de los respectivos regimenes eruptivos. La Oleada Piroclastica Valenzuela (OPV) fue una oleada de base humeda originada por el colapso de una columna de erupcion freatomagmatica, en presencia de un casquete glacial mucho mas extenso y grueso que el actual. La disminucion de la razon agua/magma durante la erupcion, habria incrementado la densidad de la columna eruptiva, generando una fase culminante de flujo piroclastico con mayor concentracion de bombas escoriaceas (Flujo Piroclastico Los Ciegos, FPLC). Dataciones AMS indican una edad holocena ~7000 AP para la erupcion. Una erupcion subpliniana ocurrida entre 1400 y 1050 AP origino el deposito de pomez de caida Los Banos (PLB) que evidencia la presencia de magmas daciticos en un sistema dominado por la generacion de basaltos a andesitas. Esta erupcion constituye un proceso unico dentro de la evolucion del volcan Planchon, tras un periodo prolongado de diferenciacion en una camara magmatica pequena. La diferencia de edad de varios miles de anos entre las erupciones explosivas holocenas mas destacadas (OPV+FPLC y PLB), asi lo justifica. Las erupciones menores de febrero de 1991 y noviembre de 1998 se produjeron por la interaccion del agua freatica con niveles rocosos sobrecalentados encima de la camara magmatica del Planchon y/o con los niveles mas elevados de esta. La camara magmatica de este volcan muestra un notable grado de diferenciacion con un volumen reducido de magma dacitico en su parte alta. Este ha sido segregado en un periodo de a lo menos 150 anos, considerando la erupcion magmatica, unica emision de lava andesitica post-glacial del volcan, ocurrida en febrero de 1837.es-ES
dc.descriptionThe Holocene activity of Planchón volcano is reduced and mainly explosive occurred through five explosive craters as the main source of the post-glacial deposits distributed to the eastern side of the volcano. Three successive phases were involved during the first Holocene eruption. An explosive column produced a short-lived tephra-fall, subplinian deposit. Phreatomagmatic explosions and the collapse of the initial column, due to crater widening, including a thick ice cap, were the causes of the second phase, the Valenzuela Pyroclastic Surge (OPV), a highly fragmented and wet base surge. The presence of a thicker and more extensive glacial cap favoured an eruption dominated by a high water/magma ratio. This also generated highly voluminous laharic deposits to the west through the avalanche caldera opening. The final column collapse was caused by the diminishing water/magma ratio, increasing the density of the explosion columns, and leading to the third final phase: a pyroclastic flow heavily laden with solid scoriaceous bombs (FPLC). AMS dating indicates a Holocene age of approximately 7,000 BP for this eruption. The presence of dacitic magmas evolved from a system dominated by basaltic andesites at Planchón volcano is evidenced by the Los Baños pumice-fall deposit (PLB). This deposit was formed during a subplinian eruption which occurred around 1,000 years ago, this being a unique process during the entire Planchón evolution. An extended differentiation period of 6 ka within a fairly small magma chamber was the probable origin for the dacite explosive event. The minor eruptions of February 1991 and November 1998, were consequences of the interaction of phreatic water with overheated rocks above the magma chamber and/or with an uppermost differentiated dacitic small magma body. The small amount of dacitic magma was produced during a 150 years period, after the unique post-glacial lava (andesite) erupted at Planchón, in February 1837.en-US
dc.formatapplication/pdf
dc.formattext/html
dc.languageeng
dc.publisherServicio Nacional de Geología y Mineríaen-US
dc.relationhttp://www.andeangeology.cl/index.php/revista1/article/view/V29n1-a06/523
dc.relationhttp://www.andeangeology.cl/index.php/revista1/article/view/V29n1-a06/html
dc.sourceAndean Geology; Vol 29, No 1 (2002); 93-111es-ES
dc.sourceAndean Geology; Vol 29, No 1 (2002); 93-111en-US
dc.source0718-7106
dc.source0718-7092
dc.titleErupciones holocenas principalmente explosivas del volcan Planchon, Andes del sur (35°15'S).es-ES
dc.titleMainly explosive Holocene eruptions of the Planchón volcano, southern Andes (35°15'S).en-US
dc.typeinfo:eu-repo/semantics/article
dc.typeinfo:eu-repo/semantics/publishedVersion
dc.typees-ES
dc.typeen-US


This item appears in the following Collection(s)

Show simple item record