<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0256-7024</journal-id>
<journal-title><![CDATA[Revista Geológica de América Central]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. Geol. Amér. Central]]></abbrev-journal-title>
<issn>0256-7024</issn>
<publisher>
<publisher-name><![CDATA[Universidad de Costa Rica]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0256-70242017000200149</article-id>
<article-id pub-id-type="doi">10.15517/rgac.v0i57.30336</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Petrographic analysis of the volcanic bombs and blocks from Poás Volcano: april-june 2017 eruptive period]]></article-title>
<article-title xml:lang="es"><![CDATA[Análisis petrográfico de las bombas y bloques volcánicos del Volcán Poás: periodo eruptivo de abril a junio de 2017]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Madrigal]]></surname>
<given-names><![CDATA[Pilar]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Lücke]]></surname>
<given-names><![CDATA[Oscar H.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad de Costa Rica Escuela Centroamericana de Geología ]]></institution>
<addr-line><![CDATA[San Pedro ]]></addr-line>
<country>CR</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad de Costa Rica Centro de Investigaciones Geológicas ]]></institution>
<addr-line><![CDATA[ ]]></addr-line>
<country>CR</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>12</month>
<year>2017</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>12</month>
<year>2017</year>
</pub-date>
<numero>57</numero>
<fpage>149</fpage>
<lpage>159</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_arttext&amp;pid=S0256-70242017000200149&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_abstract&amp;pid=S0256-70242017000200149&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.sa.cr/scielo.php?script=sci_pdf&amp;pid=S0256-70242017000200149&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[AbstractDuring the first semester of 2017, Poás Volcano, in the Central American Volcanic Arc (CAVA) initiated a period of volcanic unrest that included high energy phreatomagmatic and magmatic eruptions. The most notable eruptions occurred on April 14th and April 22nd of 2017, which produced abundant ashes and ballistic materials in the form of blocks and bombs. Here, we present results from the petrographic analyses conducted in the collected material from the largest eruptions of April 2017. Mineral textures observed on the petrographic analyses show evidence of reactivation and fragmentation of a crystal mush in the magma chamber, triggering re-melting episodes, volatile exsolution, and an increase in the pressure of the system, all of which are expected conditions during an eruption episode. Our analyses done on juvenile and non-juvenile material suggest that processes of magma mingling and injections of new batches of material of different compositions have played an important role throughout previous eruptions and likely in the current phase of volcanic activity in Poás.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[ResumenDurante el primer semestre del 2017, el volcán Poás situado en el arco volcánico centroamericano (AVCA) inició un periodo de actividad volcánica que incluyó erupciones freatomagmáticas y magmáticas. Las erupciones más destacadas ocurrieron los días 14 y 22 de abril del año 2017. Estas erupciones produjeron la dispersión de ceniza y abundantes materiales balísticos en la forma de bloques y bombas. En este trabajo, presentamos los resultados de los análisis petrográficos realizados en los productos eruptivos de Poás para el mes de abril de 2017. Las texturas minerales observadas a partir del análisis petrográfico muestran la evidencia de la reactivación y fragmentación de un agregado cristalino en la cámara magmática y el disparo de episodios de fusión, exsolución de volátiles y un incremento en la presión del sistema. Todas estas condiciones son de esperar en un proceso eruptivo. Los análisis realizados en material juvenil y no juvenil sugieren que los procesos de mezcla de magmas e inyección de volúmenes nuevos de material con distinta composición han tenido una influencia importante en procesos eruptivos anteriores y en la nueva fase de actividad volcánica en Poás.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Poás]]></kwd>
<kwd lng="en"><![CDATA[volcanic activity]]></kwd>
<kwd lng="en"><![CDATA[magmatic processes]]></kwd>
<kwd lng="en"><![CDATA[igneous petrography]]></kwd>
<kwd lng="en"><![CDATA[crystallization]]></kwd>
<kwd lng="es"><![CDATA[Poás]]></kwd>
<kwd lng="es"><![CDATA[actividad volcánica]]></kwd>
<kwd lng="es"><![CDATA[procesos magmáticos]]></kwd>
<kwd lng="es"><![CDATA[petrografía ígnea]]></kwd>
<kwd lng="es"><![CDATA[cristalización]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[A review on phreatic eruptions and their precursors]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Barberi]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
<name>
<surname><![CDATA[Bertagnini]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Landi]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Principe]]></surname>
<given-names><![CDATA[C]]></given-names>
</name>
</person-group>
<source><![CDATA[Journal of Volcanology and Geothermal Research]]></source>
<year>1992</year>
<volume>52</volume>
<numero>1992</numero>
<issue>1992</issue>
<page-range>231-46</page-range></nlm-citation>
</ref>
<ref id="B2">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Characteristics of hydrothermal eruptions, with examples from New Zealand and elsewhere]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Browne]]></surname>
<given-names><![CDATA[P. R. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Lawless]]></surname>
<given-names><![CDATA[J. V]]></given-names>
</name>
</person-group>
<source><![CDATA[Earth-Science Reviews]]></source>
<year>2001</year>
<volume>52</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>299-331</page-range></nlm-citation>
</ref>
<ref id="B3">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[El volcán Poás, Costa Rica: cronología y características de la actividad]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Casertano]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Borgia]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Cigolini]]></surname>
<given-names><![CDATA[C]]></given-names>
</name>
</person-group>
<source><![CDATA[Geofísica Internacional]]></source>
<year>1983</year>
<volume>22</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>215-33</page-range></nlm-citation>
</ref>
<ref id="B4">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Mineral disequilibrium in lavas explained by convective self-mixing in open magma chambers]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Couch]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Sparks]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Carroll]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[Nature]]></source>
<year>2001</year>
<volume>411</volume>
<numero>6841</numero>
<issue>6841</issue>
<page-range>1037-1039.</page-range></nlm-citation>
</ref>
<ref id="B5">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Monomineralic Glomerocrysts: Textural Evidence for Mineral Resorption during Crystallization of Igneous Rocks]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hogan]]></surname>
<given-names><![CDATA[J. P]]></given-names>
</name>
</person-group>
<source><![CDATA[The Journal of Geology]]></source>
<year>1993</year>
<volume>101</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>531-540.</page-range></nlm-citation>
</ref>
<ref id="B6">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Thermo-mechanical reactivation of locked crystal mushes: Melting-induced internal fracturing and assimilation processes in magmas]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Huber]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Bachmann]]></surname>
<given-names><![CDATA[O.]]></given-names>
</name>
<name>
<surname><![CDATA[Dufek]]></surname>
<given-names><![CDATA[J]]></given-names>
</name>
</person-group>
<source><![CDATA[Earth and Planetary Science Letters]]></source>
<year>2011</year>
<volume>304</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>443-54</page-range></nlm-citation>
</ref>
<ref id="B7">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Caldera size modulated by the yield stress within a crystal-rich magma reservoir]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Karlstrom]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Rudolph]]></surname>
<given-names><![CDATA[M. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Manga]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[Nature Geoscience]]></source>
<year>2012</year>
<volume>5</volume>
<numero>6</numero>
<issue>6</issue>
<page-range>402</page-range></nlm-citation>
</ref>
<ref id="B8">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[The petrogenesis of plagioclase-phyric basalts at mid-ocean ridges.]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Lange]]></surname>
<given-names><![CDATA[A. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Nielsen]]></surname>
<given-names><![CDATA[R. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Tepley]]></surname>
<given-names><![CDATA[F. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Kent]]></surname>
<given-names><![CDATA[A. J. R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Geochemistry, Geophysics, Geosystems]]></source>
<year>2013</year>
<volume>14</volume>
<numero>8</numero>
<issue>8</issue>
<page-range>3282-96</page-range></nlm-citation>
</ref>
<ref id="B9">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mora]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[Resumen de la actividad sísmica y eruptiva del Volcán Poás 13 de abril de 2017]]></source>
<year>2017</year>
<month>a</month>
<publisher-loc><![CDATA[San José ]]></publisher-loc>
<publisher-name><![CDATA[Red Sismológica Nacional, Universidad de Costa Rica]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B10">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mora]]></surname>
<given-names><![CDATA[M]]></given-names>
</name>
</person-group>
<source><![CDATA[Resumen de la actividad sísmica y eruptiva del Volcán Poás 12 al 14 de abril de 2017]]></source>
<year>2017</year>
<month>b</month>
<publisher-loc><![CDATA[San José ]]></publisher-loc>
<publisher-name><![CDATA[Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B11">
<nlm-citation citation-type="book">
<collab>OVSICORI</collab>
<source><![CDATA[Desaparición de Lago y Otros Cambios Radicales en el Fondo del Volcán Poás (Reporte de campo: 07 de junio de 2017).]]></source>
<year>2017</year>
<publisher-loc><![CDATA[San José ]]></publisher-loc>
<publisher-name><![CDATA[Observatorio Vulcanológico y Sismológico de Costa Rica, Universidad Nacional]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B12">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Mushmicrophysics and the reactivation of crystal-rich magma reservoirs]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Parmigiani]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Huber]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Bachmann]]></surname>
<given-names><![CDATA[O]]></given-names>
</name>
</person-group>
<source><![CDATA[Journal of Geophysical Research]]></source>
<year>2014</year>
<volume>119</volume>
<page-range>6308-22</page-range></nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Observations of plagioclase zoning using interference imaging]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Pearce]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
<name>
<surname><![CDATA[Kolisnik]]></surname>
<given-names><![CDATA[A]]></given-names>
</name>
</person-group>
<source><![CDATA[Earth-Science Reviews]]></source>
<year>1990</year>
<volume>29</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>9-26</page-range></nlm-citation>
</ref>
<ref id="B14">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Recognizing and tracking volcanic hazards related to non-magmatic unrest: a review]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rouwet]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Sandri]]></surname>
<given-names><![CDATA[L.]]></given-names>
</name>
<name>
<surname><![CDATA[Marzocchi]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Gottsmann]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Selva]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Tonini]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Papale]]></surname>
<given-names><![CDATA[P]]></given-names>
</name>
</person-group>
<source><![CDATA[Journal of Applied Volcanology]]></source>
<year>2014</year>
<volume>3</volume>
<numero>17</numero>
<issue>17</issue>
<page-range>1-17</page-range></nlm-citation>
</ref>
<ref id="B15">
<nlm-citation citation-type="journal">
<article-title xml:lang=""><![CDATA[Mineral Textures and Zoning as Evidence for Open System Processes]]></article-title>
<person-group person-group-type="author">
<name>
<surname><![CDATA[Streck]]></surname>
<given-names><![CDATA[M. J]]></given-names>
</name>
</person-group>
<source><![CDATA[Reviews in Mineralogy and Geochemistry]]></source>
<year>2008</year>
<volume>69</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>595-622</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
