Clinopyroxene, amphibole and phlogopite megacrysts appear in the crystal-and xenolith-rich pyroclastic deposits of the Cerro Pelado and the El Aprisco volcanoes (Calatrava volcanic field). These megacrysts display a similar composition to crystals forming clinopyroxenite and rare phlogopite-rich (glimmerite) enclaves. The host magmas are highly porphyritic, showing a complex population of mafic macrocrysts and phenocryst cores. Most of these crystals are chemically similar, suggesting that they constitute a cogenetic suite of phenocrystic origin. Geobarometric estimations indicate that megacrysts and enclaves represent high-P cumulates, mostly formed at about 12-16 kbar within the upper lithospheric mantle (35 to 55 km). The compositional variability of the analyzed minerals indicates a differentiation process controlled by fractionation of olivine, clinopyroxene, amphibole and phlogopite. The crystallization of hydrous mafic minerals at mantle depths facilitated CO 2 exsolution and subsequent boiling of the host magma, thus triggering the fragmentation of the semi-crystallized margin of the magma chamber and the excavation of mantle wall-rocks. This deep fragmentation could also explain the complex variety of crystals, enclaves and xenoliths dragged by the volcanic magmas. Two clinopyroxene types (green and colourless) have been found, both as antecrysts (macrocryst/phenocryst cores) and within enclaves. The coexistence of these clinopyroxenes within zoned crystals in clinopyroxenites suggests that they might be cognate, representing primitive and evolved products of a single fractionating magma. This study provides a model for the ascent of crystal-and xenolith-rich magmas that could be regarded in other alkaline volcanics carrying complex crystal cargos from the Cenozoic circum-Mediterranean area. Keywords Mafic megacrysts • Clinopyroxenite • Glimmerite • Melilitite melt • Calatrava volcanic field • Alkaline circum-Mediterranean province Resumen Megacristales de clinopiroxeno, anfíbol y flogopita aparecen en los depósitos piroclásticos ricos en cristales, enclaves y xenolitos, de los volcanes de El Aprisco y Cerro Pelado (campo volcánico de Calatrava). Estos megacristales muestran una composición química similar a los cristales que forman los enclaves clinopiroxeníticos asociados, incluyendo los poco comunes enclaves ricos en flogopita (glimmeritas). El magma volcánico es de textura porfídica, mostrando una compleja población de fenocristales y macrocristales máficos, con núcleos residuales, que sugieren formen una suite cogenética con aquellos. Las estimaciones geobarométricas indican que los megacristales, así como los núcleos de fenocristales y los enclaves clinopiroxeníticos representan acumulados de alta presión, formados entre 12-16 kbar, en el manto litosférico superior (de 35 a 55 km). La variabilidad composicional de estos minerales máficos apunta a un proceso de diferenciación controlado por la cristalización de olivino, clinopiroxeno, anfíbol y flogopita. La cristalización de minerales máficos hidra...
Accurately dating phenocrysts in Holocene volcanic rocks poses many challenges but is critical to placing magmatic processes that occur prior to eruption into a temporal framework. We dated alkali feldspar (i.e., orthoclase Or10 to Or46) crystals in four young phonolites from the Teide–Pico Viejo volcanic complex, Tenerife (Spain), using (226Ra)/(230Th) isotopes. Partition coefficients of Ra (DRa) and DRa/DBa of feldspars were predicted using an approach based on the lattice strain model, which yielded crystallization ages that overlap or predate known eruption ages for the Lavas Negras (ca. 1 ka), Montaña Blanca (ca. 2 ka), Arenas Blancas (ca. 2–4 ka), and Teide H (ca. 6 ka) phonolites. Crystallization of feldspar may occur up to the time of eruption, with >8 ka crystals also present, possibly suggesting extended magma differentiation times. However, feldspars yielding finite (226Ra)/(230Th) ages are mostly in equilibrium with the groundmass, unlike >8 ka crystals, which were therefore identified as antecrysts/xenocrysts. The 87Sr/86Sr ratios of feldspars indicate that crystallization predated late-stage assimilation, affecting 87Sr/86Sr ratios of some melts. The (226Ra)/(230Th) ages also constrain the tempo of phonolite magma evolution on Tenerife. Integration of (226Ra)/(230Th) ages with feldspar major elements, trace elements, and isotopes provides a powerful means for investigating crystallization histories using a dominant mineral that controls the overall magmatic evolution of phonolites on thousand-year time scales.
Formalised elicitation of expert judgements has been used to help tackle several problematic societal issues, including volcanic crises and pandemic threats. We present an expert elicitation exercise for Piton de la Fournaise volcano, La Réunion island, held remotely in April 2021. This involved 28 experts from nine countries who considered a hypothetical effusive eruption crisis involving a new vent opening in a high-risk area. The tele-elicitation presented several challenges, but is a promising and workable option for application to future volcanic crises. Our exercise considered an “uncommon” eruptive scenario with a vent outside the present caldera and within inhabited areas, and provided uncertainty ranges for several hazard-related questions for such a scenario (e.g. probability of eruption within a defined timeframe; elapsed time until lava flow reaches a critical location, and other hazard management issues). Our exercise indicated that such a scenario would probably present very different characteristics compared to recent eruptions, and that it is fundamental to include well-prepared expert elicitations in updated civil protection evacuation plans to improve disaster response procedures.
<p>Earth Sciences are booming in social media, an unexampled scenario a few years ago. In the last year, these numbers have increased because of the COVID-19, citizens are consuming even more digital information, at the same time they are looking for more simplified and easy-understanding scientific concepts. It is very important to remark the value of entertainment, humor, and visual contents, which have a light universal language to approach Earth Sciences to citizens and experts beyond the pure academic frontiers. In this work, we share some successful examples through the use of illustration, comic, and infographic content between two Instagram accounts (<strong>@ohmagmamia</strong> and <strong>@salirconunageologa</strong>) which addend more than 13,000 followers and have a potential reach up to 37.1k (based on their account insights). The audience for this content is international although it has gained great popularity among the Spanish-speaking public (the initial target audience), little by little creating an interesting and growing movement. Countries such as Chile, Argentina, Colombia, and Spain have the greatest impact according to statistics. Age range is between 18-34 years for 87% of the audience, with a clearly female predominance (55% in @Ohmagmamia and 60% in @Salirconunageologa).</p><p>One of the principal goals of these accounts is to develop visual, artistic and easy-understanding content that fits the audience. On one hand @Ohmagmamia uses photographic material (e.g. landscapes, outcrops, hand specimen samples or micro-photographies), simple geological sketches and infographic content along with small descriptions in the post captions. This approach has been well received by both Earth Science students and non-professional enthusiasts, as well as biology-geology teachers and public examination trainers. On the other hand, @Salirconunageologa (Dating a geologist) uses cartoons, humour and comics to approach Earth Sciences to professionals and the general public. Its visual material focuses on storytelling to explain what it means to be a geologist using all its universe of friendly characters. In the first season of &#8220;Dating a Geologist Universe&#8221; (with 17 episodes), the main character, Nia Stone, is involved in different hilarious situations related to Earth Sciences, like volcanoes, trilobites, or Dr. Gems (the main Villain). This &#8220;<strong>geocomics&#8221;</strong> have been very well received, being the first chapter the one which records the best audience data, with 10k accounts reached on Instagram.&#160;</p><p>Social media statistics data provide interesting information about the success of these scientific dissemination&#8217;s new methods. In the last 6 months of the 2020 both accounts reached an average of 11,000 Instagram accounts with an average more than 1,000 &#8220;likes&#8221; per post and with an engagement rate that varies from 9 to 12%. In addition, the use of other social media such as Twitter or YouTube able us to reach more people and/or accounts by using Twitter &#8220;threads&#8221; or sharing videos of invite talks or &#8220;webinars&#8221;, whose popularity grew during the quarantine period. All these results show the importance of a perfect relation between visuals, art and Earth Science and its capability to reach people from all around the globe.</p>
<p>Earth Science studies usually get less attention compared to other basic sciences, especially at teen ages. This is a pressing problem, which worsens considerably in those countries in which the primary and secondary educational systems regularly minimize or unbalance the presence of Earth Sciences in front of other branches of knowledge such as Biology or Physics. Child interests usually develop during young ages, and this will influence the interest of future generations on the understanding of our planet and the environment. &#160;In this sense, the creation of engaging educational tools and resources that captivate the younger audience is one of the current challenges. More and more, comic books, graphic novels and illustrated children&#8217;s books are becoming a powerful tool to approach scientific concepts to kids and teenagers. Here we present the digital book: &#8220;Discover the volcanoes: Accompany the Volkis to their volcanic adventure&#8221;. A creative way to explain to a child and teen audience, how volcanoes work, as well as their impacts and benefits to our society. The leading characters are the Volkis, a secret club for volcano lovers that learn different aspects related to volcanology thanks to Rocky, the most experienced member of the group.&#160; The book is composed of 13 sections covering the essential information needed to learn about volcanology. Where and why do we have volcanoes on Earth? How is the interior of a volcano? Why do volcanoes erupt? Which are the hazards derived from a volcanic eruption? are just some of the questions that are resolved in it. The Volkis, fantastic characters that represent different volcanic products, will guide young readers and instructors on their journey through the world of volcanoes. The book will be downloadable for free and&#160; accompanied by a webpage (https://descubrelosvolcanes.es) where teachers, educators and readers can find additional material such as videos, coloring pages, experiments, etc. &#160;The final aim of this book is to break the paradigms of how to teach science to children in an entertaining, striking, and didactic way, where not only children will learn, but also all adults who are accompanying them.</p><p>This project was funded by the Spanish National Research Council (CSIC) in its program &#8220;Cuenta la Ciencia &#8211; 4&#170; Edici&#243;n&#8221; (Fundaci&#243;n General del CSIC) for promoting scientific culture.&#160;</p>
<p>Whole rock and single mineral geochemical data in volcanic rocks record a wide variety of volcanic processes, such as magma storage conditions and evolution, pre-eruptive processes, transport to the surface, etc. All this information is crucial for knowing the functioning of a volcano plumbing system and trying to anticipate volcanic eruptions, especially in central volcanoes. The active Teide-Pico Viejo (T-PV) volcanic complex on the island of Tenerife (Canary Islands) combines effusive and explosive activity with long recurrence periods. This makes it necessary to carefully study the volcanic stratigraphy in order to understand how the volcano may erupt in the future and which processes may lead to eruption. Tenerife island is a very populated and touristic area, so hazard assessment at its main volcanic complex is mandatory. However, petrological and geochemical information regarding the T-PV stratovolcanoes is very dispersed and out-of-date, with analyses of individual units made over the course of several decades, using different techniques and laboratories, and sometimes difficult to relate to a systematic stratigraphy. It is therefore necessary to create a complete database that will allow further progress in this field and will avoid future repetition of analyses for which quality data are already available.</p><p>Here, we present the preliminary results from a complete geochemical database of the different T-PV volcanic units. From the available literature (more than 30 references so far), 971 whole rock, 217 residual glass and 8474 mineral chemistry analysis have been included. The inputs have been classified depending on their stratigraphic unit whenever possible. We also provide new petrological data from 79 rock samples from all outcropping units at T-PV, paying particular attention to the stratigraphy. These analyses will provide an update of the geochemical data for one of the most important active volcanic systems in Europe, allowing a better comparison between units and greater accuracy (especially in the case of trace elements) by obtaining data for a wide variety of elements, all performed in the same laboratory (Peter Hooper GeoAnalytical Lab, Washington State University). Also, a new and complete set of mineral analyses is presented, with special attention to mineral zoning, that will allow us to better understand the different magmatic processes occurred in that volcanic system.</p><p>Based on the volcanic stratigraphy and this new collection of geochemical data, this project will radiometrically date both rocks and mineral separate (feldspars), whenever possible, in order to calculate more accurate recurrence intervals and the timescales of magmatic evolution on Tenerife and will also examine still-debated aspects of the magmatic evolution of T-PV stratovolcanoes, such as the origin of phonolites or the existence or not of a &#8220;Daly Gap&#8221; in magma compositions, within a temporal context.</p><p>OD was supported by an FPU grant (FPU18/02572) and a complementary mobility grant (EST19/00297) from the Ministry of Universities of Spain. JM and AG were funded by the European Commission Grants EVE (ref: DG ECHO H2020 826292) and EUROVOLC (ref: H2020 731070).</p>
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