52 research outputs found
Maar-diatreme infill features recorded in borehole imaging
Oriented borehole images recorded with an ultrasonic acoustic televiewer and continuous coring recovery has allowed the characterization of different facies and volcanic processes involved in the infill of a maar-diatreme volcano type. Maar-diatremes are associated with strong explosions throughout most of their development, focused along feeder
dikes and generally attributed to magma-water interaction. In the case study of Camp dels Ninots maar-diatreme (Girona, Spain) we have recognized four facies types located in the center of the maar-diatreme: volcanic ash, phreatomagmatic breccia with lithics and juveniles, vesicular pyroclasts (scoria), massive basalt or welded pyroclastic fragments. Ultrasonic
televiewer images allow to characterize the different volcanic facies, since they display a different degree of reflectivity and textures. Other features such as fracturing and grain size can be directly measured on the images.Projects 2014-100575 from Departament de Cultura de and SGR2014-901 from AGAUR (both from Generalitat de Catalunya) financed the drilling
campaigns.Peer Reviewe
Electrical resistivity tomography revealing the internal structure of monogenetic volcanoes
Eruptive activity of individual monogenetic volcanoes usually lasts a few days or weeks. However, their short lifetime does not always mean that their dynamics and structure are simple. Monogenetic cones construction is rarely witnessed from the beginning to the end, and conditions for observing their internal structure are hardly reached. We provide high-resolution electrical resistivity sections (10m electrode spacing) of three monogenetic cones from northeastern Spain, comparing our results to geological observations to interpret their underground continuation. The 100m maximum depth of exploration provides information on almost the entire edifices, highlighting the relationships between Strombolian and hydromagmatic deposits in two multiphase edifices. A main observation is a column of distinct resistivity centered on the Puig d"Adri volcano, which we interpret as the eruptive conduit. This method can provide valuable information on the past volcanic dynamics of monogenetic volcanic fields, which has real implications for the forecast of future activity
Understanding the role played by the basement in the eruptive dynamics combining fieldwork and geophysical surveys: the example of El Puig d'Àdri tuff cone
El Puig d’Àdri tuff cone is one of the most peculiar edifices of the Garrotxa Volcanic Field (GVF) (0.6–0.01 Ma),which is part of the Catalan Volcanic Zone (NE of the Iberian Peninsula), one of the Quaternary alkaline volcanic provinces associated with the European Cenozoic Rift System.El Puig d’Àdri volcano was emplaced in the
northern sector of La Selva Basin, a Neogene tectonic depression bounded by ENE-WSW–and NW-SE–oriented normal fault systems, above Paleocene and Eocene materials (red sandstones, marls and limestones) covered by Neogene alluvial sediments. The area is bounded to the East by the Amer Fault and to the West by the Llorà Fault.
These two regional conjugated Neogene normal faults with a transtensional component are responsible in the area for the distribution of volcanism, seismicity and the fluvial network as well. The construction of this volcano involved various stages due to the periodic magma/water interaction that lead to the superposition of three volcanic vents. The main edifice is constituted by a tuff cone 850 m in diameter with a small scoria cone at the western side of the tuff cone and a new scoria cone further SE. Geological and geophysical surveys (performed using Electrical Resistivity Tomography-ERT and Self-Potential-SP), were reliable tools to understand the eruptive dynamics of this volcano and the major role played by the
basement. 5 different litostratigraphic units were identified in El Puig d’Àdri volcano where Strombolian and phreatomagmatic episodes alternated giving rise to complex stratigraphic sequences. A first explosive phreatomagmatic event was followed by a Strombolian episode of limited extent. The activity returned to a stronger phreatomagmatic
phase, with dilute PDCs and explosion breccias, along with a concentrate PDC running southern for more than 3 km. A final Strombolian phase gave rise to the construction of the main scoria cone, with deposits covering most of the proximal phreatomagmatic products. The eruption ended with an effusive phase that generated two lava flows causing the breaching of the northwestern flank of the scoria cone. Most of these units were recognized as well through one of the ERT profiles that allowed distinguishing phreatomagmatic and Strombolian deposits at depth as confirmed by the SP as well. Componentry analysis suggests that the explosions took place in the sandstones/marls basement although the
second Strombolian phase of the eruption shows a notable increase of limestone fragments, suggesting a switch of the explosion locus. This is also suggested by the position of the second scoria cone respect to the tuff cone and the first Strombolian edifice. One additional ERT profiles helped to understand the continuation of the volcanic deposits at depth. The pre-volcanic basement, which is constituted of limestones, marls and sandstones with different hydrogeological characteristics was described highlighting the major role on the eruptive dynamics and, thus, confirming the preliminary hypothesis obtained through field survey.
These results can be extrapolated to other phreatomagmatic volcanoes alternating phreatomagmatic and Strombolian phases and built-up on hard basement, showing how a multidisciplinary approach is a useful tool to interpret the eruptive dynamics and the evolution of an eruption.Peer Reviewe
Recent therapeutic advances in urothelial carcinoma : A paradigm shift in disease management
Altres ajuts: Pfizer.Management of first-line advanced urothelial carcinoma (UC) has consisted during the past three decades in the administration of platinum-based chemotherapy followed by observation. Despite moderate to high response rates to first-line treatment, most patients will relapse shortly after and the outcomes with subsequent therapies are poor with 5-year overall survival rates of 5% in the pre-immunotherapy era. Nonetheless, recent therapeutic developments including the paradigm shift of first-line maintenance therapy with avelumab after response or stabilization on platinum-based chemotherapy, along with the incorporation of new drug classes in further lines of treatment such as antibody drug-conjugates and fibroblast growth factor receptor inhibitors have reshaped the field leading to better outcomes in this patient population. This article reviews the current state of the art with an overview on UC management, recent advances, and the upcoming strategies currently in development in advanced UC with an insight into the biology of this disease
La consulta terapèutica : una eina complementària d'informació per a la individualització de la terapèutica
En aquest article es presenten els resultats d'un treball de recerca que analitza les característiques de la demanda d'informació sobre terapéutica atesa durant els darrers quinze anys a la Fundació Institut Catalá de Farmacologia. En una época en qué, per una banda, el volum creixent de nova informació médica disponible fa que al metge sovint sigui difícil mantenir-se al dia i, per una altra banda, davant la progressiva acceptació de la medicina basada en proves, la prestació d'un servei de consulta terapéutica representa una activitat complementária d'informació en la qual s'utilitzen les millors evidencies disponibles per a la individualització de la terapéutica
Volcano-structural analysis of La Garrotxa Volcanic Field (NE Iberia): Implications for the plumbing system
Estudi geològic del volcà Montsacopa
Treball de recerca realitzat per un alumne d’ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit científic del Jovent l’any 2005. El Montsacopa és un dels diversos volcans de la comarca de la Garrotxa dels quals hi ha pocs estudis i dades geològiques. Els inicis de l’ activitat volcànica en aquesta zona, van tenir lloc a finals de l’època terciària i inicis de la quaternària. Fins fa relativament poc es creia que la majoria d’aquests volcans tenien una activitat d’origen estrombolià però noves investigacions indiquen que podria ser d’origen freatomagmàtic o, si més no, molt més explosiva de la suposada inicialment. Els objectius de l’estudi són: confirmar l’hipòtesi esmentada; aportar dades que afirmin, s’hi ha motius per creure en l’emissió d’un flux piroclàstic en una de les últimes fases de l’activitat del volcà Montsacopa; comprovar l’hipòtesi d’una possible concordança entre el dipòsit 1 de l’aflorament sud-oest i el dipòsit de l’aflorament est; conèixer l’origen de les sorprenents coloracions rogenques de l’aflorament i per últim, interrogar-se sobre la possibilitat de l’existència d’un focus emissor diferent del cràter ja conegut
Geological and structural controls on La Garrotxa monogenetic Volcanic Field (NE Iberia) and structural controls on La Garrotxa monogenetic Volcanic Field (NE Iberia)
[cat] La present Tesi Doctoral es centra en els controls geològics i estructurals del vulcanisme monogenètic. S'ha posat especial atenció a la part més superficial de la litosfera i en el paper que juga aquesta zona en determinar la distribució de punts emissors i estils eruptius. S'ha seleccionat com a cas estudi el Camp Volcànic de la Garrotxa (GVF) (NE d'lberia). Aquest és encara poc conegut i ha esdevingut un lloc ideal per l'aplicació d'estudis multidlsciplinaris com els treballs que constitueixen aquesta Tesi Doctoral, integrant mètodes geofísics. treballs de camp, ¡ anàlisis geomorfològics i estructurals. Els primers dos treballs s'han portat a terme al sector Nord del GVF. Aquests estudis s'han basat en l'aplicació de diverses tècniques geofísiques, identificant així les estructures tectòniques principals I obtenint una informació detallada del basament. El tercer treball també s'ha realitzat a partir d'un estudi multigeofísic. En aquest cas al sector Sud del GVF, concretament al volcà de la Crosa de Sant Dalmai. Els resultats han permès la realització d'un model de la part superior de la diatrema, determinant la seva estructura interna i origen. Els resultats obtingut suggereixen que la tomografia elèctrica resulta una eina eficaç per l'estudi dels diferents tipus d'edificis monogenètics. D'aquesta manera es presenta un treball breu amb diferents exemples de l'estructura dels cons volcànics de la zona. Combinant aquests resultats amb informació geològica de camp, s'ha realitzat la primera cartografia vulcanoestratigràfica del GVF. Finalment, s'ha fet un anàlisi volcanoestructural de tot el camp volcànic, el qual Inclou la distribució geoestadística de falles, fissures i punts emissors, identificació morfo-estructural de lineacions, anàlisi morfomètric dels cons i cràters, localització de la sismicitat registrada de la zona i gasos derivats del mantell en surgències i pous, com a guia per identificar falles actives o fractures obertes, amb l'objectiu de definir els controls estructurals d'aquest vulcanisme. Tot els resultats obtinguts han permès entendre el transport del magma des de la litosfera fins la superfície, i representen un eina essencial per una correcta avaluació de la perillositat volcànica al GVF. Tanmateix, les metodologies descrites estableixen una pauta general per l'estudi dels camps monogenètics actius.[eng] Monogenetic volcanism represents the most common volcano type on Earth. The distribution of it depends in each case on their regional and local tectonic controls. The great variety of eruptive styles, edifice morphologies, and deposits shown by monogenetic volcanoes is the result of a complex combination of internal (magma composition, gas content, magma rheology, magma volume, etc.) and external (regional and local stress fields. stratigraphic and rheological contrasts of substrate rock, hydrogeology, etc.) parameters during magma transport from the source region to the surface. The present PhD Thesis focuses on the geological and structural controls of monogenetic volcanism. It pays particular attention to the uppermost part of the lithosphere and its role to determine the distribution of eruptive vents and eruptive styles. We have selected La Garrotxa Volcanic Field (GVFj as a case study. This Quaternary volcanic field is located in the Northeast of the Iberian Peninsula and includes more than SO well-preserved volcanoes. It covers an area of 600 km2, between the cities of Olot and Girona and belongs to the Catalan Volcanic Zone, one of the alkaline volcanic provinces of the European Rift System. The GVF is still poorly known and has become an ideal place for the application of the multidisciplinary studies, including geophysical methods, geological fieldwork and geomorphological and structural analyses, which constitute this PhD Thesis. The first work was carried out at the Northern sector of the GVF. This study was mainly based on the application of gravimetry and self-potential techniques, in order to identify the main tectonic structures of the volcanic area at depth. A second work was performed in order to obtain a much better detail of the shallower structures and to relate the subsurface geology to the feeding system of these monogenetic volcanoes. In this case, we applied the electrical resistivity tomography method, comparing the new data with the self-potential results. A third work was carried out at the Southern sector of the GVF, at La Crosa de Sant Dalmai volcano (10 km SW of Girona), one of the biggest maar-diatreme edifices of the Iberian Peninsula. Here, several geophysical techniques were applied, including gravimetry, magnetometry, self-potential and electrical resistivity tomography. A model of the uppermost part of the diatreme was obtained, determining the internal structure and its origin. The results obtained with the application of these geophysical methods in this volcanic field suggest that electrical resistivity tomography is a useful tool for the study the internal structures of different types of monogenetic landforms. In this way we present a short work that illustrates different examples of internal structures of monogenetic volcanic cones from GVF. Furthermore, combining the results from these geophysical studies with the geological informations obtained by fieldwork, we performed the first volcanic stratigraphy map of the GVF. Finally, we also led a detailed volcano-structural analysis of the whole volcanic field, including geostatistical distribution of faults, fissures and vents, morpho structural lineaments identified by remote sensing, a morphometrical analysis of the volcanic cones and craters, location of regional seismic events recorded in the area (since 1978), and mantle derived gases in springs and water wells, as a guide to identify active faults and open fractures and to define the structural controls of this volcanism. The results obtained from all these studies have permitted understanding how magma was transported into the lithosphere and erupted at the surface, and represent an essential tool for a correct volcanic hazard assessment of the GVF. Furthermore, the methodologies described in this PhD Thesis establish general guidelines to study active monogenetic volcanic fields and we hope that it will contribute to improve their understanding
Abstracts volume : May 21 to 25, 2018 : 7th International MAAR conference: Olot, Catalonia, Spain
Since the first “International Maar Conference” (IMC) meeting, the series has become one of the most successful discussion forums in volcanology, mainly because it provides a unique opportunity to bring together people from many different volcanological fields (physical volcanologists, sedimentologists, modellers, petrologists, etc), any of whom may become involved in some way in the study of different eruption styles of basaltic volcanism and, in particular, those occurring in monogenetic volcanic fields. Previous IMC meetings have been held in a wide diversity of places (Hungary, Slovakia and Germany) that posed different problems in terms of eruption dynamics, products and landforms in these volcanic areas.
The city of Olot, the main location of the La Garrotxa Volcanic Field, the most recent area in the Quaternary Catalan Volcanic Zone, will provide a unique opportunity for holding a multidisciplinary volcanological forum that will focus on different aspects of maars and monogenetic volcanism. In Olot and its surroundings volcanoes are present in many aspects of local society, as its cultural heritage, local history, architecture or even in its excellent cuisine. People live among volcanoes and they are aware that they represent the most characteristic feature of their region. Protection of all this area and of the volcanoes in particular, has been effective since 1982, when it was declared as a Natural Park (The Garrotxa Volcanic Zone Natural Park) by de Catalan Government.
The Local Organizing Committee and the International Association of Volcanology and Chemistry of Earth’s Interior (IAVCEI) are pleased to welcome you to the 7th International
Maar Conference (IMC) in Olot (Spain) in May 21- 25, 2018.Peer Reviewe
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