Publication: Las rocas intrusivas y brechas del área de Los Molinos, Fuerteventura (Islas Canarias)
Loading...
Official URL
Full text at PDC
Publication Date
2016-06-23
Authors
Advisors (or tutors)
Editors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad Complutense de Madrid
Citations
Exportar
Abstract
La presente tesis doctoral se centra en el estudio de las rocas intrusivas (plutónicas y filonianas) y brechas que afloran en el área de Los Molinos, localizada en la zona centro-occidental de la isla de Fuerteventura (Islas Canarias). Esta intrusión es de especial interés puesto que se localiza en la teórica zona de solape que habría existido entre los dos edificios volcánicos miocenos de mayor tamaño en Fuerteventura: el Edificio Volcánico Central y el Edificio Volcánico Norte, de modo que constituye un buen objetivo para determinar si cada edificio contaba con un sistema de alimentación independiente o si existe una situación más compleja a este respecto. En primer lugar se ha estudiado la estructura interna de la intrusión de Los Molinos, formada por distintas facies de gabros, de las cuales se han obtenido sus características petrográficas, mineralógicas y geoquímicas y se han determinado sus condiciones de presión y temperatura de cristalización, su edad y el tipo de fuente mantélica de la que proceden. Para ello se han realizado análisis químicos insitu mediante microsonda de electrones y láser ICP-MS, junto con análisis de roca total y de geoquímica isotópica. Los resultados obtenidos muestran que las diferentes facies de gabros que afloran en la intrusión están relacionadas genéticamente y que las facies más evolucionadas, leucogabros y venas félsicas, proceden de las facies menos diferenciadas, melanogabros y gabros olivínicos, mediante un proceso de cristalización fraccionada y acumulación. Las condiciones de presión y temperatura halladas indican que el proceso de cristalización tuvo lugar a altas temperaturas (1100-900 oC) y relativamente bajas presiones (3-1 Kb), en condiciones de moderada fO2. La edad de cristalización se determinó por el método U-Pb in-situ en apatito mediante láser ICP-MS, obteniéndose una edad media de cristalización de 17.4 ± 1.9 Ma para la intrusión de Los Molinos. Las relaciones isotópicas de Sr, Nd y Pb muestran que la fuente de la que proceden los magmas que dieron lugar a esta intrusión, es una mezcla entre los componentes mantélicos HIMU y DM con contribuciones menores del componente EMI...
This PhD thesis is focused on the study of the intrusive rocks (plutonic rocks and dikes) and breccias outcropping in the Los Molinos area, located in the central-west part of the Fuerteventura island (Canary Islands). This intrusion is especially interesting because of its location in the theoretical overlapping zone that would have existed between the two largest Miocene volcanic edifices in Fuerteventura: the Central Volcanic Edifice and the Northern Volcanic Edifice. Los Molinos intrusion is thus a good target for determining if each volcanic edifice had an independent feeder system or, if the situation was more complex than that. The internal structure of Los Molinos intrusion is formed by different gabbro facies, which have been studied to determine their textural features, mineralogy and geochemistry. To this aim, in-situ analyses by electron microprobe and laser ICP-MS have been performed, together with whole-rock and isotope analyses. From this data set, it was possible to determine the crystallization pressure and temperature conditions, the age of the intrusion, and type of mantle source from which it was derived. The results show that the different gabbro facies of Los Molinos intrusion are genetically related so that the most evolved facies (leucogabbro and felsic veins) are derived from the least evolved ones (melanogabbro and olivine gabbro facies) by fractional crystallization plus accumulation processes. These processes took place under high temperature (1100-900 oC) and relatively low pressure (1-3 Kb), with moderate fO2 conditions. The crystallization age was determined by in-situ U-Pb measurements in apatite using laser ICP-MS, which yielded an average of 17.4 ± 1.9 Ma. Sr, Nd and Pb isotope ratios show that the mantle source for the Los Molinos intrusion is a mixture between the HIMU and DM end members with minor EMI component contributions...
This PhD thesis is focused on the study of the intrusive rocks (plutonic rocks and dikes) and breccias outcropping in the Los Molinos area, located in the central-west part of the Fuerteventura island (Canary Islands). This intrusion is especially interesting because of its location in the theoretical overlapping zone that would have existed between the two largest Miocene volcanic edifices in Fuerteventura: the Central Volcanic Edifice and the Northern Volcanic Edifice. Los Molinos intrusion is thus a good target for determining if each volcanic edifice had an independent feeder system or, if the situation was more complex than that. The internal structure of Los Molinos intrusion is formed by different gabbro facies, which have been studied to determine their textural features, mineralogy and geochemistry. To this aim, in-situ analyses by electron microprobe and laser ICP-MS have been performed, together with whole-rock and isotope analyses. From this data set, it was possible to determine the crystallization pressure and temperature conditions, the age of the intrusion, and type of mantle source from which it was derived. The results show that the different gabbro facies of Los Molinos intrusion are genetically related so that the most evolved facies (leucogabbro and felsic veins) are derived from the least evolved ones (melanogabbro and olivine gabbro facies) by fractional crystallization plus accumulation processes. These processes took place under high temperature (1100-900 oC) and relatively low pressure (1-3 Kb), with moderate fO2 conditions. The crystallization age was determined by in-situ U-Pb measurements in apatite using laser ICP-MS, which yielded an average of 17.4 ± 1.9 Ma. Sr, Nd and Pb isotope ratios show that the mantle source for the Los Molinos intrusion is a mixture between the HIMU and DM end members with minor EMI component contributions...
Description
Tesis inédita presentada en la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, Departamento de Petrología y Geoquímica, leída el 01-02-2016