Publication: Procesos hidrotermales con enriquecimiento en REE en las
carbonatitas de Fuerteventura: evidencias en minerales
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Publication Date
2021
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Sociedad Geológica de España
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Abstract
Los diques carbonatíticos que afloran en la parte centro-occidental del Complejo Basal de Fuerteventura (Ajuy, Punta de la Nao), fueron afectados por el evento intrusivo mioceno responsable del metamorfismo de contacto y fusión parcial de parte del complejo alcalino-carbonatítico. Las
características texturales, los procesos de formación de monacita enriquecida en LREE (La, Ce, Nd) en microfracturas que afectan a los cristales de zircón, evidencian interacciones de las carbonatitas con fluidos hidrotermales y removilización parcial de REE. El pirocloro es el principal mineral reservorio de tierras raras (suma REE=216694 ppm), con valores elevados de LREE (LaN=185816 y CeN=165209) respecto a las HREE (YbN=2589 y LuN=1814) con un espectro bastante inclinado (La/Yb)N=72 en el diagrama de abundancia de REE. La paragénesis mineral representada por los interestratificados illita/esmectita, clorita y vermiculita permite encuadrar el evento hidrotermal en facies de las ceolitas (Ta ≈ 100-200 °C).
Carbonatitic dykes that crop out in the central western part of Fuerteventura Basal Complex (Ajuy, Punta de la Nao), were affected by the Miocene intrusive event responsible for contact metamorphism and partial melting of part of the alkaline-carbonatitic complex. Textural characteristics, monazite enriched in LREE (La, Ce, Nd) formation processes in microfractures that affect zircon crystals, show carbonatite interactions with hydrothermal fluids and partial REE remobilization. Pyrochlore is the main mineral carrier of rare earth elements (sum REE=216694 ppm), with high LREE (LaN=185816 y CeN=165209) with respect to HREE (YbN=2589 y LuN=1814) with a rather steep pattern (La/Yb)N=72 in REE diagram. The mineral paragenesis represented by the interstratified illite/smectite, chlorite and vermiculite allows to frame the hydrothermal event in zeolite facies (T° ≈ 100-200 °C).
Carbonatitic dykes that crop out in the central western part of Fuerteventura Basal Complex (Ajuy, Punta de la Nao), were affected by the Miocene intrusive event responsible for contact metamorphism and partial melting of part of the alkaline-carbonatitic complex. Textural characteristics, monazite enriched in LREE (La, Ce, Nd) formation processes in microfractures that affect zircon crystals, show carbonatite interactions with hydrothermal fluids and partial REE remobilization. Pyrochlore is the main mineral carrier of rare earth elements (sum REE=216694 ppm), with high LREE (LaN=185816 y CeN=165209) with respect to HREE (YbN=2589 y LuN=1814) with a rather steep pattern (La/Yb)N=72 in REE diagram. The mineral paragenesis represented by the interstratified illite/smectite, chlorite and vermiculite allows to frame the hydrothermal event in zeolite facies (T° ≈ 100-200 °C).