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Browsing by Author "Velasco, Francisco"
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The Aguablanca Cu-Ni(PGE) intraplutonic ore deposit (Extremadura, Spain). Isotope (Sr, Nd, S) constraints on the source and evolution of magmas and sulfides
Casquet Martín, César; Eguiluz, Luis; Galindo, Carmen; Tornos, Fernando; Velasco, Francisco (Sociedad Geológica de España, 1997)The Aguablanca Cu-Ni(PGE) ore is a case of an intraplutonic ore deposit. It is hosted by mafic and ultramafic cumulates of the Aguablanca Stock, which is part of the larger calc-alkaline Santa Olalla Plutonic Complex of ... -
Características petrográficas y mineralógicas de birbiritas derivadas de las peridotitas de Ronda (Cordilleras Béticas)
Esteban, José Julián; Cuevas, Julia; Tubía, José María; Velasco, Francisco; Vegas, Néstor (Sociedad Geológica de España, 2011)Por primera vez en las Cordilleras Béticas describimos, en este trabajo, la existencia y las principales características mineralógicas y petrológicas de birbiritas que son el resultado de un intenso metasomatismo de ... -
Caracterización mineralógica de los sedimentos actuales del río Nervión (Vizcaya)
Irabien, María Jesús; Velasco, Francisco (Sociedad Geológica de España, 1990)The modern sediments of the Nervión River have been investigated in order to determine the mineralogical composition of the bulk sample, and the distribution of the clay minerals in the 2-20 pm fraction and the <2 pm fraction -
Etapas de formación de dolomías masivas del entorno de La Florida-El Soplao, Cantabria
López Cilla, Ignacio; Rosales, Idoia; Najarro, María; Martín Chivelet, Javier; Velasco, Francisco; Tornos, Fernando (2009)Dolomitization played a very important role in producing porosity within the Late Aptian shallow marine carbonates hosting the El Soplao Cave and La Forida mine deposit. A detailed petrographic study of samples from a ... -
Exploración geoquímica multimedia para el oro en el área del «Aritzakun erreka», Baztan (Navarra, España)
Velasco, Francisco; Yusta, Iñaki; Rodriguez Aller, J.; Peña, A. (Sociedad Geológica de España, 1996)A geochemical exploration program was carried out to determine gol dplacers and prima y mineralizations in the Aritzakun area (Maya de Bazt&n, Navarra, SpainJ. Three sampling media were used in this study: (1) rock fragments; ... -
Geoquímica de feldespatos y moscovita de las Pegmatitas del Cap de Creus
Abella, P. A.; Velasco, Francisco; Yusta, Iñaki; Melgarejo i Draper, J. C. (Sociedad Geológica de España, 1996)The Cap de Creus (NE Spain) is the easternmost outcrop of the Hercynian basement of the Pyrenees. The peninsula is constituted by materials affected by the hercynian metamorphism. A pegmatitic field occurs within the ... -
Geoquímica de los isótopos de azufre, carbono, oxígeno y plomo de Las mineralizaciones del paleozoico del Macizo de la Demanda(Burgos-La Rioja, España)
Ibáñez Gómez, J. A.; Velasco, Francisco; Pesquera, A. (Sociedad Geológica de España, 1996)Several Pb-Cu-Zn orebodies of different size and origin occur in Paleozoic materials from the D em andam as8if d /at has been m a in ly deformed by the Hercynian orogeny. Most of the here studied deposits arevein type, ... -
Los depósitos de Mn-Al-Fe de la cueva de Lazalday (Zarate, Alava): composición química y mineralogía
Lazalday Cave is a 4 km long karstic cave where Mn deposits occur as black thin coatings covering walls and cementing conglomerates, inside calcite speleothems, and also in the floor of many passages alternating with ... -
Mineralizaciones de magnetita asociadas a skarns y bandas de cizalla: La mina de Cala (Huelva)
The Cala iron deposit has been traditionally regarded as a classic iron skarn developed on Cambrian limestone adjacent to a Variscan monzogranitic stock. Ongoing studies show that the geologic setting is more complex and ... -
Origen de las piritas de la cuenca de Cameros, (La Rioja)
Alonso Azcárate, Jacinto; Rodas, M.; Mas, Ramón; Velasco, Francisco (Sociedad Geológica de España, 1995)The pyrite mineralizations of the Cameros basin has been traditionally interpreted as diagenetic. On the basis of trace element content, S isotopes study, pyrite inclusions and geologic observations, the pyrite crystals ... -
Pautas de distribución de Sr/Ca, Mg/Ca y Mn/Fe en carbonatos urgonianos del oeste de Vizcaya (España)
Yusta, Iñaki; Herrero, J. M.; Velasco, Francisco (Sociedad Geológica de España, 1991)The distribution patterns of Ca, Si, Sr, Mn, Mg and Fe in Urgonian carbonate rocks from NW Biscay (Spain) reveals the differences between shallow-water (270 ppm Sr, 62 ppm Mn) and deepwater (820 ppm Sr, 116 ppm Mn) limestones. ... -
Quimismo de las lutitas del Cretácico Inferior en el sector central de la Cuenca Vasco-Cantábrica
Yusta, Iñaki; Velasco, Francisco; Herrero, J. M. (Sociedad Geológica de España, 1996)A lithogeochemical study of Lower Cretaceous shales (195 samples) from the Basque-Cantabrian region has been carried out to evaluate average values in major and trace elements. Mineralogy and chem ic al co n te n t o f m ...