Foreword [al Special issue "The Ossa-Morena Zone (Iberian Massif): Geological findings at the turn of the 21st Century", de la revista "Journal of iberian geology", ISSN 1698-6180.

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

Caracterización geoquímica del complejo plutónico de Taliga-Barcarrota (Badajoz, España)

[Resumen] En el Complejo Plutónico de Táliga-Barcarrota se distinguen dos tendencias geoquimicas: la primera de ellas corresponde a una "asociación peralumínica" representada por los granitos biotíticos de Táliga, la segunda de caracter "cafémico-subalcalino" está constituida por rocas de tipo básico e intermedio del macizo de Barcarrota[Abstract] In the Plutonic Táliga-Barcarrota Complex two geochemical tendences can be differenciated: the first one corresponds to "peraluminical assoeiation" represented by biotite granites of Táliga, the second one with a "cafemic-subalkaline"character is constituted by basic and intermediate type of the massif of Bacarrot

Fenómenos de endomorfismo, metamorfismo y metasomatismo en los mármoles de la Rivera de Cala (Sierra Morena)

Tesis de la Univ. Complutense de Madrid.Universidad Complutense de MadridTRUEProQuestpu

Rasgos generales de los skarns y mineralizaciones asociadas del Sistema Central español

[Resumen] La existencia en el Sistema Central Español de gran variedad de mineralizaciones ligadas a skarns permite discriminarlas en base al protalito, profundidad de emplazamiento y composición del granito asociado.Estas variables definen las condiciones fisicoqu!micas de la alteración metasomitica y por lo tanto, la paragJnesis de la ganga Y mineralización.[Abstract] The ecurrence in the Spanish Central 5ystem of a great variety of ore shewings related te skarns allew te discriminate them in basis to the original rack petrology, deepness and composition of related granite. Those parameters characterize the physicochemical conditions of metasomatic alteration, gangue minerelogu and ore campositio

Hydrothermal alteration and accessory minerals in a fault zone of the La Cabrera granite (Spanish Central System)

Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasFALSEEspaña. Ministerio de Educación y Cienciapu

Age of magma crystallization from igneous zircon showing a large range of concordant U-Pb ages: Two examples from the Sierra de Fiambalá (Sierras Pampeanas, Argentina)

Se han analizado elementos traza en circón de dos muestras de rocas ígneas de la Sierra de Fiambalá, en las Sierras Pampeanas, al NO de Argentina. En ambas muestras, una gabronorita y una granodiorita, las edades obtenidas previamente mediante SHRIMP no arrojaron resultados concluyentes, ya que la dispersión de edades concordantes varía entre 20 y 80 millones de años. Usando la composición de tierras raras del circón, que es bastante homogénea en las dos muestras, podemos justificar que la variabilidad observada en las edades no se debe probablemente a un período de cristalización magmática largo, sino que está causada por una pérdida de plomo. De esa manera, la edad de esas rocas debería de obtenerse a partir del conjunto de las edades más antiguas del rango concordante.We have analyzed trace elements in zircon from two igneous samples collected in Sierra de Fiambalá, at Sierras Pampeanas, in NW Argentina. In both samples, a gabbronorite and a granodiorite, the obtained ages using SHRIMP did not yielded a conclusive result, as the concordant ages smeared between 20 and 80 m.y. Using zircon rare earth element composition, which is quite homogeneous in both samples, we can argue that the observed age variability is not caused by a large range of magmatic crystallization ages, but it is the result of lead loss. Accordingly, the age of these rocks should be calculated from the oldest set of concordant ages.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEMinisterio de Economía y Competitividad (MINECO)CONICETFONCYTpu

The significance of «S-C» structures found in the Berzosa-Honrubia region (Spanish Central System)

En el extremo oriental del Sistema Central Español, existen evidencias de un episodio tectónico fini-hercínico, que se manifiesta en el desarrollo de una banda de 1 a 2 Km de anchura, de dirección sub meridiana y buzamiento al este en la que son frecuentes estructuras de tipo «S-C:. dúctiles. Esta banda probablemente extensional, se superpone a la estructura singular de segunda fase hercínica (D2), conocida como Zona de Cizalla de Berzosa (Z.e.B., CAPOTE, R. et alters, 1981; GONZALEZCASADO,]. M., 1986), tradicionalmente interpretada como un cabalgamiento dúctil hacia el noroeste retrovergido por la fase de pliegues longitudinales D3. La zona descrita coincide además espacialmente con una banda donde existen procesos hidrotermales tardíos, los cuales podrían relacionarse genéticamente con la estructura citada. El probable episodio extensional descrito, puede relacionarse con la etapa de extensión regional generalizada que se desarrolla durante el final del ciclo hercínico en toda la cadena. Período este bien reflejado en muchos puntos del Sistema Central Español, en forma de importantes accidentes tectónicos extensionales, principalmente de dirección este-oeste y buzamiento norte o sur.In the east end of the Spanish Central System there are some evidence of a latehercynian tectonic evento Field evidences includes the presence of «S» and «C» planes (composite planar fabrics), in a band of 1 or 2 Km of wide, with an eastwest direction and dipping ro the east. This area has probable an extensional origin and has been superimposed to a structure related to the herc,Ynian second phase (D2) know as the Berzosa Shear Zone (B.S.Z., CAPOTE, R., et alters, 1981; GONZALEZ CASADO, J. M., 1986). The B.S.Z. has ben interpreted as a ductil thrust towards the non-oest, backfolded by a phase of longitudinal folds D3. The investigated region shows a spatial correlation with a band where there are some late hidrotermal process, what could be genetic related with the studied structure. Microstructural evidence are internally consistent with field observations. lt appears that data are compatible with N-S oriented extensional detachment, dipping to the east, with and east-under-west sense of movement. This event could be correlated with a period of regional extension found elsewhere in the Spanish Central System. Developped for aH the belt during the end of the hercynian cicle. This last even is well developped in several points of the Spanish Central System and can be seen as several E-W oriented detachment systems, dipping to the N and S (extensional tectonics).Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasFALSEpu

Relaciones blastesis deformación del granate en la zona de cizalla de Berzosa

Deformation partitioning is responsible for the various textural and compositional features shown by garnets in the Berzosa Shear Zone. This process is time-and spacedependent across the fault

Metamorphic inversion in the famatinian orogen, Sierra de San Luis, Argentina

P-T conditions of Famatinian metamorphism (c. 465 Ma) were determined along a cross section in the central southern part of the Sierras de San Luis, Eastern Sierras Pampeanas. A continuity from low to high grade metamorphism is recorded here with an inverted disposition of metamorphic zones, i.e., higher grade rocks structurally overlying lower grade rocks. Foliation dip decreases accordingly downward in a fan-like arrangement. Shear zones are boundaries to the main metamorphic zones. The cross section is located on the eastern side of a large scale transpressional double vergence positive flower structure which involves most of the Sierra de San Luis. Calculated peak P-T values are: 790º and 800ºC and 7.2 to 8.9 kbar for the gneiss zone, 600º to 650ºC and 5.9 to 6.4 kbar for schist zone, and 550 ºC and 4.7 kbar for the transition schist – phyllite zone. Highest grade rocks show a clockwise P-T path with a nearly isothermal decompression to P values which are similar within error to those of the lower grade rocks. The latter suggests that metamorphic inversion was largely synmetamorphic and that it was driven by movement along shear zones and ductile flow within domains. Reactivation of shear zones is invoked however to explain some mistmach of P values particularly among the lower grade zone