Loading...
8 results
Search Results
Now showing 1 - 8 of 8
- Proyecto GEO_FPI, cartografía de la Zona Surportuguesa (ZSP). Datos preliminares de un estudio geocronológico U-PbPublication . Díez-Montes, Alejandro; Matos, João Xavier; Valverde-Vaquero, Pablo; Solá, A. Rita; Beranoaguirre, Aratz; Albardeiro, Luis; Salgueiro, Rute; Morais, Igor; Montero, P.; López, M. T.RESUMEN: La ZSP es la unidad geotectónica más al suroeste del Orógeno Varisco y se consideran los siguientes dominios: Pulo do Lobo (Frasniense inferior y Fameniense superior), Faja Pirítica Ibérica (Givetiense-Viseense superior), Grupo Flysch Baixo Alen tejo (Viseense superior-Moscoviense superior) y Grupo Suroeste (Estruniense-Bashkiriense medio). En el proyecto GEO_FPI se ha prestado especial atención a la Faja Pirítica Ibérica, ya que es una de las provincias metalogenéticas más importantes del mundo, con depósitos de sulfuros masivos (VHMS) e importantes recursos de Cu, Zn, Pb, Ag, Au, Sn, In, Se, Ge. Se ha realizado un trabajo de campo en común en la región fronteriza de España y Portugal para permitir una mejor inte gración y correlación de los datos geológicos y cartográficos. Además, se han seleccionado 31 afloramientos donde se han recogido muestras para realizar un estudio de geocronología de U-Pb en circón. Los datos de edad obtenidos son importantes para restringir las estructuras geológicas de la Faja Pirítica Ibérica que albergan la mineralización masiva de sulfuros y, por otra parte, mejoran la visión geotectónica de toda la ZSP
- Geochronology and P-T-t paths of the Berlengas Archipelago rocks, W Portugal [Abstract]Publication . Valverde-Vaquero, Pablo; Bento dos Santos, Telmo; González-Clavijo, Emilio J.; Díez-Montes, Alejandro; Ribeiro, Maria Luísa; Solá, A. Rita
- Dados geocronológicos para o soco pré-Mesozoico localizado a Oeste da Falha Porto-Tomar: implicações geodinâmicasPublication . Santos, Telmo M. Bento Dos; Chichorro, Martim; Carvalho, D.; Cachapuz, P.; Solá, A. Rita; Dantas, E.; Romão, José; Moreira, Noel; Silva, I. Dias da; Clavijo, E.; Díez-Montes, Alejandro; Valverde-Vaquero, Pablo; Santos, R. V.; Linnemann, UlfSUMMARY: Geochronological data from the pre-Mesozoic basement of the Lusitanian Basement (West of the Porto-Tomar Fault) was obtained. Results show a predominant Cadomian/Pan-African and Eburnean inheritance/source, placing this sector as a peri-Gondwanan domain. However, two major differences can be seen in the data: samples with a clear absence in Mesoproterozoic ages vs. samples with a clear presence of these ages and Silurian-Devonian ages. If the former show clear signs of affinity with the Ossa-Morena Zone, the latter are similar to the South Portuguese Zone, being one of the samples, probably deposited in the Middle-Upper Devonian, interpreted as having a mixed source.
- The Berlengas Archipelago granitoids within the frame of the Variscan Orogeny, W Portugal : new data and insightsPublication . Valverde-Vaquero, Pablo; Bento dos Santos, Telmo; González Clavijo, Emilio José; Díez-Montes, Alejandro; Ribeiro, Maria Luísa; Solá, A. Rita; Silva, I. Dias da
- New geochemical and geochronological data of early Cambrian of SW Iberia : calc-alkaline magmatism in the transition from active to passive continental margin in North GondwanaPublication . Sánchez-García, T.; Pereira, Manuel Francisco Costa; Bellido Mulas, F.; Chichorro, Martim; Silva, J. Brandão; Valverde-Vaquero, Pablo; Pin, C.; Solá, A. Rita
- Idades preliminares U-Pb, ID-TIMS, das Ilhas Berlengas, Portugal = Preliminary ID-TIMS, U-Pb ages of the Berlengas Islands, PortugalPublication . Valverde-Vaquero, Pablo; Ribeiro, Maria Luísa; González-Clavijo, Emilio J.; Bento dos Santos, TelmoApresentam-se os resultados provisórios das idades U-Pb de duas amostras das ilhas do grupo das Berlengas. No Farilhão Grande uma amostra de granito de duas micas com silimanite foi recolhida de um complexo metamórfico. Esta amostra ofereceu três fracções de monazite com idade 377+-1 Ma, interpretada como metamórfica, enquanto uma fracção de zircões de concórdia 483 Ma sugeriu uma idade Tremadoc. Esta última fracção é herdada, provavelmente do volumoso magmatismo do Ordovícico Inferior existente na Ibéria. Na Berlenga Grande o granito apresenta fracções de monazite e zircão concordantes de 307,4+-0,8 Ma.
- Early Cambrian granitoids of North Gondwana margin in the transition from a convergent setting to intra-continental rifting (Ossa-Morena Zone, SW Iberia)Publication . Sánchez-García, Teresa; Pereira, M. Francisco; Bellido, F.; Chichorro, Martim; Silva, J. Brandão; Valverde-Vaquero, Pablo; Pin, Ch.; Solá, A. RitaTwo distinct Cambrian magmatic pulses are recognized in the Ossa-Morena Zone (SW Iberia): an early rift-(ER) and a main rift-related event. This Cambrian magmatism is related to intra-continental rifting of North Gondwana that is thought to have culminated in the opening of the Rheic Ocean in Lower Ordovician times. New data of whole-rock geochemistry (19 samples), Sm–Nd–Sr isotopes (4 samples) and ID–TIMS U–Pb zircon geochronology (1 sample) of the Early Cambrian ER plutonic rocks of the Ossa-Morena Zone are presented in this contribution. The ER granitoids (Barreiros, Barquete, Calera, Salvatierra de los Barros and Tablada granitoid Massifs) are mostly peraluminous granites. The Sm–Nd isotopic data show moderate negative eNdt values ranging from -3.5 to +0.1 and TDM ages greatly in excess of emplacement ages. Most ER granitoids are crustal melts. However, a subset of samples shows a transitional anorogenic alkaline tendency, together with more primitive isotopic signatures, documenting the participation of lower crust or mantle-derived sources and suggesting a local transient advanced stage of rifting. The Barreiros granitoid is intrusive into the Ediacaran basement of the Ossa-Morena Zone (Série Negra succession) and has yielded a crystallization age of 524.7 ± 0.8 Ma consistent with other ages of ER magmatic pulse. This age: (1) constrains the age of the metamorphism developed in the Ediacaran back-arc basins before the intrusion of granites and (2) defines the time of the transition from the Ediacaran convergent setting to the Lower Cambrian intra-continental rifting in North Gondwana.
- Tales from xenoliths: the link between the Papôa Volcanic Breccia and the Berlengas Archipelago (West Portugal): geodynamic implicationsPublication . Rosa, Ana Rita; Cachapuz, P.; Santos, Telmo M. Bento Dos; Pereira, Inês; Solá, A. Rita; Carvalho, D.; Romão, José; Valverde-Vaquero, PabloABSTRACT: The Papoa Volcanic Breccia (Peniche, West Portugal) is a Mesozoic pyroclastic deposit that includes numerous igneous and metamorphic xenoliths belonging to the Variscan basement of the Lusitanian Basin, in which this unit outcrops. These rocks correspond mostly to syenogranites and diatexites affected by intense pyrometamorphism and, despite their strong secondary alteration by weathering, they still preserve several original petrographic features that are traceable to the lithologies that comprise the Berlengas Archipelago, located 15 km offshore the Peniche coast. New geochemical and mineral chemistry data now indicate a genetic relationship between these basement xenoliths and the Late Devonian migmatites outcropping in the Farilhoes Anatectic Complex. Such evidence strongly suggests the physical continuity of these high-grade metamorphic terrains at least to the Peniche region, thus constraining the nature and composition of the crustal block beneath the sedimentary sequences of the Lusitanian Basin in the studied location. In addition, in situ LA-ICP-MS U-Pb dating of rutile formed during the pyrometamorphic event endured by the xenoliths provided an age of 92.3 +/- 1.4 Ma for the Papoa volcanic eruption, placing this occurrence within the third magmatic cycle related to the opening and spreading of the North Atlantic Ocean in the West Iberian Margin.