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The role of strain localization in magma injection into a transtensional shear ...
Pereira, M Francisco; Chichorro, M; Fernández, C; Silva, JB; Matias, FThis study deals with the interaction between deformation and magmatism in mid- to deep-crustal domains. The relation is analysed between migmatites and shear zones and the spatial distribution of leucogranitoid veins and dykes running through a footwall migmatite system, and reaching a transtensional shear zone operated under amphibolite- to greenschist-facies metamorphic conditions (Boa Fé shear zone, Varisca...
Variability over time in the sources of South Portuguese Zone turbidites: evide...
Pereira, M Francisco; Ribeiro, C; Vilallonga, F; Chichorro, M; Drost, K; Albardeiro, L; Hofmann, M; Linnemann, UThis study combines geochemical and geo- chronological data in order to decipher the provenance of Carboniferous turbidites from the South Portuguese Zone (SW Iberia). Major and trace elements of 25 samples of graywackes and mudstones from the Me´rtola (Visean), Mira (Serpukhovian), and Brejeira (Moscovian) Forma- tions were analyzed, and 363 U-Pb ages were obtained on detrital zircons from five samples of gray...
Early Cambrian granitoids of North Gondwana margin in the transition from a con...
Sanchez-Garcia, T; Pereira, M Francisco; Bellido, F; Chichorro, M; Silva, JB; Valverde-Vaquero, P; Pin, Ch; Sola, ARTwo 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–P...
Sedimentary provenance of Neogene strata from the SW Portuguese coast (Sines Ca...
Albardeiro, Luis; Pereira, M. Francisco; Gama, Cristina; Chichorro, Martim; Hofmann, Mandy; Linnemann, UlfIn this preliminary study of provenance analysis Neogene sandstones and conglomerates of the Alvalade Basin were sampled, from the sea cliffs nearby the Sines Cape (SW Portuguese Coast). Detrital zircons were extracted by conventional methods of particle size separation, magnetic and heavy liquids separation. Detrital zircons were dated by U-Pb method with LA-ICPMS. The U-Pb geochronology results indicate as po...
Permo-Carboniferous magmatism in the core of Pangaea (Southern Pyreness): a pos...
Pereira, M Francisco; Castro, A.; Chichorro, M.; Fernandez, C.; Diaz-Alvarado, J.; Marti, J.; Rodriguez, C.In southern Europe and the western Mediterranean, Permo-Carboniferous magmatism is well represented in areas of Iberia, the Alps, Sardinia and the Balkan Peninsula. In Iberia, the magmatism that has been related to the Variscan orogeny is associated with syn-orogenic events at ca. 350-315 Ma and post-orogenic at ca. 310-295 Ma. In the southern Pyrenees there is Permo-Carboniferous sedimentary basins with a sign...
Early Cambrian granitoids of North Gondwana margin in the transition from a con...
Sánchez-García, Teresa; Pereira, M. Francisco; Bellido, F.; Chichorro, Martím A.; Silva, J. Brandão; Valverde-Vaquero, P.; Pin, Ch.; Solá, Ana 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...
The provenance of Late Ediacaran and Early Ordovician siliciclastic rocks in the
Pereira, M. Francisco; Linnemann, Ulf; Hofmann, Mandy; Chichorro, Martim; Sola, Rita; Medina, Jorge; Silva, Jose B.U–Pb geochronology of detrital zircon from Late Ediacaran (Beiras Group greywackes) and Early Ordovician (Sarnelhas arkosic quartzites and Armorican quartzites of Penacova) sedimentary rocks of the southwest Central Iberian Zone (SW CIZ) constrain the evolution of northern Gondwana active-passive margin transition. The LA-ICP-MS U–Pb data set (375 detrital zircons with 90–110% concordant ages) is dominated by N...
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and b...
Pereira, M. Francisco; Chichorro, M.; Silva, J. Brandão; Ordonez-Casado, B.; Lee, James K.W.; Williams, Ian S.New U–Pb and 40Ar–39Ar geochronology and structural data from high- tomedium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465±14Ma (Middle Ordovician) measured on migmatite from the Coimbra–Cordoba shear zone is inte...
Tracing the Cadomian magmatism with detrital/inherited zircon ages by in-situ U...
Pereira, M. Francisco; Chichorro, Martim; Solá, A.M. Rita; Silva, Jose B.; Sánchez-Garcia, Teresa; Bellido, FelixU–Pb SHRIMP geochronology on zircon extracted from a granite, a sandstone and a quartzite of the SW Iberian Massif (Ossa-Morena Zone), was used in order to investigate the contribution of Late Neoproterozoic (Cadomian) tectonothermal history to the crustal growth of northern Gondwana. The analysed Cambrian rocks were sampled along the southern margin of the Coimbra–Cordoba shear zone (Barquete granite and Crato...
Detrital zircon age constraints on the sediment provenance of Variscan basins i...
Pereira, M. Francisco; Chichorro, Martim; Johnston, Stephen; Gutierrez-Alonso, Gabriel; Silva, J. Brandão; Linnemann, Ulf; Hofmann, MandyThe mid- to late-Devonian Rheic suture between the Laurussia and Gondwana blocks that combined to form Pangea, can be traced along the Variscan orogenic belt across Western-Central Europe. In southwest Iberia, there are, however, no magmatic arc rocks that can be related to the closure, by subduction of its oceanic lithosphere, of the Rheic Ocean. The only magmatism recorded on both sides of the suture is of ea...
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