Encontrados 13 documentos, a visualizar página 1 de 2
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...
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...
The missing Rheic Ocean magmatic arcs: Provenance analysis of Late Paleozoic
Pereira, M.F.; Chichorro, M.; Johnston, S.T.; Gutierrez-Alonso, G.; Silva, J.B.; Linnemann, U.; Hofmann, M.; Drost, K.Early Carboniferous turbiditic sedimentary rocks in synorogenic basins located on both sides of the Rheic suture in SW Iberiawere studied for provenance analysis. An enigmatic feature of this suture, which resulted from closure of the Rheic Ocean with the amalgamation of Pangea in the Late Carboniferous, is that there are no recognizable mid- to Late Devonian subduction-related magmatic rocks,which should have ...
The provenance of Late Ediacaran and Early Ordovician siliciclastic rocks in th...
Pereira, M.F.; Linnemann, U.; Hofmann, M.; Chichorro, M.; Solá, A.R; Medina, J.; Silva, J.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 activepassive margin transition. The LAICPMS U–Pb data set (375 detrital zircons with 90–110% concordant ages) is dominated by Neop...
North-Gondwana assembly, break-up and paleogeography: U–Pb isotope evidence fro...
Pereira, M.F.; Solá, A.R.; Chichorro, M.; Lopes, L.; Gerdes, A.; Silva, J.B.The Estremoz Anticline in the Ossa-Morena Zone (SW Iberia) includes upper Ediacaran detrital rocks uncon- formably overlain by lower Cambrian detrital and carbonate rocks. The spectra of detrital zircon U–Pb ages dominated by Cryogenian and Ediacaran ages (with a typical gap in Mesoproterozoic ages) of the upper Edi- acaran greywackes and lower Cambrian arkosic sandstones indicate provenance from sources placed...
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...
Geologia de Portugal - Geologia Pré-Mesozóica de Portugal II.2.3. Maciço de Évora
Pereira, M.F.; Chichorro, M.; Moita, P.; Brandão, J.B; Santos, J.F.O Maciço de Évora (ME) representa uma área com cerca de 60 km2 (Fig. 1) que se estende entre Montemor-o-Novo e Évora (Carvalhosa, 1983), localizada nos domínios ocidentais da Zona de Ossa-Morena (ZOM, Quesada e Munhá, 1990; Pereira et al., 2007; 2008, 2009a) e incluído no sector de Montemor-Ficalho (Oliveira et al., 1991). Os seus limites foram definidos por Carvalhosa (1983) como coincidentes a sudoeste com o ...
Detrital zircon from a late Paleozoic accretionary complex of SW Iberia (Varisc...
Pereira, M.F.; Drost, K.; Chichorro, M.; Silva, J.B.; Sola, R.In this study we present new U-Pb ages of detrital zircons from greywackes and quartzites of the Pulo do Lobo Anticline (PLA) that have been interpreted to represent a Late Paleozoic accretionary complex in SW Iberia. The PLA separates the Ossa Morena Zone, which has a North- Gondwana affinity throughout Late Ediacaran and Early Paleozoic times, from the South Portuguese Zone, which is considered to be underlai...
| Financiadores do RCAAP | |||||||
|
|
|
|
|
|
||