Variability over time in the sources of South Portuguese Zone turbidites: evidence of denudation of different crustal blocks during the assembly of Pangaea

Pereira, M. Francisco; Ribeiro, Carlos; Vilallonga, F.; Chichorro, M.; Drost, Kerstin; Silva, J. B.; Albardeiro, Luís; Hofmann, Mandy; Linnemann, Ulf

doi:10.1007/s00531-013-0902-8

Cited by 39 publications

(31 citation statements)

References 57 publications

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“…Close to Cape Sines, the sea cliff is essentially made up of the Jurassic limestones of the Alentejo basin (to the north) and a Carboniferous sequence of greywacke and shale of the South‐Portuguese Zone (to the south) (Figs and ). Carboniferous turbidites were mostly derived from the denudation of the Gondwana basement during Variscan orogenesis (Pereira et al ., ), while Jurassic carbonate beds were deposited during the opening of the North Atlantic Ocean (Pereira & Alves, ).…”

Section: Geological Settingmentioning

confidence: 99%

“…However, in many of these studies the K–S test was not used, while in those in which it was used, its full potential was rarely taken advantage of. In this paper, a detailed report on the use of the K–S test for the deciphering of sediment recycling in a modern coastal system is presented, based on new U–Pb analyses conducted on Holocene beach sand detrital zircons, testing previously published U–Pb data indicating potential sources forming the sea cliff (Carboniferous greywacke, Pereira et al ., ; Pliocene–Pleistocene sand, Albardeiro et al ., ; Cretaceous syenite and gabbro, Miranda et al ., ; Grange et al ., ).…”

Section: Introductionmentioning

confidence: 99%

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Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system

et al. 2016

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Detrital zircons from Holocene beach sand and igneous zircons from the Cretaceous syenite forming Cape Sines (Western Iberian margin) were dated using laser ablation – inductively coupled plasma – mass spectrometry. The U–Pb ages obtained were used for comparison with previous radiometric data from Carboniferous greywacke, Pliocene–Pleistocene sand and Cretaceous syenite forming the sea cliff at Cape Sines and the contiguous coast. New U–Pb dating of igneous morphologically simple and complex zircons from the syenite of the Sines pluton suggests that the history of zircon crystallization was more extensive (ca 87 to 74 Ma), in contrast to the findings of previous geochronology studies (ca 76 to 74 Ma). The U–Pb ages obtained in Holocene sand revealed a wide interval, ranging from the Cretaceous to the Archean, with predominance of Cretaceous (37%), Palaeozoic (35%) and Neoproterozoic (19%) detrital‐zircon ages. The paucity of round to sub‐rounded grains seems to indicate a short transportation history for most of the Cretaceous zircons (ca 95 to 73 Ma) which are more abundant in the beach sand that was sampled south of Cape Sines. Comparative analysis using the Kolmogorov–Smirnov statistical method, analysing sub‐populations separately, suggests that the zircon populations of the Carboniferous and Cretaceous rocks forming the sea cliff were reproduced faithfully in Quaternary sand, indicating sediment recycling. The similarity of the pre‐Cretaceous ages (>ca 280 Ma) of detrital zircons found in Holocene sand, as compared with Carboniferous greywacke and Pliocene–Pleistocene sand, provides support for the hypothesis that detritus was reworked into the beach from older sedimentary rocks exposed along the sea cliff. The largest percentage of Cretaceous zircons (

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Section: Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system

et al. 2016

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“…The South Portuguese Zone includes: (1) the Pulo do Lobo Zone, which has been interpreted to be an accretionary prism (Eden 1991;Silva et al 1990;Quesada et al 1994;Onézime et al 2003;Braid et al 2010Braid et al , 2011 (2) the Iberian Pyrite Belt with upper Devonian to lower Carboniferous sedimentary and volcanic rocks (Dunning et al 2002;Rosa et al 2008); and (3) the Carboniferous Culm series turbidites (Oliveira 1990;Oliveira and Quesada 1998;Pereira et al 2013a).…”

Section: Geological Settingmentioning

confidence: 99%

“…1). The oldest rocks of the Serie Negra Group are Ediacaran pelites and graywackes deposited in a Cadomian magmatic Pereira et al 2012aPereira et al , 2013a arc setting in North Gondwana . The Cambro-Ordovician sequence is related to the formation of ensialic rift basins with voluminous felsic and mafic magmatism .…”

Section: Geological Settingmentioning

confidence: 99%

“…Fg, together with the diatexites, is locally folded and intruded by trondhjemite, tonalite and andesite dykes. The shear criteria related to the Variscan ductile deformation that folds and stretches the diatexites and granitoid veins indicate a sinistral sense of movement (Pereira et al 2013a).…”

Section: Calc-alkaline Granitoids: Field Relations Petrography and Gmentioning

confidence: 99%

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The multistage crystallization of zircon in calc-alkaline granitoids: U–Pb age constraints on the timing of Variscan tectonic activity in SW Iberia

Pereira

Chichorro

Moita

et al. 2015

Int J Earth Sci (Geol Rundsch)

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explained by: (1) crystallization from melts with different compositions (felsic peraluminous to felsic-intermediate metaluminous; 0.001 < Th/U ratio < 0.5) and (2) transient temperature fluctuations in a system where anatectic felsic melts periodically underwent injection of more mafic magmas at higher temperatures. The two studied calc-alkaline granitoids do not include inherited zircons (pre-Carboniferous), probably because they were formed at the highest grade of metamorphism (T > 837 °C; granulite facies) and/or because they were derived from inheritance-poor felsic and mafic rocks from a previous cycle, as suggested by the internal structures of zircon cores. These Variscan magmatic rocks with crystallization ages estimated at ca. 336-335 Ma are spatially and temporally related to hightemperature metamorphism, anatexis, processes of interaction between crustal-and mantle-derived magmas and intra-orogenic extension that acted in SW Iberia during the Early Carboniferous.

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The elusive nature of the Rheic Ocean suture in SW Iberia

et al. 2015

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The Rheic Ocean suture resulted from pre-Carboniferous oceanic subduction followed by Late Devonian-Carboniferous Variscan collision. In SW Iberia, this suture has been classically located along the boundary between the Ossa-Morena and South Portuguese Zones based on the presence of three units: (i) a conspicuous metamafic unit (Beja-Acebuches) that crops out along this boundary and has been interpreted as a pre-Carboniferous Rheic Ocean ophiolite; (ii) a low-grade metasedimentary unit with minor mid-ocean ridge basalt-like lithologies (Pulo do Lobo unit), thought to represent a Rheic Ocean subduction-related accretionary prism; and (iii) the allochthonous Cubito-Moura unit that contains high-pressure and ophiolitic-like rocks. We report new structural and geochronological data that allow us to reinterpret the origin and internal structure of the Beja-Acebuches and the Pulo do Lobo units. Thus, both the Beja-Acebuches protoliths and the Pulo do Lobo metabasalts would have been formed in the context of an intracollisional extensional stage that interrupted the Variscan collision at early Carboniferous time, after the Rheic Ocean consumption, and the first continental collision. Later on, collision was resumed in an oblique left-lateral regime that gave way to coeval frontal (folds and thrusts) and lateral (shear zones and strike-slip faults) structures, with variable pressure-temperature conditions and space distribution along time. As a consequence of the superposition of transtension and complex transpression, the Rheic suture in SW Iberia has an obscure nearly cryptic appearance.

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Variability over time in the sources of South Portuguese Zone turbidites: evidence of denudation of different crustal blocks during the assembly of Pangaea

Cited by 39 publications

References 57 publications

Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system

Provenance of Holocene beach sand in the Western Iberian margin: the use of the Kolmogorov–Smirnov test for the deciphering of sediment recycling in a modern coastal system

The multistage crystallization of zircon in calc-alkaline granitoids: U–Pb age constraints on the timing of Variscan tectonic activity in SW Iberia

The elusive nature of the Rheic Ocean suture in SW Iberia

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