Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

Fernández, Rubén Díez; Castiñeiras, Pedro; Barreiro, Juan Gómez

doi:10.1016/j.gr.2011.07.028

Cited by 91 publications

(47 citation statements)

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“…These data sit along an average crustal evolution trend together with those from the 550 Ma-old zircons, corresponding to Hf model ages comprised between 1.0 and 1.5 Ga, in agreement with Hf and Nd isotope data from the FMC granitoids Pin and Duthou, 1990;Turpin et al, 1990). Such model ages clearly have no geological significance as zircon in all Gondwana derived sediments throughout Europe provide no evidence for magmatism during this period (Balintoni et al, 2014;Díez Fernández et al, 2012;Drost et al, 2011;Gebauer et al, 1989;Gerdes and Zeh, 2006;Linnemann et al, 2014;Morag et al, 2011a;Pastor-Galán et al, 2013;Pereira et al, 2012a;2012b;Shaw et al, 2014;Sirevaag et al, 2016;Villaseca et al, 2016;Williams et al, 2012;Zeh and Gerdes, 2010). Instead, this Hf isotope signature would correspond again to a mixed source consisting of Neoproterozoic (0.6-0.8 Ga), juvenile crust and Archean/Paleoproterozoic crust (2.0-3.3 Ga).…”

Section: Accepted Manuscriptsupporting

confidence: 77%

“…Nevertheless, the Rheic suture zone is now recognized in southern England and south of the Rhenish Massif, while south of this suture, many relicts of mafic-ultramafic complexes, MORB-type eclogites, alkalic magmas and contemporaneous crust-derived acidic magmatic rocks of Upper Cambrian-Lower Ordovician ages are found (see compilations in: Berger et von Raumer et al, 2013;Villaseca et al, 2015). Despite some disagreement about the source and geodynamic implication of such magmatism, it is generally agreed that at this period the northern Gondwana margin was under widespread extensional tectonics that locally led to the formation of slow-spreading oceanic crust, distinct from that of the Rheic Ocean (Berger et al, 2006;Bouchardon et al, 1989;Briand et al, 1991;Díez Fernández et al, 2012;Matte, 2001;Montes et al, 2010;Pin and Marini, 1993;von Raumer and Stampfli, 2008). In the Massif Central, this "oceanic" domain is often referred to as the Galicia-Brittany…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

Chelle-Michou¹

2017

Preprint

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The East Massif Central (EMC), France, is part of the internal zone of the Variscan belt where late Carboniferous crustal melting and orogenic collapse have largely obliterated the pre-to early-Variscan geological record. Nevertheless, parts of this history can be reconstructed by using in-situ U-Th-Pb-Lu-Hf isotopic data of texturally well-defined zircon grains from different lithological units. All the main rock units commonly described in the EMC are present in the area of Tournon and include meta-sedimentary and meta-igneous rocks of the Upper Gneiss Unit (UGU) and of the Lower Gneiss Unit (LGU), as well as cross-cuttingVariscan granitoid dikes and a heterogeneous granite coring the major Velay dome. Herein we demonstrate that the UGU and the LGU have markedly distinct zircon records. The results of this study are consistent with deposition of the protoliths of the paragneisses within a backarc basin that was located adjacent to the Arabian-Nubian shield and/or the Saharan Metacraton during the late Ediacaran and collected detritus from the Gondwana continent. At ~545 Ma some of these sedimentary rocks were affected by a first melting event that formed the protoliths of the LGU orthogneisses, those of which subsequently remelted at ca. 308 Ma to form the Velay granite-migmatite dome. Protoliths of the UGU result mainly from a bimodal rift-related magmatism at ~480 Ma, corresponding to melting of the Ediacaran sediments and depleted mantle. Zircon rims from the UGU additionally provide evidence for a metamorphic/migmatitic overprint during the Lower Carboniferous (~350-340 Ma).Finally, several generations of granite dikes of which inherited zircons display characteristics of both the UGU and the LGU were protractedly emplaced from ~322 Ma to ~308 Ma, the youngest of which being coeval with the formation of the Velay dome. Our data further show that the vast majority of crustal material ultimately involved in the Variscan orogeny, which forms the present-day basement in the EMC, was derived from a sedimentary mixture of ACCEPTED MANUSCRIPTA C C E P T E D M A N U S C R I P T various components from the Gondwana continent deposited in Ediacaran times, with no evidence for the involvement of an older autochthonous crust.

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Section: Accepted Manuscriptsupporting

confidence: 77%

Section: Accepted Manuscriptmentioning

confidence: 99%

Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

Chelle-Michou¹

2017

Preprint

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“…Major and trace element geochemistry of the metagreywackes suggests deposition in association with a peri-Gondwanan arc system built upon a thinned continental margin. Calc-alkaline (c. 493 Ma; Abati et al, 2010) and alkaline-peralkaline (c. 475-470 Ma;Díez Fernández et al, 2012b) granitoids were generated within this arc, suggesting a change over time from convergence to continental rifting. The Basal Units are considered to represent a section of the most external margin of Gondwana originally located somewhere between the West African and Saharan cratons .…”

Section: Terranes Incorporated Into the Variscan Suture Of Nw Iberiamentioning

confidence: 89%

Variscan ophiolites in NW Iberia: Tracking lost Paleozoic oceans and the assembly of Pangea

Arenas¹,

Martı́nez²

2015

Episodes

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“…Such an event may reflect post-collisional rifting of the Gondwana supercontinent during the Paleozoic (e.g. Dèzes, 1999;Fernández et al, 2012) with the Kafiristan pluton intruded as the Cimmerian terranes, including the Hindu Kush and Karakoram, rifted and drifted away from periGondwana toward Eurasia (Sengör, 1979;Rogers et al, 1995;Gaetani, 1997;Heuberger, 2004;Zanchi and Gaetani, 2011). Similar CambroOrovician plutons, interpreted to be related to the same rifting event, have been identified in the nearby Zanskar (Dèzes, 1999), Karakoram (LeFort et al, 1986;Noble and Searle, 1995;Rolland et al, 2002;Zanchi and Gaetani, 2011) and Wakhan (Debon et al, 1987) regions.…”

Section: Discussion and Tectonic Significancementioning

confidence: 99%

Rifting, subduction and collisional records from pluton petrogenesis and geochronology in the Hindu Kush, NW Pakistan

et al. 2016

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New U-(Th)/Pb geochronology and geochemical analyses of plutonic bodies in the Hindu Kush range, NW Pakistan, provide insight on the crustal growth and tectonic evolution of the southern Eurasian margin. These new data outline a protracted magmatic history that spans the Cambrian to the Neogene (ca. 538 to 23 Ma) and record a variety of petrogenetic associations variably influenced by within plate, volcanic arc, and collision tectonic environments. The Kafiristan pluton (538 ± 4 to 487 ± 3 Ma) yields geochemical signatures consistent with extensional plutonism and rifting of the Hindu Kush terrane from Gondwana. The Tirich Mir (127 ± 1 to 123 ± 1 Ma) and Buni-Zom (110 ± 1 to 104 ± 1 Ma) plutons have geochemical signatures that can be attributed to a subduction related continental volcanic arc system that developed along the southern margin of Eurasia in the Mesozoic. The Garam Chasma pluton, the youngest body in the study area (27.3 ± 0.5 to 22.8 ± 0.4 Ma), yields a geochemical signature consistent with widespread anatexis during crustal thickening related to the development of the Himalaya. The present geochemical and geochronological analysis from the Hindu Kush have produced important new constraints on the timing of tectonic events and variable tectonic settings along the south Eurasian margin before and after the continued India-Asia collision.

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Age constraints on Lower Paleozoic convection system: Magmatic events in the NW Iberian Gondwana margin

Cited by 91 publications

References 74 publications

Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

Pre-Cadomian to late-Variscan odyssey of the eastern Massif Central, France: Formation of the West European crust in a nutshell

Variscan ophiolites in NW Iberia: Tracking lost Paleozoic oceans and the assembly of Pangea

Rifting, subduction and collisional records from pluton petrogenesis and geochronology in the Hindu Kush, NW Pakistan

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