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Crustal melting and recycling: geochronology and sources of Variscan syn-kinematic anatectic granitoids of the Tormes Dome (Central Iberian Zone). A U–Pb LA-ICP-MS study

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López Moro, Francisco Javier and López Plaza, Miguel and Gutiérrez-Alonso, Gabriel and Fernández Suárez, Javier and López-Carmona, Alicia and Hofmann, Mandy and Romer, Rolf L. (2018) Crustal melting and recycling: geochronology and sources of Variscan syn-kinematic anatectic granitoids of the Tormes Dome (Central Iberian Zone). A U–Pb LA-ICP-MS study. International Journal of Earth Sciences, 107 (3). pp. 985-1004. ISSN ISSN: 1437-3254, onlinr ISSN: 1437-3262

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Official URL: https://link.springer.com/article/10.1007/s00531-017-1483-8


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Abstract

In this study, we report U–Pb Laser Ablation ICP-MS zircon and ID-TIMS monazite ages for peraluminous granitoid plutons (biotite ± muscovite ± cordierite ± sillimanite) in the Tormes Dome, one of the gneiss-cored domes located in the Central Iberian Zone of the Variscan belt of northern Spain. Textural domains in zircon, interpreted to represent the magmatic crystallization of the granitoids (and one monazite fraction in the Ledesma pluton) yielded ages around 320 Ma, in agreement with other geochronological studies in the region. This age is interpreted to date the timing of decompression crustal melting driven by the extensional collapse of the orogenic belt in this domain of the Variscan chain of western Europe. In addition, there are several populations of inherited (xenocrystic) zircon: (1) Carboniferous zircon crystals (ca. 345 Ma) as well as one of the monazite fractions in the coarse-grained facies of the Ledesma pluton that also yielded an age of ca. 343 Ma. (2) Devonian–Silurian zircon xenocrysts with scattered ages between ca. 390 and 432 Ma. (3) Middle Cambrian–Ordovician (ca. 450–511 Ma). (4) Ediacaran–Cryogenian zircon ages (ca. 540–840 Ma). (5) Mesoproterozoic to Archaean zircon (900–2700 Ma). The abundance of Carboniferous-inherited zircon shows that crustal recycling/cannibalization may often happen at a fast pace in orogenic scenarios with only short lapses of quiescence. In our case study, it seems plausible that a “crustal layer” of ca. 340 Ma granitoids/migmatites was recycled, partially or totally, only 15–20 My after its emplacement.


Item Type:Article
Uncontrolled Keywords:U–Pb geochronology, Laser ablation, Iberia, Variscan, Anatectic granitoids
Subjects:Sciences > Geology > Geochemistry
Sciences > Geology > Petrology
ID Code:47602
Deposited On:17 May 2018 18:07
Last Modified:18 May 2018 07:34

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