S-type granite generation and emplacement during a regional switch from extensional to contractional deformation (Central Iberian Zone, Iberian autochthonous domain, Variscan Orogeny)

Abstract

formed during magmatic crystallization and subsequent solid-state deformation. Field relationships suggest contemporaneity between the ca. 319-317 Ma old magmatism of the study area and the switch from late D 2 extensional deformation to early D 3 contractional deformation. Inherited zircon cores are well preserved in these late D 2 -early D 3 S-type granite plutons. U-Pb ages of inherited zircon cores range from ca. 2576 to ca. 421 Ma. The spectra of inherited cores overlap closely the range of detrital and magmatic zircon grains displayed by the Ediacaran to Silurian metasedimentary and metaigneous rocks of the Iberian autochthonous and parautochthonous domains. This is evidence of a genetic relationship between S-type granites and the host metamorphic rocks. There is no substantial evidence for the addition of mantle-derived material in the genesis of these late D 2 -early D 3 S-type granitic rocks. The εNd arrays of heterogeneous crustal anatectic melts may be just inherited from the source, probably reflecting mixing of a range of crustal materials with different ages and primary isotopic signatures. The generation of the Bashkirian S-type granites has been dominated by continental crust recycling, rather than the addition of new material from mantle sources.

Exhuming a cold case: The early granodiorites of the northwest Iberian Variscan belt—A Visean magmatic flare-up?

“…The origin of the zircons in this age group is not clear but zircons of this age are present in some mafic volcanic rocks in central Iberia and are also abundant as detrital components in Devonian-Carboniferous sequences of southwest Iberia, where they have been interpreted as derived from the dismantling of (intra?) Rheic oceanic arc rocks (Pereira et al, 2018).…”

“…Synextensional collapse granitoids (ca. 325-315 Ma), mostly crustal (S-type) peraluminous leucogranites, were generated by decompression melting following the extensional collapse of the mountain belt (e.g., Dias et al, 1998;Fernández-Suárez et al, 2000;Valle Aguado et al, 2005;Teixeira et al, 2012;López-Moro et al, 2018;Pereira et al, 2018).…”

Magnetic mineralogy of Variscan granites from northern Portugal: an approach to their petrogenesis and metallogenic potential

“…360-337Ma, e.g. Castiñeiras et al, 2008;Dallmeyer et al, 1997;Díez Fernández et al, 2016;Martínez Catalán et al, 2014;Pereira et al, 2018), and D 3 (ca. 321─300Ma, e.g.…”

“…321─300Ma, e.g. Ferreira et al, 1987;Pereira et al, 2018). D 1 produced isoclinal folds with a subvertical axial plane with a NW-SE strike and a well-marked axial plane schistosity (S 1 ), and D 3 is characterized by wide folding of small amplitude on the subvertical axial plane and sub-horizontal NW-SE axis.…”

The enigmatic curvature of Central Iberia and its puzzling kinematics

“…General decompression produced a Buchan-type metamorphic event (M2; e.g , Solís- Alulima et al, 2019. and widespread anatectic melting (e.g López-Moro et al, 2018;Pereira et al, 2018)…”