%0 Journal Article
%A Orejana García, David
%A Merino Martínez, Enrique
%A Villaseca González, Carlos
%A Pérez-Soba Aguilar, Cecilia María
%A Cuesta, Andrés
%T Electron microprobe monazite geochronology of granitic intrusions from theMontes de Toledo batholith (central Spain)
%D 2012
%@ 0072-1050
%U https://hdl.handle.net/20.500.14352/42409
%X U–Th–Pb monazite dating by electron microprobe has been applied to three peraluminous granitic intrusions of the western Montes de Toledobatholith (MTB). Back scattered electron images of monazite crystals reveal a variety of internal textures: patchy zoning, overgrowths aroundolder cores and unzoned crystals. On the basis of their zoning pattern and chemical composition, two monazite domains can be distinguished:(1) corroded cores and crystals with patchy zoning, exhibiting relatively constant Th/U ratios and broadly older ages, and (2) unzoned grainsand monazite rims, with variable Th/U ratios and younger ages. The first monazite group represents inherited domains from metamorphicsources, which accounts for pre-magmatic monazite growth events. Two average ages from Torrico and Belvís de Monroy granites(33318 and 3335 Ma, respectively) relate these cores to a Viséan extensional deformation phase. The second group represents igneousmonazites which have provided the following crystallization ages for the host granite: 29811 Ma (Villar del Pedroso), 3036Ma (Torrico)and 3143Ma (Belvís de Monroy). Two main magmatic pulses, the first about 314Ma and the second at the end of the Carboniferous(303–298Ma), might be envisaged in the western MTB. While Belvís de Monroy leucogranite is likely a syn- to late-tectonic intrusion,the Villar del Pedroso and Torrico plutons represent post-tectonic magmas with emplacement ages similar to those of equivalentintrusions from nearby Variscan magmatic sectors.
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