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Electron microprobe monazite geochronology of granitic intrusions from the Montes de Toledo batholith (central Spain)

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Orejana García, David and Merino Martínez, Enrique and Villaseca González, Carlos and Pérez-Soba Aguilar, Cecilia and Cuesta, Andrés (2012) Electron microprobe monazite geochronology of granitic intrusions from the Montes de Toledo batholith (central Spain). Geological Journal, 47 . pp. 41-58. ISSN 0072-1050

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Official URL: http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1034/



Abstract

U–Th–Pb monazite dating by electron microprobe has been applied to three peraluminous granitic intrusions of the western Montes de Toledo
batholith (MTB). Back scattered electron images of monazite crystals reveal a variety of internal textures: patchy zoning, overgrowths around
older 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 grains
and monazite rims, with variable Th/U ratios and younger ages. The first monazite group represents inherited domains from metamorphic
sources, 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 igneous
monazites 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 equivalent
intrusions from nearby Variscan magmatic sectors.


Item Type:Article
Uncontrolled Keywords:monazite dating; peraluminous granites; post-tectonic Intrusions; Montes de Toledo batholith; Variscan Iberian Belt; Electron microprobe
Subjects:Sciences > Geology > Petrology
ID Code:17209
Deposited On:26 Nov 2012 13:17
Last Modified:26 Nov 2012 13:17

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