U-Pb and Ar-39/Ar-40 data constraining the ages of the source, emplacement and recrystallization/cooling events from late- to post-D-3 Variscan granites of the Gouveia area, central Portugal

作者：Neiva A M R^*; Williams I S; Lima S M; Teixeira R J S

来源：Lithos, 2012, 153: 72-83.

DOI：10.1016/j.lithos.2012.02.012

• Zircon
• Muscovite
• Emplacement ages
• Inheritance
• Recrystallization/cooling ages

Late Carboniferous U-Pb ages have been measured on igneous zircon from late- and post-D-3 Sn-bearing twomica granites from the Gouveia area in the Central Iberian Zone. Inherited zircon from these granites is mainly of Neoproterozoic age, a small amount is Paleoproterozoic and Cambrian, and none is Mesoproterozoic. The most likely source of the granites is Gondwanan sediments derived from the West African Craton and surrounding Pan-African belts. Rare inherited zircon of Ordovician, Silurian, Devonian and Carboniferous age is of similar age to zircon in synorogenic greywackes and conglomerates of the NW Iberian Massif. Ordovician granitic rocks might have contributed to the source. Igneous zircon (310.1 +/- 4.3 Ma) from a late-D-3 granite is older than coexisting monazite (301.4 +/- 2.6 Ma). The monazite (re)crystallized, and is of similar age to zircon from a post-D-3 granite (297.3 +/- 3.1 Ma) that surrounds this granite. Monazite from post-D-3 granites is of similar age (similar to 289 Ma), but slightly younger than the zircon from the same granites (297.3 +/- 3.1 and 302.6 +/- 6.7 Ma). The Ar-39-Ar-40 age of muscovite from Variscan late- and post-D-3 granites of the Gouveia area is the same (similar to 286 Ma), showing that the area was heated above similar to 350 degrees C in the Late Carboniferous-Early Permian. Muscovite from Variscan late-D-3 granites suffered Ar loss and muscovite from Variscan post-D-3 granites records cooling after emplacement.

• 出版日期2012-11-15