U–Pb zircon and monazite geochronology of post-collisional Hercynian granitoids from the Central Iberian Zone

.In the Central Iberian Zone CIZ of the Iberian Massif large volumes of granitoids were emplaced during the .post-collisional stage of the Hercynian orogeny syn- to post-D3, the last ductile deformation phase. Twelve granitic units and a quartz monzodiorite were selected for a U–Pb zircon and monazite geochronological study. They represent successive stages of the D3 event. The Ucanha-Vilar, Lamego, Sameiro and Refoios do Lima plutons are coeval 313"2 Ma, 319"4.Ma, 316"2 Ma and 314"2 Ma, respectively and belong to the earliest stage. Later on the Braga massif was emplaced, its different units yielding the same age: 309"3 Ma for the Braga granite, 309"1 Ma for the Gonça granite and 311"5 Ma for a related quartz monzodiorite. The Braga massif is subcontemporaneous with the Agrela and Celeiros plutons 307"3.5´. .Ma and 306"2 Ma, respectively, in agreement with field data. The Briteiros granite is younger 300"1 Ma, followed by .the emplacement of the Peneda–Geres massif Geres, Paufito, Illa and Carris granites. The Geres granite, emplaced at ˆ ˆ ˆ 296"2 Ma, seems to represent a first magmatic pulse immediately followed by the intrusion of the Paufito granite at 290"2.5 Ma. For the Carris granite a minimum emplacement age of 280"5 Ma was obtained. Based on these results the . .following chronology is proposed: 1 syn-D3 biotite granitoids, 313–319 Ma; 2 late-D3 biotite-dominant granitoids, . .306–311 Ma; 3 late- to post-D3 granitoids, ca. 300 Ma; 4 post-D3 granitoids, 290–296 Ma. These chronological data indicate that successive granitic intrusions were emplaced in the CIZ during a short time span of about 30 Ma that corresponds to the latest stages of the Hercynian orogeny. A rapid and drastic change occurred at about 300 Ma, between