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enberg Naturhistorische Sammlungen, Dresden. Mineral separa- tion and selection of the zircon grains by hand-picking under a binocular microscope were performed before mounting in resin blocks and polishing. Cathodoluminescence (CL)-imaging was per- formed using a Zeiss EVO 50 SEM coupled to a HONOLD CL detector prior to U-Pb analysis. Zircons were analysed by LA-SF ICP-MS using a Thermo-Scientific Element 2 XR sector field ICP-MS (single-collector) coupled to a RESOlution 193 nm excimer laser, at the Senckenberg Naturhistorische Sammlungen, Dresden. Each analysis consisted of 15 s background acquisition followed by 30 s data acquisition, using a laser spot-size of 25 and 35 l m, respectively. A common-Pb correction was carried out, if neces- sary, based on the interference- and background-corrected 204 Pb signal and a model Pb composition (Stacey and Kramers, 1975). The necessity of the correction is judged on whether the corrected 207 Pb/ 206 Pb lies outside of the internal errors of the measured ratios (Frei and Gerdes, 2009). Raw data were corrected for back- ground signal, common Pb, laser-induced elemental fractionation, instrumental mass discrimination, and time-dependant elemental fractionation of Pb/Th and Pb/U using an Excel spreadsheet pro- gram developed by Axel Gerdes (Institute of Geosciences, Johann Wolfgang Goethe University Frankfurt, Frankfurt am Main, Ger- many). Reported uncertainties were propagated by quadratic addi- tion of the external reproducibility obtained from the standard zircon GJ-1 ( 0.6% and 0.5–1% for the 207 Pb/ 206 Pb and 206 Pb/ 238 U, respectively; Jackson et al., 2004) during individual analytical ses- sions and within-run precision of each analysis. In order to test the accuracy of the measurements and data reduction, we included the Plešovice zircon as a secondary standard in our analyses, which gave reproducibly ages of c. 337 Ma, fitting with the results of Sláma et al. (2008). Concordia diagrams (2 r error ellipses), concordia ages (95% confidence level) and relative probability plots were produced using Isoplot/Ex 4.15 (Ludwig, 2012). The 206 Pb/ 238 U ages were used for zircon grains younger than 1.0 Ga, the 207 Pb/ 206 Pb age was used for a single grain older than 1.0 Ga from sample MEGA03 Fig. 3. Microphotographs of representative samples from the Mérida Massif. (a) and (b) metabasites of the Montemolín Formation (PPL); note in (a) the regional foliation defined by orientation of amphiboles and plagioclases. (c) and (d) metatonalites of Don Álvaro Metaigneous Complex (PPL and XPL, respectively); note the large size of amphibole, biotite, and plagioclase crystals and the limited strain. (e) and (f) felsic orthogneisses of the San Andrés Metaigneous Complex (PPl and XPL, respectively); note the recrystallized polycrystalline quartz texture, typical of strained rocks. E. Rojo-Pérez, U. Linnemann, M. Hofmann et al. Gondwana Research 109 (2022) 89–112 &KDSWHU