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fractions, which were loaded onto a preconditioned Re triple filament arrangement. The sample analysis was carried out following a single or dynamic multicollection method for Sm and Nd, respectively. Nd isotope ratios were normalized to 146 Nd/ 144 Nd = 0.7219 (O’Nions et al . 1979), and possible 142 Ce and 144 Sm interferences were corrected. Eight replicas of an Nd isotope standard (JNdi- 1; Tanaka et al. 2000JNdi1) were run along with the studied samples yielding an average value of 143 Nd/ 144 Nd = 0.512106, with an internal precision of ±0.000014 (2σ). Analytical errors on 147 Sm/ 144 Nd and 143 Nd/ 144 Nd ratios were estimated at less than 0.1% and 0.006%, respectively, and the total procedural blanks using this procedure were always below 0.1 ng. 4.2. Zircon U-Pb geochronology and Hf isotope data To further determine the protolith age and magmatic source of the mafic rocks of the Mérida Ophiolite and the scarce granitic rocks included in this terrane, U-Pb and Hf isotope data were obtained in two samples of metagab- bro (OM-2) and metatonalite (OM-1). Both samples were collected in Mérida city. Metagabbro OM-2 is a common medium-grained poorly foliated metagabbro with all igneous minerals replaced by a metamorphic mineral assemblage of amphibole, plagioclase, quartz, clinozoi- site, ilmenite, sphene, and scarce chlorite. Complete replacement of the igneous minerals by a metamorphic assemblage is a common feature of the mafic and ultra- mafic rocks of the Mérida Ophiolite. The metatonalite sample was collected from a < 1 metre thick, medium- grained highly sheared felsic intercalation within the mafic rocks. It contains quartz, plagioclase, biotite, chlor- ite, sericite, and ilmenite. Zircon crystals were separated from bulk samples using conventional mineral separation techniques at the Complutense University of Madrid (UCM, Spain) and the Goethe University of Frankfurt am Main (GUF, Germany), following the methodology described by Albert et al . (2015). Zircon hand picking, mounting, ima- ging, and isotopic analyses were performed at GUF. Cathodoluminescence (CL) and backscattered electron (BSE) images were taken using a JSM 6490 scanning electron microscope. Zircon grains were analysed for U–Pb isotopes with a ThermoScientific ElementXr sector field inductively coupled plasma mass spectrometer (ICP–MS) and for Lu-Hf analyses with a ThermoScientific Neptune Plus MC-ICP–MS in different analytical sessions. For U–Pb and Lu–Hf analyses, mass spectrometers were coupled to a RESOlution M-50 (ASI) 193 nm ArF excimer laser system (COMpex Pro 102, Coherent) to conduct laser ablation. Zircon surfaces were cleaned by four pre-ablation laser pulses, and ana- lyses were performed with a laser frequency of 6 Hz and fluence of 2.1 J/cm 2 . Raw data were corrected offline using an in-house Microsoft Excel spreadsheet program (Gerdes and Zeh 2006, 2009). U–Pb analyses were com- mon Pb corrected following the method described in Millonig et al . (2012). The primary reference material (RM) used was GJ1 (Jackson et al . 2004; n = 24, excess of scatter = 0.34, 1σ per cent). Secondary RMs were BB- 14 (Santos et al . 2017; 551.8 ± 7.8 Ma, n = 12) and 91,500 (Wiedenbeck et al . 1995; 1063.5 ± 10 Ma, n = 12). These results are within the RM accepted values. Plots were drawn with Isoplot 4.16 (Ludwig 2012), spot sizes were 30 μm, reported ages are always 206 Pb/ 238 U ages and uncertainties are at a 2σ level (Supplementary Table 3; Supplementary Metadata 2). Laser spots for Lu-Hf analy- sis were 33 μm in diameter and were set immediately beside the U-Pb spots within the same zone as deter- mined petrographically by CL images. ɛ Hf (t) values were calculated with the decay constant of 1.867 × 10 −11 (average of Scherer et al . 2001; Söderlund et al . 2004) and CHUR values (chondritic uniform reservoir) of 176 Lu/ 177 Hf = 0.0336 and 176 Hf/ 177 Hf = 0.282785 (Söderlund et al . 2004; Bouvier et al . 2008). All data were adjusted relative to the JMC475 ratio of 176 Hf/ 177 Hf = 0.282160, and quoted uncertainties are quadratic additions of the within run precision of each analysis and the reproducibility of the JMC475 (2SD = 0.0029%, n = 8). Accuracy and daily reproduci- bility of the method were verified by repeated analyses of reference zircon GJ-1 and Temora (Supplementary Table 4; Supplementary Metadata 3), which yielded a 176 Hf/ 177 Hf of 0.282010 ± 0.000022 (2SD, n = 28) and 0.282680 ± 0.000037 (n = 28), respectively. 4.3. Garnet U-Pb geochronology Garnet from sample 117,350 was dated using U-Pb geo- chronology and following a similar methodology to that used in zircon. One of the largest garnet crystals in this sample ( c . 1 cm in diameter) was selected for this pur- pose. Sample was screened and analysed in situ from polished section using a RESOLution S-155 (Resonetics) 193 nm ArF Excimer laser (CompexPro 102, Coherent) equipped with a two-volume ablation cell (Laurin Technic, Australia) coupled to a sector field ICP-MS (ElementXr, ThermoScientific) at Goethe University, Frankfurt. Specific details for garnet analysis about sam- ple preparation, laser ablation system, ICP-MS instru- ment and data processing are given in Supplementary Table 5 and Supplementary Metadata 4. Points of the sample data set derived from a small area (<1 cm 2 ) and defining linear arrays in the 207 Pb/ 206 Pb vs 238 U/ 206 Pb 8 R. ARENAS ET AL. &KDSWHU