# Late Ediacaran juvenile magmatism in the Variscan Monts-du-Lyonnais metamorphic complex (Massif Central, France)

Simon Couzinié, Oscar Laurent, Pierre Bouilhol, Cyril Chelle-Michou, Anne-Céline Ganzhorn, Véronique Gardien, Jean-François Moyen

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Simon Couzinié, Oscar Laurent, Pierre Bouilhol, Cyril Chelle-Michou, Anne-Céline Ganzhorn, et al. Late Ediacaran juvenile magmatism in the Variscan Monts-du-Lyonnais metamorphic complex (Massif Central, France). Bulletin de la Société Géologique de France, In press, 10.1051/bsgf/2024023. hal-04822267

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1 Late Ediacaran juvenile magmatism in the Variscan Monts-du-Lyonnais

2 metamorphic complex (Massif Central, France)

3 Identification d'un magmatisme juvénile fini-édiacarien dans le complexe

4 métamorphique varisque des Monts-du-Lyonnais (Massif Central, France)

5 Simon Couzinié¹,²,³*, Oscar Laurent⁴, Pierre Bouilhol¹, Cyril Chelle-Michou⁵, Anne-

6 Céline Ganzhorn³**, Véronique Gardien³, Jean-François Moyen⁶

7 ¹Université de Lorraine, CNRS, CRPG, 54000 Nancy, France

8 ²Université Jean Monnet, CNRS, LGL-TPE UMR5276, F-42023 Saint-Etienne, France

9 ³LGL-TPE UMR 5276, CNRS, Université Lyon 1, ENS de Lyon, 69622 Villeurbanne, France

10 ⁴CNRS, Géosciences Environnement Toulouse, Observatoire Midi-Pyrénées, 14 avenue Edouard

11 Belin, 31400 Toulouse, France

12 ⁵Institute of Geochemistry and Petrology, ETH Zürich, CH-8092 Zürich, Switzerland

13 ⁶Université Jean-Monnet, Laboratoire Magmas et Volcans, UCA-CNRS-IRD, Aubière, France

14 *Corresponding author. simon.couzinie@univ-lorraine.fr

15 **Present address: Saint-Gobain Recherche, Aubervilliers, France

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20 **Keywords:** Northern Gondwana margin, Cadomian orogeny, Variscan orogeny,

21 French Massif Central, zircon U-Pb-Hf isotopes

22 **Mots clés:** marge nord-gondwanienne, orogenèse cadomienne, orogenèse varisque,

23 Massif Central français, isotopie U-Pb-Hf sur zircon
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**Abstract**

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49 Résumé

50 Localiser les sutures océaniques est essentiel pour comprendre l'évolution de la
51 chaîne varisque et la structure de la lithosphère de l'Europe occidentale. Dans le
52 Massif Central français, la suture d'un océan "Médio-varisque" serait marquée par des
53 formations particulières connues sous le nom de "complexes leptyno-amphiboliques"
54 (CLA). Ceux-ci incluent une diversité de roches méta-ignées datées du Cambrien-
55 Ordovicien et interprétées comme les témoins d'un magmatisme associé au rifting. Ils
56 préservent également des reliques d'un métamorphisme de haute pression au
57 Dévonien (385-360 Ma). Notre étude fournit de nouvelles données géochronologiques
58 et géochimiques sur les roches mafiques et felsiques de la « bande de Riverie », un
59 des trois complexes leptyno-amphiboliques des Monts-du-Lyonnais. Les roches
60 felsiques sont des gneiss amphiboliques métalumineux qui correspondent à
61 d'anciennes tonalites intimement associées à des roches mafiques (représentées
62 aujourd'hui par des amphibolites). La datation U-Pb par LA-ICP-MS de grains de
63 zircon magmatique a révélé un âge de cristallisation tardi-édiacarien (autour de 545
64 Ma) pour les (meta)tonalites. La géochimie des roches totales (notamment les
65 anomalies négatives en Nb) et les compositions isotopiques en hafnium très
66 radiogéniques mesurées sur les grains de zircon (avec des εHf(545Ma) d'environ +11)
67 indiquent que les magmas parents des tonalites se sont formés par différentiation d'un
68 liquide issu de la fusion d'un manteau métasomatisé par des fluides dérivés d'une
69 lithosphère océanique. Les amphibolites spatialement associées aux (méta)tonalites
70 présentent elles-aussi une signature de type "arc" et leurs protolithes ont pu être
71 générées à partir de la même source mantellique. L'association bimodale de la
72 « bande de Riverie » n'est pas liée au rifting ayant conduit à l'ouverture de l'océan
73 Médio-varisque et ne peut representer sa suture. Elle doit être corrélée à un
74 événement magmatique juvénile identifié dans tout le domaine varisque et relié à la
dynamique d'arc/arrière-arc de l'orogenèse cadomienne.
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1. Introduction
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Within the framework of plate tectonics theory, sutures, i.e. zones along which oceanic lithospheres were subducted, are key to deciphering the evolution of orogens (Dewey, 1987). Their identification remains challenging in the case of old and deeply eroded collisional orogenic systems such as the European Variscan belt, formed through the convergence of Laurussia and Gondwana during the late Paleozoic (Edel et al., 2018; Matte, 1986; Stampfli et al., 2013). Indeed, the diagnostic suture rock associations (high-pressure metamorphic belts and ophiolite sequences) have been largely dismantled by early erosion and intensely reworked by collisional processes, leading to conflicting views on the number of suture zones and their associated oceans (see discussions in Franke et al., 2017; Kroner and Romer, 2013)). Paleomagnetic data and paleobiogeography (Domeier, 2016; Paris and Robardet, 1990; Van der Voo et al., 1980) suggest that the formation of the Variscan belt followed the closure of a single >1000 km-wide Ordovician oceanic domain called the Rheic Ocean. On the other hand, petrological evidence coupled with geophysical data collectively indicate the existence of at least three sutures (Fig. 1a, Schulmann et al., 2022). The subduction of an Ordovician-early Devonian "Mid-Variscan" ocean (Galicia/Southern Brittany/Tepla ocean of Matte, 1986) would have initiated in the mid- to late-Devonian period (390–360 Ma). The narrower Saxothuringian ocean would have closed shortly after in the early Carboniferous (360–340 Ma). Lastly, subduction of the Devonian Lizard–Rhenohercynian Ocean would have occurred at 340–330 Ma (Zeh and Gerdes, 2010).
Delineating the suture zones along the belt is of marked importance to unravel the architecture of the European continental crust and the evolution of the Variscan orogeny. However, accurately correlating their locations and geometries in the eastern French Massif Central (eFMC, Fig. 1a) has proven challenging due to a lack of comprehensive seismic survey and the absence of ophiolite sequences (Schulmann et al., 2022). In the eFMC, it is commonly inferred (Lardeaux et al., 2014; Matte, 1986; Pin, 1990; Vanderhaeghe et al., 2020) that the Mid-Variscan suture is stamped by distinctive heterogeneous lithological formations referred to as “Leptynite–Amphibolite Complexes” (LACs, see review in Santallier et al., 1988). The latter encompass mafic meta-igneous rocks occurring as metric to kilometric boudins embedded in paragneisses and/or are intimately associated with metarhyolites/metagranites of crustal derivation (Briand et al., 1995, 1991; Chelle-Michou et al., 2017; Pin and Marini, 1993). The metabasites often bear relics of Devonian (385–360 Ma) high-pressure metamorphism defining a P–T gradient consistent with subduction (Lardeaux, 2023). Ultramafic bodies representing subducted mantle material are also present (Gardien et al., 1990). Early geochronological studies suggested that both mafic and felsic igneous protoliths were emplaced contemporaneously during the Cambrian–Ordovician period (Pin and Lancelot, 1982). This has led many authors to interpret the wide variety of geochemical signatures displayed by mafic rocks, ranging from MORB-type tholeiites to back-arc basalts and OIB (Briand et al., 1995, 1991; Downes et al., 1989; Giraud et al., 1984; Piboule and Briand, 1985; Pin and Marini, 1993) as reflecting an emplacement in an attenuated continental lithosphere at the incipient stages of oceanization (Lardeaux et al., 2014 and references therein). In this context, the LACs were proposed to represent fragments of the passive margin to ocean–continent transition zone of the Mid-Variscan ocean, which were subsequently buried through
oceanic subduction and later exhumed as tectonic mélanges along major thrust zones
in the orogenic wedge (Burg and Matte, 1978; Lardeaux et al., 2014, 2001), or possibly
extruded through the upper plate (de Hoÿm de Marien et al., 2023; Keppie et al., 2010;
Maierová et al., 2021).

Following the recognition of the main nappe architecture in the eFMC during the mid-
1980s, the various LACs were grouped into a single litho-tectonic unit referred to as
"the LAC" (singular) and were assumed to share the same geodynamic significance
(Bouchez and Jover, 1986; Lardeaux et al., 2014; Matte, 1986; Vanderhaeghe et al.,
2020). This broad correlation was questioned by Santallier et al. (1988), who pointed
out the lack of age data on the protoliths and the uncertainty on the respective
petrogenesis of individual LACs. This concern is echoed in the adjacent Maures
Massif, where three LACs were initially identified, yet only two are currently regarded
as delineating a suture zone (Bellot et al., 2010; Briand et al., 2002; Jouffray et al.,
2023; Schneider et al., 2014). Therefore, a reexamination of individual (ultra)mafic-
felsic rock associations across the eFMC appears necessary to ascertain whether
each LAC record the same geodynamic events and collectively represent a single litho-
tectonic unit. In this context, the increasing versatility of in-situ laser ablation-
inductively coupled plasma-mass spectrometry (LA-ICP-MS) zircon U-Pb dating
offers new opportunities to unravel the protolith ages of the LAC rocks and clarify their
origin (Chelle-Michou et al., 2017; de Hoÿm de Marien et al., 2023; Lotout et al., 2020;
Paquette et al., 2017).

This contribution focuses on the Riverie LAC from the Monts-du-Lyonnais
metamorphic complex in the eFMC. Novel petrological and geochronological data
demonstrate that this mafic-felsic association consists of juvenile arc/back-arc-derived
magmatic rocks of late Ediacaran age which are unrelated to the opening and closure
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of the Mid-Variscan ocean. These findings highlight the necessity for a reevaluation of
the tectonic history of individual LACs within the eFMC.

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## 2. Geological setting

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### 2.1 The eastern French Massif Central

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The eFMC is part of the internal zone of the Variscan belt (Fig. 1), primarily composed of metamorphic nappes intruded by various Carboniferous granitoids (see review in Faure et al., 2009). In the northern part of the eFMC, metamorphic rocks are overlain by Visean sediments and volcanics indicating that the main orogenic phase occurred before 345 Ma. In contrast, compression persisted till the Namurian (corresponding to the Serpukhovian and Bashkirian pro parte, c. 325 Ma) in the foreland basin to the south. Upper Carboniferous (Stephanian, i.e. Kasimovian–Gzhelian pro parte) to Permian sediments were unconformably deposited over the metamorphic-plutonic basement in a late to post-orogenic setting. The nappe pile consists of the high-grade “Upper Gneiss Unit” overlying a crustal package of parautochtonous terrains, sometimes divided into the Lower Gneiss Unit and the (lower-grade) Parautochtonous Unit (Ledru et al., 1989). Southwards-directed thrusting of the Upper Gneiss Unit was coeval to the development of an inverted Barrovian metamorphic sequence (Burg et al., 1984) at 360–345 Ma (Chelle-Michou et al., 2017; Costa, 1989). The LACs are commonly located at the base of the Upper Gneiss Unit and mark the contact between this unit and the underlying parautochtonous terrains. Within most LACs, mafic meta-igneous rocks preserve a record of high-pressure subduction-related metamorphism with pressures exceeding 15 kbar at 385–360 Ma (de Hoÿm de Marien et al., 2023; Joanny et al., 1991; Lardeaux et al., 2001; Lotout et al., 2020, 2018). The
173 parautochtonous terrains were locally affected by a low-pressure high-temperature
174 Buchan-type metamorphic event coeval with crust extension and the formation of the
175 Velay and Montagne Noire gneiss domes (Gardien et al., 2022, 1997; Ledru et al.,
176 2001). The latter hosts mafic eclogites whose origin is disputed: they could either
177 correspond to Upper Gneiss Unit material (and thus be subduction-related, Pitra et al.,
178 2022) or lower crustal rocks exhumed during doming (Whitney et al., 2020). Lastly, the
179 Brévenne unit is a bimodal volcanic sequence of late Devonian age metamorphosed
180 under greenschist- to lower amphibolite-facies conditions and juxtaposed to the Upper
181 Gneiss Unit during the main collisional phase (Feybesse et al., 1995).

182 The protoliths of the Upper Gneiss Unit and parautochtonous terrains consist of
183 Ediacaran to Ordovician detrital (volcano-)sedimentary units, intruded by several
184 generations of plutonic rocks (Couzinié et al., 2022, 2019). No rock older than
185 Neoproterozoic has been described so far. Pre-Variscan magmatic rocks include: (i)
186 latest Ediacaran (c. 545 Ma) and Cambro-Ordovician granites and rhyodacites of
187 crustal origin, found throughout the nappe pile regardless the metamorphic grade
188 (Chelle-Michou et al., 2017; Couzinié et al., 2022, 2017; Couzinié and Laurent, 2021);
189 (ii) mafic (gabbroic and basaltic) rocks, mainly in the LACs of the Upper Gneiss Unit
190 but also in the parautochtonous terrains as lava flows, pyroclastic deposits, and
191 subvolcanic sills (Briand et al., 1995, 1992). Mafic rocks exhibit a large range of
192 geochemical signatures ranging from tholeiitic to alkaline and calc-alkaline (Briand et
193 al., 1992; Pouclet et al., 2017). The crust-derived magmas attest to the reworking of
194 Ediacaran sediments (Couzinié et al., 2022, 2017), while mafic magmas would
195 originate from the lithospheric and asthenospheric mantle, with the subordinate
196 involvement of a garnet-bearing source (Pin and Marini, 1993; Pouclet et al., 2017).
197 The latest Ediacaran crustal melting was possibly a distal manifestation of the
198 Cadomian orogenic events (Couzinié et al., 2017), while Cambro-Ordovician crust-
mantle magmatism should be tied to protracted lithosphere extension that prevailed at
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200 that time along the northern Gondwana margin (Chelle-Michou et al., 2017; Couzinié
201 et al., 2022; Pin, 1990; Pin and Marini, 1993).

202 2.2 The Monts-du-Lyonnais metamorphic complex

203 The Monts-du-Lyonnais metamorphic complex (Fig. 2) belongs to the Upper Gneiss
204 Unit. Its litho-tectonic pile consists of a set of amphibolite-(granulite-)facies
205 metamorphic rocks including from bottom to top (Feybesse et al., 1995): (i) a lower
206 metasedimentary unit corresponding to cordierite-bearing migmatites and garnet-
207 sillimanite-biotite paragneisses in the northwestern and southeastern part of the
208 complex, respectively, (ii) three (ultra)mafic-felsic rock associations cartographically
209 corresponding to "belts" and assimilated to LACs by Chantraine et al. (2003); (iii) mildly
210 peraluminous, locally anatectic orthogneisses; (iv) an upper metasedimentary unit,
211 also migmatitic, with relics of high-pressure granulite-facies metamorphism. The first,
212 southernmost (ultra)mafic-felsic belt includes 100-3000 m-long amphibolite boudins
213 corresponding to retrogressed eclogites stretched within a paragneiss matrix and
214 associated with garnet-bearing mantle peridotites (Blanc, 1981; Gardien et al., 1990).

215 The second, northernmost Chaussan belt is composed of fine-grained leucogneisses
216 (leptynites) enclosing numerous hecto- to kilometric massifs of meta-igneous mafic
217 and felsic granulites (Dufour, 1985). Finally, the Riverie belt located in-between the
218 previous two features an association of amphibolites and amphibole-bearing gneisses,
219 locally leucocratic (leptynites) (Blanc, 1981).

220 Metasediments experienced peak metamorphic conditions of 750-800°C at 7-9 kbar
221 coeval to the development of the regional foliation S₁₋₂ (Feybesse et al., 1995; Gardien
222 et al., 1990). Anatexis initiated at that stage and persisted during exhumation down to
c. 4 kbar. The age of this anatexis is poorly constrained, as the only published data consist of a whole-rock Rb-Sr isochron date of 384 ± 16 Ma, interpreted as the age of partial melting (Duthou et al., 1994). Relictual kyanite in metasediments suggests an early high-pressure evolution at P>10 kbar (Feybesse et al., 1995). Rocks from the LACs record different metamorphic conditions. Eclogites from the southern belt experienced peak conditions of P>15 kbar and 750-850°C (Dufour et al., 1985; Joanny et al., 1991). One coesite grain retrieved from an eclogite sample would even suggest P>28 kbar (Lardeaux et al., 2001). Meta-igneous granulites from the Chaussan belt record P of 8-10 kbar and T in the range 800-870°C (Dufour, 1985). Metamorphic conditions for the Riverie belt have not been estimated but Feybesse et al. (1995) stressed that these rocks lack any evidence of a high-pressure evolution.

A late event of ductile deformation thought to have occurred at around 500°C (Feybesse et al., 1995; Gardien et al., 1990) juxtaposed the Monts-du-Lyonnais metamorphic complex to the adjacent lower-grade Brévenne Unit (Fig. 2). The last increment of this tectonic phase was marked by the activation of NE-SW trending strike-slip shear zones and the intrusion of several synkinematic granitoids (Feybesse et al., 1995) at 345-335 Ma (Ar-Ar dating on micas and amphibole, Costa et al., 1993). Notably, the Riverie LAC is bounded by such shear zones to the other constituents of the metamorphic complex. Late brittle deformation reworked the original thrust contact between the Monts-du-Lyonnais metamorphic complex and the underlying Pilat unit (representing the parautochtonous terrains).

Little is known about the age of the Monts-du-Lyonnais metamorphic complex protoliths. There are no chronological constraints available on the depositional age of the detrital metasediments. The age of the orthogneiss protolith is estimated to be around 470 Ma (based on zircon Pb evaporation and whole-rock Rb-Sr ages, Dufour,
248 1982; Feybesse et al., 1995), although Duthou et al. (1984) report a significantly older
249 whole-rock Rb-Sr isochron date of 502 ± 7 Ma. An identical date of 497 ± 8 Ma was
250 obtained for felsic granulites and interpreted as the emplacement age of their igneous
251 protolith (Duthou et al., 1981). Mafic meta-igneous rocks display a variety of
252 geochemical types, ranging from N-MORB to LREE-rich tholeiites and even
253 transitional rocks with alkaline affinities (Briand et al., 1995). They have never been
254 dated, and a Cambro-Ordovician emplacement age has been postulated by analogy
255 with other bimodal meta-igneous associations from the eFMC, notably in the nearby
256 Vivarais area (Chelle-Michou et al., 2017).

257 In the Riverie belt, felsic rocks described as "amphibole-bearing (felsic) gneisses" and
258 closely associated with amphibolites were first reported by Peterlongo (1958) and later
259 studied by Blanc (1981). The relationships between amphibole-bearing felsic gneisses
260 and amphibolites (the constituent rocks of the belt) are well-exposed in the disused
261 "Les Roches" quarry near Riverie (Fig. 2). Amphibole-bearing felsic gneisses known in
262 other eFMC LACs have been variously regarded as former pyroclastic/epiclastic rocks
263 coeval to the amphibolite protoliths (Pin and Lancelot, 1982), metadiorites (Bodinier et
264 al., 1986) or anatectic magmas formed by partial melting of the amphibolites at
265 Variscan times (Benmammar et al., 2020).

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267 3. Analytical methods

268 Eight samples of amphibole-bearing felsic gneisses and four samples of amphibolites
269 collected from the pit#2 of the "Les Roches" quarry (GPS coordinates: 45.5964N,
270 4.5879E) were analyzed for major and trace element compositions by the ALS Global
271 firm (details on the procedures, detection limits and accuracy/reproducibility in
Supplementary text, full dataset available as Supplementary Table S1). Recalculation and plotting of the whole-rock geochemical data were performed using the GCDkit plugin for R (Janoušek et al., 2006). Mineral major element compositions were obtained using a Zeiss EVO MA15 Scanning Electron Microscope at the Central Analytical Facility of Stellenbosch University, South Africa. Mineral compositions were determined by EDX (Energy Dispersive X-ray) analysis using an Oxford Instruments® X-Max 20 mm2 detector and the Oxford INCA software. Beam conditions were 20 kV accelerating voltage, 1.5 nA probe current, a working distance of 8.5 mm and a specimen beam current of 20 nA. Analyses were quantified using natural mineral standards and representative mineral compositions are reported in the Supplementary Table S2. Biotite and amphibole structural formulas (including ferric iron contents) were calculated using the spreadsheets of Li et al., (2020a, 2020b). Two samples of amphibole-bearing felsic gneisses (RV-1 and RV-2) were selected for zircon U-Pb-Hf determinations to constrain the emplacement age and isotopic signature of their protoliths. Zircon grains were separated from the crushed rock samples at Saint-Etienne University using conventional techniques (sieving, panning, magnetic and heavy liquids separation followed by handpicking). Selected grains were subsequently cast into epoxy mounts and polished down to a subequatorial grain section. BSE and CL-imaging were performed at the Central Analytical Facility of Stellenbosch University using a Zeiss MERLIN Scanning Electron Microscope. In situ U-Pb dating and zircon Lu-Hf isotope measurements were carried out by LA-ICP-MS at the J.W. Goethe University, Frankfurt-am-Main (Germany). Plotting and calculation of Concordia dates were performed using IsoplotR (Vermeesch, 2018). Information on the analytical methods is presented in the Supplementary Text. The full datasets (standards and samples) are reported in Supplementary Tables S3 to S6.
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## 4. Sample petrography and geochemistry

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The Riverie belt occurs as a tectonic boudin bounded by dextral shear zones and syn-kinematic (mylonitic) granites (Fig. 2a). In the largest pit (#2) of the disused Les Roches quarry (Fig. 2b), felsic gneisses exhibiting a vertical foliation and wrapping around 1 to 3 m-wide amphibolite bodies (Fig. 3a,b) constitute the main petrographic type. Amphibolites are particularly abundant in the SE part of the pit. Both mafic and felsic rocks are cut across by a network of decimeter-scale discordant or concordant granitic and pegmatitic veins.

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The felsic gneisses are primarily composed of plagioclase, quartz, green amphibole with low amounts of brown biotite either in the matrix or rimming amphibole (Fig. 3c,d,e). The foliation is underlined by alternating layers with varying proportions of mafic minerals (Fig. 3c). The felsic rocks show a high-temperature texture with interlobate grain contacts and preservation of high-energy surfaces (Fig. 3d), with amphibole often being interstitial. Inclusions of plagioclase in amphibole and vice versa are locally observed (Fig. 3e). Amphibole is a magnesio-ferri-hornblende with mg# of 0.63 and Fe³⁺/Fetot ratios in the range 0.29–0.37, slightly higher than the value (0.27) estimated through wet chemistry by Blanc (1981). Biotite is also magnesian, with mg# of 0.65–0.72, and TiO₂-rich (>3 wt.%). Plagioclase is chemically unzoned and has an oligoclase composition (An₂₄-2₆). Accessory minerals are magnetite, apatite, zircon, and sulphides (Fig. 3c,d,e). The edenite-richterite thermometer of Holland and Blundy (1994) and the barometer of Molina et al. (2015) for paired plagioclase–amphibole compositions yielded equilibration temperatures of c. 700 °C for upper to mid-crustal pressures of 2–4 kbar.

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The amphibole-bearing felsic gneisses do not deviate from the igneous trend in the FMW plot of Ohta and Arai (2007) which points to an igneous and not volcanosedimentary origin for their protoliths (Fig. 4a). They show SiO₂ contents ranging from 61 to 69 wt.%, reflecting the varying mineral modes at the scale of the quarry (50 m). They are metaluminous to subaluminous with A/CNK (molar Al₂O₃/[CaO + Na₂O + K₂O]) below 1.05, and markedly poor in K₂O (≤1 wt.% and mostly below 0.7 wt.%, Table S1). Accordingly, they plot in the field of tonalites in the P–Q diagram of Debon and Le Fort (1983) (Fig. 4b). All samples show similar immobile, incompatible trace elements patterns characterized by overall low concentrations. The amphibole- bearing felsic gneisses are depleted in HREE (by a factor 0.3 to 0.6) and slightly enriched in LREE–Zr (by a factor 2 to 3) and Th (10 times) with respect to N-MORBs (Fig. 4c). Of importance are the pronounced Nb and Ti negative anomalies (with Nb/Nb*: 0.2–0.3; Ti/Ti*: 0.3–0.6), along with a weakly positive Zr anomaly (Zr/Zr*: 1.2–2.1). Th/Nb ratios are high, clustering around 0.6–0.7 (Fig. 4e). The concentrations of LILE such as Ba (100–400 ppm), Sr (200–300 ppm) and Rb (8–20 ppm) are lower than those of the Bulk Continental Crust (Rudnick and Gao, 2003). Chondrite-normalized REE patterns (Boynton, 1984) are moderately fractionated (La/N/Yb_N = 2.9–7.1) and show a slight depletion in mid-HREE (Dy to Tm, Fig. 4d). A weak Eu negative anomaly is observed (Eu/Eu* = 0.71–0.95). Vanadium contents are low (78–151 ppm) with V/Ti ratios close to 20 (Fig. 4f). Most trace element compositions (except Zr) show a rough decrease with the SiO₂ content.

The mafic rocks have a nematoblastic texture and are dominantly composed of an equigranular assemblage of euhedral to subhedral amphibole and plagioclase (Fig. 4f) with apatite and titanite as the main accessory minerals. These amphibolites show mildly alkaline basic compositions (SiO₂: 46.6–51.9 wt.%; Na₂O+K₂O: 4.2–5.1 wt.%),
346 Fig. 4b). Three samples show primitive compositions (i.e. close to that of primary
347 mantle-derived melts) as indicated by their elevated Mg# (62–63), MgO (7.5–9.0 wt.%)
348 and Cr (270–320 ppm) contents and the lack of Eu anomaly. They are slightly enriched
349 in Th and LREE with respect to N-MORBs, and three samples display a pronounced
350 negative Nb anomaly (with Th/Nb>0.2, Fig. 4c,e). REE patterns are nearly flat (La/N/Yb_N
351 = 1.5–2.0, Fig. 4d). Vanadium contents are moderately elevated (227–362 ppm) with
352 V/Ti ratios between 25 and 40 (Fig. 4f).

353 Several observations suggest that the igneous protolith of the amphibole-bearing felsic
354 gneisses was plutonic and coeval to or younger than that of the amphibolites: (i) the
355 contacts between the two rock types are often intricate, with preserved evidence for
356 intrusive relationships of the former in the latter (see white triangles, Fig. 3a); (ii) pluri-
357 centimetric amphibole-rich clusters in the felsic rocks resemble assimilated mafic
358 material (black triangle, Fig. 3a); (iii) the foliation of the gneisses fades in strain
359 shadows at the edges of the mafic bodies so that the felsic rock appears isotropic
360 (white triangle, Fig. 3b).

361

362 **5. Zircon data**

363 5.1 Zircon textures

364 Zircon grains extracted from amphibole-bearing felsic gneisses are euhedral to
365 subhedral, ranging in length between 70 and 200 µm, and often show width-to-length
366 ratios higher than 1:2 with well-developed pyramidal tips (Fig. 5a). A few grains are
367 stubbier with lower aspect ratios down to 1:1. CL-images reveal concentric oscillatory
368 zoning, locally associated with sector zoning (see for instance zircon 1 of sample RV-
369 2, Fig. 5a). The zoning pattern may differ from the inner to outer part of few grains, due
to varying relative growth rate of crystal faces upon crystallization (white triangles on Fig. 5a). However, there is no marked textural break such as a change in CL intensity or clear evidence for resorption. Only very thin (<10 µm-large) CL-bright overgrowths truncate the zoning pattern of some grains. Local recrystallization is also evidenced (black triangles on Fig. 5a).

### 5.2 U-Pb results

In gneiss sample RV-1, 40 measurements were performed on 32 grains, all within zones displaying clear oscillatory zoning (Fig. 5a). Seven spots showed moderate common Pb contents (up to 3%) and were markedly discordant. These spots will not be discussed further. A total of 16 concordant spots are statistically equivalent, and a Concordia date of 545.9 ± 1.9 Ma (± 6.4 Ma after propagation of systematic uncertainties) can be calculated from them (MSWD of concordance and equivalence = 1.6). Besides, 6 analyses yielded similar $^{206}\text{Pb}/^{238}\text{U}$ dates but were discordant, presumably owing to small amounts of common Pb. Eleven analyses showed younger, slightly discordant to concordant $^{206}\text{Pb}/^{238}\text{U}$ dates ranging between 536 ± 10 and 509 ± 9 Ma.

In gneiss sample RV-2, 33 analyses were performed on 25 grains. A Concordia date of 543.9 ± 1.5 Ma (± 6.3 after propagation of systematic uncertainties) can be calculated from 19 statistically equivalent concordant analyses (with a MSWD of concordance and equivalence equal to 1.4, Fig. 5b). Spot a58 yielded an identical yet discordant $^{206}\text{Pb}/^{238}\text{U}$ date owing to the presence of common Pb. Nine measurements devoid of common Pb yielded concordant to moderately discordant $^{206}\text{Pb}/^{238}\text{U}$ dates ranging from 536 ± 6 down to 520 ± 6 Ma. Two analyses (a50 and a60) characterized by minor common Pb contents (0.3-0.8%) showed discordant and younger $^{206}\text{Pb}/^{238}\text{U}$ dates of 484 ± 5 and 438 ± 7 Ma respectively. Two measurements performed on a
single zircon grain yielded a concordant $^{206}$Pb/$^{238}$U date of 361 ± 4 Ma and a discordant $^{206}$Pb/$^{238}$U date of 354 ± 4 Ma (estimated common Pb content: 0.4%). Both also featured markedly lower Th/U ratios (0.02 and 0.04, respectively) than grains yielding $^{206}$Pb/$^{238}$U dates of c. 545 Ma (always >0.15).

5.3 Lu-Hf isotopes

Twenty-eight measurements were performed on grain domains analogous to those that previously yielded concordant $^{206}$Pb/$^{238}$U dates (at ca. 545 Ma) and three on undated grains texturally identical to the main zircon population. Initial Hf isotope compositions were calculated using the intrusion age determined for each sample. The $^{176}$Hf/$^{177}$Hf(t) ratios of RV-1 zircons were all identical within uncertainty, ranging from 0.282709 ± 42 to 0.282752 ± 35 (at 2s), corresponding to εHf(t) of +9.5 to +11.0 with an average value of +10.5 ± 0.9 (2 S.D. – standard deviation; n = 14; Fig. 6). Zircons from sample RV-2 showed a similar range of $^{176}$Hf/$^{177}$Hf(t) ratios, from 0.282717 ± 33 to 0.282787 ± 44 (2 S.E.) corresponding to εHf(t) of +9.7 to +12.2 and yielding an identical average εHf(t) at 10.6 ± 1.2 (2 S.D.; n = 18).

410

6. Discussion

6.1 Interpretation of U-Pb data

Field relationships, petrographic, and geochemical data indicate that the amphibole-
bearing felsic gneisses represent former tonalites (see section 4). Zircon grains show
euhedral shapes and oscillatory zoning, as typically observed in zircon grown from
melts (Corfu et al., 2003). Hence, the Concordia dates of 545.9 ± 1.9 (6.4) and 543.9
± 1.5 (6.3) Ma are interpreted as late Ediacaran crystallization ages of the
(meta)tonalites RV-1 and RV-2, respectively. The other, discordant, zircon U-Pb data
419 for both samples can be explained by a combination of initial Pb incorporation and/or
420 Pb loss from zircons that originally belonged to the dominant population of concordant,
421 c. 545 Ma-old grains. This interpretation is consistent with the fact that all zircons show
422 identical ¹⁷⁶Hf/¹⁷⁷Hf ratios within uncertainties regardless the apparent ²⁰⁶Pb/²³⁸U date,
423 as disturbance of the U–Pb system does not affect Hf isotopes (Gerdes and Zeh,
424 2009).

425 Analyses a65 and a66 were both performed close to the rims of the same zircon grain
426 and showed younger ²³⁸U/²⁰⁶Pb dates of c. 360 Ma, concordant for a65. CL images do
427 not provide clear evidence for the existence of textural discontinuities associated with
428 new zircon growth or extensive zircon recrystallization. Yet, both analyses show very
429 low Th/U ratios, different from the main c. 545 Ma population. This suggests that upon
430 laser ablation both analyses may have (partly or wholly) sampled narrow CL-bright
431 overgrowths or recrystallized domains visible on a few grains (Fig. 5a). Therefore, it is
432 unclear whether the c. 360 Ma dates correspond to the age of a Variscan metamorphic
433 overprint, which would be in agreement with what is observed in the Upper Gneiss Unit
434 of the eFMC (Chelle-Michou et al., 2017), or represent geologically meaningless,
435 mixed ages.

## 6.2 Typology of the mafic-felsic association

436 At the scale of the quarry outcrop (approximately 50 m), the (meta)tonalites exhibit a
437 range of major element compositions yet very similar mineral assemblages. Since they
438 derive from a plutonic protolith, these characteristics may reflect different proportions
439 between igneous minerals, resulting from variable extents of crystal accumulation
440 versus crystal/melt separation during solidification of a mush at the emplacement site
441 (e.g. Barnes et al., 2016; Cornet et al., 2022; Laurent et al., 2020; Lee and Morton,
442 2015). By considering a crystallizing low-K dacitic melt with a chemical composition
443
similar to the average of the (meta)tonalites, the samples can be modeled as a
combination of (Fig. 7): (i) residual melts resulting from the separation of 5–20 wt.%
plagioclase An₂₅ + hornblende ± magnetite from the initial melt (for samples LY25, RV-
1, RV-2); (ii) cumulates, corresponding to the initial melt plus 5–25 wt.% accumulated
plagioclase An₂₅ ± hornblende ± magnetite (for samples LY23, -24, 26, -27, -28). Trace
element data are consistent with this interpretation given the relatively gradual
decrease in most trace elements with SiO₂ contents.

In general, low-K dacitic melts are known to derive from mantle melting followed by
fractionation of a primary H₂O-rich basaltic melt or from dehydration melting of
amphibolites (Beard, 1995; Stern et al., 1996). Zircon Hf isotope data indicate that the
dacitic melt from which the Riverie felsic rocks originated had a composition
overlapping with that of the Depleted Mantle (DM) reservoir at c. 545 Ma, ruling out an
origin by melting of an old mafic (amphibolitic) crust (Fig. 6). Therefore, we favor the
formation of the dacitic melt through crystal fractionation from a primary mantle-derived
melt, consistent with its weak depletion in mid-HREE (Dy to Tm) and the Eu negative
anomaly, which are indicative of amphibole and plagioclase fractionation (Bédard,
2006; Nandedkar et al., 2016). The pronounced Nb–Ti negative anomaly (Fig. 4c) and
the radiogenic Hf isotope composition (εHf(545Ma) of c. +11) of the low-K dacitic melt
collectively indicate that its depleted mantle source had been metasomatized by fluids
derived from an oceanic slab (Fig. 4e; Pearce and Peate, 1995). The presence of
magnetite, the elevated amphibole Fe³⁺/Fetot as well as the low bulk-rock V/Ti ratios
displayed by the (meta)tonalites are consistent with a parental melt having formed
under relatively oxidizing conditions (Fig. 4f), which aligns with a metasomatized
mantle source.
The country-rocks of the tonalitic intrusion corresponded to gabbros or basalts (now amphibolites). Those have near-primary mantle melt compositions which entails that their negative Nb anomalies can be regarded as pristine and not related to crustal contamination (Fig. 4e). Therefore, the igneous protolith of the amphibolites originated from a mantle having incorporated a slab-derived component, as for the parental melt of the (meta)tonalites, meaning that both mafic and felsic rocks were possibly generated from the same metasomatized mantle source.

## 6.3 Geodynamic setting of the Riverie magmatism

As demonstrated in the previous section, the felsic rocks from the Riverie belt can be traced back to a mantle metasomatized by slab-derived fluids shortly prior to melting, namely in the Ediacaran period. At that time, the terrains currently exposed in the eFMC were situated along the northern Gondwana margin, which was significantly influenced by the Avalonian–Cadomian accretionary orogeny (Andonaegui et al., 2016; Collett et al., 2020; Garfunkel, 2015; Linnemann et al., 2014, 2008; Soejono et al., 2017). Therefore, it is likely that the Riverie magmatism tapped into a mantle imprinted by Cadomian subduction. In fact, the Riverie rocks share isotopic similarities with the late Cryogenian–early Ediacaran juvenile arc rocks of the Cadomian type-area in northern France (Samson et al., 2003; Fig. 6).

According to full-plate tectonic models, the southwards subduction of the lapetus/Mirovoi oceans was still ongoing at the late Ediacaran/early Cambrian transition (Fig. 8a, Merdith et al., 2021). Consistently, evidence for the existence of 0.55 Ga juvenile arcs along the northern Gondwana margin is provided by the detrital zircon record of the parautochtonous terrains in the eFMC (Couzinié et al., 2019), the Corsica basement (Avigad et al., 2018), the Upper Allochton of the Iberian Massif
493 (Albert et al., 2015), and the Polish Góry Sowie Massif (Tabaud et al., 2021).

494 Additionally, in the Ossa-Morena Zone of the Iberian Massif, juvenile arc-derived
495 magmatism is represented by andesites-dacites interbedded within the late
496 Ediacaran/early Cambrian Malcocinado/San Jerónimo formations and diorites-
497 tonalites from the c. 555 Ma-old Mérida-Montoro igneous complex (Bandres et al.,
498 2002; Pin et al., 2002). Both suites exhibit positive εNd(t) values along with trace
499 element characteristics that resemble the Riverie (meta)tonalites.

500 In the Maures massif, the Bormes orthogneiss was recently regarded as a remnant of
501 an Ediacaran (590-556 Ma) arc by Tabaud et al. (2023). However, the presence in
502 their samples of 505-460 Ma-old zircon rims together with the major and trace element
503 signature of the peraluminous high-K host rocks rather suggest that they represent
504 Cambrian-Ordovician crust-derived granitoids related to the rifting event that led to the
505 opening of the Variscan oceans (e.g. Couzinié et al., 2022). Arc magmatism in the
506 Maures massif is more likely represented by the Arcs-Gassin *leptynites*, which have
507 εNd(t) values ranging from +1 to +2 and yielded a protolith emplacement age of 548
508 +15/-7 Ma (U-Pb on zircon; Innocent et al., 2003). As this age was obtained by isotope-
509 dilution thermal ionization mass spectrometry on multi-grain fractions, it deserves to
510 be confirmed using in situ techniques (Paquette et al., 2017).

511 The Riverie rocks represent modest volumes and their V/Ti systematics suggest a
512 distal position with respect to the Cadomian arc (Fig. 4f). Therefore, we infer that this
513 juvenile magmatism would have occurred within the back-arc domain of the Cadomian
514 orogen and resulted from the convective thinning of the lithospheric mantle (Fig. 8b).

**6.4 Implications for the architecture of the eFMC**

515
516
The Riverie mafic-felsic association represents the first unambiguous record of late Ediacaran magmatism in the Upper Gneiss Unit of the eFMC and is distinctly different from coeval magmatic rocks in the parautochtonous terrains (Fig. 4). In the latter, the c. 550-530 Ma period is marked by voluminous peraluminous felsic magmatism, which corresponds today to the Velay Orthogneiss Formation (Couzinié et al., 2017), the Montredon-Labessonié orthogneiss (Couzinié and Laurent, 2021), the Plaisance-Cammazes orthogneiss (Guérangé-Lozes et al., 2013) and the Rivernous and Sériès dacites-rhyolites in the Montagne Noire area (Lescuyer and Cocherie, 1992; Padel et al., 2017). Collectively, the geochemical (major/trace element and isotopic) signatures (Fig. 4) and zircon inheritance patterns exhibited by these rocks indicate significant crust reworking through the melting of Neoproterozoic sedimentary sequences (Chelle-Michou et al., 2017; Couzinié et al., 2017). The absence of evidence for late Ediacaran compressional deformation (Álvaro et al., 2014) suggests that this crustal melting event took place in an extensional environment, presumably in the back-arc of the Cadomian orogen (Couzinié and Laurent, 2021). The very contrasted typology of late Ediacaran magmatism between the Upper Gneiss Unit and the parautochtonous terrains indicates that they represent two distinct crust segments which had different paleogeographic positions within the late Ediacaran Cadomian back-arc.

The age of magmatism observed in the Riverie belt is unusual compared to other eFMC LACs. The compilation of LA-ICP-MS zircon U-Pb dates obtained from LACs' meta-igneous rocks (Fig. 9) indicates that magmatism mostly occurred between 492 and 472 Ma i.e., the Furongian-Lower Ordovician epochs (Chelle-Michou et al., 2017; de Hoÿm de Marien et al., 2023; Lotout et al., 2020, 2018; Paquette et al., 2017; Whitney et al., 2020). However, the rocks from the Riverie belt are at least 50 million years older, dating back to the late Ediacaran period. Furthermore, the meta-igneous
felsic rocks of the LACs are generally potassic and display time-integrated
unradiogenic Nd-Hf isotope compositions (εNd(t) < -3; εHf(t) < -1), which is interpreted
as reflecting an origin through melting of the local continental crust (Chelle-Michou et
al., 2017; Pin and Marini, 1993). In contrast, the felsic rocks in the Riverie belt are
sodic, have radiogenic Hf isotope compositions, and ultimately originated from a
juvenile source. The pressure and temperature of mineral equilibration estimated for
the Riverie felsic rocks are close to the tonalite solidus (Schmidt and Thompson, 1996)
at relatively low pressures (2–4 kbar), possibly reflecting the crystallization conditions
of the parental low-K dacitic melt. These rocks do not record evidence for a high-
pressure metamorphic evolution, and no eclogite has ever been recovered from the
Riverie belt (Blanc, 1981; Feybesse et al., 1995). Collectively, petrographic,
geochemical (including isotopic) and geochronological data obtained on the Riverie
belt show that the igneous protoliths of this LAC did not form during the rifting of the
northern Gondwana margin that resulted in the opening of the Mid-Variscan ocean and
were presumably not subducted during the Devonian. These results highlight that all
LACs from the Monts-du-Lyonnais, and more generally from the eFMC, are not
identical in terms of age, petrogenesis and metamorphic evolution, arguing against
their grouping as a single litho-tectonic unit.

560

## 6 Conclusion

The amphibole-bearing felsic gneisses from the Riverie LAC in the Monts-du-Lyonnais
metamorphic complex represent a former tonalitic intrusion of late Ediacaran age (c.
545 Ma). The parental melt underwent variable amounts (5–25 wt.%) of crystal
accumulation versus crystal/melt separation at the emplacement site and formed
through fractionation of a mafic melt that originated from a mantle source
metasomatized by slab-derived fluids. The (meta)tonalites are intimately associated with mafic (meta-)igneous rocks, which were likely derived from the same source. The Riverie mafic-felsic association is unrelated to the Furongian (late Cambrian)-Lower Ordovician rifting that resulted in the opening of the Mid-Variscan ocean and instead represents a newly identified remnant of Cadomian arc/back-arc magmatism along the northern Gondwana margin. Overall, our results challenge the assumption that all mafic-felsic associations (LACs) from the high-grade domains of the eFMC can be grouped together as a single litho-tectonic unit ("the" LAC). A detailed reexamination of undated LACs in the eFMC (e.g. the Artense, Sioule, Truyère, Marvejols massifs) using modern techniques is essential for clarifying the diversity of these associations and refining their correlations.

578

579 Acknowledgements

C. Guilbaud made the thin sections. G. Stevens and A. Gerdes granted access to the Stellenbosch CAF and Frankfurt LA-ICP-MS laboratory, respectively. A. Laurie, M. R. Franzenburg and L. Marko assisted during the SEM and LA-ICP-MS sessions. O. Vanderhaeghe provided a template for Fig. 1. L.-S. Doucet drew Fig. 9a. H. Bertrand introduced the quarry to SC in 2011. Thorough reviews were provided by F. Roger and an anonymous reviewer. The manuscript was handled by V. Bosse and L. Jolivet. We extend our gratitude to all of them.

This work is dedicated to the memory of J.-L. Paquette, our collaborator for a decade, for all his input on topics related to the eFMC, geochronology and granitoids.
589 **Figure captions**

590 Figure 1. (a) Sketch map depicting the exposed Variscan domains of western Europe
591 and the location of the inferred suture zones, based on Schulmann et al. (2022). SXT:
592 Saxo-Thuringian suture. (b) Geological map of the eastern French Massif Central
593 showing the main nappe architecture. Are also depicted the locations/names of
594 "Leptynite-Amphibolite Complex" occurrences (in black), adapted from Chantraine et
595 al. (2003).

596 Figure 1. (a) Carte simplifiée montrant les zones où affleurent les terrains varisques et
597 les sutures supposées. (b) Carte géologique de l'Est du Massif Central français oriental
598 localisant les zones où affleure les "complexes leptyno-amphiboliques".

599 Figure 2. (a) Simplified geological map of the Monts-du-Lyonnais metamorphic
600 complex, adapted from Feybesse et al. (1995). (b) Aerial photograph of the Riverie
601 disused quarry, illustrating the location of the studied pit.

602 Figure 2. (a) Carte géologique simplifiée du complexe métamorphique des Monts-du-
603 Lyonnais. (b) vue aérienne des anciennes carrières de Riverie.

604 Figure 3: Field observations and petrography of the Riverie felsic gneisses and
605 amphibolites. (a) Amphibole-rich clusters embedded within the felsic gneisses (black
606 triangles) recalling assimilated mafic material. Veins of felsic rocks cutting across the
607 amphibolite (white triangles). (b) Felsic gneisses with plagioclase–quartz leucocratic
608 bands rimmed by coarse amphibole underlining the vertical foliation (black triangles)
609 and isotropic zones between the amphibolite boudins (white triangles). (c) Polarized-
610 light thin section scan showing the variation in amphibole mode typically observed in
611 the felsic gneisses. (d,e) Polarized-light photomicrographs of felsic gneisses illustrating
612 the main plagioclase–quartz–amphibole assemblage with biotite rimming amphibole.
613 (f) Polarized-light photomicrograph of a mafic rock showing the equigranular
614 plagioclase–amphibole assemblage.

615 Figure 3. Observations de terrain et pétrographie des gneiss et amphibolites de
616 Riverie. (a) Amas riches en amphibole dans les gneiss (triangles noirs) pouvant
617 correspondre à du matériel mafique assimilé et veines de roches felsiques dans les
618 amphibolites (triangles blancs). (b) Gneiss felsiques avec des bandes leucocratiques
619 de plagioclase-quartz bordées par de l'amphibole soulignant la foliation verticale
620 (triangles noirs) et des zones isotropes entre les boudins d'amphibolite (triangles
621 blancs). (c) Variation de la proportion d'amphibole dans les gneiss.. (d, e) Assemblage
622 des gneiss à plagioclase-quartz-amphibole-biotite. (f) Assemblage équigranulaire
623 plagioclase-amphibole des amphibolites.

624 Figure 4: Whole-rock geochemical data of the Riverie felsic gneisses and amphibolites.
625 (a) FMW diagram of Ohta and Arai (2007) demonstrating the igneous origin of felsic
626 gneisses. The M and F values characterize mafic and felsic rock sources, respectively.
627 The W value quantifies the degree of weathering. The references of data for
628 (presumably) meta-igneous from "Leptynite-Amphibolite Complexes" are available in
629 the Supplementary Text. (b) P–Q classification diagram of Debon and Le Fort (1983).
630 The dotted lines represent the contour encompassing 75% of the data (n=75) for the
631 Velay orthogneiss formation, a coeval (meta)igneous suite from the parautochtonous
632 terrains (Couzinié et al., 2017). (c) Incompatible, immobile element patterns of the
633 Riverie meta-igneous rocks normalized to the composition of NMORBs (Sun and
634 McDonough, 1989). (d) Chondrite-normalized (Boynton, 1984) Rare Earth Elements
635 patterns. (e) Th/Yb vs. Nb/Yb diagram of Pearce (2008). Oceanic rocks plot within the
636 MORB–OIB array. Magmas contaminated by the continental crust during ascent or
637 which mantle source incorporated a slab-derived (SZ) component plot in the volcanic
arc array. (f) V–Ti diagram of Shervais (1982). This diagram highlights the effects of
the change in vanadium redox state when the mantle is metasomatized by slab-derived
fluids. Vanadium becomes more incompatible and resulting magmas exhibit high V/Ti
ratios. The magnetite + amphibole fractionation trend is from Shervais (1982). Data for
the Bulk Continental Crust are from Rudnick and Gao (2003).

Figure 4. Données géochimiques des roches totales des gneiss et amphibolites de Riverie. (a) Diagramme FMW démontrant l'origine ignée des gneiss. (b) Diagramme de classification P-Q de Debon et Le Fort (1983). (c) Profils d'éléments incompatibles normalisés à la composition des N-MORB. (d) Profils de terres rares normalisés aux chondrites. (e) Diagramme Th/Yb vs. Nb/Yb de Pearce (2008). Les roches océaniques se situent dans le domaine MORB-OIB. Les magmas contaminés par la croûte continentale lors de leur mise en place ou dont la source mantellique a incorporé un composant dérivé de la plaque subduite se situent dans le domaine des arcs volcaniques. (f) Diagramme V-Ti de Shervais (1982).

Figure 5: Zircon textural and U–Pb–Hf data for the Riverie amphibole gneisses. (a) Representative cathodoluminescence images with the locations of laser spots (white and yellow circles for U–Pb and Lu–Hf analyses respectively) indicated along with the spot name (aXX or YYa/b). The corresponding $^{206}$Pb/$^{238}$U dates are quoted with 2σ uncertainty, in Ma. All displayed analyses are concordant (except those in italic). Hf isotope data are reported using the $\epsilon$Hf calculated at the $^{206}$Pb/$^{238}$U date obtained on the same zircon domain, quoted with 2σ uncertainty. The white and black triangles highlight changes in the zoning pattern and local grain recrystallization, respectively. Laser spot sizes are 30 µm for U–Pb and 40 µm for Lu–Hf. (b) Tera-Wasserburg diagrams ($^{238}$U/$^{206}$Pb vs. $^{207}$Pb/$^{206}$Pb). Error ellipses and ages are displayed at 95%
level of uncertainty. Green ellipses are those considered for Concordia age calculations. The reported MSWDs are those of concordance plus equivalence.

Figure 5. Données texturales et U-Pb-Hf des zircons extraits des gneiss de Riverie. (a) Images en cathodoluminescence montrant la zonation magmatique des grains et la localisation de quelques points d'analyse. (b) Diagrammes Tera-Wasserburg. Les ellipses vertes sont celles considérées pour les calculs d'âge Concordia.

Figure 6: Measured $\epsilon$Hf(t) on magmatic zircon grains, recalculated and plotted using the $^{206}$Pb/$^{238}$U date. When such value was not available, the crystallization age determined for the sample was used. The range for the Depleted Mantle reservoir is bracketed by the models of Naeraa et al. (2012) and Griffin et al. (2002). The background red shading mimics the contours of the distribution of 223 zircon analyses from crust-derived felsic (meta-)igneous rock from the French Massif Central (Chelle-Michou et al., 2017; Couzinié et al., 2017; Moyen et al., 2017). These data are taken as representative of the Hf isotopic composition of the local continental crust. Data for the Armorican Massif Cadomian juvenile arc magmatism are from Samson et al. (2003). An $\epsilon$Hf(t)-time crust evolution array calculated with an average $^{176}$Lu/$^{177}$Hf ratio of 0.015 (Griffin et al., 2002) is also depicted.

Figure 6. Valeurs de $\epsilon$Hf des grains de zircon recalculées à l'âge de mise en place. L'arrière-plan rouge représente la composition isotopique en Hf de la croûte continentale de l'Est du Massif Central.

Figure 7: Results of mass balance calculations performed by least-square regression considering the average composition of felsic gneisses as representative of the intrusive low-K dacitic melt. Samples LY25-, RV-1 and RV-2 are modelled as residual
melts, while the remaining samples are considered cumulates. $Σr^2$ represents the sum of squared residuals.

Figure 7. Résultats des calculs de bilan de masse réalisés par régression des moindres carrés en considérant la composition moyenne des gneiss comme représentative du liquide dacique initial. Les échantillons LY25-, RV-1 et RV-2 sont modélisés comme des liquides résiduels alors que les autres sont considérés comme des cumulats.

Figure 8: (a) Paleogeography at 545 Ma based on the full-plate model of Merdith et al. (2021), drawn using Python 3 with opensource packages pyGMT and pyGplates. The yellow star depicts the putative location of the terrains today exposed in Upper Gneiss Unit (UGU) of the eFMC. (b) Geodynamic sketch of the northern Gondwana margin at 545 Ma highlighting the context and mechanism through which the Riverie rocks formed, inspired from Erdős et al. (2022).

Figure 8. (a) Paléogéographie à 545 Ma basée sur le modèle de plaque de Merdith et al. (2021). L'étoile indique l'emplacement supposé des terrains correspondant aujourd'hui à l'Unité Supérieure des Gneiss. (b) Schéma géodynamique de la marge nord du Gondwana à 545 Ma, soulignant le contexte et le mécanisme par lesquels les roches de Riverie se sont formées.

Figure 9: Available LA-ICP-MS zircon U-Pb data on meta-igneous rocks from the "Leptynite-Amphibolite Complexes" in the eastern French Massif Central (represented as Kernel Density Estimates of concordant $^{206}$Pb/$^{238}$U dates (calculated with IsoplotR using an adaptive bandwith). Zircon data are from Whitney et al. (2020) for the Montagne Noire, de Hoÿm de Marien et al. (2023) for the Haut-Allier, Paquette et al. (2017) for the Lot, Lotout et al. (2020, 2018) for the Rouergue, Chelle-Michou et al. (2017) for the Vivarais, and this study for the Monts-du-Lyonnais.
709 **Figure 9.** Données U-Pb sur zircons obtenues pour les roches méta-ignées des
"complexes leptyno-amphiboliques" de l'Est du Massif Central français.

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1065

1066
<figure><img src="image_2.png" /></figure>

<figure><img src="image_3.png" /><figcaption>Fig. 2</figcaption></figure>
<figure><img src="image_4.png" /></figure>

Ductile shear
zone

Brittle fault

Reworked thrust

<figure><img src="image_5.png" /></figure>

Late Carboniferous (Stephanian)
sedimentary rocks

<figure><img src="image_6.png" /></figure>

Visean synkinematic granitoids
(345–335 Ma)

## Monts-du-Lyonnais metamorphic complex (Upper Gneiss Unit)

<figure><img src="image_7.png" /></figure>

Paragneisses, locally with high-pressure granulite-facies relics

a. lower unit; b. upper unit

<figure><img src="image_8.png" /></figure>

Peraluminous orthogneisses (500–470 Ma)

## Units referred to as «Leptynite–Amphibolite Complexes» (LACs)

<figure><img src="image_9.png" /></figure>

Amphibolites associated with (retrograde) eclogites ⭐ and garnet-bearing peridotites in a paragneiss matrix

<figure><img src="image_10.png" /></figure>

Chaussan leucogneisses with numerous boudins of mafic and felsic meta-igneous granulites, also found in the adjacent orthogneiss ⭐

<figure><img src="image_11.png" /></figure>

Riverie belt: amphibolites and amphibole-bearing gneisses, devoid of high-pressure metamorphic relics

## Pilat unit (parautochtonous terrains)

<figure><img src="image_12.png" /></figure>

Micaschists and orthogneisses
<figure><img src="image_13.png" /></figure>

a

<figure><img src="image_14.png" /></figure>

b

<figure><img src="image_15.png" /></figure>

amp-rich

amp-poor leucocratic domain

amp-rich

<figure><img src="image_16.png" /></figure>

d

<figure><img src="image_17.png" /></figure>

e

<figure><img src="image_18.png" /></figure>

f
<figure><img src="image_19.png" /></figure>

<figure><img src="image_20.png" /></figure>

<figure><img src="image_21.png" /></figure>

<figure><img src="image_22.png" /></figure>

<figure><img src="image_23.png" /></figure>

<figure><img src="image_24.png" /></figure>
<figure><img src="image_25.png" /><figcaption>RV-2 felsic gneiss</figcaption></figure>

<figure><img src="image_26.png" /></figure>

a

<figure><img src="image_27.png" /></figure>

Concordia date:
**545.9 ± 1.9 (6.4) Ma**

(95% conf.); MSWD = 1.6; n = 16/40
int. err. = 0.4%; syst. err. = 1.1%

<figure><img src="image_28.png" /><figcaption>RV-2</figcaption></figure>

Concordia date:
**543.9 ± 1.5 (6.3) Ma**

(95% conf.); MSWD = 1.4; n = 19/33
int. err. = 0.3%; syst. err. = 1.1%

b
<figure><img src="image_29.png" /></figure>

Monts-du-Lyonnais
metamorphic complex

RV-1 amp-bearing

RV-2 felsic gneisses

Cadomian

juvenile

magmatism

(Armorican Massif)

<figure><img src="image_30.png" /></figure>

zircon from crust-derived
(meta-)igneous rocks
from the eastern French
Massif Central n=223
<figure><img src="image_31.png" /></figure>

<figure><img src="image_32.png" /><figcaption>$\sum r^2$ Fractionated melts</figcaption></figure>

<figure><img src="image_33.png" /><figcaption>Cumulates</figcaption></figure>

<figure><img src="image_34.png" /></figure>
<figure><img src="image_35.png" /></figure>

<figure><img src="image_36.png" /></figure>
<figure><img src="image_37.png" /></figure>

Leptynite-
Amphibolite
Complexes

Lot n=44

Vivarais n=98

Haut-Allier n=43

Rouergue n=53

Montagne Noire n=18

Riviere rocks
n=58
Supplementary text of the manuscript:

Late Ediacaran juvenile magmatism in the Variscan Monts-du-Lyonnais
metamorphic complex (Massif Central, France)

Identification d'un magmatisme juvénile fini-édiacarien dans le complexe métamorphique varisque des Monts-du-Lyonnais (Massif Central, France)

Simon Couzinié<fnref n="1" />,<fnref n="2" />,<fnref n="3" />*, Oscar Laurent<fnref n="4" />, Pierre Bouilhol<fnref n="1" />, Cyril Chelle-Michou<fnref n="5" />, Anne-Céline Ganzhorn<fnref n="3" />**, Véronique Gardien<fnref n="3" />, Jean-François Moyen<fnref n="6" />

<footnote n="1">¹Université de Lorraine, CNRS, CRPG, 54000 Nancy, France</footnote>

<footnote n="2">²Université Jean Monnet, CNRS, LGL-TPE UMR5276, F-42023 Saint-Etienne, France</footnote>

<footnote n="3">³LGL-TPE UMR 5276, CNRS, Université Lyon 1, ENS de Lyon, 69622 Villeurbanne, France</footnote>

<footnote n="4">⁴CNRS, Géosciences Environnement Toulouse, Observatoire Midi-Pyrénées, 14 avenue Edouard Belin, 31400 Toulouse, France</footnote>

<footnote n="5">⁵Institute of Geochemistry and Petrology, ETH Zürich, CH-8092 Zürich, Switzerland</footnote>

<footnote n="6">⁶Université Jean-Monnet, Laboratoire Magmas et Volcans, UCA-CNRS-IRD, Aubière, France</footnote>

<footnote>*Corresponding author. simon.couzinie@univ-lorraine.fr</footnote>

<footnote>**Present address: Saint-Gobain Recherche, Aubervilliers, France</footnote>
# 1. Analytical procedures

## A. Whole-rock major and trace element compositions

Samples were sawed at Saint-Etienne University and a c. 500 g fragment of each sample was sent to ALS Global for whole-rock chemical composition measurements. We chose the "Complete Characterization Package" which combines ICP-AES and ICP-MS analyses for major and trace elements, respectively. More information about analytical routines used by this company can be found at http://www.alsglobal.com/. Repeated analyses of standards SY-4, GRE-3, OREAS-121 and AMIS0304 were realized during the analytical session. Analyses of the standards were reproducible to <1.7% for most major elements except K₂O (2.4%), MgO (6.4%) and P₂O₅ (4.6%); <7.9% for trace elements except Cr (25%), V (12.5%) and Ba (10.9%); and consistent within uncertainty with the expected values. Duplicate measurements of four samples show external reproducibility better than 1.1% (RSD) for major elements (except P₂O₅ at 4.6%) and generally better than 5.4% (RSD) for trace elements except for Tl, Tm, Lu, Hf and V. Fifteen blanks display measured values typically under detection limits for all major and trace elements.

## B. Zircon U-Pb dating

Zircon U-Pb isotopic analyses were carried out at Goethe Universität Frankfurt (GUF) by laser ablation using a Resolution M-50 (Resonetics) 193 nm ArF excimer laser system attached to ThermoFinnigan Element 2 sector field ICP-MS. We applied the same methods as in Zeh and Gerdes (2012). We used a repetition rate of 5.5 Hz, and a laser spot-size of 30 µm for measurements of unknowns and zircon reference materials GJ-1, Plešovice and BB-16. The on-sample fluence was ~2.5 to 3 J.cm⁻². Sample surface was cleaned directly before each analysis by three pre-ablation pulses. Ablation was performed in a two-volume ablation cell (Laurin Technic, Australia) characterized by a very quick response time (<1 s until maximum signal strength is reached) and wash-out delay (<3 s to get <1% of maximum signal intensity). It was fluxed during ablation with carrier gas consisting of a ~0.6 L.min⁻¹ He stream, mixed directly after the ablation cell with make-up gas consisting of ~0.07 L.min⁻¹ N₂ and 0.68 L.min⁻¹ Ar prior introduction into the plasma of the sector field ICP-MS. All gases had a purity of 99.999% and no homogenizer was used while mixing the gases, to prevent smoothing of the signal and thus to be able to detect significant variations of the ²⁰⁷Pb/²⁰⁶Pb and ²³⁸U/²⁰⁶Pb ratios during measurements, possibly revealing the sequential sampling of different age domains within single zircon grains. Signal was tuned for maximum sensitivity for Pb and U while keeping low the production of oxides (²⁵⁴UO/²³⁸U ≤ 0.5%). The obtained sensitivity on zircon standard GJ-1 for ²³⁸U and a 30 µm spot size is close to 10000 cps.ppm⁻¹ at 5.5 Hz and 3 J.cm⁻². Data were acquired using time resolved-peak jumping, the detector being set to analogue mode for ²³²Th and ²³⁸U and counting mode for ²⁰⁴(Hg+Pb), ²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb. A total of 356 mass scans were acquired over ~41 s measurement (20 s of background measurement followed by 21 s of sample ablation) and integrated to 89 ratios (4 mass scans per
integration, time resolution = 0.46 s). Those ratios were subsequently corrected offline for background signal, common Pb, instrumental mass discrimination and Pb/U fractionation (both laser-induced during individual measurements, and over the day) using an in-house MS Excel® spreadsheet. No common Pb correction was performed. The inter-elemental fractionation $^{206}$Pb/$^{238}$U during the 21 s of sample ablation was corrected for each analysis by applying a linear regression through all measured ratios, excluding the outliers (±2σ), and considering that the intercept with the y-axis represents the "true" ratio. Elemental fractionation over the analytical session, as well as instrumental mass discrimination, were corrected by normalization to the $^{206}$Pb/$^{238}$U (0.0982) and $^{207}$Pb/$^{206}$Pb (0.061) ratios of reference zircon GJ-1 (Jackson et al., 2004) using standard bracketing. Elemental concentrations in U and Pb were calculated using raw signal (in cps) of $^{238}$U and $^{206}$Pb for each spot, corrected from the analytical drift over the session (monitored using GJ-1) and normalized to the recommended values of the GJ-1 zircon standard (U = 280.1 ppm; Pb = 25.5 ppm). Th/U ratio was determined for each spot using the mass fractionation-corrected $^{232}$Th/$^{238}$U ratio, normalized to the recommended value of the GJ-1 zircon standard (Th/U = 0.0296).

The quoted uncertainties for each individual analysis are (i) for the $^{206}$Pb/$^{238}$U ratio, the quadratic addition of the within-run precision (2σ) with the external reproducibility of standard zircon GJ-1 during the corresponding analytical session (0.5 to 1.5%, 2σ); and (ii) for the $^{207}$Pb/$^{206}$Pb ratio, a $^{207}$Pb signal-dependent uncertainty propagation, as described by Gerdes and Zeh (2009). The $^{207}$Pb/$^{235}$U ratio was calculated using the $^{206}$Pb/$^{238}$U and $^{207}$Pb/$^{206}$Pb ratios and assuming a natural $^{238}$U/$^{235}$U of 137.818, and its uncertainty was obtained by quadratic addition of propagated errors on both ratios. Age calculations and data plotting were performed using IsoplotR (Vermeesch, 2018).

Data from secondary standards were processed as unknowns to check the accuracy of the corrections (Fig. S1) and the results reported Supplementary Table S3. Calculated pooled dates are within error of the recommended TIMS values for Plešovice and BB-16, i.e. 337.13 ± 0.37 Ma and 560 ± 0.8 Ma, respectively (Santos et al., 2017; Sláma et al., 2008). The dataset for the Riverie samples is presented in Supplementary Table S4.

Additional systematic errors were propagated to every U–Pb Concordia date calculated out of several individual analyses following the scheme of Horstwood et al., (2016). Those include the uncertainties on: (i) the decay constants for $^{238}$U and $^{235}$U, set at 0.107% and 0.136% for $^{238}$U and $^{235}$U, respectively (Jaffey et al., 1971); (ii) the isotope ratios of the primary standard (GJ–1), set at 0.5%; (iii) the overall reproducibility of the method, estimated based on the long-term excess scatter of secondary zircon reference materials, i.e. 1% relative. Error propagation involved the quadratic addition of the “internal” error calculated by IsoplotR and the other systematic errors listed above.

A summary of analytical operating conditions is provided in Supplementary Table ST0 (see below).
<figure><img src="image_38.png" /><figcaption>Figure S1: Wetherill diagrams ($^{206}\text{Pb}/^{238}\text{U}$ vs. $^{207}\text{Pb}/^{235}\text{U}$) for secondary zircon standards Plešovice and BB-16 analysed during the two analytical sessions at GUF. Error ellipses are displayed at $2\sigma$ level of uncertainty. Green ellipses are those considered for pooled date calculations.</figcaption></figure>
<table><tr><td colspan="2"><strong>Sample Preparation</strong></td></tr><tr><td>Laboratory name</td><td>University of Saint-Etienne (FR) and University of Stellenbosch (RSA)</td></tr><tr><td>Sample type/mineral</td><td>Zircon</td></tr><tr><td>Sample preparation</td><td>Conventional techniques (sieving, panning, magnetic and heavy liquids separation followed by handpicking). Grains cast into epoxy mounts.</td></tr><tr><td>Imaging</td><td>BSE and CL-imaging performed at the Central Analytical Facility of Stellenbosch University using a Zeiss MERLIN Scanning Electron Microscope</td></tr><tr><td colspan="2"><strong>Laser ablation system</strong></td></tr><tr><td>Laboratory name</td><td>Goethe Universität Frankfurt, Germany</td></tr><tr><td>Make, Model & type</td><td>RESOLution M-50 (Resonetics) ArF-excimer</td></tr><tr><td>Ablation cell</td><td>Two-volume ablation cell (Laurin Technic, Australia)</td></tr><tr><td>Laser wavelength</td><td>193 nm</td></tr><tr><td>Pulse width</td><td>~ 25 ns</td></tr><tr><td>Fluence</td><td>2.5 – 3 J/cm²</td></tr><tr><td>Repetition rate</td><td>5.5 Hz</td></tr><tr><td>Spot diameter</td><td>30 µm</td></tr><tr><td>Ablation duration</td><td>21 seconds</td></tr><tr><td>Sampling mode</td><td>Static single spot</td></tr><tr><td>Carrier gas</td><td>100% He mixed directly after the ablation cell with make-up gas consisting of</td></tr><tr><td>Carrier gas flow (He)</td><td>0.6 L/min</td></tr><tr><td colspan="2"><strong>ICP-MS Instrument</strong></td></tr><tr><td>Make, Model & type</td><td>ThermoFinnigan Element 2 sector field ICP-MS</td></tr><tr><td>Sample introduction</td><td>Ablation aerosol</td></tr><tr><td>Make-up gas flow</td><td>~0.07 L.min<sup>-1</sup> N<sub>2</sub> and 0.68 L.min<sup>-1</sup> Ar</td></tr><tr><td>Detection system</td><td>Secondary Electron Multiplier with dual detector mode (pulse counting and analog, cross calibrated daily with <sup>238</sup>U measured on analog mode only)</td></tr><tr><td>Masses measured</td><td><sup>204</sup>(Hg + Pb), <sup>206</sup>Pb, <sup>207</sup>Pb, <sup>208</sup>Pb, <sup>232</sup>Th, <sup>238</sup>U</td></tr><tr><td>Integration time per peak</td><td>10 ms except at amu 206 and 207 (20 ms)</td></tr><tr><td>Total integration time per output data point (s)</td><td>108 ms</td></tr><tr><td>Sensitivity/Efficiency</td><td>10000 cps.ppm<sup>-1</sup> for <sup>238</sup>U on GJ-1</td></tr><tr><td colspan="2"><strong>Data processing</strong></td></tr><tr><td>Gas blank</td><td>20 seconds on-peak</td></tr><tr><td>Calibration strategy</td><td>GJ-1 zircon standard used as primary reference material, Plešovice and BB-16 used as secondary reference material (quality control)</td></tr><tr><td>Common-Pb correction, composition and uncertainty</td><td>No common-Pb correction</td></tr><tr><td>Reference Material info</td><td>GJ1 (Jackson et al., 2004), Plešovice (Sláma et al., 2008), BB-16 (Santos et al., 2017)</td></tr><tr><td>Data processing package</td><td>in-house MS Excel® spreadsheet</td></tr><tr><td>Uncertainty level and propagation</td><td>Ages are quoted at 95% conf. level; propagation of systematic uncertainties by quadratic addition according to Horstwood et al. (2016)</td></tr><tr><td>Quality control/validation</td><td>Plešovice: Concordia age: 337.6 ± 4.4 Ma (n = 14/14 | MSWD = 3.1) and 337.8 ± 4.2 Ma (n = 13/13 | MSWD = 2.7); accepted value: 337.1 ± 0.4 Ma (Sláma et al., 2008)<br>BB-16: Concordia age: 562.0 ± 6.7 Ma (n = 11/13 | MSWD = 1.1) and 361.0 ± 6.5 Ma (n = 13/13 | MSWD = 1.1); accepted value: 560.0 ± 0.8 Ma (Santos et al., 2017)</td></tr></table>

Supplementary Table ST0: Summary of operating conditions for zircon LA–ICP–MS dating.

### C. Zircon Lu–Hf isotope measurements

Measurements were performed at GUF using a Thermo-Finnigan Neptune multicollector ICP–MS attached to a Resolution M-50193 nm Ar–F excimer laser ablation system, equipped with a two-volume Laurin Technic ablation cell. Laser spots with diameters of 40 or 60 µm were drilled “on top” of the existing spots already analyzed for U–Pb dating or in the same domain as identified based on CL images, with repetition rates of 4 Hz and an energy density of 5 to 6 J·cm⁻². He was used as a carrier gas (~0.6 L·min⁻¹) and make-up gas consisting of high-purity Ar (~0.75 L·min⁻¹)
and N₂ (~0.07 L·min⁻¹) was admixed to the carrier gas to improve sensitivity. Post-ablation homogenization is performed by fluxing the gases through a Resolution Instruments Squid® tubing. Data were acquired using multi-collector static mode, during 58 s of measurement characterized by 1.052 s integration time (55 baseline-corrected ratios). ¹⁷²Yb, ¹⁷³Yb and ¹⁷⁵Lu masses were monitored to allow the correction of isobaric interferences (¹⁷⁶Yb and ¹⁷⁶Lu on ¹⁷⁶Hf). Instrumental mass bias for Yb isotopes (calculation of βYb) was monitored for each measurement using an exponential law and corrected to the natural ratio ¹⁷²Yb/¹⁷³Yb=1.35351. Mass fractionation of Lu isotopes was assumed identical to that of Yb isotopes (βLu=βYb). The isobaric interferences were subsequently corrected to mass bias-corrected ¹⁷⁶Yb/¹⁷³Yb = 0.79502 and ¹⁷⁶Lu/¹⁷⁵Lu = 0.02656 (see Gerdes and Zeh, 2006). Mass bias for Hf isotopes (βHf) was determined using an exponential law and normalized to ¹⁷⁹Hf/¹⁷⁷Hf= 0.7325. Accuracy and external reproducibility of the method were controlled by repeated analyses of reference zircon standards GJ-1 (Jackson et al., 2004; Morel et al., 2008), Plešovice (Sláma et al., 2008), and Temora (Woodhead et al., 2004). Results for standards are presented in the Supplementary Table S5 and for samples in the Supplementary Table S6.

The quoted uncertainties on ¹⁷⁶Hf/¹⁷⁷Hf ratios and εHf(t) are quadratic additions of within-run precision of each measurement with the external reproducibility (2 S.D.) of the reference zircon standard GJ-1 (~70 ppm). Data reduction was carried out using an in-house MS Excel© spreadsheet (Gerdes and Zeh, 2009, 2006).

Calculation of initial ¹⁷⁶Hf/¹⁷⁷Hf ratios was performed using the individual ¹⁷⁶Lu/¹⁷⁷Hf ratio of each measurement, a decay constant of λ₁₇₆Lu = 1.867 × 10⁻¹¹ (Scherer et al., 2001; Söderlund et al., 2004) and the emplacement age obtained by U–Pb zircon dating. For the calculation of the εHf(t), parameters of the chondritic uniform reservoir (CHUR) recommended by Bouvier et al. (2008) were used (¹⁷⁶Lu/¹⁷⁷Hf = 0.0336; ¹⁷⁶Hf/¹⁷⁷Hf = 0.282785).

## 2. Data compilation

The data used in Figure 4 were compiled from Blanc, 1981; Bodinier, 1983; Briand et al., 1991, 1988; Brousse et al., 1990; Brousse and Varet, 1972; Cabanis et al., 1983; Chelle-Michou et al., 2017; Chenevoy et al., 1998; Coffrant and Piboule, 1971; Collomb, 1970; Davoine, 1969; Demange, 1985; Downes et al., 1989; Downes and Duthou, 1988; Dufour, 1982; Forestier, 1961; Giraud et al., 1984; Lasnier, 1977; Ouali, 1993; Paquette et al., 1995; Piboule, 1977; Piboule and Briand, 1985; Pin and Marini, 1993; Ravier and Chenevoy, 1979; Thiéblemont, 1990; Whitney et al., 2020.
References

Blanc, D., 1981. Les roches basiques et ultrabasiques des Monts du Lyonnais. Etude pétrographique, minéralogique et géochimique (PhD thesis).

Bodinier, J.L., 1983. Etude géochimique du massif basique et ultrabasique de Najac (Aveyron). Conséquences géotectoniques. Bulletin de la Société Géologique de France 25, 185–193.

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<caption>Table S1: Whole-rock major and trace element compositions of samples from the Riverie belt</caption>

Analyses performed by ALS Global

<table><thead><tr><th>Sample</th><th>RV-1</th><th>RV-2</th><th>LY23</th><th>LY24</th><th>LY25</th><th>LY26</th><th>LY27</th><th>LY28</th><th>LY21</th><th>LY22</th><th>MG05</th><th>MG06</th></tr></thead><tbody><tr><th>Type</th><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>felsic<br>gneiss</td><td>amphibolite</td><td>amphibolite</td><td>amphibolite</td><td>amphibolite</td></tr></tbody></table>

Major elements (wt.%), measured by ICP-AES

<table><tbody><tr><td>SiO<sub>2</sub></td><td>68.40</td><td>65.50</td><td>64.00</td><td>64.00</td><td>67.70</td><td>63.00</td><td>62.60</td><td>64.80</td><td>48.00</td><td>46.60</td><td>51.90</td><td>51.40</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>15.20</td><td>15.55</td><td>15.45</td><td>15.10</td><td>14.40</td><td>16.05</td><td>16.40</td><td>16.15</td><td>15.95</td><td>17.05</td><td>15.65</td><td>14.95</td></tr><tr><td>Fe<sub>2</sub>O<sub>3</sub></td><td>4.33</td><td>5.47</td><td>6.15</td><td>5.77</td><td>4.62</td><td>5.71</td><td>5.82</td><td>5.01</td><td>10.60</td><td>10.60</td><td>8.86</td><td>12.20</td></tr><tr><td>CaO</td><td>4.50</td><td>3.77</td><td>5.51</td><td>4.88</td><td>4.47</td><td>5.41</td><td>5.31</td><td>3.93</td><td>9.42</td><td>8.01</td><td>8.64</td><td>7.39</td></tr><tr><td>MgO</td><td>2.13</td><td>2.84</td><td>3.36</td><td>2.98</td><td>2.01</td><td>2.66</td><td>2.83</td><td>2.65</td><td>8.61</td><td>9.04</td><td>7.50</td><td>4.97</td></tr><tr><td>Na<sub>2</sub>O</td><td>5.08</td><td>4.96</td><td>4.57</td><td>4.41</td><td>4.31</td><td>4.68</td><td>4.73</td><td>4.66</td><td>3.46</td><td>3.22</td><td>4.04</td><td>4.32</td></tr><tr><td>K<sub>2</sub>O</td><td>0.40</td><td>0.57</td><td>0.46</td><td>0.49</td><td>0.33</td><td>0.51</td><td>0.67</td><td>0.59</td><td>0.70</td><td>0.96</td><td>0.87</td><td>0.81</td></tr><tr><td>Cr<sub>2</sub>O<sub>3</sub></td><td>0.01</td><td>&lt;0.01</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>-</td><td>0.04</td><td>&lt;0.01</td></tr><tr><td>TiO<sub>2</sub></td><td>0.37</td><td>0.40</td><td>0.57</td><td>0.51</td><td>0.40</td><td>0.41</td><td>0.41</td><td>0.40</td><td>1.42</td><td>1.35</td><td>1.30</td><td>2.36</td></tr><tr><td>MnO</td><td>0.08</td><td>0.07</td><td>0.10</td><td>0.09</td><td>0.06</td><td>0.09</td><td>0.10</td><td>0.07</td><td>0.20</td><td>0.17</td><td>0.17</td><td>0.21</td></tr><tr><td>P<sub>2</sub>O<sub>5</sub></td><td>0.04</td><td>0.06</td><td>0.08</td><td>0.10</td><td>0.07</td><td>0.07</td><td>0.08</td><td>0.08</td><td>0.14</td><td>0.19</td><td>0.13</td><td>0.28</td></tr><tr><td>S</td><td>0.11</td><td>&lt;0.01</td><td>0.11</td><td>0.02</td><td>0.25</td><td>0.01</td><td>0.01</td><td>0.03</td><td>0.01</td><td>0.01</td><td>&lt;0.01</td><td>0.07</td></tr><tr><td>LOI</td><td>0.51</td><td>2.25</td><td>0.61</td><td>0.61</td><td>0.79</td><td>0.37</td><td>0.53</td><td>2.07</td><td>1.24</td><td>2.82</td><td>1.01</td><td>1.23</td></tr><tr><td>Total</td><td>101.09</td><td>101.50</td><td>100.86</td><td>98.94</td><td>99.16</td><td>98.96</td><td>99.48</td><td>100.41</td><td>99.74</td><td>100.01</td><td>100.11</td><td>100.12</td></tr><tr><td>Mg#</td><td>49</td><td>51</td><td>52</td><td>51</td><td>46</td><td>48</td><td>49</td><td>51</td><td>62</td><td>63</td><td>63</td><td>45</td></tr><tr><td>A/CNK</td><td>0.90</td><td>0.99</td><td>0.86</td><td>0.91</td><td>0.92</td><td>0.89</td><td>0.90</td><td>1.05</td><td>0.68</td><td>0.82</td><td>0.67</td><td>0.70</td></tr></tbody></table>

Trace elements (ppm), measured by ICP-MS

<table><tbody><tr><td>Ba</td><td>222</td><td>244</td><td>217</td><td>260</td><td>203</td><td>284</td><td>398</td><td>371</td><td>235</td><td>214</td><td>323</td><td>198</td></tr><tr><td>Ce</td><td>19.9</td><td>16.8</td><td>22.0</td><td>19.8</td><td>14.6</td><td>20.4</td><td>21.6</td><td>17.2</td><td>15.2</td><td>17.0</td><td>14.7</td><td>23.9</td></tr><tr><td>Cr</td><td>20</td><td>10</td><td>40</td><td>60</td><td>30</td><td>20</td><td>20</td><td>10</td><td>320</td><td>300</td><td>270</td><td>30</td></tr><tr><td>Cs</td><td>0.26</td><td>1.18</td><td>0.35</td><td>0.54</td><td>0.40</td><td>0.39</td><td>0.49</td><td>1.06</td><td>0.93</td><td>1.90</td><td>0.76</td><td>1.12</td></tr><tr><td>Dy</td><td>2.33</td><td>1.62</td><td>2.56</td><td>2.72</td><td>1.65</td><td>2.06</td><td>2.40</td><td>1.88</td><td>3.99</td><td>4.47</td><td>4.30</td><td>7.04</td></tr><tr><td>Er</td><td>1.53</td><td>1.10</td><td>1.76</td><td>1.70</td><td>0.91</td><td>1.18</td><td>1.51</td><td>1.13</td><td>2.35</td><td>2.68</td><td>2.94</td><td>4.17</td></tr><tr><td>Eu</td><td>0.66</td><td>0.57</td><td>0.72</td><td>0.76</td><td>0.44</td><td>0.57</td><td>0.64</td><td>0.62</td><td>1.23</td><td>1.49</td><td>1.16</td><td>1.80</td></tr><tr><td>Ga</td><td>14.5</td><td>15.9</td><td>15.9</td><td>16.5</td><td>15.0</td><td>17.6</td><td>17.6</td><td>15.9</td><td>16.9</td><td>22.2</td><td>17.1</td><td>23.6</td></tr><tr><td>Gd</td><td>2.44</td><td>1.69</td><td>3.09</td><td>3.09</td><td>1.62</td><td>2.46</td><td>2.93</td><td>2.33</td><td>4.31</td><td>4.64</td><td>4.47</td><td>7.14</td></tr><tr><td>Hf</td><td>3.5</td><td>3.5</td><td>3.3</td><td>4.0</td><td>3.2</td><td>2.9</td><td>3.0</td><td>3.1</td><td>2.9</td><td>2.7</td><td>2.6</td><td>4.0</td></tr><tr><td>Ho</td><td>0.50</td><td>0.33</td><td>0.56</td><td>0.60</td><td>0.32</td><td>0.44</td><td>0.56</td><td>0.38</td><td>0.97</td><td>1.02</td><td>0.97</td><td>1.41</td></tr><tr><td>La</td><td>8.3</td><td>8.0</td><td>9.7</td><td>9.4</td><td>7.8</td><td>10.0</td><td>10.0</td><td>8.6</td><td>6.4</td><td>7.9</td><td>6.4</td><td>9.8</td></tr><tr><td>Lu</td><td>0.27</td><td>0.20</td><td>0.29</td><td>0.34</td><td>0.14</td><td>0.22</td><td>0.29</td><td>0.21</td><td>0.41</td><td>0.44</td><td>0.37</td><td>0.59</td></tr><tr><td>Nb</td><td>2.3</td><td>1.9</td><td>3.4</td><td>3.3</td><td>1.9</td><td>2.4</td><td>2.0</td><td>2.0</td><td>4.0</td><td>4.9</td><td>3.8</td><td>4.4</td></tr><tr><td>Nd</td><td>10.8</td><td>9.2</td><td>12.5</td><td>12.2</td><td>7.7</td><td>11.0</td><td>11.7</td><td>9.8</td><td>10.4</td><td>13.6</td><td>10.6</td><td>19.1</td></tr><tr><td>Pr</td><td>2.41</td><td>2.06</td><td>3.03</td><td>2.85</td><td>1.76</td><td>2.86</td><td>2.94</td><td>2.44</td><td>2.14</td><td>2.76</td><td>2.23</td><td>3.85</td></tr><tr><td>Rb</td><td>7.9</td><td>13.9</td><td>7.0</td><td>10.8</td><td>5.3</td><td>8.9</td><td>14.1</td><td>14.2</td><td>12.0</td><td>28.8</td><td>16.4</td><td>17.6</td></tr><tr><td>Sm</td><td>2.71</td><td>1.99</td><td>2.67</td><td>3.10</td><td>1.62</td><td>2.25</td><td>2.56</td><td>2.26</td><td>3.00</td><td>3.88</td><td>3.40</td><td>5.28</td></tr><tr><td>Sr</td><td>250.0</td><td>287.0</td><td>298.0</td><td>292.0</td><td>288.0</td><td>308.0</td><td>319.0</td><td>331.0</td><td>167.5</td><td>267.0</td><td>192.0</td><td>249.0</td></tr><tr><td>Ta</td><td>0.3</td><td>0.4</td><td>0.4</td><td>0.6</td><td>0.1</td><td>-</td><td>-</td><td>-</td><td>0.2</td><td>0.6</td><td>0.2</td><td>0.1</td></tr><tr><td>Tb</td><td>0.36</td><td>0.23</td><td>0.45</td><td>0.48</td><td>0.25</td><td>0.40</td><td>0.35</td><td>0.33</td><td>0.72</td><td>0.79</td><td>0.74</td><td>1.11</td></tr><tr><td>Th</td><td>0.74</td><td>1.14</td><td>1.15</td><td>1.32</td><td>1.43</td><td>1.62</td><td>1.23</td><td>1.37</td><td>0.96</td><td>0.35</td><td>0.84</td><td>1.21</td></tr><tr><td>Tm</td><td>0.24</td><td>0.16</td><td>0.29</td><td>0.26</td><td>0.13</td><td>0.22</td><td>0.24</td><td>0.19</td><td>0.41</td><td>0.40</td><td>0.39</td><td>0.63</td></tr><tr><td>U</td><td>0.38</td><td>0.55</td><td>0.69</td><td>0.53</td><td>0.78</td><td>0.97</td><td>0.41</td><td>0.38</td><td>1.22</td><td>0.76</td><td>0.56</td><td>0.65</td></tr><tr><td>V</td><td>78</td><td>113</td><td>151</td><td>132</td><td>99</td><td>130</td><td>135</td><td>110</td><td>257</td><td>316</td><td>227</td><td>362</td></tr><tr><td>Y</td><td>14.9</td><td>9.9</td><td>16.6</td><td>17.5</td><td>9.1</td><td>14.2</td><td>15.5</td><td>11</td><td>22.4</td><td>26.1</td><td>24.2</td><td>40.6</td></tr><tr><td>Yb</td><td>1.66</td><td>1.18</td><td>2.09</td><td>2.15</td><td>1.03</td><td>1.71</td><td>1.92</td><td>1.45</td><td>2.63</td><td>2.65</td><td>2.51</td><td>4.37</td></tr><tr><td>Zr</td><td>134</td><td>107</td><td>126</td><td>143</td><td>105</td><td>98</td><td>97</td><td>110</td><td>96</td><td>107</td><td>99</td><td>193</td></tr><tr><td>Ni</td><td>13</td><td>10</td><td>18</td><td>19</td><td>18</td><td>11</td><td>12</td><td>10</td><td>55</td><td>97</td><td>53</td><td>5</td></tr><tr><td>Pb</td><td>2</td><td>&lt;2</td><td>-</td><td>3</td><td>-</td><td>5</td><td>3</td><td>3</td><td>2</td><td>2</td><td>&lt;2</td><td>&lt;2</td></tr><tr><td>Sc</td><td>10</td><td>14</td><td>16</td><td>15</td><td>10</td><td>14</td><td>14</td><td>13</td><td>33</td><td>21</td><td>35</td><td>31</td></tr><tr><td>Zn</td><td>33</td><td>46</td><td>52</td><td>50</td><td>38</td><td>48</td><td>50</td><td>52</td><td>90</td><td>86</td><td>81</td><td>73</td></tr><tr><td>Nb/Nb*<sup>1</sup></td><td>0.3</td><td>0.2</td><td>0.3</td><td>0.3</td><td>0.2</td><td>0.2</td><td>0.2</td><td>0.2</td><td>0.5</td><td>1.0</td><td>0.6</td><td>0.4</td></tr><tr><td>Zr/Zr*<sup>2</sup></td><td>1.7</td><td>1.7</td><td>1.5</td><td>1.6</td><td>2.1</td><td>1.4</td><td>1.2</td><td>1.6</td><td>1.2</td><td>1.0</td><td>1.1</td><td>1.3</td></tr><tr><td>Ti/Ti*<sup>3</sup></td><td>0.3</td><td>0.5</td><td>0.5</td><td>0.4</td><td>0.6</td><td>0.4</td><td>0.4</td><td>0.4</td><td>0.9</td><td>0.8</td><td>0.8</td><td>0.9</td></tr><tr><td>Eu/Eu*<sup>4</sup></td><td>0.78</td><td>0.95</td><td>0.77</td><td>0.75</td><td>0.83</td><td>0.74</td><td>0.71</td><td>0.83</td><td>1.05</td><td>1.07</td><td>0.91</td><td>0.90</td></tr></tbody></table>

<footnote n="1">¹ Nb* defined as NbN/sqrt(ThN*LaN) where N stands for normalized to N-MORB values</footnote>

<footnote n="2">² Zr* defined as ZrN/sqrt(SmN*NdN) where N stands for normalized to N-MORB values</footnote>

<footnote n="3">³ Ti* defined as TiN/sqrt(SmN*GdN) where N stands for normalized to N-MORB values</footnote>

<footnote n="4">⁴ Eu* defined as EuN/sqrt(SmN*GdN') where N' stands for normalized to chondrite values</footnote>
<table><caption>Table S2: Representative mineral analyses of the amphibole-bearing felsic gneisses RV-1 & RV-2</caption><thead><tr><th colspan="4">biotite (A<sub>1</sub>M<sub>3</sub>T<sub>4</sub>O<sub>10</sub>W<sub>2</sub>)</th></tr><tr><th></th><th>RV1-b13</th><th>RV1-b14</th><th>RV1-b18</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>36.91</td><td>37.06</td><td>37.21</td></tr><tr><td>TiO<sub>2</sub></td><td>3.27</td><td>3.42</td><td>3.41</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>14.52</td><td>14.18</td><td>14.74</td></tr><tr><td>FeOt</td><td>17.50</td><td>17.96</td><td>17.51</td></tr><tr><td>MnO</td><td>0.15</td><td>0.20</td><td>0.23</td></tr><tr><td>MgO</td><td>12.84</td><td>12.99</td><td>12.94</td></tr><tr><td>CaO</td><td>0.00</td><td>0.00</td><td>0.00</td></tr><tr><td>Na<sub>2</sub>O</td><td>0.24</td><td>0.27</td><td>0.29</td></tr><tr><td>K<sub>2</sub>O</td><td>9.30</td><td>9.16</td><td>8.99</td></tr><tr><td>Total</td><td>94.74</td><td>95.25</td><td>95.32</td></tr><tr><td>T. Si</td><td>2.83</td><td>2.83</td><td>2.83</td></tr><tr><td>T.Al</td><td>1.03</td><td>1.01</td><td>1.04</td></tr><tr><td>T.Fe<sup>3+</sup></td><td>0.15</td><td>0.16</td><td>0.13</td></tr><tr><td>M.Al</td><td>0.28</td><td>0.26</td><td>0.28</td></tr><tr><td>M.Mg</td><td>1.46</td><td>1.47</td><td>1.45</td></tr><tr><td>M.Fe<sup>2+</sup></td><td>0.87</td><td>0.86</td><td>0.84</td></tr><tr><td>M.Fe<sup>3+</sup></td><td>0.10</td><td>0.13</td><td>0.14</td></tr><tr><td>M.Ti</td><td>0.19</td><td>0.20</td><td>0.19</td></tr><tr><td>M.Mn</td><td>0.0</td><td>0.0</td><td>0.0</td></tr><tr><td>sum oct</td><td>2.91</td><td>2.93</td><td>2.92</td></tr><tr><td>A.K</td><td>0.91</td><td>0.89</td><td>0.88</td></tr><tr><td>A.Na</td><td>0.04</td><td>0.04</td><td>0.04</td></tr><tr><td>sum inter</td><td>0.95</td><td>0.93</td><td>0.92</td></tr><tr><td>W.OH</td><td>1.55</td><td>1.52</td><td>1.51</td></tr><tr><td>W.O<sup>2-</sup></td><td>0.45</td><td>0.48</td><td>0.49</td></tr><tr><td>Fe<sup>3+</sup>/Fe<sub>tot</sub></td><td>0.22</td><td>0.25</td><td>0.25</td></tr><tr><td>mg#</td><td>0.63</td><td>0.63</td><td>0.63</td></tr></tbody></table>

<table><thead><tr><th colspan="8">amphibole (A<sub>0.1</sub>B<sub>2</sub>C<sub>5</sub>T<sub>8</sub>O<sub>22</sub>W<sub>2</sub>)</th></tr><tr><th></th><th>RV1-a1</th><th>RV1-a2</th><th>RV1-a11</th><th>RV1-a6</th><th>RV1-a7</th><th>RV2-a14</th><th>RV2-a2</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>46.43</td><td>46.12</td><td>47.48</td><td>46.62</td><td>46.41</td><td>46.62</td><td>46.04</td></tr><tr><td>TiO<sub>2</sub></td><td>0.86</td><td>0.94</td><td>0.97</td><td>0.85</td><td>0.86</td><td>0.90</td><td>0.76</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>8.51</td><td>8.67</td><td>7.58</td><td>8.79</td><td>8.39</td><td>8.23</td><td>9.49</td></tr><tr><td>FeOt</td><td>15.15</td><td>14.76</td><td>13.85</td><td>14.71</td><td>14.81</td><td>15.31</td><td>16.35</td></tr><tr><td>MnO</td><td>0.55</td><td>0.58</td><td>0.53</td><td>0.53</td><td>0.58</td><td>0.56</td><td>0.50</td></tr><tr><td>MgO</td><td>13.33</td><td>13.44</td><td>13.71</td><td>13.09</td><td>13.32</td><td>13.77</td><td>12.04</td></tr><tr><td>CaO</td><td>10.80</td><td>11.30</td><td>11.55</td><td>10.94</td><td>11.22</td><td>10.35</td><td>11.39</td></tr><tr><td>Na<sub>2</sub>O</td><td>1.58</td><td>1.39</td><td>1.24</td><td>1.58</td><td>1.46</td><td>1.35</td><td>1.34</td></tr><tr><td>K<sub>2</sub>O</td><td>0.38</td><td>0.28</td><td>0.34</td><td>0.31</td><td>0.33</td><td>0.37</td><td>0.38</td></tr><tr><td>Total</td><td>97.59</td><td>97.50</td><td>97.24</td><td>97.41</td><td>97.37</td><td>97.44</td><td>98.29</td></tr><tr><td>T.Si</td><td>6.78</td><td>6.74</td><td>6.92</td><td>6.80</td><td>6.79</td><td>6.80</td><td>6.73</td></tr><tr><td>T.Al</td><td>1.24</td><td>1.29</td><td>1.10</td><td>1.22</td><td>1.24</td><td>1.22</td><td>1.30</td></tr><tr><td>T.sum</td><td>8.02</td><td>8.03</td><td>8.02</td><td>8.02</td><td>8.03</td><td>8.03</td><td>8.02</td></tr><tr><td>C.Al</td><td>0.22</td><td>0.20</td><td>0.20</td><td>0.29</td><td>0.20</td><td>0.19</td><td>0.34</td></tr><tr><td>C.Ti</td><td>0.12</td><td>0.14</td><td>0.13</td><td>0.12</td><td>0.13</td><td>0.14</td><td>0.11</td></tr><tr><td>C.Fe<sup>3+</sup></td><td>0.64</td><td>0.62</td><td>0.51</td><td>0.57</td><td>0.61</td><td>0.70</td><td>0.57</td></tr><tr><td>C.Mn<sup>2+</sup></td><td>0.04</td><td>0.05</td><td>0.04</td><td>0.04</td><td>0.05</td><td>0.04</td><td>0.04</td></tr><tr><td>C.Mg</td><td>2.83</td><td>2.86</td><td>2.94</td><td>2.79</td><td>2.84</td><td>2.89</td><td>2.57</td></tr><tr><td>C.Fe<sup>2+</sup></td><td>1.11</td><td>1.09</td><td>1.14</td><td>1.15</td><td>1.13</td><td>1.01</td><td>1.35</td></tr><tr><td>C.sum</td><td>4.96</td><td>4.96</td><td>4.96</td><td>4.97</td><td>4.96</td><td>4.96</td><td>4.98</td></tr><tr><td>B.Mn<sup>2+</sup></td><td>0.02</td><td>0.02</td><td>0.02</td><td>0.02</td><td>0.02</td><td>0.03</td><td>0.02</td></tr><tr><td>B.Fe<sup>2+</sup></td><td>0.10</td><td>0.09</td><td>0.03</td><td>0.07</td><td>0.07</td><td>0.16</td><td>0.08</td></tr><tr><td>B.Mg</td><td>0.08</td><td>0.07</td><td>0.04</td><td>0.06</td><td>0.06</td><td>0.11</td><td>0.05</td></tr><tr><td>B.Ca</td><td>1.70</td><td>1.78</td><td>1.81</td><td>1.72</td><td>1.77</td><td>1.63</td><td>1.79</td></tr><tr><td>B.Na</td><td>0.08</td><td>0.02</td><td>0.08</td><td>0.11</td><td>0.06</td><td>0.04</td><td>0.04</td></tr><tr><td>B.sum</td><td>1.98</td><td>1.98</td><td>1.99</td><td>1.98</td><td>1.98</td><td>1.97</td><td>1.98</td></tr><tr><td>A.Na</td><td>0.37</td><td>0.37</td><td>0.27</td><td>0.34</td><td>0.35</td><td>0.34</td><td>0.34</td></tr><tr><td>A.K</td><td>0.07</td><td>0.06</td><td>0.06</td><td>0.06</td><td>0.07</td><td>0.07</td><td>0.07</td></tr><tr><td>A.sum</td><td>0.44</td><td>0.43</td><td>0.33</td><td>0.40</td><td>0.42</td><td>0.41</td><td>0.41</td></tr><tr><td>W.OH</td><td>1.80</td><td>1.80</td><td>1.88</td><td>1.84</td><td>1.84</td><td>1.73</td><td>1.82</td></tr><tr><td>W.O<sup>2-</sup></td><td>0.20</td><td>0.20</td><td>0.12</td><td>0.16</td><td>0.16</td><td>0.27</td><td>0.18</td></tr><tr><td>Fe<sup>3+</sup>/Fe<sub>tot</sub></td><td>0.34</td><td>0.35</td><td>0.30</td><td>0.32</td><td>0.34</td><td>0.37</td><td>0.29</td></tr><tr><td>mg#</td><td>0.70</td><td>0.71</td><td>0.72</td><td>0.70</td><td>0.71</td><td>0.72</td><td>0.65</td></tr></tbody></table>

<table><thead><tr><th colspan="8">plagioclase</th></tr><tr><th></th><th>RV1-p2</th><th>RV1-p6</th><th>RV1-p8</th><th>RV1-p13</th><th>RV2-p1</th><th>RV2-p3</th><th>RV2-p8</th></tr></thead><tbody><tr><td>SiO<sub>2</sub></td><td>62.43</td><td>62.18</td><td>62.12</td><td>62.24</td><td>62.12</td><td>62.02</td><td>62.12</td></tr><tr><td>Al<sub>2</sub>O<sub>3</sub></td><td>23.75</td><td>23.54</td><td>23.71</td><td>23.78</td><td>23.23</td><td>23.60</td><td>23.63</td></tr><tr><td>FeOt</td><td>0.00</td><td>0.00</td><td>0.14</td><td>0.00</td><td>0.00</td><td>0.17</td><td>0.00</td></tr><tr><td>CaO</td><td>5.38</td><td>5.07</td><td>5.18</td><td>5.57</td><td>5.28</td><td>5.78</td><td>5.54</td></tr><tr><td>Na<sub>2</sub>O</td><td>8.44</td><td>8.64</td><td>8.78</td><td>8.40</td><td>8.80</td><td>8.60</td><td>8.78</td></tr><tr><td>K<sub>2</sub>O</td><td>0.23</td><td>0.22</td><td>0.19</td><td>0.22</td><td>0.15</td><td>0.24</td><td>0.11</td></tr><tr><td>Total</td><td>100.23</td><td>99.65</td><td>100.13</td><td>100.22</td><td>99.58</td><td>100.42</td><td>100.17</td></tr><tr><td>Si</td><td>2.76</td><td>2.76</td><td>2.75</td><td>2.75</td><td>2.77</td><td>2.75</td><td>2.75</td></tr><tr><td>Al</td><td>1.24</td><td>1.23</td><td>1.24</td><td>1.24</td><td>1.22</td><td>1.23</td><td>1.23</td></tr><tr><td>Fe<sup>2+</sup></td><td>0.00</td><td>0.00</td><td>0.01</td><td>0.00</td><td>0.00</td><td>0.01</td><td>0.00</td></tr><tr><td>Ca</td><td>0.25</td><td>0.24</td><td>0.25</td><td>0.26</td><td>0.25</td><td>0.27</td><td>0.26</td></tr><tr><td>Na</td><td>0.72</td><td>0.75</td><td>0.75</td><td>0.72</td><td>0.76</td><td>0.74</td><td>0.75</td></tr><tr><td>K</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td><td>0.01</td></tr><tr><td>Sum</td><td>4.99</td><td>5.00</td><td>5.01</td><td>4.99</td><td>5.01</td><td>5.01</td><td>5.01</td></tr><tr><td>An</td><td>25.7</td><td>24.2</td><td>24.3</td><td>26.5</td><td>24.7</td><td>26.7</td><td>25.7</td></tr><tr><td>Ab</td><td>73.0</td><td>74.6</td><td>74.6</td><td>72.3</td><td>74.5</td><td>71.9</td><td>73.7</td></tr><tr><td>Or</td><td>1.3</td><td>1.2</td><td>1.1</td><td>1.3</td><td>0.8</td><td>1.3</td><td>0.6</td></tr></tbody></table>
<table><caption>Table S3: Results of LA-ICP-MS U-Pb analyses of zircon standards performed during the sessions at GUF</caption><thead><tr><th rowspan="2">grain</th><th colspan="2"><sup>207</sup>Pb<sup>a</sup></th><th colspan="2">U<sup>b</sup></th><th colspan="2">Th<sup>b</sup></th><th colspan="2"><sup>206</sup>Pb<sup>c</sup></th><th colspan="2"><sup>206</sup>Pb<sup>d</sup></th><th colspan="2"><sup>207</sup>Pb<sup>d</sup></th><th colspan="2"><sup>207</sup>Pb<sup>d</sup></th><th colspan="2"><sup>206</sup>Pb</th><th colspan="2"><sup>207</sup>Pb</th><th colspan="2"><sup>207</sup>Pb</th><th colspan="2">conc.<sup>f</sup></th></tr><tr><th>(cps)</th><th>(ppm)</th><th>(ppm)</th><th>U</th><th>U</th><th>U</th><th>U</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(Ma)</th><th>(Ma)</th><th>(Ma)</th><th>(Ma)</th><th>(%)</th><th>(%)</th><th>(%)</th><th>(%)</th></tr></thead><tbody><tr><td colspan="15"><strong>Seq.1</strong></td></tr><tr><td>Pleso-01</td><td>35868</td><td>16433</td><td>854</td><td>0.18</td><td>0.07</td><td>0.05462</td><td>1.4</td><td>0.4004</td><td>1.9</td><td>0.05317</td><td>1.3</td><td>0.74</td><td>343</td><td>5</td><td>342</td><td>6</td><td>336</td><td>30</td><td>102</td><td></td><td></td></tr><tr><td>Pleso-02</td><td>36752</td><td>17580</td><td>922</td><td>0.18</td><td>0.01</td><td>0.05516</td><td>1.4</td><td>0.4077</td><td>1.5</td><td>0.05360</td><td>0.6</td><td>0.91</td><td>346</td><td>5</td><td>347</td><td>5</td><td>354</td><td>15</td><td>98</td><td></td><td></td></tr><tr><td>Pleso-03</td><td>32918</td><td>16568</td><td>864</td><td>0.18</td><td>0.00</td><td>0.05488</td><td>1.4</td><td>0.4017</td><td>1.6</td><td>0.05309</td><td>0.7</td><td>0.89</td><td>344</td><td>5</td><td>343</td><td>5</td><td>333</td><td>16</td><td>104</td><td></td><td></td></tr><tr><td>Pleso-04</td><td>32844</td><td>17053</td><td>867</td><td>0.18</td><td>b.d.</td><td>0.05344</td><td>1.4</td><td>0.3922</td><td>1.6</td><td>0.05323</td><td>0.7</td><td>0.90</td><td>336</td><td>5</td><td>336</td><td>5</td><td>339</td><td>16</td><td>99</td><td></td><td></td></tr><tr><td>Pleso-05</td><td>32105</td><td>17287</td><td>884</td><td>0.18</td><td>b.d.</td><td>0.05380</td><td>1.4</td><td>0.3919</td><td>1.5</td><td>0.05284</td><td>0.7</td><td>0.89</td><td>338</td><td>4</td><td>336</td><td>4</td><td>322</td><td>16</td><td>105</td><td></td><td></td></tr><tr><td>Pleso-06</td><td>29247</td><td>15678</td><td>818</td><td>0.19</td><td>b.d.</td><td>0.05468</td><td>1.4</td><td>0.4055</td><td>1.6</td><td>0.05378</td><td>0.8</td><td>0.87</td><td>343</td><td>5</td><td>346</td><td>5</td><td>362</td><td>18</td><td>95</td><td></td><td></td></tr><tr><td>Pleso-07</td><td>28914</td><td>16278</td><td>834</td><td>0.19</td><td>0.00</td><td>0.05377</td><td>1.4</td><td>0.3955</td><td>1.5</td><td>0.05335</td><td>0.6</td><td>0.91</td><td>338</td><td>5</td><td>338</td><td>4</td><td>344</td><td>15</td><td>98</td><td></td><td></td></tr><tr><td>Pleso-08</td><td>27534</td><td>16446</td><td>835</td><td>0.18</td><td>0.00</td><td>0.05338</td><td>1.4</td><td>0.3873</td><td>1.6</td><td>0.05263</td><td>0.9</td><td>0.84</td><td>335</td><td>4</td><td>332</td><td>5</td><td>313</td><td>20</td><td>107</td><td></td><td></td></tr><tr><td>Pleso-09</td><td>27940</td><td>16927</td><td>856</td><td>0.18</td><td>0.00</td><td>0.05311</td><td>1.4</td><td>0.3878</td><td>1.6</td><td>0.05295</td><td>0.8</td><td>0.87</td><td>334</td><td>5</td><td>333</td><td>5</td><td>327</td><td>18</td><td>102</td><td></td><td></td></tr><tr><td>Pleso-10</td><td>28760</td><td>17792</td><td>897</td><td>0.18</td><td>b.d.</td><td>0.05295</td><td>1.4</td><td>0.3891</td><td>1.6</td><td>0.05330</td><td>0.7</td><td>0.90</td><td>333</td><td>5</td><td>334</td><td>4</td><td>342</td><td>15</td><td>97</td><td></td><td></td></tr><tr><td>Pleso-11</td><td>27316</td><td>17250</td><td>875</td><td>0.18</td><td>0.00</td><td>0.05326</td><td>1.4</td><td>0.3928</td><td>1.6</td><td>0.05350</td><td>0.8</td><td>0.87</td><td>334</td><td>5</td><td>336</td><td>5</td><td>350</td><td>18</td><td>96</td><td></td><td></td></tr><tr><td>Pleso-12</td><td>27316</td><td>17248</td><td>878</td><td>0.18</td><td>0.00</td><td>0.05346</td><td>1.4</td><td>0.3943</td><td>1.6</td><td>0.05350</td><td>0.8</td><td>0.87</td><td>336</td><td>5</td><td>338</td><td>5</td><td>350</td><td>18</td><td>96</td><td></td><td></td></tr><tr><td>Pleso-13</td><td>24378</td><td>15912</td><td>806</td><td>0.18</td><td>b.d.</td><td>0.05319</td><td>1.4</td><td>0.3921</td><td>1.6</td><td>0.05347</td><td>0.7</td><td>0.89</td><td>334</td><td>5</td><td>336</td><td>5</td><td>349</td><td>16</td><td>96</td><td></td><td></td></tr><tr><td>Pleso-14</td><td>27660</td><td>17529</td><td>891</td><td>0.18</td><td>0.00</td><td>0.05337</td><td>1.4</td><td>0.3938</td><td>1.5</td><td>0.05352</td><td>0.7</td><td>0.88</td><td>335</td><td>4</td><td>337</td><td>4</td><td>351</td><td>16</td><td>96</td><td></td><td></td></tr><tr><td>BB16-1</td><td>21488</td><td>5433</td><td>486</td><td>0.31</td><td>b.d.</td><td>0.09059</td><td>1.4</td><td>0.7415</td><td>1.7</td><td>0.05937</td><td>0.8</td><td>0.86</td><td>559</td><td>8</td><td>563</td><td>7</td><td>581</td><td>18</td><td>96</td><td></td><td></td></tr><tr><td>BB16-2</td><td>18605</td><td>5106</td><td>450</td><td>0.32</td><td>0.02</td><td>0.08926</td><td>1.4</td><td>0.7370</td><td>1.6</td><td>0.05988</td><td>0.8</td><td>0.86</td><td>551</td><td>7</td><td>561</td><td>7</td><td>599</td><td>18</td><td>92</td><td></td><td></td></tr><tr><td>BB16-3</td><td>15540</td><td>5166</td><td>464</td><td>0.31</td><td>0.00</td><td>0.09142</td><td>1.4</td><td>0.7390</td><td>1.7</td><td>0.05863</td><td>1.0</td><td>0.81</td><td>564</td><td>7</td><td>562</td><td>7</td><td>553</td><td>21</td><td>102</td><td></td><td></td></tr><tr><td>BB16-4</td><td>14731</td><td>5471</td><td>491</td><td>0.28</td><td>0.01</td><td>0.09167</td><td>1.4</td><td>0.7492</td><td>1.7</td><td>0.05927</td><td>0.9</td><td>0.82</td><td>565</td><td>7</td><td>568</td><td>7</td><td>577</td><td>21</td><td>98</td><td></td><td></td></tr><tr><td>BB16-5</td><td>19335</td><td>5004</td><td>447</td><td>0.32</td><td>0.10</td><td>0.09059</td><td>1.4</td><td>0.7341</td><td>1.7</td><td>0.05877</td><td>0.9</td><td>0.83</td><td>559</td><td>7</td><td>559</td><td>7</td><td>559</td><td>20</td><td>100</td><td></td><td></td></tr><tr><td>BB16-6</td><td>19147</td><td>5239</td><td>457</td><td>0.31</td><td>0.02</td><td>0.08847</td><td>1.4</td><td>0.7204</td><td>1.6</td><td>0.05905</td><td>0.8</td><td>0.86</td><td>546</td><td>7</td><td>551</td><td>7</td><td>569</td><td>18</td><td>96</td><td></td><td></td></tr><tr><td>BB16-7</td><td>17506</td><td>5087</td><td>454</td><td>0.32</td><td>0.02</td><td>0.09050</td><td>1.4</td><td>0.7368</td><td>1.7</td><td>0.05905</td><td>0.9</td><td>0.83</td><td>558</td><td>8</td><td>561</td><td>7</td><td>569</td><td>20</td><td>98</td><td></td><td></td></tr><tr><td>BB16-8</td><td>18202</td><td>5608</td><td>502</td><td>0.30</td><td>0.11</td><td>0.09112</td><td>1.4</td><td>0.7394</td><td>1.6</td><td>0.05885</td><td>0.8</td><td>0.88</td><td>562</td><td>8</td><td>562</td><td>7</td><td>562</td><td>17</td><td>100</td><td></td><td></td></tr><tr><td>BB16-9</td><td>17249</td><td>5210</td><td>465</td><td>0.32</td><td>0.00</td><td>0.09052</td><td>1.4</td><td>0.7416</td><td>1.6</td><td>0.05942</td><td>0.9</td><td>0.85</td><td>559</td><td>7</td><td>563</td><td>7</td><td>583</td><td>19</td><td>96</td><td></td><td></td></tr><tr><td>BB16-10</td><td>16662</td><td>5166</td><td>465</td><td>0.32</td><td>0.00</td><td>0.09119</td><td>1.4</td><td>0.7498</td><td>1.7</td><td>0.05963</td><td>1.0</td><td>0.81</td><td>563</td><td>8</td><td>568</td><td>7</td><td>590</td><td>22</td><td>95</td><td></td><td></td></tr><tr><td>BB16-11</td><td>15400</td><td>5189</td><td>464</td><td>0.31</td><td>0.00</td><td>0.09074</td><td>1.4</td><td>0.7422</td><td>1.8</td><td>0.05932</td><td>1.1</td><td>0.79</td><td>560</td><td>7</td><td>564</td><td>8</td><td>579</td><td>23</td><td>97</td><td></td><td></td></tr><tr><td>BB16-12</td><td>15617</td><td>5202</td><td>466</td><td>0.32</td><td>b.d.</td><td>0.09082</td><td>1.4</td><td>0.7404</td><td>1.7</td><td>0.05913</td><td>0.9</td><td>0.83</td><td>560</td><td>7</td><td>563</td><td>7</td><td>572</td><td>20</td><td>98</td><td></td><td></td></tr><tr><td>BB16-13</td><td>12574</td><td>4289</td><td>385</td><td>0.31</td><td>b.d.</td><td>0.09112</td><td>1.4</td><td>0.7380</td><td>1.6</td><td>0.05874</td><td>0.9</td><td>0.83</td><td>562</td><td>7</td><td>561</td><td>7</td><td>557</td><td>20</td><td>101</td><td></td><td></td></tr><tr><td colspan="15"><strong>Seq.2</strong></td></tr><tr><td>Pleso-01</td><td>41966</td><td>21077</td><td>1096</td><td>0.18</td><td>0.14</td><td>0.05471</td><td>1.0</td><td>0.4036</td><td>1.2</td><td>0.05351</td><td>0.6</td><td>0.85</td><td>343</td><td>3</td><td>344</td><td>4</td><td>350</td><td>15</td><td>98</td><td></td><td></td></tr><tr><td>Pleso-02</td><td>40803</td><td>18094</td><td>947</td><td>0.20</td><td>0.71</td><td>0.05426</td><td>1.1</td><td>0.3968</td><td>2.3</td><td>0.05304</td><td>2.0</td><td>0.47</td><td>341</td><td>4</td><td>339</td><td>7</td><td>330</td><td>46</td><td>103</td><td></td><td></td></tr><tr><td>Pleso-03</td><td>36733</td><td>19273</td><td>985</td><td>0.19</td><td>0.10</td><td>0.05373</td><td>1.1</td><td>0.3919</td><td>1.2</td><td>0.05290</td><td>0.6</td><td>0.88</td><td>337</td><td>4</td><td>336</td><td>3</td><td>325</td><td>13</td><td>104</td><td></td><td></td></tr><tr><td>Pleso-04</td><td>37351</td><td>19504</td><td>1010</td><td>0.20</td><td>0.14</td><td>0.05448</td><td>1.1</td><td>0.4005</td><td>1.3</td><td>0.05332</td><td>0.8</td><td>0.82</td><td>342</td><td>4</td><td>342</td><td>4</td><td>342</td><td>17</td><td>100</td><td></td><td></td></tr><tr><td>Pleso-05</td><td>35210</td><td>18668</td><td>954</td><td>0.20</td><td>b.d.</td><td>0.05364</td><td>1.1</td><td>0.3928</td><td>1.3</td><td>0.05311</td><td>0.8</td><td>0.82</td><td>337</td><td>4</td><td>336</td><td>4</td><td>333</td><td>17</td><td>101</td><td></td><td></td></tr><tr><td>Pleso-06</td><td>34759</td><td>18762</td><td>977</td><td>0.20</td><td>0.19</td><td>0.05471</td><td>1.1</td><td>0.4036</td><td>1.4</td><td>0.05351</td><td>0.8</td><td>0.79</td><td>343</td><td>4</td><td>344</td><td>4</td><td>350</td><td>19</td><td>98</td><td></td><td></td></tr><tr><td>Pleso-07</td><td>34602</td><td>19160</td><td>982</td><td>0.20</td><td>b.d.</td><td>0.05386</td><td>1.1</td><td>0.3961</td><td>1.3</td><td>0.05334</td><td>0.6</td><td>0.86</td><td>338</td><td>4</td><td>339</td><td>4</td><td>343</td><td>15</td><td>99</td><td></td><td></td></tr><tr><td>Pleso-08</td><td>32719</td><td>18352</td><td>930</td><td>0.20</td><td>b.d.</td><td>0.05319</td><td>1.2</td><td>0.3892</td><td>1.4</td><td>0.05307</td><td>0.7</td><td>0.85</td><td>334</td><td>4</td><td>334</td><td>4</td><td>332</td><td>17</td><td>101</td><td></td><td></td></tr><tr><td>Pleso-09</td><td>33495</td><td>18896</td><td>953</td><td>0.20</td><td>b.d.</td><td>0.05298</td><td>1.1</td><td>0.3898</td><td>1.3</td><td>0.05336</td><td>0.7</td><td>0.85</td><td>333</td><td>4</td><td>334</td><td>4</td><td>344</td><td>15</td><td>97</td><td></td><td></td></tr><tr><td>Pleso-10</td><td>30845</td><td>17070</td><td>874</td><td>0.21</td><td>b.d.</td><td>0.05365</td><td>1.1</td><td>0.3967</td><td>1.3</td><td>0.05363</td><td>0.8</td><td>0.81</td><td>337</td><td>3</td><td>339</td><td>4</td><td>356</td><td>17</td><td>95</td><td></td><td></td></tr><tr><td>Pleso-11</td><td>27316</td><td>17055</td><td>801</td><td>0.20</td><td>0.00</td><td>0.04931</td><td>1.1</td><td>0.3640</td><td>1.4</td><td>0.05354</td><td>0.8</td><td>0.82</td><td>310</td><td>3</td><td>315</td><td>4</td><td>352</td><td>18</td><td>88</td><td></td><td></td></tr><tr><td>Pleso-12</td><td>29334</td><td>16937</td><td>867</td><td>0.21</td><td>0.26</td><td>0.05367</td><td>1.2</td><td>0.3952</td><td>1.5</td><td>0.05340</td><td>0.9</td><td>0.79</td><td>337</td><td>4</td><td>338</td><td>4</td><td>346</td><td>21</td><td>97</td><td></td><td></td></tr><tr><td>Pleso-13</td><td>35935</td><td>17731</td><td>911</td><td>0.20</td><td>1.65</td><td>0.05294</td><td>1.1</td><td>0.3901</td><td>3.2</td><td>0.05345</td><td>3.0</td><td>0.35</td><td>333</td><td>4</td><td>334</td><td>9</td><td>348</td><td>67</td><td>96</td><td></td><td></td></tr><tr><td>Pleso-14</td><td>33275</td><td>19651</td><td>1001</td><td>0.20</td><td>b.d.</td><td>0.05348</td><td>1.2</td><td>0.3951</td><td>1.3</td><td>0.05358</td><td>0.7</td><td>0.86</td><td>336</td><td>4</td><td>338</td><td>4</td><td>353</td><td>15</td><td>95</td><td></td><td></td></tr><tr><td>BB16-1</td><td>22924</td><td>5769</td><td>524</td><td>0.34</td><td>0.07</td><td>0.09208</td><td>1.1</td><td>0.7480</td><td>2.6</td><td>0.05892</td><td>2.3</td><td>0.43</td><td>568</td><td>6</td><td>567</td><td>11</td><td>564</td><td>50</td><td>101</td><td></td><td></td></tr><tr><td>BB16-2</td><td>19468</td><td>5318</td><td>478</td><td>0.35</td><td>0.29</td><td>0.09116</td><td>1.1</td><td>0.7375</td><td>3.1</td><td>0.05868</td><td>2.9</td><td>0.36</td><td>562</td><td>6</td><td>561</td><td>13</td><td>555</td><td>63</td><td>101</td><td></td><td></td></tr><tr><td>BB16-3</td><td>17271</td><td>5089</td><td>455</td><td>0.35</td><td>0.18</td><td>0.09055</td><td>1.1</td><td>0.7347</td><td>1.5</td><td>0.05884</td><td>1.1</td><td>0.72</td><td>559</td><td>6</td><td>559</td><td>7</td><td>561</td><td>23</td><td>100</td><td></td><td></td></tr><tr><td>BB16-4</td><td>18041</td><td>5421</td><td>492</td><td>0.45</td><td>b.d.</td><td>0.09039</td><td>1.1</td><td>0.7411</td><td>2.3</td><td>0.05947</td><td>2.0</td><td>0.49</td><td>558</td><td>6</td><td>563</td><td>10</td><td>584</td><td>43</td><td>95</td><td></td><td></td></tr></tbody></table>
<table><caption>Table S3 (cont.): Results of LA-ICP-MS U–Pb analyses of zircon standards performed during the sessions at GUF</caption><thead><tr><th rowspan="2">grain</th><th><sup>207</sup>Pb<sup>a</sup></th><th>U<sup>b</sup></th><th>Pb<sup>b</sup></th><th>Th<sup>b</sup></th><th><sup>206</sup>Pb<sup>c</sup></th><th><sup>206</sup>Pb<sup>d</sup></th><th>±2σ</th><th><sup>207</sup>Pb<sup>d</sup></th><th>±2σ</th><th><sup>207</sup>Pb<sup>d</sup></th><th>±2σ</th><th>rho<sup>e</sup></th><th><sup>206</sup>Pb</th><th>±2σ</th><th><sup>207</sup>Pb</th><th>±2σ</th><th><sup>207</sup>Pb</th><th>±2σ</th><th>conc.<sup>f</sup></th></tr><tr><th>(cps)</th><th>(ppm)</th><th>(ppm)</th><th>U</th><th>(%)</th><th><sup>238</sup>U</th><th>(%)</th><th><sup>235</sup>U</th><th>(%)</th><th><sup>206</sup>Pb</th><th>(%)</th><th><sup>238</sup>U</th><th>(Ma)</th><th><sup>235</sup>U</th><th>(Ma)</th><th><sup>206</sup>Pb</th><th>(Ma)</th><th>(%)</th></tr></thead><tbody><tr><td>BB16-5</td><td>20108</td><td>5355</td><td>485</td><td>0.35</td><td>b.d.</td><td>0.09172</td><td>1.1</td><td>0.7477</td><td>1.5</td><td>0.05912</td><td>1.1</td><td>0.72</td><td>566</td><td>6</td><td>567</td><td>7</td><td>572</td><td>23</td><td>99</td></tr><tr><td>BB16-6</td><td>20313</td><td>5574</td><td>501</td><td>0.34</td><td>b.d.</td><td>0.09116</td><td>1.1</td><td>0.7434</td><td>1.4</td><td>0.05914</td><td>0.8</td><td>0.79</td><td>562</td><td>6</td><td>564</td><td>6</td><td>572</td><td>18</td><td>98</td></tr><tr><td>BB16-7</td><td>20668</td><td>5886</td><td>523</td><td>0.35</td><td>0.15</td><td>0.09008</td><td>1.1</td><td>0.7315</td><td>1.4</td><td>0.05890</td><td>0.8</td><td>0.80</td><td>556</td><td>6</td><td>557</td><td>6</td><td>563</td><td>18</td><td>99</td></tr><tr><td>BB16-8</td><td>19610</td><td>5637</td><td>506</td><td>0.35</td><td>0.01</td><td>0.09101</td><td>1.1</td><td>0.7401</td><td>1.3</td><td>0.05898</td><td>0.8</td><td>0.83</td><td>561</td><td>6</td><td>562</td><td>6</td><td>566</td><td>16</td><td>99</td></tr><tr><td>BB16-9</td><td>19025</td><td>5573</td><td>494</td><td>0.35</td><td>0.18</td><td>0.08977</td><td>1.1</td><td>0.7295</td><td>1.4</td><td>0.05894</td><td>0.9</td><td>0.78</td><td>554</td><td>6</td><td>556</td><td>6</td><td>565</td><td>19</td><td>98</td></tr><tr><td>BB16-10</td><td>19577</td><td>5695</td><td>510</td><td>0.36</td><td>0.40</td><td>0.09086</td><td>1.1</td><td>0.7336</td><td>3.4</td><td>0.05856</td><td>3.2</td><td>0.32</td><td>561</td><td>6</td><td>559</td><td>15</td><td>551</td><td>70</td><td>102</td></tr><tr><td>BB16-11</td><td>18476</td><td>5593</td><td>498</td><td>0.35</td><td>b.d.</td><td>0.09040</td><td>1.1</td><td>0.7377</td><td>1.4</td><td>0.05918</td><td>0.9</td><td>0.77</td><td>558</td><td>6</td><td>561</td><td>6</td><td>574</td><td>20</td><td>97</td></tr><tr><td>BB16-12</td><td>18840</td><td>5670</td><td>506</td><td>0.36</td><td>0.16</td><td>0.09037</td><td>1.1</td><td>0.7356</td><td>1.5</td><td>0.05903</td><td>0.9</td><td>0.76</td><td>558</td><td>6</td><td>560</td><td>6</td><td>568</td><td>21</td><td>98</td></tr><tr><td>BB16-13</td><td>18033</td><td>5700</td><td>515</td><td>0.35</td><td>b.d.</td><td>0.09165</td><td>1.1</td><td>0.7445</td><td>1.4</td><td>0.05891</td><td>0.9</td><td>0.79</td><td>565</td><td>6</td><td>565</td><td>6</td><td>564</td><td>19</td><td>100</td></tr></tbody></table>

Spot size = 30µm; depth of crater ~20µm. <sup>206</sup>Pb/<sup>238</sup>U error is the quadratic additions of the within run precision (2 SE) and the external reproducibility (2 SD) of the reference zircon.

<sup>207</sup>Pb/<sup>206</sup>Pb error propagation (<sup>207</sup>Pb signal dependent) following Gerdes & Zeh (2009). <sup>207</sup>Pb/<sup>235</sup>U error is the quadratic addition of the <sup>207</sup>Pb/<sup>206</sup>Pb and <sup>206</sup>Pb/<sup>238</sup>U uncertainty.

<sup>a</sup>Within run background-corrected mean <sup>207</sup>Pb signal in cps (counts per second).

<sup>b</sup> U and Pb content and Th/U ratio were calculated relative to GJ-1 reference zircon.

<sup>c</sup> percentage of the common Pb on the <sup>206</sup>Pb. b.d. = below detection limit.

<sup>d</sup> corrected for background, within-run Pb/U fractionation (in case of <sup>206</sup>Pb/<sup>238</sup>U) and subsequently normalised to GJ-1 (ID-TIMS value/measured value);

<sup>207</sup>Pb/<sup>235</sup>U calculated using <sup>207</sup>Pb/<sup>206</sup>Pb/(<sup>238</sup>U/<sup>206</sup>Pb*1/137.88)

<sup>e</sup> rho is the <sup>206</sup>Pb/<sup>238</sup>U/<sup>207</sup>Pb/<sup>235</sup>U error correlation coefficient.

<sup>f</sup> degree of concordance = <sup>206</sup>Pb/<sup>238</sup>U age / <sup>207</sup>Pb/<sup>206</sup>Pb age x 100
<table><caption>Table S4: Results of LA-ICP-MS zircon U-Pb analyses performed during the sessions at GUF</caption><thead><tr><th>grain</th><th><sup>207</sup>Pb<sup>a</sup><br>(cps)</th><th>U<sup>b</sup><br>(ppm)</th><th>Pb<sup>b</sup><br>(ppm)</th><th><u>Th</u><sup>b</sup><br>U</th><th><sup>206</sup>Pbc<sup>c</sup><br>(%)</th><th><sup>206</sup>Pb<sup>d</sup><br><sup>238</sup>U</th><th>±2s<br>(%)</th><th><sup>207</sup>Pb<sup>d</sup><br><sup>235</sup>U</th><th>±2s<br>(%)</th><th><sup>207</sup>Pb<sup>d</sup><br><sup>206</sup>Pb</th><th>±2s<br>(%)</th><th>rho<sup>e</sup></th><th><sup>206</sup>Pb<br><sup>238</sup>U</th><th>±2s<br>(Ma)</th><th><sup>207</sup>Pb<br><sup>235</sup>U</th><th>±2s<br>(Ma)</th><th><sup>207</sup>Pb<br><sup>206</sup>Pb</th><th>±2s<br>(Ma)</th><th>conc.<sup>f</sup><br>(%)</th></tr></thead><tbody><tr><td colspan="21"><em>Seq.1</em></td></tr><tr><td colspan="21"><strong>RV-1 Riverie tonalite</strong></td></tr><tr><td>a585</td><td>8430</td><td>2826</td><td>204</td><td>0.19</td><td>0.51</td><td>0.07213</td><td>1.7</td><td>0.6911</td><td>2.1</td><td>0.06949</td><td>1.3</td><td>0.80</td><td>449</td><td>7</td><td>533</td><td>9</td><td>913</td><td>26</td><td>49</td></tr><tr><td>a586</td><td>10989</td><td>3594</td><td>309</td><td>0.33</td><td>0.52</td><td>0.08485</td><td>1.4</td><td>0.7847</td><td>1.8</td><td>0.06707</td><td>1.2</td><td>0.78</td><td>525</td><td>7</td><td>588</td><td>8</td><td>840</td><td>24</td><td>63</td></tr><tr><td>a587</td><td>5431</td><td>1877</td><td>158</td><td>0.24</td><td>0.80</td><td>0.08644</td><td>1.8</td><td>0.7115</td><td>2.2</td><td>0.05969</td><td>1.3</td><td>0.80</td><td>534</td><td>9</td><td>546</td><td>9</td><td>593</td><td>29</td><td>90</td></tr><tr><td>a588</td><td>5922</td><td>2264</td><td>182</td><td>0.27</td><td>0.42</td><td>0.08220</td><td>1.9</td><td>0.6633</td><td>2.3</td><td>0.05852</td><td>1.2</td><td>0.85</td><td>509</td><td>9</td><td>517</td><td>9</td><td>549</td><td>26</td><td>93</td></tr><tr><td>a589</td><td>9900</td><td>4484</td><td>281</td><td>0.11</td><td>0.83</td><td>0.06550</td><td>1.6</td><td>0.5542</td><td>1.9</td><td>0.06136</td><td>1.1</td><td>0.83</td><td>409</td><td>6</td><td>448</td><td>7</td><td>652</td><td>23</td><td>63</td></tr><tr><td>a590</td><td>6832</td><td>2423</td><td>201</td><td>0.17</td><td>0.25</td><td>0.08686</td><td>1.6</td><td>0.7028</td><td>2.4</td><td>0.05869</td><td>1.7</td><td>0.68</td><td>537</td><td>8</td><td>540</td><td>10</td><td>556</td><td>38</td><td>97</td></tr><tr><td>a595</td><td>6912</td><td>1986</td><td>171</td><td>0.26</td><td>b.d.</td><td>0.08865</td><td>1.8</td><td>0.7287</td><td>2.2</td><td>0.05962</td><td>1.3</td><td>0.80</td><td>548</td><td>9</td><td>556</td><td>9</td><td>590</td><td>29</td><td>93</td></tr><tr><td>a596</td><td>4811</td><td>1127</td><td>95</td><td>0.18</td><td>b.d.</td><td>0.08795</td><td>2.2</td><td>0.7001</td><td>2.7</td><td>0.05774</td><td>1.6</td><td>0.81</td><td>543</td><td>11</td><td>539</td><td>11</td><td>520</td><td>35</td><td>105</td></tr><tr><td>a598</td><td>9600</td><td>3426</td><td>288</td><td>0.17</td><td>0.31</td><td>0.08827</td><td>1.5</td><td>0.7162</td><td>1.9</td><td>0.05885</td><td>1.2</td><td>0.78</td><td>545</td><td>8</td><td>548</td><td>8</td><td>562</td><td>26</td><td>97</td></tr><tr><td colspan="21"><em>Seq.2</em></td></tr><tr><td colspan="21"><strong>RV-1 Riverie tonalite</strong></td></tr><tr><td>a06</td><td>9688</td><td>2655</td><td>222</td><td>0.18</td><td>b.d.</td><td>0.08766</td><td>1.1</td><td>0.7075</td><td>1.8</td><td>0.05854</td><td>1.4</td><td>0.63</td><td>542</td><td>6</td><td>543</td><td>8</td><td>550</td><td>31</td><td>99</td></tr><tr><td>a08</td><td>18090</td><td>4995</td><td>426</td><td>0.25</td><td>b.d.</td><td>0.08814</td><td>1.2</td><td>0.7159</td><td>1.7</td><td>0.05891</td><td>1.3</td><td>0.68</td><td>545</td><td>6</td><td>548</td><td>7</td><td>564</td><td>28</td><td>97</td></tr><tr><td>a09</td><td>6981</td><td>1930</td><td>166</td><td>0.29</td><td>b.d.</td><td>0.08847</td><td>1.3</td><td>0.7186</td><td>1.9</td><td>0.05891</td><td>1.4</td><td>0.67</td><td>547</td><td>7</td><td>550</td><td>8</td><td>564</td><td>31</td><td>97</td></tr><tr><td>a10</td><td>25713</td><td>7190</td><td>622</td><td>0.45</td><td>0.12</td><td>0.08625</td><td>1.1</td><td>0.7012</td><td>1.3</td><td>0.05896</td><td>0.7</td><td>0.83</td><td>533</td><td>6</td><td>539</td><td>5</td><td>566</td><td>16</td><td>94</td></tr><tr><td>a11</td><td>20421</td><td>6176</td><td>496</td><td>0.20</td><td>0.60</td><td>0.08348</td><td>1.1</td><td>0.6864</td><td>1.7</td><td>0.05963</td><td>1.3</td><td>0.67</td><td>517</td><td>6</td><td>531</td><td>7</td><td>590</td><td>27</td><td>88</td></tr><tr><td>a12</td><td>24433</td><td>6250</td><td>491</td><td>0.14</td><td>0.30</td><td>0.08257</td><td>1.4</td><td>0.6855</td><td>1.9</td><td>0.06021</td><td>1.2</td><td>0.75</td><td>511</td><td>7</td><td>530</td><td>8</td><td>611</td><td>26</td><td>84</td></tr><tr><td>a13</td><td>13206</td><td>3800</td><td>323</td><td>0.26</td><td>0.22</td><td>0.08766</td><td>1.3</td><td>0.7219</td><td>1.9</td><td>0.05973</td><td>1.3</td><td>0.72</td><td>542</td><td>7</td><td>552</td><td>8</td><td>594</td><td>28</td><td>91</td></tr><tr><td>a14</td><td>53651</td><td>14479</td><td>901</td><td>0.16</td><td>3.07</td><td>0.05980</td><td>1.6</td><td>0.6609</td><td>7.8</td><td>0.08015</td><td>7.7</td><td>0.20</td><td>374</td><td>6</td><td>515</td><td>32</td><td>1201</td><td>151</td><td>31</td></tr><tr><td>a15</td><td>14078</td><td>3741</td><td>330</td><td>0.38</td><td>0.11</td><td>0.08869</td><td>1.1</td><td>0.7250</td><td>1.5</td><td>0.05929</td><td>1.0</td><td>0.73</td><td>548</td><td>6</td><td>554</td><td>6</td><td>578</td><td>22</td><td>95</td></tr><tr><td>a16</td><td>23141</td><td>6227</td><td>388</td><td>0.14</td><td>2.51</td><td>0.06080</td><td>1.4</td><td>0.6388</td><td>3.4</td><td>0.07619</td><td>3.1</td><td>0.40</td><td>381</td><td>5</td><td>502</td><td>14</td><td>1100</td><td>62</td><td>35</td></tr><tr><td>a17</td><td>5766</td><td>1552</td><td>133</td><td>0.24</td><td>b.d.</td><td>0.08882</td><td>1.2</td><td>0.7193</td><td>1.9</td><td>0.05874</td><td>1.5</td><td>0.60</td><td>549</td><td>6</td><td>550</td><td>8</td><td>557</td><td>34</td><td>98</td></tr><tr><td>a18</td><td>11666</td><td>3173</td><td>268</td><td>0.16</td><td>0.37</td><td>0.08893</td><td>1.1</td><td>0.7145</td><td>1.6</td><td>0.05827</td><td>1.2</td><td>0.67</td><td>549</td><td>6</td><td>547</td><td>7</td><td>540</td><td>26</td><td>102</td></tr><tr><td>a19</td><td>26879</td><td>7211</td><td>636</td><td>0.43</td><td>0.34</td><td>0.08793</td><td>1.1</td><td>0.7199</td><td>1.5</td><td>0.05938</td><td>1.0</td><td>0.76</td><td>543</td><td>6</td><td>551</td><td>6</td><td>581</td><td>21</td><td>93</td></tr><tr><td>a20</td><td>8492</td><td>2252</td><td>193</td><td>0.34</td><td>b.d.</td><td>0.08675</td><td>1.9</td><td>0.6913</td><td>2.3</td><td>0.05780</td><td>1.4</td><td>0.80</td><td>536</td><td>10</td><td>534</td><td>10</td><td>522</td><td>31</td><td>103</td></tr><tr><td>a21</td><td>15679</td><td>4029</td><td>342</td><td>0.18</td><td>b.d.</td><td>0.08871</td><td>1.2</td><td>0.7193</td><td>1.5</td><td>0.05881</td><td>0.9</td><td>0.81</td><td>548</td><td>6</td><td>550</td><td>6</td><td>560</td><td>19</td><td>98</td></tr><tr><td>a22</td><td>18932</td><td>4363</td><td>397</td><td>0.33</td><td>0.73</td><td>0.08880</td><td>1.3</td><td>0.8837</td><td>2.8</td><td>0.07218</td><td>2.5</td><td>0.45</td><td>548</td><td>7</td><td>643</td><td>14</td><td>991</td><td>51</td><td>55</td></tr><tr><td>a23</td><td>12437</td><td>3210</td><td>271</td><td>0.20</td><td>0.13</td><td>0.08753</td><td>1.2</td><td>0.7460</td><td>2.1</td><td>0.06181</td><td>1.7</td><td>0.57</td><td>541</td><td>6</td><td>566</td><td>9</td><td>668</td><td>37</td><td>81</td></tr><tr><td>a24</td><td>13707</td><td>3788</td><td>320</td><td>0.18</td><td>b.d.</td><td>0.08846</td><td>1.4</td><td>0.7163</td><td>2.2</td><td>0.05873</td><td>1.8</td><td>0.61</td><td>546</td><td>7</td><td>548</td><td>9</td><td>557</td><td>39</td><td>98</td></tr><tr><td>a25</td><td>10735</td><td>3021</td><td>255</td><td>0.21</td><td>0.20</td><td>0.08822</td><td>1.1</td><td>0.7120</td><td>1.5</td><td>0.05853</td><td>1.0</td><td>0.73</td><td>545</td><td>6</td><td>546</td><td>6</td><td>550</td><td>23</td><td>99</td></tr><tr><td>a26</td><td>20787</td><td>6006</td><td>425</td><td>0.52</td><td>1.34</td><td>0.06922</td><td>1.4</td><td>0.6544</td><td>2.5</td><td>0.06857</td><td>2.1</td><td>0.55</td><td>431</td><td>6</td><td>511</td><td>10</td><td>886</td><td>43</td><td>49</td></tr><tr><td>a30</td><td>7549</td><td>2271</td><td>180</td><td>0.17</td><td>0.19</td><td>0.08321</td><td>1.2</td><td>0.6680</td><td>1.9</td><td>0.05822</td><td>1.5</td><td>0.62</td><td>515</td><td>6</td><td>519</td><td>8</td><td>538</td><td>32</td><td>96</td></tr><tr><td>a31</td><td>12129</td><td>3529</td><td>300</td><td>0.23</td><td>0.08</td><td>0.08827</td><td>1.3</td><td>0.7193</td><td>1.9</td><td>0.05910</td><td>1.3</td><td>0.70</td><td>545</td><td>7</td><td>550</td><td>8</td><td>571</td><td>29</td><td>96</td></tr><tr><td>a39</td><td>9017</td><td>2542</td><td>219</td><td>0.35</td><td>0.56</td><td>0.08744</td><td>1.2</td><td>0.7084</td><td>1.9</td><td>0.05876</td><td>1.5</td><td>0.60</td><td>540</td><td>6</td><td>544</td><td>8</td><td>558</td><td>34</td><td>97</td></tr><tr><td>a40</td><td>11338</td><td>3210</td><td>276</td><td>0.30</td><td>0.05</td><td>0.08804</td><td>1.1</td><td>0.7132</td><td>1.6</td><td>0.05875</td><td>1.2</td><td>0.69</td><td>544</td><td>6</td><td>547</td><td>7</td><td>558</td><td>25</td><td>97</td></tr><tr><td>a41</td><td>19538</td><td>5463</td><td>449</td><td>0.26</td><td>0.14</td><td>0.08474</td><td>1.1</td><td>0.6879</td><td>1.5</td><td>0.05888</td><td>1.0</td><td>0.75</td><td>524</td><td>6</td><td>532</td><td>6</td><td>562</td><td>21</td><td>93</td></tr><tr><td>a42</td><td>6893</td><td>1945</td><td>165</td><td>0.24</td><td>0.17</td><td>0.08771</td><td>1.1</td><td>0.7159</td><td>1.9</td><td>0.05920</td><td>1.5</td><td>0.62</td><td>542</td><td>6</td><td>548</td><td>8</td><td>574</td><td>32</td><td>94</td></tr><tr><td>a43</td><td>16084</td><td>4535</td><td>383</td><td>0.22</td><td>0.37</td><td>0.08791</td><td>1.1</td><td>0.7102</td><td>1.6</td><td>0.05859</td><td>1.2</td><td>0.67</td><td>543</td><td>6</td><td>545</td><td>7</td><td>552</td><td>26</td><td>98</td></tr><tr><td>a44</td><td>15981</td><td>4483</td><td>379</td><td>0.28</td><td>b.d.</td><td>0.08661</td><td>1.1</td><td>0.7178</td><td>1.8</td><td>0.06011</td><td>1.4</td><td>0.61</td><td>535</td><td>6</td><td>549</td><td>8</td><td>607</td><td>31</td><td>88</td></tr><tr><td>a45</td><td>12947</td><td>3444</td><td>284</td><td>0.33</td><td>0.02</td><td>0.08367</td><td>1.2</td><td>0.6817</td><td>2.1</td><td>0.05909</td><td>1.8</td><td>0.55</td><td>518</td><td>6</td><td>528</td><td>9</td><td>570</td><td>39</td><td>91</td></tr><tr><td>a46</td><td>22829</td><td>6172</td><td>520</td><td>0.24</td><td>0.14</td><td>0.08721</td><td>1.2</td><td>0.7145</td><td>1.5</td><td>0.05942</td><td>0.9</td><td>0.82</td><td>539</td><td>6</td><td>547</td><td>6</td><td>583</td><td>19</td><td>93</td></tr><tr><td>a47</td><td>12283</td><td>3383</td><td>296</td><td>0.44</td><td>0.37</td><td>0.08575</td><td>1.1</td><td>0.7361</td><td>1.8</td><td>0.06226</td><td>1.5</td><td>0.61</td><td>530</td><td>6</td><td>560</td><td>8</td><td>683</td><td>31</td><td>78</td></tr></tbody></table>
<table><caption>Table S4 (cont.): Results of LA-ICP-MS zircon U-Pb analyses performed during the sessions at GUF</caption><thead><tr><th>grain</th><th><sup>207</sup>Pb<sup>a</sup><br>(cps)</th><th>U<sup>b</sup><br>(ppm)</th><th>Pb<sup>b</sup><br>(ppm)</th><th>Th<sup>b</sup><br>U</th><th><sup>206</sup>Pbc<sup>c</sup><br>(%)</th><th><sup>206</sup>Pbd<sup>d</sup><br><sup>238</sup>U</th><th>±2s<br>(%)</th><th><sup>207</sup>Pbd<sup>d</sup><br><sup>235</sup>U</th><th>±2s<br>(%)</th><th><sup>207</sup>Pbd<sup>d</sup><br><sup>206</sup>Pb</th><th>±2s<br>(%)</th><th>rho<sup>e</sup></th><th><sup>206</sup>Pb<br><sup>238</sup>U</th><th>±2s<br>(Ma)</th><th><sup>207</sup>Pb<br><sup>235</sup>U</th><th>±2s<br>(Ma)</th><th><sup>207</sup>Pb<br><sup>206</sup>Pb</th><th>±2s<br>(Ma)</th><th>conc.<sup>f</sup><br>(%)</th></tr></thead><tbody><tr><td colspan="21"><strong>RV-2 Riverie tonalite</strong></td></tr><tr><td>a48</td><td>25583</td><td>6386</td><td>548</td><td>0.35</td><td>b.d.</td><td>0.08671</td><td>1.2</td><td>0.7024</td><td>1.4</td><td>0.05875</td><td>0.8</td><td>0.83</td><td>536</td><td>6</td><td>540</td><td>6</td><td>558</td><td>17</td><td>96</td></tr><tr><td>a49</td><td>23129</td><td>6639</td><td>560</td><td>0.30</td><td>0.13</td><td>0.08650</td><td>1.0</td><td>0.7019</td><td>1.3</td><td>0.05885</td><td>0.8</td><td>0.80</td><td>535</td><td>5</td><td>540</td><td>5</td><td>561</td><td>17</td><td>95</td></tr><tr><td>a50</td><td>20688</td><td>6456</td><td>491</td><td>0.23</td><td>0.82</td><td>0.07800</td><td>1.1</td><td>0.7203</td><td>2.4</td><td>0.06697</td><td>2.1</td><td>0.48</td><td>484</td><td>5</td><td>551</td><td>10</td><td>837</td><td>43</td><td>58</td></tr><tr><td>a52</td><td>9945</td><td>2884</td><td>242</td><td>0.15</td><td>b.d.</td><td>0.08845</td><td>1.3</td><td>0.7166</td><td>1.7</td><td>0.05876</td><td>1.2</td><td>0.74</td><td>546</td><td>7</td><td>549</td><td>7</td><td>558</td><td>25</td><td>98</td></tr><tr><td>a53</td><td>12588</td><td>3570</td><td>296</td><td>0.16</td><td>b.d.</td><td>0.08760</td><td>1.3</td><td>0.7100</td><td>1.6</td><td>0.05878</td><td>1.1</td><td>0.76</td><td>541</td><td>7</td><td>545</td><td>7</td><td>559</td><td>23</td><td>97</td></tr><tr><td>a54</td><td>14985</td><td>6119</td><td>503</td><td>0.17</td><td>0.10</td><td>0.08675</td><td>1.1</td><td>0.6978</td><td>1.6</td><td>0.05834</td><td>1.2</td><td>0.68</td><td>536</td><td>6</td><td>537</td><td>7</td><td>543</td><td>25</td><td>99</td></tr><tr><td>a55</td><td>8856</td><td>2546</td><td>213</td><td>0.15</td><td>b.d.</td><td>0.08831</td><td>1.3</td><td>0.7163</td><td>1.9</td><td>0.05882</td><td>1.3</td><td>0.72</td><td>546</td><td>7</td><td>548</td><td>8</td><td>561</td><td>29</td><td>97</td></tr><tr><td>a56</td><td>9125</td><td>1713</td><td>143</td><td>0.35</td><td>b.d.</td><td>0.08398</td><td>1.3</td><td>0.6815</td><td>1.8</td><td>0.05885</td><td>1.3</td><td>0.72</td><td>520</td><td>6</td><td>528</td><td>7</td><td>562</td><td>27</td><td>93</td></tr><tr><td>a57</td><td>9625</td><td>2758</td><td>235</td><td>0.20</td><td>0.15</td><td>0.08902</td><td>1.4</td><td>0.7256</td><td>2.0</td><td>0.05912</td><td>1.5</td><td>0.68</td><td>550</td><td>7</td><td>554</td><td>9</td><td>571</td><td>32</td><td>96</td></tr><tr><td>a58</td><td>28610</td><td>7910</td><td>688</td><td>0.31</td><td>0.15</td><td>0.08861</td><td>1.2</td><td>0.7425</td><td>1.5</td><td>0.06078</td><td>0.8</td><td>0.82</td><td>547</td><td>6</td><td>564</td><td>6</td><td>631</td><td>18</td><td>87</td></tr><tr><td>a59</td><td>21735</td><td>6533</td><td>537</td><td>0.25</td><td>b.d.</td><td>0.08519</td><td>1.2</td><td>0.6896</td><td>1.9</td><td>0.05871</td><td>1.4</td><td>0.67</td><td>527</td><td>6</td><td>533</td><td>8</td><td>556</td><td>30</td><td>95</td></tr><tr><td>a60</td><td>17491</td><td>5636</td><td>392</td><td>0.37</td><td>0.31</td><td>0.07033</td><td>1.6</td><td>0.5948</td><td>2.1</td><td>0.06134</td><td>1.4</td><td>0.74</td><td>438</td><td>7</td><td>474</td><td>8</td><td>651</td><td>31</td><td>67</td></tr><tr><td>a61</td><td>20187</td><td>5762</td><td>488</td><td>0.29</td><td>b.d.</td><td>0.08716</td><td>1.1</td><td>0.7050</td><td>1.4</td><td>0.05867</td><td>0.9</td><td>0.78</td><td>539</td><td>6</td><td>542</td><td>6</td><td>555</td><td>19</td><td>97</td></tr><tr><td>a62</td><td>7942</td><td>2271</td><td>194</td><td>0.25</td><td>0.82</td><td>0.08874</td><td>1.4</td><td>0.7105</td><td>2.2</td><td>0.05807</td><td>1.7</td><td>0.64</td><td>548</td><td>7</td><td>545</td><td>9</td><td>532</td><td>36</td><td>103</td></tr><tr><td>a63</td><td>16612</td><td>4685</td><td>399</td><td>0.22</td><td>0.03</td><td>0.08877</td><td>1.2</td><td>0.7183</td><td>1.5</td><td>0.05869</td><td>0.8</td><td>0.83</td><td>548</td><td>6</td><td>550</td><td>6</td><td>556</td><td>18</td><td>99</td></tr><tr><td>a64</td><td>7247</td><td>2086</td><td>178</td><td>0.29</td><td>0.27</td><td>0.08795</td><td>1.2</td><td>0.7041</td><td>2.3</td><td>0.05806</td><td>1.9</td><td>0.53</td><td>543</td><td>6</td><td>541</td><td>10</td><td>532</td><td>42</td><td>102</td></tr><tr><td>a65</td><td>41973</td><td>18749</td><td>990</td><td>0.02</td><td>0.11</td><td>0.05764</td><td>1.2</td><td>0.4285</td><td>1.4</td><td>0.05392</td><td>0.7</td><td>0.85</td><td>361</td><td>4</td><td>362</td><td>4</td><td>368</td><td>17</td><td>98</td></tr><tr><td>a66</td><td>48222</td><td>14744</td><td>771</td><td>0.04</td><td>0.38</td><td>0.05638</td><td>1.3</td><td>0.4369</td><td>1.6</td><td>0.05620</td><td>1.0</td><td>0.78</td><td>354</td><td>4</td><td>368</td><td>5</td><td>460</td><td>22</td><td>77</td></tr><tr><td>a72</td><td>17516</td><td>5068</td><td>435</td><td>0.25</td><td>b.d.</td><td>0.08880</td><td>1.2</td><td>0.7124</td><td>1.6</td><td>0.05819</td><td>1.1</td><td>0.74</td><td>548</td><td>6</td><td>546</td><td>7</td><td>537</td><td>23</td><td>102</td></tr><tr><td>a73</td><td>18478</td><td>5346</td><td>442</td><td>0.20</td><td>b.d.</td><td>0.08649</td><td>1.1</td><td>0.6985</td><td>1.4</td><td>0.05857</td><td>0.9</td><td>0.77</td><td>535</td><td>5</td><td>538</td><td>6</td><td>551</td><td>19</td><td>97</td></tr><tr><td>a74</td><td>10193</td><td>2954</td><td>245</td><td>0.17</td><td>0.48</td><td>0.08726</td><td>1.3</td><td>0.7060</td><td>2.0</td><td>0.05869</td><td>1.6</td><td>0.64</td><td>539</td><td>7</td><td>542</td><td>9</td><td>555</td><td>34</td><td>97</td></tr><tr><td>a75</td><td>20755</td><td>6060</td><td>513</td><td>0.23</td><td>0.18</td><td>0.08812</td><td>1.2</td><td>0.7119</td><td>1.5</td><td>0.05859</td><td>0.9</td><td>0.79</td><td>544</td><td>6</td><td>546</td><td>6</td><td>552</td><td>19</td><td>99</td></tr><tr><td>a76</td><td>17379</td><td>5120</td><td>440</td><td>0.34</td><td>0.19</td><td>0.08738</td><td>1.1</td><td>0.7001</td><td>1.5</td><td>0.05811</td><td>0.9</td><td>0.76</td><td>540</td><td>6</td><td>539</td><td>6</td><td>534</td><td>21</td><td>101</td></tr><tr><td>a79</td><td>8186</td><td>2395</td><td>202</td><td>0.21</td><td>b.d.</td><td>0.08814</td><td>1.2</td><td>0.7185</td><td>1.9</td><td>0.05912</td><td>1.4</td><td>0.65</td><td>545</td><td>6</td><td>550</td><td>8</td><td>571</td><td>31</td><td>95</td></tr><tr><td>a80</td><td>25436</td><td>7531</td><td>634</td><td>0.26</td><td>b.d.</td><td>0.08716</td><td>1.2</td><td>0.6972</td><td>1.4</td><td>0.05802</td><td>0.7</td><td>0.85</td><td>539</td><td>6</td><td>537</td><td>6</td><td>531</td><td>16</td><td>102</td></tr><tr><td>a81</td><td>17242</td><td>4824</td><td>399</td><td>0.25</td><td>b.d.</td><td>0.08547</td><td>1.1</td><td>0.6878</td><td>1.3</td><td>0.05837</td><td>0.8</td><td>0.79</td><td>529</td><td>5</td><td>531</td><td>6</td><td>543</td><td>18</td><td>97</td></tr><tr><td>a82</td><td>16995</td><td>5061</td><td>425</td><td>0.21</td><td>0.01</td><td>0.08761</td><td>1.2</td><td>0.7054</td><td>1.5</td><td>0.05840</td><td>1.0</td><td>0.77</td><td>541</td><td>6</td><td>542</td><td>6</td><td>545</td><td>21</td><td>99</td></tr><tr><td>a83</td><td>11907</td><td>3319</td><td>284</td><td>0.30</td><td>0.34</td><td>0.08768</td><td>1.4</td><td>0.7059</td><td>1.9</td><td>0.05840</td><td>1.2</td><td>0.76</td><td>542</td><td>7</td><td>542</td><td>8</td><td>545</td><td>26</td><td>99</td></tr><tr><td>a84</td><td>12669</td><td>3718</td><td>305</td><td>0.16</td><td>b.d.</td><td>0.08638</td><td>1.2</td><td>0.7084</td><td>1.5</td><td>0.05949</td><td>1.0</td><td>0.76</td><td>534</td><td>6</td><td>544</td><td>6</td><td>585</td><td>22</td><td>91</td></tr><tr><td>a85</td><td>17119</td><td>4992</td><td>419</td><td>0.24</td><td>b.d.</td><td>0.08704</td><td>1.2</td><td>0.6986</td><td>1.5</td><td>0.05821</td><td>1.0</td><td>0.76</td><td>538</td><td>6</td><td>538</td><td>6</td><td>538</td><td>22</td><td>100</td></tr><tr><td>a86</td><td>17862</td><td>4978</td><td>425</td><td>0.24</td><td>0.07</td><td>0.08812</td><td>1.3</td><td>0.7175</td><td>1.6</td><td>0.05905</td><td>0.9</td><td>0.81</td><td>544</td><td>7</td><td>549</td><td>7</td><td>569</td><td>20</td><td>96</td></tr><tr><td>a88</td><td>15424</td><td>2921</td><td>249</td><td>0.20</td><td>0.48</td><td>0.08903</td><td>1.3</td><td>0.7186</td><td>1.8</td><td>0.05854</td><td>1.3</td><td>0.70</td><td>550</td><td>7</td><td>550</td><td>8</td><td>550</td><td>28</td><td>100</td></tr><tr><td>a89</td><td>13516</td><td>5457</td><td>438</td><td>0.13</td><td>b.d.</td><td>0.08513</td><td>1.3</td><td>0.6858</td><td>1.8</td><td>0.05843</td><td>1.2</td><td>0.74</td><td>527</td><td>7</td><td>530</td><td>8</td><td>546</td><td>27</td><td>96</td></tr></tbody></table>

Spot size = 30µm; depth of crater ~20µm. $^{206}$Pb/$^{238}$U error is the quadratic additions of the within run precision (2 SE) and the external reproducibility (2 SD) of the reference zircon.

$^{207}$Pb/$^{206}$Pb error propagation ($^{207}$Pb signal dependent) following Gerdes & Zeh (2009). $^{207}$Pb/$^{235}$U error is the quadratic addition of the $^{207}$Pb/$^{206}$Pb and $^{206}$Pb/$^{238}$U uncertainty.

<sup>a</sup>Within run background-corrected mean $^{207}$Pb signal in cps (counts per second).

<sup>b</sup> U and Pb content and Th/U ratio were calculated relative to GJ-1 reference zircon.

<sup>c</sup> percentage of the common Pb on the $^{206}$Pb. b.d. = below detection limit.

<sup>d</sup> corrected for background, within-run Pb/U fractionation (in case of $^{206}$Pb/$^{238}$U), common Pb using Stacy and Kramers (1975) model Pb composition (specified by a *, see text for discussion) and subsequently normalised to GJ-1 (ID-TIMS value/measured value); $^{207}$Pb/$^{235}$U calculated using $^{207}$Pb/$^{206}$Pb/($^{238}$U/$^{206}$Pb*1/137.88)

<sup>e</sup> rho is the $^{206}$Pb/$^{238}$U/$^{207}$Pb/$^{235}$U error correlation coefficient.

<sup>f</sup> degree of concordance = $^{206}$Pb/$^{238}$U age / $^{207}$Pb/$^{206}$Pb age x 100
<table><caption>Table S5: Results of LA-MC-ICP-MS Lu-Hf analyses of zircon standards performed during the session at GUF</caption><thead><tr><th></th><th>Spot size<br>(µm)</th><th><sup>176</sup>Yb<sup>a</sup><br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>176</sup>Lu<sup>a</sup><br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>178</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>180</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th>Sig<sub>Hf</sub><sup>b</sup><br>(V)</th><th><sup>176</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>176</sup>Hf<sup>c</sup><br><sup>177</sup>Hf<sub>(t)</sub></th><th>εHf<sub>(t)</sub><sup>c</sup></th><th>±2σ<br>(abs.)</th></tr></thead><tbody><tr><td colspan="16"><strong>GJ-1</strong></td></tr><tr><td>GJ1-40-12Jcm_1</td><td>40</td><td>0.0084</td><td>0.0007</td><td>0.00025</td><td>0.00003</td><td>1.46720</td><td>0.00005</td><td>1.88668</td><td>0.00010</td><td>11</td><td><strong>0.281977</strong></td><td>0.000033</td><td>0.281974</td><td>-15.3</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_2</td><td>40</td><td>0.0080</td><td>0.0006</td><td>0.00027</td><td>0.00002</td><td>1.46725</td><td>0.00004</td><td>1.88639</td><td>0.00015</td><td>8</td><td><strong>0.282005</strong></td><td>0.000031</td><td>0.282002</td><td>-14.3</td><td>1.1</td></tr><tr><td>GJ1-40-12Jcm_3</td><td>40</td><td>0.0080</td><td>0.0006</td><td>0.00026</td><td>0.00002</td><td>1.46723</td><td>0.00007</td><td>1.88633</td><td>0.00016</td><td>8</td><td><strong>0.282014</strong></td><td>0.000029</td><td>0.282011</td><td>-14.0</td><td>1.0</td></tr><tr><td>GJ1-40-12Jcm_4</td><td>40</td><td>0.0080</td><td>0.0006</td><td>0.00027</td><td>0.00002</td><td>1.46722</td><td>0.00006</td><td>1.88630</td><td>0.00012</td><td>9</td><td><strong>0.282027</strong></td><td>0.000033</td><td>0.282024</td><td>-13.5</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_5</td><td>40</td><td>0.0076</td><td>0.0006</td><td>0.00026</td><td>0.00002</td><td>1.46727</td><td>0.00006</td><td>1.88650</td><td>0.00019</td><td>7</td><td><strong>0.282001</strong></td><td>0.000034</td><td>0.281998</td><td>-14.4</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_6</td><td>40</td><td>0.0076</td><td>0.0006</td><td>0.00026</td><td>0.00002</td><td>1.46725</td><td>0.00006</td><td>1.88663</td><td>0.00017</td><td>8</td><td><strong>0.282016</strong></td><td>0.000033</td><td>0.282013</td><td>-13.9</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_7</td><td>40</td><td>0.0078</td><td>0.0006</td><td>0.00026</td><td>0.00002</td><td>1.46724</td><td>0.00007</td><td>1.88635</td><td>0.00014</td><td>7</td><td><strong>0.282020</strong></td><td>0.000030</td><td>0.282017</td><td>-13.8</td><td>1.0</td></tr><tr><td>GJ1-40-12Jcm_8</td><td>40</td><td>0.0078</td><td>0.0006</td><td>0.00025</td><td>0.00002</td><td>1.46727</td><td>0.00004</td><td>1.88626</td><td>0.00013</td><td>8</td><td><strong>0.282026</strong></td><td>0.000029</td><td>0.282023</td><td>-13.6</td><td>1.0</td></tr><tr><td>GJ1-40-12Jcm_9</td><td>40</td><td>0.0078</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46729</td><td>0.00006</td><td>1.88630</td><td>0.00014</td><td>8</td><td><strong>0.282021</strong></td><td>0.000033</td><td>0.282018</td><td>-13.7</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_10</td><td>40</td><td>0.0078</td><td>0.0006</td><td>0.00025</td><td>0.00002</td><td>1.46734</td><td>0.00006</td><td>1.88652</td><td>0.00014</td><td>8</td><td><strong>0.282021</strong></td><td>0.000032</td><td>0.282018</td><td>-13.7</td><td>1.1</td></tr><tr><td>GJ1-40-12Jcm_11</td><td>40</td><td>0.0078</td><td>0.0006</td><td>0.00025</td><td>0.00002</td><td>1.46729</td><td>0.00005</td><td>1.88632</td><td>0.00012</td><td>8</td><td><strong>0.282013</strong></td><td>0.000036</td><td>0.282010</td><td>-14.0</td><td>1.3</td></tr><tr><td>GJ1-40-12Jcm_12</td><td>40</td><td>0.0076</td><td>0.0006</td><td>0.00025</td><td>0.00002</td><td>1.46718</td><td>0.00006</td><td>1.88642</td><td>0.00011</td><td>8</td><td><strong>0.282005</strong></td><td>0.000040</td><td>0.282002</td><td>-14.3</td><td>1.4</td></tr><tr><td>GJ1-40-12Jcm_13</td><td>40</td><td>0.0077</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46727</td><td>0.00005</td><td>1.88655</td><td>0.00015</td><td>7</td><td><strong>0.282023</strong></td><td>0.000034</td><td>0.282020</td><td>-13.7</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_14</td><td>40</td><td>0.0074</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46729</td><td>0.00006</td><td>1.88618</td><td>0.00011</td><td>8</td><td><strong>0.282027</strong></td><td>0.000030</td><td>0.282024</td><td>-13.5</td><td>1.1</td></tr><tr><td>GJ1-40-12Jcm_15</td><td>40</td><td>0.0072</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46729</td><td>0.00005</td><td>1.88626</td><td>0.00013</td><td>8</td><td><strong>0.282021</strong></td><td>0.000033</td><td>0.282018</td><td>-13.7</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_16</td><td>40</td><td>0.0074</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46720</td><td>0.00005</td><td>1.88627</td><td>0.00014</td><td>7</td><td><strong>0.282013</strong></td><td>0.000031</td><td>0.282010</td><td>-14.0</td><td>1.1</td></tr><tr><td>GJ1-40-12Jcm_17</td><td>40</td><td>0.0073</td><td>0.0006</td><td>0.00025</td><td>0.00001</td><td>1.46729</td><td>0.00006</td><td>1.88623</td><td>0.00012</td><td>7</td><td><strong>0.282016</strong></td><td>0.000036</td><td>0.282014</td><td>-13.9</td><td>1.3</td></tr><tr><td>GJ1-40-12Jcm_18</td><td>40</td><td>0.0073</td><td>0.0006</td><td>0.00024</td><td>0.00001</td><td>1.46723</td><td>0.00005</td><td>1.88613</td><td>0.00015</td><td>7</td><td><strong>0.282029</strong></td><td>0.000037</td><td>0.282026</td><td>-13.5</td><td>1.3</td></tr><tr><td>GJ1-40-12Jcm_19</td><td>40</td><td>0.0073</td><td>0.0006</td><td>0.00024</td><td>0.00001</td><td>1.46732</td><td>0.00006</td><td>1.88638</td><td>0.00013</td><td>6</td><td><strong>0.282027</strong></td><td>0.000033</td><td>0.282025</td><td>-13.5</td><td>1.2</td></tr><tr><td>GJ1-40-12Jcm_20</td><td>40</td><td>0.0072</td><td>0.0006</td><td>0.00024</td><td>0.00001</td><td>1.46722</td><td>0.00006</td><td>1.88643</td><td>0.00014</td><td>6</td><td><strong>0.281989</strong></td><td>0.000034</td><td>0.281987</td><td>-14.8</td><td>1.2</td></tr><tr><td>GJ1-60-12Jcm_1</td><td>60</td><td>0.0074</td><td>0.0006</td><td>0.00024</td><td>0.00001</td><td>1.46724</td><td>0.00004</td><td>1.88649</td><td>0.00010</td><td>14</td><td><strong>0.282020</strong></td><td>0.000027</td><td>0.282017</td><td>-13.8</td><td>0.9</td></tr><tr><td>GJ1-60-12Jcm_2</td><td>60</td><td>0.0074</td><td>0.0006</td><td>0.00024</td><td>0.00001</td><td>1.46721</td><td>0.00004</td><td>1.88661</td><td>0.00008</td><td>15</td><td><strong>0.282005</strong></td><td>0.000026</td><td>0.282003</td><td>-14.3</td><td>0.9</td></tr><tr><td><strong>Average</strong></td><td></td><td><strong>0.0076</strong></td><td></td><td><strong>0.00025</strong></td><td></td><td><strong>1.46725</strong></td><td></td><td><strong>1.88639</strong></td><td></td><td></td><td><strong>0.282014</strong></td><td></td><td><strong>0.282012</strong></td><td><strong>-14.0</strong></td><td></td></tr><tr><td><strong>2 S.E. (abs.)</strong></td><td></td><td><strong>0.0006</strong></td><td></td><td><strong>0.00002</strong></td><td></td><td><strong>0.00008</strong></td><td></td><td><strong>0.00030</strong></td><td></td><td></td><td><strong>0.000026</strong></td><td></td><td><strong>0.000026</strong></td><td><strong>0.9</strong></td><td></td></tr><tr><td><strong>2 S.E. (%)</strong></td><td></td><td><strong>8</strong></td><td></td><td><strong>7</strong></td><td></td><td><strong>0.006</strong></td><td></td><td><strong>0.02</strong></td><td></td><td></td><td><strong>0.0093</strong></td><td></td><td><strong>0.0093</strong></td><td></td><td></td></tr><tr><td>Reference value</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td><strong>0.282000</strong></td><td>± 23</td><td></td></tr><tr><td colspan="16"><strong>Plešovice</strong></td></tr><tr><td>Pleso-40-12Jcm_1</td><td>40</td><td>0.0066</td><td>0.0005</td><td>0.00014</td><td>0.00001</td><td>1.46722</td><td>0.00006</td><td>1.88643</td><td>0.00012</td><td>10</td><td><strong>0.282472</strong></td><td>0.000031</td><td>0.282471</td><td>-3.6</td><td>1.1</td></tr><tr><td>Pleso-40-12Jcm_2</td><td>40</td><td>0.0071</td><td>0.0006</td><td>0.00015</td><td>0.00001</td><td>1.46723</td><td>0.00004</td><td>1.88653</td><td>0.00011</td><td>11</td><td><strong>0.282483</strong></td><td>0.000031</td><td>0.282482</td><td>-3.2</td><td>1.1</td></tr><tr><td>Pleso-40-12Jcm_3</td><td>40</td><td>0.0072</td><td>0.0006</td><td>0.00015</td><td>0.00001</td><td>1.46728</td><td>0.00006</td><td>1.88646</td><td>0.00012</td><td>11</td><td><strong>0.282474</strong></td><td>0.000032</td><td>0.282473</td><td>-3.5</td><td>1.1</td></tr><tr><td>Pleso-40-12Jcm_4</td><td>40</td><td>0.0071</td><td>0.0006</td><td>0.00014</td><td>0.00001</td><td>1.46727</td><td>0.00004</td><td>1.88662</td><td>0.00009</td><td>12</td><td><strong>0.282470</strong></td><td>0.000029</td><td>0.282469</td><td>-3.7</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_5</td><td>40</td><td>0.0070</td><td>0.0006</td><td>0.00014</td><td>0.00001</td><td>1.46726</td><td>0.00004</td><td>1.88652</td><td>0.00011</td><td>12</td><td><strong>0.282484</strong></td><td>0.000028</td><td>0.282483</td><td>-3.2</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_6</td><td>40</td><td>0.0070</td><td>0.0006</td><td>0.00014</td><td>0.00001</td><td>1.46727</td><td>0.00005</td><td>1.88655</td><td>0.00011</td><td>12</td><td><strong>0.282480</strong></td><td>0.000030</td><td>0.282479</td><td>-3.3</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_7</td><td>40</td><td>0.0068</td><td>0.0005</td><td>0.00014</td><td>0.00001</td><td>1.46724</td><td>0.00005</td><td>1.88644</td><td>0.00013</td><td>11</td><td><strong>0.282478</strong></td><td>0.000029</td><td>0.282477</td><td>-3.4</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_8</td><td>40</td><td>0.0069</td><td>0.0006</td><td>0.00014</td><td>0.00001</td><td>1.46721</td><td>0.00005</td><td>1.88652</td><td>0.00012</td><td>11</td><td><strong>0.282485</strong></td><td>0.000028</td><td>0.282484</td><td>-3.1</td><td>1.0</td></tr></tbody></table>
<table><caption>Table S5 (cont.): Results of LA-MC-ICP-MS Lu–Hf analyses of zircon standards performed during the session at GUF</caption><thead><tr><th></th><th>Spot size<br>(µm)</th><th><sup>176</sup>Yb<sup>a</sup><br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>176</sup>Lu<sup>a</sup><br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>178</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>180</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th>Sig<sub>Hf</sub><sup>b</sup><br>(V)</th><th><sup>176</sup>Hf<br><sup>177</sup>Hf</th><th>±2σ<br>(abs.)</th><th><sup>176</sup>Hf<sup>c</sup><br><sup>177</sup>Hf<sub>(t)</sub></th><th>εHf<sub>(t)</sub><sup>c</sup></th><th>±2σ<br>(abs.)</th></tr></thead><tbody><tr><td>Pleso-40-12Jcm_9</td><td>40</td><td>0.0063</td><td>0.0005</td><td>0.00013</td><td>0.00001</td><td>1.46721</td><td>0.00005</td><td>1.88632</td><td>0.00011</td><td>10</td><td><strong>0.282486</strong></td><td>0.000032</td><td>0.282485</td><td>-3.1</td><td>1.1</td></tr><tr><td>Pleso-40-12Jcm_10</td><td>40</td><td>0.0064</td><td>0.0005</td><td>0.00012</td><td>0.00002</td><td>1.46722</td><td>0.00005</td><td>1.88652</td><td>0.00009</td><td>10</td><td><strong>0.282472</strong></td><td>0.000028</td><td>0.282471</td><td>-3.6</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_11</td><td>40</td><td>0.0069</td><td>0.0005</td><td>0.00014</td><td>0.00001</td><td>1.46722</td><td>0.00004</td><td>1.88625</td><td>0.00010</td><td>10</td><td><strong>0.282478</strong></td><td>0.000028</td><td>0.282477</td><td>-3.4</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_12</td><td>40</td><td>0.0067</td><td>0.0006</td><td>0.00014</td><td>0.00001</td><td>1.46728</td><td>0.00005</td><td>1.88643</td><td>0.00012</td><td>10</td><td><strong>0.282483</strong></td><td>0.000030</td><td>0.282482</td><td>-3.2</td><td>1.1</td></tr><tr><td>Pleso-40-12Jcm_13</td><td>40</td><td>0.0067</td><td>0.0005</td><td>0.00014</td><td>0.00001</td><td>1.46725</td><td>0.00006</td><td>1.88637</td><td>0.00012</td><td>10</td><td><strong>0.282473</strong></td><td>0.000027</td><td>0.282472</td><td>-3.5</td><td>1.0</td></tr><tr><td>Pleso-40-12Jcm_14</td><td>40</td><td>0.0063</td><td>0.0005</td><td>0.00013</td><td>0.00001</td><td>1.46726</td><td>0.00004</td><td>1.88640</td><td>0.00010</td><td>11</td><td><strong>0.282487</strong></td><td>0.000031</td><td>0.282486</td><td>-3.1</td><td>1.1</td></tr><tr><td><strong>Average</strong></td><td></td><td><strong>0.0068</strong></td><td></td><td><strong>0.00014</strong></td><td></td><td><strong>1.46724</strong></td><td></td><td><strong>1.88645</strong></td><td></td><td></td><td><strong>0.282479</strong></td><td></td><td><strong>0.282478</strong></td><td><strong>-3.3</strong></td><td></td></tr><tr><td><strong>2 S.E. (abs.)</strong></td><td></td><td><strong>0.0006</strong></td><td></td><td><strong>0.00002</strong></td><td></td><td><strong>0.00005</strong></td><td></td><td><strong>0.00020</strong></td><td></td><td></td><td><strong>0.000012</strong></td><td></td><td><strong>0.000012</strong></td><td><strong>0.4</strong></td><td></td></tr><tr><td><strong>2 S.E. (%)</strong></td><td></td><td><strong>9</strong></td><td></td><td><strong>12</strong></td><td></td><td><strong>0.004</strong></td><td></td><td><strong>0.01</strong></td><td></td><td></td><td><strong>0.0041</strong></td><td></td><td><strong>0.0041</strong></td><td></td><td></td></tr><tr><td>Reference value</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td><strong>0.282482</strong></td><td>± 13</td><td></td></tr><tr><td><strong>Temora</strong></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>TM-40-12Jcm_1</td><td>40</td><td>0.0190</td><td>0.0027</td><td>0.00066</td><td>0.00008</td><td>1.46746</td><td>0.00013</td><td>1.88586</td><td>0.00043</td><td>9</td><td><strong>0.282710</strong></td><td>0.000046</td><td>0.282705</td><td>6.5</td><td>1.6</td></tr><tr><td>TM-40-12Jcm_2</td><td>40</td><td>0.0391</td><td>0.0033</td><td>0.00130</td><td>0.00008</td><td>1.46717</td><td>0.00004</td><td>1.88639</td><td>0.00012</td><td>9</td><td><strong>0.282692</strong></td><td>0.000034</td><td>0.282682</td><td>5.7</td><td>1.2</td></tr><tr><td>TM-40-12Jcm_3</td><td>40</td><td>0.0408</td><td>0.0034</td><td>0.00130</td><td>0.00008</td><td>1.46726</td><td>0.00005</td><td>1.88636</td><td>0.00014</td><td>9</td><td><strong>0.282688</strong></td><td>0.000031</td><td>0.282678</td><td>5.5</td><td>1.1</td></tr><tr><td>TM-40-12Jcm_4</td><td>40</td><td>0.0416</td><td>0.0041</td><td>0.00128</td><td>0.00010</td><td>1.46719</td><td>0.00004</td><td>1.88649</td><td>0.00013</td><td>9</td><td><strong>0.282695</strong></td><td>0.000030</td><td>0.282685</td><td>5.8</td><td>1.1</td></tr><tr><td>TM-40-12Jcm_5</td><td>40</td><td>0.0282</td><td>0.0025</td><td>0.00093</td><td>0.00006</td><td>1.46727</td><td>0.00007</td><td>1.88642</td><td>0.00016</td><td>9</td><td><strong>0.282684</strong></td><td>0.000030</td><td>0.282677</td><td>5.5</td><td>1.0</td></tr><tr><td>TM-40-12Jcm_6</td><td>40</td><td>0.0240</td><td>0.0019</td><td>0.00078</td><td>0.00005</td><td>1.46733</td><td>0.00008</td><td>1.88626</td><td>0.00024</td><td>9</td><td><strong>0.282715</strong></td><td>0.000040</td><td>0.282709</td><td>6.6</td><td>1.4</td></tr><tr><td>TM-40-12Jcm_7</td><td>40</td><td>0.0190</td><td>0.0015</td><td>0.00066</td><td>0.00004</td><td>1.46727</td><td>0.00007</td><td>1.88633</td><td>0.00013</td><td>7</td><td><strong>0.282702</strong></td><td>0.000034</td><td>0.282697</td><td>6.2</td><td>1.2</td></tr><tr><td>TM-40-12Jcm_8</td><td>40</td><td>0.0196</td><td>0.0017</td><td>0.00061</td><td>0.00004</td><td>1.46731</td><td>0.00006</td><td>1.88632</td><td>0.00014</td><td>8</td><td><strong>0.282695</strong></td><td>0.000031</td><td>0.282690</td><td>6.0</td><td>1.1</td></tr><tr><td>TM-40-12Jcm_9</td><td>40</td><td>0.0190</td><td>0.0015</td><td>0.00066</td><td>0.00004</td><td>1.46725</td><td>0.00007</td><td>1.88631</td><td>0.00012</td><td>7</td><td><strong>0.282696</strong></td><td>0.000030</td><td>0.282691</td><td>6.0</td><td>1.1</td></tr><tr><td>TM-40-12Jcm_10</td><td>40</td><td>0.0152</td><td>0.0013</td><td>0.00053</td><td>0.00004</td><td>1.46723</td><td>0.00004</td><td>1.88623</td><td>0.00011</td><td>8</td><td><strong>0.282682</strong></td><td>0.000033</td><td>0.282678</td><td>5.6</td><td>1.2</td></tr><tr><td>TM-40-12Jcm_11</td><td>40</td><td>0.0161</td><td>0.0014</td><td>0.00055</td><td>0.00004</td><td>1.46728</td><td>0.00007</td><td>1.88632</td><td>0.00016</td><td>7</td><td><strong>0.282682</strong></td><td>0.000036</td><td>0.282678</td><td>5.5</td><td>1.3</td></tr><tr><td>TM-40-12Jcm_12</td><td>40</td><td>0.0249</td><td>0.0021</td><td>0.00090</td><td>0.00006</td><td>1.46738</td><td>0.00010</td><td>1.88620</td><td>0.00027</td><td>8</td><td><strong>0.282701</strong></td><td>0.000041</td><td>0.282694</td><td>6.1</td><td>1.4</td></tr><tr><td><strong>Average</strong></td><td></td><td><strong>0.0255</strong></td><td></td><td><strong>0.00085</strong></td><td></td><td><strong>1.46728</strong></td><td></td><td><strong>1.88629</strong></td><td></td><td></td><td><strong>0.282695</strong></td><td></td><td><strong>0.282689</strong></td><td><strong>5.9</strong></td><td></td></tr><tr><td><strong>2 S.E. (abs.)</strong></td><td></td><td><strong>0.0195</strong></td><td></td><td><strong>0.00059</strong></td><td></td><td><strong>0.00016</strong></td><td></td><td><strong>0.00031</strong></td><td></td><td></td><td><strong>0.000021</strong></td><td></td><td><strong>0.000022</strong></td><td><strong>0.8</strong></td><td></td></tr><tr><td><strong>2 S.E. (%)</strong></td><td></td><td><strong>76</strong></td><td></td><td><strong>70</strong></td><td></td><td><strong>0.011</strong></td><td></td><td><strong>0.02</strong></td><td></td><td></td><td><strong>0.0075</strong></td><td></td><td><strong>0.0078</strong></td><td></td><td></td></tr><tr><td>Reference value</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td><strong>0.282686</strong></td><td>± 8</td><td></td></tr></tbody></table>

(a) $^{176}$Yb/$^{177}$Hf = ($^{176}$Yb/$^{177}$Yb)$_{true}$ x ($^{178}$Yb/$^{177}$Hf)$_{meas}$ x (M$_{173(Yb)}/M_{177(Hf)})^{b(Hf)}$, b(Hf) = ln($^{179}$Hf/$^{177}$Hf$_{true}$ / $^{179}$Hf/$^{177}$Hf$_{measured}$) / ln (M$_{179(Hf)}/M_{177(Hf)}), M=mass of respective isotope. The $^{176}$Lu/$^{177}$Hf were calculated in a similar way by using the $^{175}$Lu/$^{177}$Hf and b(Yb).

(b) Mean Hf signal in volt.

(c) Initial $^{176}$Hf/$^{177}$Hf and eHf calculated using the reference age for each zircon standard, and the CHUR parameters: $^{176}$Lu/$^{177}$Hf = 0.0336, and $^{176}$Hf/$^{177}$Hf = 0.282785 (Bouvier et al., 2008).