The Variscan Upper Allochthon is a continental-affinity terrane that recorded a Cambrian-Ediacara... more The Variscan Upper Allochthon is a continental-affinity terrane that recorded a Cambrian-Ediacaran magmatic arc generation, a subsequent transition to a passive margin, and a collision-related high-P metamorphism during the Devonian-Carboniferous amalgamation of Pangea. The bottom member of the Upper Allochthon recorded this HP-HT Devonian metamorphism, which was attained by a subduction process. To know which continental margin subducted a provenance study was carried out on the metasedimentary rocks of the Banded Gneisses (5 samples), which form part of the Upper Allochthon subducted terrane. The provenance of this terrane has been established using combined U-Pb (n = 613) and Lu-Hf (n = 463) isotopic LA-ICP-MS zircon analyses. These data show that the Variscan Upper Allochthon has a West African provenance and therefore, it strongly suggests that the NW Iberian allochthonous complexes and their correlative European terranes are also West Africa derived. These results allow us to finally clarify that the first high-P event, recorded during the eo-Variscan amalgamation of Pangea, was attained by the subduction of the margin of Gondwana under the colliding retro-continent, presumably Laurussia.
International Journal of Earth Sciences, Aug 12, 2021
Late Paleozoic (Variscan) magmatism is widespread in Central Europe. The Lusatian Block is locate... more Late Paleozoic (Variscan) magmatism is widespread in Central Europe. The Lusatian Block is located in the NE Bohemian Massif and it is part of the Saxothuringian Zone of the Variscan orogen. It is bordered by two major NW-trending shear zones, the Intra-Sudetic Fault Zone towards NE and the Elbe Fault Zone towards SW. The scarce Variscan igneous rocks of the Lusatian Block are situated close to these faults. We investigated 19 samples from Variscan plutonic and volcanic rocks of the Lusatian Block, considering all petrological varieties (biotite-bearing granites from the Koenigshain and Stolpen plutons, amphibole-bearing granites from three boreholes, several volcanic dykes, and two volcanites from the intramontane Weissig basin). We applied whole-rock geochemistry (18 samples) and zircon evaporation dating (19 samples). From the evaporation data, we selected six representative samples for additional zircon SHRIMP and CA-ID-TIMS dating. For the Koenigshain pluton, possible protoliths were identified using whole-rock Nd-isotopes, and zircon Hf-and O-isotopes. The new age data allow a subdivision of Variscan igneous rocks in the Lusatian Block into two distinct magmatic episodes. The spatial relation of the two age groups to either the Elbe Fault Zone (298-299 Ma) or the Intra-Sudetic Fault Zone (312-313 Ma) together with reports on the fault-bound character of the dated intrusions suggests an interpretation as two major post-collisional faulting episodes. This assumption of two distinct magmatic periods is confirmed by a compilation of recently published zircon U-Pb CA-ID-TIMS data on further Variscan igneous rocks from the Saxothuringian Zone. New geochemical data allow us to exclude a dominant sedimentary protolith for the Koenigshain pluton as supposed by previous investigations. This conclusion is mainly based on new O-and Hf-isotope data on zircon and the scarcity of inherited zircons. Instead, acid or intermediate igneous rocks are supposed as the main source for these I-type granitoids from the Koenigshain pluton.
The sources and critical enrichment processes for granite related tin ores are still not well und... more The sources and critical enrichment processes for granite related tin ores are still not well understood. The Erzgebirge represents one of the classical regions for tin mineralization. We investigated the four largest plutons from the Western Erzgebirge (Germany) for the geochemistry of bulk rocks and autocrystic zircons and relate this information to their intrusion ages. The source rocks of the Variscan granites were identified as high-grade metamorphic rocks based on the comparison of Hf-O isotope data on zircons, the abundance of xenocrystic zircon ages as well as Nd and Hf model ages. Among these rocks, restite is the most likely candidate for later Variscan melts. Based on the evolution with time, we could reconstruct enrichment factors for tin and tungsten starting from the protoliths (575 Ma) that were later converted to high-grade metamorphic rocks (340 Ma) and served as sources for the older biotite granites (323-318 Ma) and the tin granites . This evolution involved a continuous enrichment of both tin and tungsten with an enrichment factor of ~15 for tin and ~7 for tungsten compared to the upper continental crust (UCC). Ore level concentrations (>10-100 times enrichment) were achieved only in the greisen bodies and dykes by subsequent hydrothermal processes.
Results of a combined petrological, geochemical and geochronological study suggest that metasedim... more Results of a combined petrological, geochemical and geochronological study suggest that metasedimentary rock units in the Krndija region of the Slavonian Mountains, Croatia, were affected by at least three major tectonometamorphic imprints: during the Middle Ordovician (Sardic event), the early Carboniferous (Variscan event), and the Cretaceous (Alpine event). All three metamorphic phases are established by electron microprobe-based in-situ U–Th–Pb dating of monazite grains. The Sardic metamorphic event is additionally confirmed by a precise Lu–Hf garnet-whole-rock isochron age of 466.0 ± 2.3 Ma. Taken together, the data unveil a relatively large and well-preserved piece of the cryptic Sardic orogen in central Krndija, that we name the Kutjevo Zone. A Sardic subduction-related metamorphic event (ca. 540-580 ℃, 8–11 kbar) at ca. 466 Ma is manifested in the mineral paragenesis Ca-rich garnet plus rutile. A low degree of retrograde reequilibration suggests a subsequent fast exhumation....
The Altenberg–Teplice Volcanic Complex (ATVC) is a large ~ NNW–SSE trending volcano-plutonic syst... more The Altenberg–Teplice Volcanic Complex (ATVC) is a large ~ NNW–SSE trending volcano-plutonic system in the southern part of the Eastern Erzgebirge (northern Bohemian Massif, south-eastern Germany and northern Czech Republic). This study presents high precision U–Pb CA-ID-TIMS zircon ages for the pre-caldera volcano-sedimentary Schönfeld–Altenberg Complex and various rocks of the caldera stage: the Teplice rhyolite, the microgranite ring dyke, and the Sayda-Berggießhübel dyke swarm. These data revealed a prolonged time gap of ca. 7–8 Myr between the pre-caldera stage (Schönfeld–Altenberg Complex) and the climactic caldera stage. The volcanic rocks of the Schönfeld–Altenberg Complex represent the earliest volcanic activity in the Erzgebirge and central Europe at ca. 322 Ma. The subsequent Teplice rhyolite was formed during a relatively short time interval of only 1–2 Myr (314–313 Ma). During the same time interval (314–313 Ma), the microgranite ring dyke intruded at the rim of the cal...
The Upper Units of the allochthonous complexes of the NW Iberian Massif constitute a terrane with... more The Upper Units of the allochthonous complexes of the NW Iberian Massif constitute a terrane with continental affinity. They represent the vestiges of a Cambrian magmatic arc developed in the periphery of Gondwana (West African Craton) which was involved in the Devonian Variscan collision, undergoing high‐P, high‐T metamorphism. This includes ultramafic rocks, high‐P mafic rocks (eclogites and granulites) and high‐P migmatitic paragneisses. The latter rocks show an extensive migmatization with the leucosomes oriented parallel to the regional foliation. The migmatitic paragneisses are composed of garnet, kyanite, biotite, quartz, plagioclase, K‐feldspar, rutile and Ti‐hematite. Thermodynamic modelling using the measured bulk composition in the NCKFMASTHO system indicates metamorphic peak conditions of ~15 kbar and ~800 to 835°C, followed by a significant cooling. The prograde evolution is assessed by means of a melt‐reintegration approach, using the composition of the garnet and its ...
The post-tectonic Sedmihoří Stock (SCS) is a circular body in plan-view, made up of three nested ... more The post-tectonic Sedmihoří Stock (SCS) is a circular body in plan-view, made up of three nested units: (i) 'Outer granite' (OG), less fractionated Kfs-phyric Bt monzogranite (326.2 ± 1.2 Ma (2σ), LA ICP-MS Zrn), (ii) 'Inner granite' (IG), more evolved Bt-Ms monzogranite (326.6 ± 1.2 Ma), and (iii) innermost leucogranite ('LG'), fine-grained Tur-Ms leucogranite. All the varieties of this body are silica-rich (SiO 2 > 71 wt. %) and subaluminous to strongly peraluminous (A/CNK = 1.01-1.25). Major-element contents do not vary greatly but the trace elements show more significant differences between the granite varieties. From OG to LG, the rocks show decreasing overall REE abundances and La/Yb ratios. Significant differences in Th and U concentrations occur between the marginal OG (~49 ppm Th; ~9 ppm U) and the more central IG (~8 ppm Th, ~4 ppm U). Hydrothermal thorite (found in the OG), xenotime and monazite are the main accessories concentrating these radioactive elements. The final stage of the magma evolution is represented by the central LG pulse containing beryl, wolframite and high-Li muscovite. All pulses of the SCS are characterized by crust-like Sr-Nd isotopic signatures. The inner IG shows more evolved Sr ( 87 Sr/ 86 Sr 326 = 0.7098-0.7130) and less radiogenic Nd (εNd 326 = -4.6 to -3.7) than the outer OG ( 87 Sr/ 86 Sr 326 = 0.7067-0.7076; εNd 326 = -2.5 to -2.7). The granite batches were probably derived by anatexis of Neoproterozoic or, more likely, Cambrian metagreywackes of the Teplá-Barrandian Unit. Enriched-mantle derived magmas (redwitzites) played a very important role as they not only provided the heat needed for the anatexis but also variably contributed material via magma mixing processes. The hybridization was particularly significant for the origin of the outer unit, which is rich in mafic microgranular enclaves and whose Sr is the least and Nd most radiogenic within the SCS. Taken together, field observations, structural relations, U-Pb zircon dating, and geochemistry indicate that all pulses in the SCS were emplaced nearly simultaneously. However, each of them represented a single batch of magma with its own geochemical characteristics and petrogenetic features.
The sources and critical enrichment processes for granite related tin ores are still not well und... more The sources and critical enrichment processes for granite related tin ores are still not well understood. The Erzgebirge represents one of the classical regions for tin mineralization. We investigated the four largest plutons from the Western Erzgebirge (Germany) for the geochemistry of bulk rocks and autocrystic zircons and relate this information to their intrusion ages. The source rocks of the Variscan granites were identified as high-grade metamorphic rocks based on the comparison of Hf-O isotope data on zircons, the abundance of xenocrystic zircon ages as well as Nd and Hf model ages. Among these rocks, restite is the most likely candidate for later Variscan melts. Based on the evolution with time, we could reconstruct enrichment factors for tin and tungsten starting from the protoliths (575 Ma) that were later converted to high-grade metamorphic rocks (340 Ma) and served as sources for the older biotite granites (323–318 Ma) and the tin granites (315–314 Ma). This evolution in...
Zircons from Carboniferous sandstones (three samples) and Mid-Late Triassic sandstones (four samp... more Zircons from Carboniferous sandstones (three samples) and Mid-Late Triassic sandstones (four samples) from the Tauride and Anatolide continental units were analysed for U-Pb-Hf isotopes. For comparison, zircons were also analysed from Carboniferous granites of the Afyon Zone, Anatolides (three samples). A NE African/Arabian source is inferred for both the Carboniferous sandstones of the Taurides (Aladağ) and the Anatolides (Konya Complex). In contrast, the Carboniferous Karaburun Melange is characterised by a NW African provenance. A prominent Devonian population occurs in the Carboniferous Karaburun Melange, characterised by mainly positive ε Hf(t) values that differ significantly from those of the Devonian granites of the Sakarya continental crustal unit (Pontides). Middle-Late Triassic Tauride sandstones include minor Paleozoic and Early Mesozoic zircons. In contrast, Devonian and Carboniferous zircons are relatively abundant in Late Triassic sandstones of the Karaburun Peninsula. The Hf isotopic compositions of 25 Carboniferous-aged zircons from three samples of Mid-Late Triassic sandstone and one of Late Carboniferous age (one sample) overlap with the ε Hf(t) values of Carboniferous arc-type granites in the Anatolides. Taking account of the available U-Pb and Lu-Hf isotopic data from comparative crustal units, the Devonian zircon populations from the melanges in the Karaburun Peninsula and the Konya Complex are inferred to have a westerly source (e.g. granitic rocks of Aegean region or central European). A tectonic model is proposed in which Paleozoic Tethys sutured during the late Carboniferous in the west (Aegean region westwards), leaving an eastward-widening oceanic gulf in which sandstone turbidites accumulated, including Devonian zircons.
Between the eastern Mediterranean basin in the South and the East European (Baltica) Craton to th... more Between the eastern Mediterranean basin in the South and the East European (Baltica) Craton to the north, we distinguish two fundamental pre‐Variscan geological domains: an Internal domain, which hosts Ordovician‐Devonian (450–400 Ma) igneous rocks and detrital zircon populations, and an External domain, which contains no 450‐ to 400‐Ma zircon ages. From the Balkan Peninsula to the Turkish plate, the aforementioned Internal domain includes the Serbo‐Macedonian Massif, the Istanbul and Sakarya terranes, whereas the External domain, holding a more distal position relative to Baltica, includes the Pelagonian terrane and the External Hellenides. The two domains are interpreted as two consecutive (i.e., Caledonian and Variscan) Paleozoic accretionary belts, attached to the southern margin of Baltica. The Cycladic and Pelagonian terranes are currently juxtaposed along strike of the central Hellenides in Northern Greece. The Cycladic Massif is a Cadomian‐type terrane, while the Pelagonian ...
We trace source variations of active margin granitoids which crystallised intermittently over ~30... more We trace source variations of active margin granitoids which crystallised intermittently over ~300 Ma in varying kinematic regimes, by combining zircon Lu-Hf isotopic data from Early Palaeozoic to Early Jurassic igneous and metaigneous rocks in the Mérida Andes, Venezuela and the Santander Massif, Colombia, with new whole rock Rb/Sr and Sm-Nd isotopic data, and quartz O isotopic data. These new data are unique in South America because they were obtained from discrete magmatic and metamorphic zircon populations, providing a high temporal resolution dataset, and compare several isotopic systems on the same samples. Collectively, these data provide valuable insight into the evolution of the isotopic structure of the continental crust in long-lived active margins.
The Carlos Chagas batholith (CCB) is a very large (~14,000 km 2 ) S-type granitic body formed dur... more The Carlos Chagas batholith (CCB) is a very large (~14,000 km 2 ) S-type granitic body formed during the syn-collisional stage of the Araçuaí orogen (southeastern Brazil). Zircons extracted from the CCB record a wide range of U-Pb ages (from 825 to 490 Ma), indicating a complex history of inheritance, magmatic crystallization and partial melting during the evolution of the orogeny. Magmatic zircons (ca. 578-588 Ma) are marked by similar Hf isotope compositions and REE patterns to those of inherited cores (ca. 825-600 Ma), indicating that these aspects of the chemical signature of the magmatic zircons have likely been inherited from the source. The U-Pb ages and initial 176 Hf/ 177 Hf ratios from anatectic and metamorphic zircon domains are consistent with a twostage metamorphic evolution marked by contrasting mechanisms of zircon growth and recrystallization during the orogeny. Ti-in-zircon thermometry is consistent with the findings of previous metamorphic work and indicates that the two metamorphic events in the batholith reached granulite facies conditions (N 800 °C) producing two generations of garnet via fluid-absent partial melting reactions. The oldest metamorphic episode (ca. 570-550 Ma) is recorded by development of thin anatectic overgrowths on older cores and by growth of new anatectic zircon crystals. Both domains have higher initial 176 Hf/ 177 Hf values compared to relict cores and display REE patterns typical of zircon that grew contemporaneously with peritectic garnet through biotite-absent fluid partial melting reactions. Hf isotopic and chemical evidences indicate that a second anatectic episode (ca. 535-500 Ma) is only recorded in parts from the CCB. In these rocks, the growth of new anatectic zircon and/or overgrowths is marked by high initial 176 Hf/ 177 Hf values and also by formation of second generation of garnet, as indicated by petrographic observations and REE patterns. In addition, some rocks contain zircon crystals formed by solid-state recrystallization of pre-existing zircon, which exhibit similar Hf isotope composition to those of inherited/magmatic core domains. The first anatectic event is interpreted as result of crustal thickening after the intrusion of the batholith. This introduced the batholith to a depth in excess of 30 km and produced widespread anatexis throughout the batholith. The second event was associated with asthenospheric upwelling during extensional thinning and gravitational collapse of the orogen, this produced anatexis in parts from the CCB that had been re-fertilized for anatexis by retrogression along shear zones following the first granulite facies event.
The tectonometamorphic and magmatic evolution of the Uppermost Unit in central Crete (Melambes ar... more The tectonometamorphic and magmatic evolution of the Uppermost Unit in central Crete (Melambes area): Constraints on a Late Cretaceous magmatic arc in the Internal Hellenides (Greece). The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Gr(2017),
Bügeleisen-Geschiebe"), facetted pebbles, dreikanters, and zircon grains affected by ice abrasion... more Bügeleisen-Geschiebe"), facetted pebbles, dreikanters, and zircon grains affected by ice abrasion. For age and provenance determination, LA-ICP-MS U-Pb ages (n = 1124) and Hf isotope (n = 446) analyses were performed. The maximum age of the glaciomarine deposits within a Cadomian back-arc basin based on U-Pb analytics resulted in the youngest detrital zircon populations showing ages of 562-565 Ma and of c. 566-576 Ma old zircon derived from granitoid pebbles within the diamictites. The youngest age recorded was 538-540 Ma based on zircon from the plutons which had intruded the previously deformed Ediacaran metasedimentary rocks. Previously described glaciomarine diamictites of Cadomia (Weesenstein, Clanzschwitz, and Orellana diamictites) are most definitely younger than the Abstract In the Cadomian orogen of the NE Bohemian Massif and of SW Iberia, a post-Gaskiers glacial event dated at c. 565 Ma has been detected. Such Ediacaran-aged glaciomarine deposits occur in the Weesenstein and Clanzschwitz groups of the Saxo-Thuringian zone (Bohemia) and in the Lower Alcudian group of the southern Central Iberian zone (Iberia). Both areas are parts of Cadomia situated in the Western and Central European Variscides. Glaciomarine sedimentary rocks are characterized by such features as dropstones, flat iron-shaped pebbles
The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-P... more The Cap de Creus granitic pegmatites in the eastern Catalan Pyrenees were dated using in situ U-Pb geochronology by laser ablation ICP-MS on zircon and columbite-group minerals (CGM), which are present in the different types of pegmatites from type I (K-feldspar pegmatites, least evolved) to type IV (albite pegmatites, most evolved) and therefore allow dating the different Click here to download Manuscript publication_text_v9.doc 2 pegmatitic pulses. In a type III pegmatite where zircon and CGM are co-genetically associated in the same sample, both minerals were dated using zircon and tantalite reference materials, respectively, to avoid laser-induced matrix-dependent fractionation. In one sample, xenotime genetically associated with zircon was also dated. Two ages were obtained for type I and three ages for type III pegmatites. Three of these 5 ages range from 296.2 ± 2.5 to 301.9 ± 3.8 Ma and are allocated to the primary magmatic stage of crystallization and therefore to the emplacement event. Two younger ages (290.5 ± 2.5 and 292.9 ± 2.9 Ma) obtained on secondary zircon and xenotime, respectively, are interpreted as late post-solidus hydrothermal remobilization. There is no age difference between type I and type III pegmatites. The mean 299 Ma primary magmatic age allows the main late Carboniferous deformation event to be dated and is also synchronous with other peraluminous and calc-alkaline granites in the Pyrenees. However, the youngest ages around 292 Ma imply that tectonics was still active in Early Permian times in the Cap de Creus area.
Detrital zircon populations in sedimentary rocks from the Laurentian margin and the accreted micr... more Detrital zircon populations in sedimentary rocks from the Laurentian margin and the accreted microcontinent Ganderia on both sides of the main Iapetus suture (Red Indian Line) in central Newfoundland have been studied by combined U–Pb and Lu–Hf isotope analyses. Variation in εHf(t) values with age of zircon populations of distal provenance (>900 Ma) reflect the crustal evolution within the source continents: in zircon derived from Laurentia, episodes of juvenile magma production in the source could be detected at 1.00 – 1.65 and 2.55 – 3.00 Ga, and mixing of juvenile and recycled crust in continental magmatic arcs occurred at 0.95 – 1.40, 1.45 – 1.60, 1.65 – 2.05 and 2.55 – 2.75 Ga. These ages are consistent with the crustal history of northeastern Laurentia. Similarly, zircon of distal provenance from Ganderia reveals times of juvenile magma production in the source at 0.70 – 0.90, 1.40 – 1.75, 1.85 – 2.40 and 2.7 – 3.5 Ga, and episodes of mixing juvenile and recycled crust at 0...
Intrusion of the Cambrian Burd Gol Granite Massif into the Proterozoic metamorphic rocks of the Z... more Intrusion of the Cambrian Burd Gol Granite Massif into the Proterozoic metamorphic rocks of the Zamtyn Nuruu and molasse-like sediments of the Boomyn Khudag Fm. culminated the collisional events of the Caledonian evolution in the SE part of the Lake Zone, Gobi Altay, SW Mongolia. The monotonous leucogranites of the Burd Gol Massif have a high-K calc-alkaline, subaluminous to slightly peraluminous geochemical signature with an intermediate initial Sr ratio ( 87 Sr/ 86 Sr 510 = 0.7064) and rather unradiogenic Nd (ε 5 Nd 10 = -1.5 and -0.2). The laser ablation ICP-MS U-Th-Pb radiometric dating of monazites and zircons from these rocks yields intrusive ages between 506.4 ± 5.4 and 513.4 ± 4.3 Ma (2σ). The final stage of magmatic activity is documented by the Ar-Ar dating of muscovite from a pegmatite dyke at 485.1 ± 3.2 Ma. The granites intruded and thermally influenced the terrestrial clastic sediments of the Boomyn Khudag Formation, whereby the thermal metamorphism of sediments was characterized by a muscovite growth. These new data argue against the previously assumed Permian age of the Burd Gol Massif and the Lower-Middle Devonian age of the Boomyn Khudag sedimentary formation and illustrates the terrestrial evolution in this part of the Lake Zone during the Cambrian.
For a long time the Moslavac ˇka Gora Massif in Croatia has been regarded as a major outcrop of V... more For a long time the Moslavac ˇka Gora Massif in Croatia has been regarded as a major outcrop of Variscan crystalline basement of the South Tisia block. However, new geochronological data indicate that this massif consists of a Cretaceous S-type granite pluton intruding a Cretaceous low-pressure/high-temperature (LP/HT) metamorphic envelope. The age of the LP/HT metamorphism is estimated at *90-100 Ma using the method of electron microprobe based monazite dating. The Central Granite was dated at 82 ± 1 Ma (LA-SF-ICP-MS zircon age). The metamorphic complex comprises mainly felsic anatexites and orthogneisses of granitic composition, some metapelites (paragneisses and mica schists) and amphibolites. Zircons from three different samples of metagranite were dated at 486 ± 6, 483 ± 6, and 491 ± 1 Ma, suggesting that most of the metamorphic complex represents an Early Ordovician granitic series. The Cretaceous regional metamorphism culminated in granulite facies conditions of *750°C and 3-4 kbar. A retrograde metamorphic event at lower amphibolite facies conditions overprinted the metamorphic complex. This event is probably related to the intrusion of the Central Granite. The southeastern sector of the massif was additionally affected by post-granitic, predominantly NE oriented shearing at greenschist facies conditions. As yet there is no clear evidence for Variscan events in the Moslavac ˇka Gora Massif. Mineral relics of a medium-pressure amphibolite facies metamorphism are preserved in amphibolites. They are older than the Cretaceous LP/HT regional metamorphism, but their age is presently unknown. Some indications for a Permian regional metamorphic event are provided by inherited zircons in the Central Granite that have been dated with a Permian age, and by Permian monazite relics in metapelites. The Cretaceous high heat flow regime recorded in the Moslavac ˇka Gora Massif is unique in the subcrop of the Pannonian Basin and may be a local feature triggered by a mafic intrusion in the lower crust.
This paper presents laser-ablation (MC)-ICP-MS single-zircon Hf isotopic data coupled with U-Pb g... more This paper presents laser-ablation (MC)-ICP-MS single-zircon Hf isotopic data coupled with U-Pb geochronology from a unique rock inventory in southern Israel, recording ca. 300 m.y. of Neoproterozoic crustal evolution in the northern Arabian-Nubian Shield (ANS). The early, island-arc magmatic cycle in this area is recorded by detrital zircons from arc-derived metasediments, dated between 870 and 760 Ma, and by ca. 790 and 740 Ma orthogneisses. Zircon ε Hf(t) values from these rocks are all positive, supporting previous isotopic evidence for the overall juvenile nature of northern ANS crust. Nonetheless, detrital zircons from the metasedimentary units display a wide range of ε Hf(t) values between +1 and +13. The lower values in this range suggest some contribution from an older crustal component. The involvement of pre-Neoproterozoic crustal component is also indicated by the occurrence of
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