Geochemical, isotopic, and geochronological evidence for subsynchronous island-arc magmatism and terrigenous sedimentation (Predivinsk terrane of the Yenisei Ridge)

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Geochemical, isotopic, and geochronological evidence for subsynchronous island-arc magmatism and terrigenous sedimentation (Predivinsk terrane of the Yenisei Ridge) A.D. Nozhkin a,*, N.V. Dmitrieva a,b, I I. Likhanov a, P.A. Serov c, P.S. Kozlov d a

V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia b Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia c Geological Institute, Kola Scientific Center of the Russian Academy of Sciences, ul. Fersmana 14, Apatity, 184209, Russia d A.N. Zavaritsky Institute of Geology and Geochemistry, Ural Branch of the Russian Academy of Sciences, Pochtovyi per. 7, Yekaterinburg, 620075, Russia Received 26 November 2015; accepted 16 March 2016

Abstract In this study we present data on the geologic setting, geochemical and isotopic compositions, timing and P-T conditions of metamorphism of Neoproterozoic terrigenous metasediments, and associated island-arc metavolcanics of the Predivinsk terrane of the Yenisei Ridge. Relatively immature terrigenous rocks were eroded from a local source which is associated with island-arc magmatic complexes. The geochronological constraints indicate that the terrigenous rocks were eroded from juvenile crustal sources represented primarily by magmatic rocks, which are similar to those of the Predivinsk terrane. This is supported by a similar range of model ages, positive εNd values of terrigenous and magmatic rocks, and correspondence between the concordant ages of detrital zircons from metasedimentary rocks (610–640 Ma) and the U–Pb ages of zircons from rhyolites (ca. 620–640 Ma) from two suites within different sequences. The P-T conditions for volcanosedimentary rocks of the Predivinsk terrane correspond to the epidote-amphibolite facies and the transition from epidote-amphibolite to amphibolite facies. The most likely age of metamorphism due to Vendian accretion/collision events is given by Ar–Ar dates of 600–610 Ma. © 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. Keywords: Late Precambrian; volcanosedimentary rocks; LA–ICP-MS dating; SHRIMP II; Sm–Nd isotopy; Predivinsk terrane; Yenisei Ridge

Introduction The present-day southwestern margin of the Siberian craton is represented by its Early Precambrian basement inliers (Angara–Kan and Sayan) Mesoproterozoic–Neoproterozoic marginal continental region that includes the Yenisei Ridge. the Precambrian terrane (Isakovka, Predivinsk, Arzybei, Shumikha-Kirel, etc.) made up of Neoproterozoic ophiolites and island-arc rocks (Chernykh, 2001; Khain et al., 1993; Kuzmichev, 1987; Mironov and Nozhkin, 1978; Nozhkin, 1997; Rumyantsev et al., 2000; Turkina et al., 2004; Vernikovsky et al., 1994) were accreted to the Siberian craton in the Vendian (Likhanov et al., 2013b; Nozhkin et al., 2007; Turkina et al., 2007). The Predivinsk terrane located in the southwestern part of the Yenisei Ridge is one of the structural elements of the

* Corresponding author. E-mail address: [email protected] (A.D. Nozhkin)

Sayan–Yenisei accretionary-collision belt (Fig. 1) that formed during the earliest evolutionary history of the Central Asian orogenic belt. The geology and composition of igneous rocks of the Predivinsk volcanic zone have been described in detail in previous publications (Chernykh, 2001; Nozhkin, 1985a,b, 1996, 1997; Vernikovsky et al., 1999; Zablotskii et al., 1986); however, terrigenous sediments found in association with island-arc volcanics have not yet been studied intensively. The analysis of major and trace elements in these sediments, unraveling the contribution of the juvenile and Early Precambrian cratonic crust, and deciphering protolith ages may be of great importance in this respect. The goal of this study is to describe the major and trace element geochemistry, and the isotopic composition of Neoproterozoic terrigenous rocks of the Predivinsk terrane, and to use these data to constrain the age of volcanosedimentary units, conditions and timing of metamorphism.

1068-7971/$ - see front matter D 201 6, V.S. So bolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.rgg.201 + 6.10.004

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Fig. 1. Geological sketch map of the Predivinsk terrane, modified after Zablotskii et al. (1986) and Vernikovsky et al. (2009). 1, sedimentary cover (MZ–KZ); 2–7, island-arc and oceanic complexes of the Predivinsk terrane (NP): 2, granitoids of the Yagun massif; 3, gabbros and pyroxenites of the Shivera massif; 4, harzburgite serpentinites; 5, metavolcanics and metasediments of the Western Block; 6, metagabbros of the Yarlychikha massif; 7, metavolcanics and metasediments of the Eastern Block; 8, gneisses and amphibolites of the Yenisei complex (PR1); 9, faults, mapped (a) and inferred (b); 10, Yenisei thrust; 11, sampling sites for U–Pb dating of zircons from metarhyolites (a) and metasandstones (b) and for Ar–Ar dating of hornblende from amphibolites (c). Numbers in circles: I, Western and II, Eastern Blocks. Inset: 1, continental margin of the Yenisei Ridge; 2, Isakovka terrane; 3, Predivinsk terrane.

Geologic setting and composition of volcanosedimentary complexes The Predivinsk terrane, some 40–45 km long and 7–8 km wide, extends in a NW direction along the right bank of the Yenisei River. This feature is traced by gravity and magnetic trends to the north along the left bank of the Yenisei River under the cover of Meso-Cenozoic sediments. The terrane is thrust over the Paleoproterozoic Yenisei amphibolite-facies gneisses of the Angara–Kan block of the Siberian craton to the east, and is bordered to the west by Phanerozoic sediments of the West Siberian plate along a tectonic suture (Fig. 1) (Chernykh, 2001; Nozhkin, 1997; Vernikovsky et al., 2009; Zablotskii et al., 1986). In general, the Predivinsk terrane adjoins the Yenisei fault zone, which is considered as an extension of the Main Sayan Fault, a major tectonic structure

bordering the Siberian craton to the west and southwest (Likhanov et al., 2013a, 2014; Vernikovsky et al., 2009). The terrane appears as a complex assemblage of tectonic sheets, which can be attributed to two large tectonic blocks (Western and Eastern) composed of different rock series. The island-arc complexes of the Western block consist of epidoteamphibolite facies metamorphic rocks represented mostly by amphibolites, with compositions corresponding to low-Ti, high-Al tholeiitic basalts; minor microgneisses and micaquartz-feldspar schists with low-alkaline plagiorhyodacitic compositions; plagioclase amphibolites, biotite-amphibole-plagioclase schists and porphyritic quartz-feldspar rocks of a calc-alkaline basalt-andesibasalt-andesite-dacite series (Nozhkin, 1996, 1997). The latter prevail in the upper part of the section where they are usually interlayered with members and horizons of metaterrigenous mica-quartz-feldspar schists and metasandstones, mica-feldspar quartzitic schists and calcitic

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marbles. The metavolcanic sedimentary rocks of this block are assigned to the Yudinka sequence in the legend of the state geologic map (Kachevskii, 2002). In addition to metasediments, these metavolcanics comprise many stratified bodies of highly aluminous apogabbro amphibolites (Yarlychikha complex) and veins of foliated granitoids, representing the intrusive equivalent of the respective extrusives. Field relations and geochemical data indicate that the initial rocks of the Western block form five rock suites: plagiorhyolite-basalt, basalt-andesibasalt-andesite-dacite, carbonate-terrigenous, gabbro, and diorite-plagiogranite. The whole-rock major and trace element signatures of these volcanic suites correspond to magmatic rocks from a juvenile island-arc setting (Kovalenko, 1987). The island-arc rocks of the Eastern Block form a suite of differentiated calc-alkaline and bimodal subalkaline K-Na-type extrusive rocks and their tuffs metamorphosed at epidote-amphibolite- to greenschist-facies conditions. They are mostly amphibolites, plagioclase-biotite-amphibole schists, micaceous quartz-feldspar schists and porphyroids for which the protoliths are a suite of basalt, andesite, and rhyolite. Compared to the metavolcanic rocks of the Western Block, they exhibit enrichments in alkalis and other LILE (Rb, Ba, U, and Th), HFSE, and REE, typical of more mature island arcs (Nozhkin, 1997). The bimodal basalt-rhyolite suite comprises alkaline Fe-Ti-P-rich metabasalts, subalkaline rhyodacite and rhyolites, as well as their subvolcanic equivalents, such as subalkaline microgranites (Nozhkin, 1997). Both basic and felsic metavolcanic rocks are intercalated with plagioclase- and mica-rich quartzites, quartzite schists, greenish gray two-mica plagioclase-quartz and amphibole-plagioclase-quartz aleuroschists, with rare interlayers of iron-rich quartzites and members of thinly-laminated terrigenous and volcaniclastic greenschists. The metavolcanosedimentary rocks of the Eastern block are assigned to the Predivinsk sequence in the legend of the state geologic map (Kachevskii, 2002). A tectonized section of this unit comprises lenses and thin bands of dynamically metamorphosed apoharzburgite serpentinite and apogabbro amphibolite in association with tholeiitic basalts with an N-MORB affinity typical of ophiolites (Chernykh, 2001; Nozhkin, 1997). The island-arc volcanic sequences that crop out in the southern part of the Eastern Block include metamorphosed high-Ti gabbros and diorites of the Shivera massif, corresponding in chemical composition to high-Ti subalkaline metabasalts from a bimodal suite, as well as granodiorites and plagiogranites of the Yagunov massif (Fig. 1). The following types of terrigenous metasedimentary rocks of the Predivinsk terrane are recognized: mica-quartz-feldspar aleuroschists and metasandstones (Bt + Qz + Pl + Ms ± Grt ± Or ± Ep ± Ttn + Ap + Zrn), mica-feldspar quartzite schists (metasandstones) (Qz + Pl ± Ms ± Bt ± Or ± Ap + Zrn) in the Yudinka sequence; greenish gray two-mica plagioclase-quartz and biotite-amphibole-plagioclase-quartz aleuroschists (Pl + Qz + Amp + Bt + Ep ± Chl ± Ms ± Mag), plagioclase and mica quartzites and quartzite schists (metasandstones) (Qz + Pl + Ms ± Bt ± Ep ± Grt), and thinly laminated greenschists (Pl + Amp + Bt + Ep + Zo ± Chl ± Ms ± Kls + Mag) in the

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Predivinsk sequence. All mineral abbreviations are from Whitney and Evans (2010).

Methods Whole-rock major elements were analyzed by X-ray fluorescence with an ARL-9900-XP spectrometer at the Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences (analysts N.M. Glukhova and N.G. Karmanov). The precision of the data for all components was not better than 5% rel. Trace and rare-earth elements were analyzed using a a Finnigan MAT Element high-resolution inductively coupled plasma-mass spectrometer (ICP-MS) at the Institute of Geology and Geochemistry, Ural branch, Russian Academy of Sciences under the guidance of Yu.L. Ronkin. For all these elements, the detection limits ranged between 0.005 and 0.1 µg/g. The precision averaged 2–7% rel. Concentrations of REE and other trace elements were analyzed in a few metavolcanic samples using neutron activation analysis (analyst V.S. Parkhomenko) and synchrotron radiation X-ray fluorescence (analyst Yu.P. Kolomogorov), respectively. The results obtained using different analytical methods on the same samples were in reasonable agreement. The composition of mineral phases was determined using a JEOL JXA-8100 electron microprobe at the Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences (Novosibirsk) following a standard procedure described elsewhere (Kozlov et al., 2012; Likhanov and Reverdatto, 2007). Zircons for U–Pb analysis were separated using conventional heavy liquid and magnetic mineral separation techniques at the Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences. Zircon internal structures were investigated by reflected and transmitted light microscopy as well as by cathodoluminescence images. U–Pb analyses of zircons from terrigenous metasedimentary rocks were performed using a Nu Plasma ICP-MS (Nu Instruments) coupled with an excimer laser ablation system (Resonetics Resolution M-50-HR) at the Department of Earth Sciences, University of Hong Kong. The 91,500 zircon was used as the external reference standard for U-Pb isotope analyses. Detailed analytical protocols are provided in Xia et al. (2011). The GJ-1 zircon standard with a weighted mean 206 Pb/238U 605.3 ± 1.4 Ma (2σ, MSWD = 0.052, probability = 1.0, n = 28) was used for quality control. The reduction of data and age calculation were carried out using ICPMSDataCal (Liu et al., 2010) and Isoplot/Ex v.3 (Ludwig, 2003). The ages and the ratios obtained from the individual analysis are within ±1σ error. The U–Pb dating of zircons from felsic metavolcanics of the Yudinka sequence was performed using a SHRIMP-II ion microprobe at the Center for Isotopic Research, All-Russian Research Institute of Geology (VSEGEI), St. Petersburg (analyst E.N. Lepikhina). Zircon grains were handpicked and mounted in epoxy together with chips of the reference zircons

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(TEMORA and 91500). SHRIMP-II U-Pb isotope analyses were made using the procedure described by Williams (1998). The data were processed using SQUID (Ludwig, 2000) and Isoplot/Ex (Ludwig, 1999). Concentrations of Nd and Sm were analyzed at the Geological Institute, Komi Scientific Center, Russian Academy of Sciences, Apatity (analyst P.A. Serov) using a Finnigan Mat-262 (RPQ) seven-channel solid phase mass spectrometer in static collection mode on a Re and Ta filament configuration following the methods described by Bayanova (2004). Analytical errors for Nd isotopic composition in the individual analysis did not exceed 0.004%. Total procedural blanks were 0.3 ng for Nd and 0.06 ng for Sm. Concentrations of Sm and Nd were measured with a typical precision of ±0.5%. Isotope ratios were normalized to 146Nd/144Nd values of 0.7219 and then corrected to 143Nd/144Nd values of 0.511860 reported for the La Jolla standard. The εNd values and T(DM) model ages were calculated using the currently accepted CHUR (chondritic uniform reservoir) values of 143Nd/144Nd = 0.512638, 147 Sm/144Nd = 0.1967 (Jacobsen and Wasserburg, 1984) and DM (depleted mantle) values of 143Nd/144Nd=0.513151, 147 Sm/144Nd = 0.2136 (Goldstein and Jacobsen, 1988). The Ar–Ar dating was performed at the Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, following the methods described by Ponomarchuk et al. (1998). Argon isotopes were measured on a Micromass Noble Gas 5400 mass spectrometer (analysts V.A. Ponomarchuk and A.V. Travin). All ages are quoted at ±1σ. The plateau definition was carried out using the criteria of Fleck et al. (1977).

Rock geochemistry and isotope composition Table 1 shows representative major, trace and rare-earth element compositions of rock samples from the Predivinsk terrane. Major elements. All the studied rock samples (over 200) were designated ortho- and pararocks based on their petrography and major-element geochemistry. The values of the chemical index of alteration, CIA = (Al2O3/(Al2O3 + CaO + Na2O + K2O)) × 100) (Nesbitt and Young, 1982, 1984) equal to 50 were used to discriminate between ortho- and pararocks. Mica-quartz-feldspar aleuroschistsand metasandstones of the Yudinka sequence, as well as plagioclase- and mica-rich quartzites and quartzite schists of the Predivinsk sequence have lower CIA values of 50–67. These rocks show a general positive correlation between Al and Ti (rAl-Ti = 0.54 and 0.68 for Yudinka and Predivinsk rocks, respectively) and a negative correlation between SiO2 and Th (rSi-Th = –0.57; –0.77), which can be explained by a marked decrease in the content of Th with increasing quartz content in terrigenous rocks. This suggests a sedimentary origin for these rocks. Amphibole-plagioclase-quartz and thinly laminated greenschists of the Predivinsk sequence with CIA of 47–50 are also likely to be of metasedimentary origin. This is confirmed by the presence of bedding and elemental variations that are atypical of

igneous rocks (a strong negative, not positive, correlation between Th and SiO2 (rSi-Th = –0.72) and a positive correlation between K2O and Al2O3, TiO2 (rAl-K = 0.71, rTi-K = 0.71). In general, the analyzed terrigenous rocks are characterized by wide variations in major-element chemistry (in wt.%): SiO2 (56–78%), TiO2 (0.22–1.99), Al2O3 (11–19), Fe2O3* (1.9– 9.8), MgO (0.5–3.7), CaO (0.5–6.2), Na2O (1.75–6.0), K2O (0.32–3.05) (Table 1), with the predominance of Na2O over K2O. Greenschists are more enriched in Ti, Fe, Mg, and Ca, whereas quartzite schists and metasandstones have higher silica and alkali contents as compared to aleuroschists. Trace and rare-earth elements. The terrigenous rocks of the Predivinsk terrane are characterized by a relative depletion of LILE and HFSE (Cs, Rb, Ba, Ti, U, Th, La, Ce, Zr, Hf, and Nb), as well as Cr, Co, Ni, Cu, Zn, Sn, Mo, W, and Ga and enrichment of HREE and Y relative to PAAS (PostArchean Australian Shale) (Table 1, Fig. 2), except for quartzites and quartzite schists, which are characterized by a relative enrichment of some HFSE (Nb, Zr, Hf, and Y) found in heavy minerals. Some elements, such as Sc and Sr, as well as Fe, Mg, and Ca, typical of basic and intermediate igneous rocks are enriched in mica-amphibole-feldspar-quartz and thinly laminated greenschists of the Predivinsk sequence relative to PAAS (Table 1, Fig. 2b, c). Mica-quartz-feldspar aleuroschistsand metasandstones of the Yudinka sequence show the strongest enrichment of K, Th, Rb, and Cs compared with other types of terrigenous rocks. For example, the average contents of K and Th measured in 15 samples are equal to 2.4 ± 0.4% and 9.5 ± 2.5 ppm, whereas these values may reach 14–15 ppm (for Th) and 3–3.2% (for K) in individual samples. Note for comparison that K and Th contents of amphiboleplagioclase-quartz and thinly laminated greenschists are equal to 1.3% and 4.1 ppm. The associated volcanics have the _ highest Th content, _e.g., rhyolites (xTh = 6.6 ± 1.9; n = 28) and trachyrhyolites (xTh = 8.1 ± 1; n = 9) (Nozhkin, 1985b). But even thses values are lower than those of aleuroschistsand sandstones. Such elevated conentrations of K and Th in terrigenous rocks of the Yudinka sequence may point to a highly differentiated crustal component, i.e., granitic gneisses. The measured REE patterns for mica-quartz-feldspar aleuroschistsand metasandstones of the Yudinka sequence and thinly laminated greenschists of the Predivinsk sequence have a slight negative Eu anomaly (Eu/Eu* = 0.8–0.97) and generally low (La/Yb)n ratio of 2.8–6.1 (Table 1, Fig. 3a, c). Quartzites and quartzite schists of the Predivinsk sequence have more pronounced negative Eu anomaly (0.5–0.6) and low (La/Yb)n ratio of 2.0–4.5 (Fig. 3d). Most silica-poor mica-amphibole-feldspar-quartz schists of the Predivinsk sequence have a less pronounced Eu anomaly (Eu/Eu* = 0.63–0.89) (Fig. 3b). Comparison between REE contents of quartzites and schists shows a general inverse correlation between Eu/Eu* and SiO2 (Table 2). Nd isotopic characteristics. 147Sm/144Nd ratios of most of the analyzed rocks are different from the typical average crustal value of 0.12, which allows interpretation using single-stage T(DM) model ages (Table 3). Terrigenous me-

SiO2 TiO2 Al2O3 Fe2O3* MnO MgO CaO Na2O K2O P2O5 LOI Total Li Be Sc V Cr Co Ni Cu Zn Ga Ge Rb Cs Sr Y Zr Nb Mo Sn Ba La Ce Pr Nd Sm Eu Gd Tb

65 0.62 14.42 4.73 0.07 1.2 2.94 2.81 2.8 0.22 1.96 96.77 1.4 0.9 27.0 239 24 19 20 22 113 14 14 29 1.3 313 52.5 31.5 8.9 1.0 1.8 327 20.5 49.7 6.7 31.1 8.8 2.8 9.1 1.5

65.14 1.12 15.9 7.25 0.11 1.97 1.96 3.08 2.52 0.14 1.22 100.41 1.9 1.3 15.5 113 37 16 29 29 51 21 8 58 1.6 649 32.4 65.3 16.5 0.8 1.4 502 17.1 40.4 5.2 23.1 4.9 1.4 5.3 0.8

64.11 0.64 17.5 4.35 0.05 1.93 4.78 3.46 2.36 0.18 0.72 100.08 4.0 1.8 6.8 76 15 10 17 11 49 20 6 104 5.6 516 14.0 62.5 16.9 0.4 1.7 616 29.1 60.1 6.2 23.5 4.7 1.4 4.1 0.6

61.01 0.93 17.38 5.71 0.07 2.27 4.66 3.67 2.57 0.31 0.77 99.35 – – 10.9 79 57 12 28 – – – – 74 2.3 706 18.4 281 9.9 – – 747 33 66 8.1 30 6.1 1.54 4.9 0.68

62.98 1.1 17.93 6.67 0.19 2.95 2.54 1.89 3.05 0.13 1.1 100.53 2.6 0.9 23.3 103 79 18 48 18 61 23 9 124 3.6 200 27.9 56.5 14.5 0.4 2.2 690 24.0 56.0 6.8 24.2 5.1 1.4 5.1 0.8

4-85

37-12 A-146-82a 127-82a 6-85

Compo- Yudinka sequence nent 1 3

4

65.22 0.89 19.43 3.94 0.07 1.5 3.42 2.52 2.58 0.14 1.00 100.71 1.8 1.5 22.0 165 25 15 14 15 90 18 11 50 1.5 414 48.6 9.1 8.1 0.4 1.1 478 19.8 47.1 6.6 29.6 7.8 2.3 7.7 1.3

72.96 0.24 14.62 1.88 0.03 0.53 2.00 3.69 3.04 0.08 0.76 99.85 1.7 1.1 24.6 207 54 22 32 29 87 13 12 22 0.3 214 43.2 33.6 8.6 0.6 1.6 353 17.9 43.1 6.0 27.3 7.4 2.3 7.9 1.3

62.53 0.58 16.53 5.80 0.10 2.81 4.98 3.60 2.09 0.22 1.20 100.44 1.8 0.9 12.8 83 198 13 30 15 61 17 8 47 1.5 206 19.9 34.1 13.1 0.7 2.4 462 27.7 61.1 7.3 31.0 7.5 1.5 6.7 0.9

64.00 0.61 14.58 8.41 0.22 1.84 4.88 3.60 0.49 0.31 1.40 100.34 1.8 1.4 29.2 223 31 20 1 29 110 18 12 64 2.5 264 57.5 30.6 10.1 2.9 1.4 495 28.3 65.9 8.7 39.1 10.0 2.7 10.6 1.6

66.85 1.07 13.75 6.52 0.22 1.31 2.38 4.76 1.56 0.22 1.02 99.67 1.2 0.8 21.2 74 5 13 10 31 86 10 11 8 0.2 256 44.7 32.8 6.2 0.2 1.2 126 24.2 56.1 7.5 33.3 8.8 2.3 9.5 1.5

66.07 0.76 15.66 3.89 0.09 1.63 3.53 4.60 1.56 0.14 2.38 100.31 0.9 1.0 22.3 158 27 21 24 14 58 15 8 23 0.2 192 40.5 47.3 8.4 0.5 1.6 366 17.3 42.3 6.0 27.1 6.9 2.1 7.1 1.2

66.62 0.76 13.52 6.42 0.10 2.06 4.60 4.05 0.32 0.15 2.10 100.70 0.3 2.1 6.6 11 5 2 6 8 31 16 4 31 0.4 91 51.5 612.1 16.4 0.8 3.9 317 27.4 63.8 8.7 39.1 10.2 1.4 10.4 1.7

56.87 1.55 16.60 8.96 0.14 3.50 3.88 4.97 0.48 0.61 2.95 100.51 11.0 2.2 21.0 – 23 13 13 15 91 18 7 36 0.2 244 65.4 246.0 15.0 1.4 3.3 125 16.4 37.0 – 23.0 6.4 2.2 7.2 1.2

56.37 1.99 14.24 9.79 0.18 3.36 5.39 3.23 2.33 0.37 2.73 99.99 1.6 1.3 26.7 287 27 24 23 23 113 16 13 70 2.4 269 51.5 26.8 10.1 3.5 1.6 446 18.2 44.5 5.9 25.5 6.6 2.2 6.4 1.2

57.94 1.28 15.00 7.29 0.13 2.88 5.29 4.63 1.17 0.23 4.53 100.37 0.4 1.2 7.3 66 4 5 8 6 49 19 5 38 0.5 247 66.1 69.4 10.2 0.2 2.5 564 28.9 69.8 9.5 41.5 11.0 2.8 10.5 1.9

57.97 1.44 15.24 8.77 0.19 3.00 4.81 4.07 1.90 0.42 2.07 99.89 1.1 0.6 23.6 180 26 17 15 14 78 32 12 52 0.6 559 44.7 37.8 7.7 0.5 1.1 1049 23.1 51.2 5.7 22.0 5.4 1.6 5.5 1.0

59.74 0.67 15.98 7.37 0.14 3.71 6.19 3.86 1.71 0.21 0.93 100.52 2.1 1.1 24.8 195 66 23 30 14 51 14 10 45 1.4 546 22.3 33.2 6.2 0.5 1.3 324 12.7 29.5 3.9 15.1 3.8 1.2 3.7 0.6

70.59 0.53 14.55 3.92 0.08 0.95 2.11 5.60 1.05 0.07 0.71 100.15 1.6 3.3 3.7 9 7 1 4 4 20 25 3 72 0.5 23 81.8 357.8 23.5 3.9 5.1 605 28.1 63.5 8.0 35.0 8.2 1.4 9.0 1.5

72.29 0.35 13.92 3.38 0.07 1.18 1.06 6.00 1.38 0.05 0.81 100.49 1.1 4.1 6.0 9 3 1 4 4 99 26 6 40 0.6 71 128.6 373.7 29.4 0.5 5.1 485 40.2 104.2 14.2 66.0 17.1 2.8 18.4 3.4

72.80 0.45 13.86 3.20 0.09 0.34 0.92 5.90 1.65 0.07 1.04 100.32 0.2 0.3 7.0 10 3 2 5 4 21 7 3 4 0.1 87 32.1 4.2 0.8 0.2 0.7 91 32.7 76.2 10.9 48.7 12.0 2.4 12.3 2.1

75.28 0.30 13.75 2.49 0.11 0.82 0.48 1.75 2.93 0.03 1.89 99.83 1.2 3.4 8.6 50 27 3 10 5 44 25 5 28 0.8 110 78.1 184.9 24.1 0.2 4.5 582 31.7 76.2 10.3 43.7 10.8 1.7 11.3 2.1

76.20 0.33 11.40 3.01 0.10 0.52 0.98 4.09 1.66 0.04 1.29 99.62 1.0 0.7 12.3 83 45 13 17 13 53 9 7 26 1.1 358 16.4 24.1 4.4 0.3 0.9 216 10.4 24.2 3.3 14.2 3.7 1.0 3.6 0.6

78.00 0.22 11.34 1.32 0.07 0.41 2.31 3.89 0.48 0.07 0.33 99.87 0.4 1.5 7.9 12 2 1 3 4 44 13 4 32 0.5 70 69.6 603.2 18.0 0.2 3.1 337 21.8 52.4 7.4 35.2 9.4 2.0 10.8 1.8

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76.20 0.35 11.48 4.07 0.10 0.54 0.61 3.72 2.06 0.05 1.32 100.51 1.0 3.5 6.8 10 3 1 4 4 78 21 7 45 0.6 58 110.4 385.5 27.6 0.6 6.7 479 47.9 109.3 15.0 67.2 15.3 2.6 15.1 2.6

104-82 148-82 162-78 220-78 142-78 88-78 163-78 98-78 126-78 85-78 125-78 102-78 204-78 226-78 211-78 184-78 196-78 225-78 164-78

2

Predivinsk sequence

Table 1. Representative major (wt.%) and trace element (ppm) analyses of metasedimentary rocks of the Predivinsk terrane

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 1574

3.7 0.68 1.75 0.27 1.64 0.23 6.6 0.72 – – 4.5 1.55 13.6 0.86 2.9 50 0.36 3.03 37 33 22 33 4 20 13 0 0 0 0 7 1 0.39 0.32 0.054 0.36

4.6 1.0 2.6 0.4 2.7 0.4 1.6 0.9 0.5 11.1 9.8 2.3 6.1 0.84 4.3 62 0.55 1.03 16 49 29 16 0 31 14 3 0 0 0 4 2 0.40 0.34 0.061 0.28

3.3 0.6 1.4 0.2 1.1 0.1 1.6 1.4 0.2 22.9 13.4 2.4 18.0 0.97 5.6 51 1.32 4.26 30 36 25 30 0 24 8 4 0 0 0 7 1 0.35 0.23 0.037 0.33

10.5 2.2 6.0 0.8 5.0 0.7 1.1 0.7 0.4 9.0 4.1 1.0 2.8 0.96 4.1 53 0.22 0.76 29 26 34 26 2 26 0 0 0 0 2 8 1 0.30 0.31 0.043 0.39

5.0 1.1 2.9 0.4 2.7 0.4 2.1 1.0 0.7 10.9 5.4 1.5 4.3 0.82 3.6 58 0.34 1.10 34 31 30 28 6 15 15 0 0 0 0 4 2 0.37 0.41 0.070 0.35

4-85

3

4

9.1 1.9 5.0 0.7 4.1 0.6 0.5 0.6 0.4 13.6 4.0 0.8 3.2 0.89 4.8 60 0.27 0.90 14 55 20 14 0 24 0 31 0 0 0 10 1 0.37 0.19 0.046 0.26

8.7 1.8 5.0 0.7 4.3 0.6 1.3 0.7 0.7 7.0 3.1 0.9 2.8 0.93 3.4 53 0.14 0.73 42 17 36 34 8 17 0 0 0 0 0 4 0 0.23 0.13 0.017 0.46

5.1 1.0 2.4 0.3 2.1 0.3 1.0 0.6 0.5 12.7 7.0 1.5 8.9 0.63 4.7 49 0.55 2.17 34 33 25 32 2 18 15 0 0 0 0 7 1 0.37 0.34 0.035 0.34

10.4 2.1 6.0 0.9 5.1 0.7 1.0 0.7 0.6 9.7 3.4 1.0 3.8 0.80 3.4 49 0.17 0.97 33 28 44 33 0 5 7 0 0 0 0 10 2 0.36 0.54 0.042 0.28

9.6 2.1 5.2 0.7 4.3 0.6 1.1 0.5 0.3 6.1 3.4 1.0 3.8 0.76 3.4 50 0.26 1.14 47 12 29 44 3 11 0 0 0 0 7 4 2 0.32 0.46 0.078 0.46

7.7 1.6 4.5 0.6 3.8 0.5 1.6 0.6 0.7 6.2 4.2 0.8 3.1 0.89 5.3 50 0.20 0.77 44 23 27 43 2 13 9 0 0 0 0 5 1 0.31 0.24 0.048 0.39

10.0 2.0 5.2 0.8 4.4 0.6 14.5 1.2 0.5 7.0 4.0 1.5 4.2 0.43 2.7 47 1.95 4.12 35 25 31 35 0 3 14 7 0 0 0 8 1 0.31 0.46 0.056 0.32

– – – – 3.1 0.4 3.2 0.3 0.7 10.8 3.0 0.8 3.5 0.99 3.8 51 0.23 0.78 38 30 21 34 4 10 20 0 0 0 0 9 1 0.47 0.48 0.093 0.33

7.6 1.6 4.6 0.6 3.7 0.5 0.9 0.7 0.5 9.2 3.0 0.9 3.4 1.05 3.3 45 0.13 0.68 48 24 19 37 11 1 23 0 0 0 0 7 2 0.46 0.61 0.139 0.39

11.7 2.4 6.4 0.9 5.5 0.8 2.4 0.9 0.8 10.5 5.5 1.3 3.5 0.80 4.2 45 1.19 3.96 49 22 19 43 6 2 20 0 0 0 0 8 2 0.41 0.46 0.085 0.39

5.9 1.3 3.4 0.5 3.0 0.4 1.2 0.2 0.3 17.1 4.5 1.0 5.2 0.87 4.5 47 0.27 0.98 29 22 23 29 1 22 0 0 0 0 9 14 3 0.44 0.54 0.095 0.39

3.3 0.7 1.9 0.3 2.1 0.3 1.2 0.6 0.4 8.0 2.1 0.7 4.1 1.00 3.0 45 0.09 0.51 46 30 17 46 0 5 24 1 0 0 0 5 3 0.40 0.45 0.042 0.35

11.0 2.6 8.0 1.3 8.8 1.4 12.3 1.7 1.2 14.0 10.0 2.8 2.1 0.51 3.6 51 10.65 7.57 52 10 30 51 1 10 0 0 0 0 4 3 1 0.27 0.27 0.036 0.46

21.5 4.5 12.6 1.8 10.9 1.4 10.2 2.0 0.8 18.6 8.6 2.0 2.5 0.49 4.4 51 7.66 6.75 62 5 28 56 6 3 0 0 0 2 4 0 1 0.25 0.24 0.025 0.53

12.5 2.6 7.0 1.1 7.6 1.4 15.5 0.1 0.3 1.9 7.0 2.2 2.9 0.60 3.2 51 3.22 4.67 62 4 30 54 8 4 0 0 0 1 3 0 1 0.24 0.23 0.033 0.55

12.2 2.6 7.3 1.1 6.8 1.0 5.5 1.8 0.7 14.4 8.0 2.6 3.2 0.47 3.1 67 2.31 3.68 16 32 50 16 0 31 0 0 0 0 1 0 0 0.22 0.18 0.022 0.34

17.4 3.5 9.4 1.3 7.8 1.2 10.0 1.8 0.7 15.4 7.8 2.2 4.1 0.52 3.5 55 5.20 7.01 41 10 44 34 7 9 0 0 0 1 4 0 1 0.21 0.35 0.030 0.50

3.5 0.7 1.9 0.3 1.5 0.2 1.2 0.5 0.4 7.9 2.7 1.0 4.5 0.87 2.7 53 0.21 0.85 45 7 44 39 6 7 0 0 0 0 3 1 1 0.19 0.27 0.029 0.50

12.5 2.8 8.0 1.2 7.5 1.1 13.6 1.3 0.5 15.7 3.5 0.8 2.0 0.60 4.4 50 2.79 2.75 37 12 50 35 2 5 4 0 0 0 0 4 0 0.18 0.24 0.019 0.39

104-82 148-82 162-78 220-78 142-78 88-78 163-78 98-78 126-78 85-78 125-78 102-78 204-78 226-78 211-78 184-78 196-78 225-78 164-78

2

Predivinsk sequence

Note. 1, mica-quartz-feldspar aleuroschists and metasandstones; 2, amphibole-plagioclase-quartz ± Bt ± Chl aleuroschists; 3, thinly laminated greenschists; 4, mica- and feldspar-rich quartzites and quartzite schists. (La/Yb)n ratios were normalized to chondrite (Boynton, 1984), Eu/Eu* = Eun/((Smn + Gdn)1/2) (Taylor and McLennan, 1985). The normative mineral composition recalculated after Rosen et al. (1999): F, total feldspar; P, total clay minerals; Q, quartz; Pl, plagioclase; Or, orthoclase; Ill, illite; Chl, chlorite; Mm, montmorillonite; Kn, kaolinite; Srp, serpentine; Gt, goethite; Car, carbonate minerals (calcite, dolomite, ankerite, rhodochrosite); SM, secondary minerals (rutile, apatite). Petrochemical modules (Yudovich and Ketris, 2011): HM (hydrolysate module) = (TiO2 + Al2O3 + Fe2O3 + FeO + MnO)/SiO2, FM (femic module) = (Fe2O3 + FeO + MnO)/(TiO2 + Al2O3), TM (titanium module) = TiO2/Al2O3; NAM (normalized alkalinity module) = (Na2O + K2O)/Al2O3. Fe2O3*, Total iron. Dash denotes not analyzed.

Dy Ho Er Tm Yb Lu Hf Ta W Pb Th U (La/Yb)n Eu/Eu* Th/U CIA Th/Co La/Sc F P Q Pl Or Ill CHl Mm Kn Srp Gt Car Sm HM FM TM NAM

37-12 A-146-82a 127-82a 6-85

Compo- Yudinka sequence nent 1

Table 1 (continued)

1575 A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

Fig. 2. PAAS-normalized (Taylor and McLennan, 1985) patterns of trace element concentrations in terrigenous metasediments: a, biotite-quartz-feldspar schists and metasandstones of the Yudinka sequence; b, amphibole-feldspar-quartz aleuroschists; c, thinly laminated greenschists; d, mica-feldspar quartzite of the Predivinsk sequence. The numbers of samples are the same as in Table 1.

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 1576

Fig. 3. Comparison of chondrite-normalized REE patterns (Boynton, 1984) for terrigenous metasedimets and associated metavolcanics. The composition of metavolcanics (samples 140-82, 21-12, 170-78a, 21-85, 10, 193-78) are given in Table 2. a, b, c, d, Types of terrigenous rocks are the same as in Fig. 2.

1577 A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

1578

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 Table 2. Representative compositions of metavolcanics associated with metasediments Component

1

2

3

4

5

6

140-82

A-21-12

170-78à

21-85

193-78

10

SiO2

54.09

66.76

63.48

66.58

74.90

74.68

TiO2

0.9

1.08

0.79

0.57

0.23

0.2

Al2O3

17.5

13.66

16.27

15.27

12.99

12.61

Fe2O3*

8.27

6.39

4.20

3.41

2.7

2.09

MnO

0.13

0.11

0.18

0.04

0.07

0.15

MgO

4.6

1.94

1.17

1.39

0.30

0.01

CaO

7.4

2.77

3.08

2.8

0.61

0.39

Na2O

4.54

2.82

5.85

4.75

5.40

4.52

K2O

1.54

1.75

1.74

2.27

1.58

4.36

P2O5

0.272

0.16

0.21

0.16

0.03

0.02 0.46

LOI

0.88

0.51

2.51

2.88

0.71

Total

100.12

97.95

99.48

100.12

99.52

99.49

Th

2.3

6.6

5.3

3.6

7.3

9.2

U

0.3

1.4

1.23

0.8

2.1

1.7

La

19

28

22

28

39

37

Ce

39

59

50

65

89

82

Pr

–

7.4

6.5

–

11.8

–

Nd

22

29

29

35

52

52

Sm

5.2

6.2

6.1

8

11.6

14.8

Eu

1.4

1.55

1.90

2.2

1.72

1.75

Gd

4.5

5.7

6.6

9.3

12.3

17

Tb

0.69

0.91

1.17

1.7

2.3

2.9

Dy

–

5

7.1

–

14.9

–

Ho

–

1.05

1.44

–

3.3

–

Er

–

3

4.5

–

10.0

–

Tm

–

0.48

0.69

–

1.63

–

Yb

1.34

3.1

4.3

6.5

10.2

10.9

Lu

0.18

0.47

0.68

1

1.56

1.63

Rb

33

58

44

50

16.7

72

Ba

270

482

530

500

459

–

Sr

700

338

232

90

66

10

Zr

170

260

222

–

626

400

Hf

2.3

6.9

5.3

4.5

14.9

12.7

Ta

0.2

0.67

0.63

0.7

1.53

1.8

Nb

–

9.8

9.6

–

22

– –

Y

–

31

43

–

96

Sc

25

20

10.9

7

4.0

2.8

V

200

–

29

–

9.1

< 20

Cr

72

30

8.4

32

2.7

94

Co

26

10

3.8

5

1.0

3

Ni

35

14

5

2

5

5

(La/Yb)n

9.56

6.09

3.47

2.90

2.56

2.29

Eu/Eu*

0.88

0.80

0.91

0.78

0.44

0.34

Th/Co

0.09

0.66

1.40

0.72

7.32

3.07

La/Sc

0.76

1.40

2.05

4.00

9.65

13.21

Note. 1–2, Yudinka sequence (Western Block): 1, andesibasalt, 2, dacite (metabasalt-andesibasalt-andesite-dacite suite); 3–6, Predivinsk sequence (Eastern Block): 3, andesite, 4, dacite, 5, rhyolite (metabasalt-andesite-rhyolite suite); 6, trchyrhyolite (subalkaline basalt-rhyolite suite).

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A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

Table 3. Sm–Nd isotope data for rocks of the Predivinsk terrane No.

Rock, sample

Sm

Nd

147

Sm/144Nd

143

Nd/144Nd

T(DM), Ma

εNd

21.5

0.1237

0.512226 ± 17

1565

–2.2

ppm 1

Aleuroschist (A-146-82)

4.39

2

Metasandstone (A-104-82)

3.04

22.2

0.0828

0.512488 ± 5

773

+6.3

3

Metaandesite (A-140-82)

5.15

25.2

0.1237

0.512668 ± 15

819

+6.3

4

Schist (A-162-78)

4.33

20.6

0.1270

0.512723 ± 7

753

+7.3

5

Schist (A-126-78)

7.13

27.8

0.1550

0.512826 ± 3

845

+7.0

6

Schist (A-85-78)

5.54

22.7

0.1473

0.512814 ± 5

775

+7.4

7

Metadacite (A-21-85)

9.47

38.9

0.1470

0.51277 ± 20

872

+6.6

Note. The εNd values were calculated for an age of 630 Ma. 1–3, Yudinka sequence: 1, garnet-biotite aleuroschist, 2, muscovite-biotite metasandstone, 3, metaandesite; 4–7, Predivinsk sequence: 4, two-mica plagioclase-quartz schist, 5, amphibole-biotite-chlorite schist, 6, thinly laminated greenschist, 7, metadacite.

tasedimentary rocks of the Predivinsk terrane yielded TNd(DM) model ages within the range of 753–845 (εNd(630) from +6.3 to +7.4), except for one sample of garnet-biotitequartz-feldspar aleuroschistsfrom the Yudinka sequence (A146-82a), which has a significantly negative εNd value (–2.3) and older TNd(DM) age (1565 Ma).

Isotope geochronology U–Pb age of island-arc suites. The timing of formation of volcano-terrigenous rocks of the Yudinka sequence was determined based on the results of SHRIMP II U–Pb zircon dating of metarhyodacite from the basalt-andesibasalt-an-

desite-dacite suite of the Western Block. Interlayering of metavolcanics, metasediments and marmorized limestones in this suite implies their approximately synchronous formation. Sample A-35-12 was collected from exposed bedrock on the right side of the Yudinka River valley (a tributary of the Yenisei River), 1.5 km above the mouth (57°00′18.9″ N, 93°23′41.8″ E). The studied rhyodacite is composed primarily of quartz, plagioclase, K-feldspar and minor (up to 5%) biotite, muscovite, clinozoisite, with accessory apatite and zircon. The rock has a fine-grained granoblastic texture. Zircons occur as transparent pale pink, long-prismatic or bipyramidal grains, 200–500 µm in size, with an elongation ratio of 1–1.5. Cathodoluminescence (CL) imaging reveals fine oscillatory zoning typical of magmatic zircons. Nine

Fig. 4. Concordia diagram for zircons from metarhyodacite of the Yudinka sequence (sample A-35-12).

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A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 Table 4. U–Pb isotope data for zircons from metarhyodacite of the Yudinka sequence Spot

206

Pbc, U

Th

232

Th/ 206Pb*, Age, Ma U ppm 206 Pb/238U ± 1s

D, %

238

U/206Pb*

207

Pb*/206Pb*

207

Pb*/235U

206

Pb*/238U

Rho

238

% ppm

207

206

Pb/

Pb ± 1s

A-35-12.5.1

0.47

105 11

0.10

9.0

607 ± 8

616 ± 110

2

10.13 ± 1.3

0.0604 ± 5.1

0.82 ± 5.3

0.0987 ± 1.3 0.257

A-35-12.9.1

0.92

106 26

0.26

9.2

614 ± 8

509 ± 167

–17

10.01 ± 1.4

0.0575 ± 7.6

0.79 ± 7.7

0.0999 ± 1.4 0.182

A-35-12.1.1

0.29

278 158 0.59

24.0

614 ± 6

590 ± 68

–4

10.01 ± 1.0

0.0596 ± 3.1

0.82 ± 3.3

0.0999 ± 1.0 0.294

A-35-12.6.1

0.27

199 187 0.97

17.3

619 ± 6

627 ± 72

1

9.92 ± 1.1

0.0607 ± 3.4

0.84 ± 3.5

0.1007 ± 1.1 0.301

A-35-12.2.1

0.28

341 215 0.65

29.6

619 ± 5

611 ± 62

–1

9.91 ± 0.9

0.0602 ± 2.9

0.84 ± 3.0

0.1008 ± 0.9 0.302

A-35-12.3.1

0.00

194 80

16.8

621 ± 6

621 ± 51

0

9.89 ± 1.0

0.0605 ± 2.4

0.84 ± 2.6

0.1011 ± 1.0 0.407

0.42

A-35-12.7.1

0.05

276 159 0.59

24.0

622 ± 6

600 ± 44

–4

9.88 ± 0.9

0.0599 ± 2.0

0.84 ± 2.3

0.1012 ± 0.9 0.418

A-35-12.8.1

0.13

951 132 0.14

82.8

622 ± 4

602 ± 32

–3

9.88 ± 0.8

0.0600 ± 1.5

0.84 ± 1.7

0.1012 ± 0.8 0.450

A-35-12.4.1

0.00

296 130 0.45

25.9

625 ± 6

586 ± 41

–6

9.83 ± 0.9

0.0595 ± 1.9

0.83 ± 2.1

0.1017 ± 0.9 0.437

Note. Errors are 1σ; Pbc and Pb*, common and radiogenic portions, respectively. Error in standard calibration was 0.33%. Rho, Error correlation between 207Pb/235U and 206Pb/238U. Common Pb corrected using measured 204Pb. D, discordance.

analyses of nine zircon grains yielded a concordant age of 618.8 ± 3.9 Ma (MSWD = 0.96) (Fig. 4, Table 4). The age of 618.8 ± 3.9 Ma obtained on zoned zircon grains is taken to record zircon crystallization from an andesite-dacite melt and to reflect the ages of basalt-andesibasalt-andesite-dacite volcanics and sedimentary rocks of the Yudinka sequence. Previous zircon U–Pb dating of trachyrhyolites from the bimodal volcanic suite of the Eastern Block and plagiogranites of the Yagun massif show that they formed at 637 ± 5.7 Ma and 628 ± 3 Ma, respectively (Vernikovsky et al., 1999, 2009). The results indicate that these island-arc rocks formed during the late Neoproterozoic–Vendian. LA–ICP-MS U–Pb dating of detrital zircons. LA–ICPMS U–Pb dating of detrital zircons separated from a biotitequartz-feldspar metasandstone (sample A-37-12) (Qz + Pl + Bt + Ms + Grt + Ep + Ttn + Ap + Zrn) was carried out to determine the crystallization age of the protoliths of the Yudinka terrigenous metasedimentary rocks. This sample was collected on the right side of the Yenisei River valley, 0.6 km above the mouth of the Yudinka River (56°59′89.0″ N, 93°22′48.8″ E). The rocks is foliated, inequigranular; the clastic component is represented by long-prismatic or, more rarely, isometric, thin tabular plagioclase grains ranging in size from 0.2–3 to 4–5 mm. the fine-grained blastically recrystallized groundmass consists of a biotite-quartz-feldspar aggregate, with minor muscovite, titanite, epidote, garnet, and accessory apatite and zircon. All the zircons extracted from this sample are transparent to translucent pale pink and brownish grains, with variably preserved long-prismatic outline and smooth bipyramidal edges, ranging in size from 100 to 250 µm and have an elongation ratio of 1:4–1:1. Cathodoluminescence (CL) imaging reveals fine oscillatory zoning typical of magmatic zircons. The age histogram and relative probability curve were built on data from 57 zircon grains with >95% concordance (Table 5). The detrital zircon population is dominated by grains between 610 and 640 Ma, with the peak at 620 Ma (Fig. 5). All the analysis points define three clusters in a concordia diagram at 619, 628, and 637 Ma (Fig. 5). These

data are consistent with the ages of island-arc rhyodacites (619 ± 4 Ma) of the Yudinka sequence, Western Block, trachyrhyolites (637 ± 5.7 Ma) of the Predivinsk sequence, Eastern Block, and plagiogranites of the Yagun massif (628 ± 3 Ma), which could be likely sources of detrital material for terrigenous rocks of the Yudinka sequence. For discordant zircons clustering at 590–610 Ma, the original older age can be rejuvenated during Vendian metamorphism events.

P-T conditions and timing and metamorphism Mineral assemblages indicate that the volcanosedimentary rocks of the Predivinsk terrane range in metamorphic grade from epidote-amphibolite facies to locally retrograde greenschist facies along zones of intense shearing and brecciation (Reverdatto and Khlestov, 1986). This is confirmed by P-T estimated based on coexisting minerals. The mineral assemblages used to constrain P-T conditions of metamorphism include: Grt-Pl-Bt in felsic metavolcanics (sample 324-1), Grt-Bt-Ms-Pl in metapelites (sample 319) and Amp-Pl-Bt in metabasites (sample 332) of the Yudinka sequence (samples collected on the right side of the Yenisei River valley, 4.5–2.0 km upstream the Yudinka River), and Amp-Pl in metagabbro-amphibolites (sample 40-12) of the Yarlychikha massif. The mineral assemblages in metapelites and felsic metavolcanics are usually represented by coarsegrained weakly deformed garnet porphyroblasts in contact with other mineral (plagioclase and mica) in the absence of any reaction textures. The mineral assemblages in metabasites of the Yudinka sequence were subjected to intense dynamic metamorphism and recrystallization accompanied by the formation of prominent blastomylonite zones. The bulk chemical composition and P-T estimates are given in Table 6. Garnet from the rocks of the Yudinka sequence ranges in composition from Alm58, Prp15, Grs6, Sps21 with XFe = 0.80 in metapelites to Alm86, Prp7, Grs7, Spsl with XFe = 0.92 in felsic metavolcanics (Table 6). The anorthite component in plagioclase XAn = Ca/(Ca + Na + K) varies from 0.33

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A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

Table 5. U–Pb isotope data for zircons from biotite-quartz-feldspar metasandstone of the Yudinka sequence (sample A-37-12) No.

Spot, sample no.

Isotope ratios

1

A-37-12-02

0.0610

0.0002 0.8529

0.0053 0.1015

0.0006 0.93

639

6

626

3

623

3

0.9

2

A-37-12-03

0.0605

0.0003 0.8513

0.0062 0.1020

0.0006 0.83

633

9

625

3

626

4

0.7

3

A-37-12-06

0.0611

0.0002 0.8819

0.0051 0.1047

0.0005 0.91

643

7

642

3

642

3

0.6

4

A-37-12-09

0.0608

0.0002 0.8452

0.0076 0.1008

0.0008 0.92

632

3

622

4

619

5

0.7

5

A-37-12-11

0.0606

0.0001 0.8538

0.0046 0.1021

0.0006 0.80

628

5

627

3

627

3

0.2

6

A-37-12-13

0.0607

0.0002 0.8216

0.0040 0.0981

0.0004 0.70

632

1

609

2

603

3

0.7

7

A-37-12-14

0.0607

0.0002 0.8383

0.0049 0.1001

0.0005 0.90

628

7

618

3

615

3

1.0

8

A-37-12-16

0.0609

0.0002 0.8460

0.0047 0.1007

0.0005 0.80

635

7

622

3

619

3

0.6

207

Pb/206Pb 1δ

Rho 207

Pb/235U 1δ

206

Pb/238U 1δ

Age, Ma

Th/U

207

Pb/206Pb 1δ

207

Pb/235U 1δ

206

Pb/238U 1δ

9

A-37-12-17

0.0606

0.0002 0.8233

0.0047 0.0986

0.0005 0.82

633

7

610

3

606

3

0.6

10

A-37-12-18

0.0603

0.0002 0.8337

0.0056 0.1002

0.0006 0.88

617

14

616

3

616

3

0.6

11

A-37-12-19

0.0604

0.0002 0.8437

0.0056 0.1013

0.0006 0.88

617

12

621

3

622

3

0.6

12

A-37-12-20

0.0604

0.0002 0.8313

0.0048 0.0998

0.0005 0.84

618

9

614

3

613

3

0.9

13

A-37-12-21

0.0605

0.0003 0.8852

0.0071 0.1061

0.0008 0.80

620

9

644

4

650

5

0.6

14

A-37-12-23

0.0613

0.0003 0.8645

0.0064 0.1023

0.0007 0.92

650

9

633

3

628

4

0.6

15

A-37-12-26

0.0607

0.0002 0.8513

0.0059 0.1017

0.0006 0.88

628

7

625

3

625

4

0.8

16

A-37-12-27

0.0607

0.0003 0.8448

0.0055 0.1009

0.0005 0.77

628

9

622

3

620

3

0.7

17

A-37-12-31

0.0607

0.0002 0.8311

0.0060 0.0992

0.0006 0.85

629

9

614

3

610

4

0.6

18

A-37-12-33

0.0608

0.0002 0.8441

0.0064 0.1007

0.0007 0.88

632

3

621

4

618

4

0.7

19

A-37-12-36

0.0612

0.0002 0.8352

0.0050 0.0991

0.0006 0.70

656

7

617

3

609

3

0.7

20

A-37-12-37

0.0615

0.0002 0.8699

0.0085 0.1026

0.0009 0.94

657

7

636

5

629

5

0.5

21

A-37-12-38

0.0608

0.0002 0.8438

0.0057 0.1007

0.0006 0.93

632

3

621

3

619

4

0.9

22

A-37-12-39

0.0603

0.0002 0.8353

0.0058 0.1005

0.0007 0.96

613

6

617

3

617

4

1.1

23

A-37-12-40

0.0607

0.0003 0.8656

0.0073 0.1035

0.0008 0.87

628

9

633

4

635

4

0.7

24

A-37-12-43

0.0606

0.0002 0.8446

0.0057 0.1011

0.0006 0.83

633

7

622

3

621

3

0.3

25

A-37-12-46

0.0606

0.0002 0.8207

0.0052 0.0983

0.0006 0.90

633

6

608

3

604

3

0.3

26

A-37-12-48

0.0610

0.0003 0.8468

0.0060 0.1008

0.0006 0.91

639

14

623

3

619

4

0.5

27

A-37-12-51

0.0609

0.0003 0.8646

0.0057 0.1030

0.0005 0.77

635

7

633

3

632

3

0.6

28

A-37-12-52

0.0605

0.0003 0.8421

0.0056 0.1009

0.0005 0.78

620

9

620

3

620

3

0.6

29

A-37-12-53

0.0609

0.0003 0.8450

0.0060 0.1007

0.0006 0.86

635

11

622

3

618

4

0.6

30

A-37-12-54

0.0610

0.0003 0.8459

0.0062 0.1007

0.0006 0.84

639

14

622

3

618

4

0.6

31

A-37-12-55

0.0607

0.0002 0.8431

0.0051 0.1007

0.0006 0.95

632

3

621

3

619

3

0.6

32

A-37-12-57

0.0615

0.0003 0.8686

0.0053 0.1024

0.0005 0.70

657

42

635

3

629

3

0.7

33

A-37-12-66

0.0603

0.0002 0.8375

0.0051 0.1007

0.0005 0.89

617

12

618

3

618

3

0.9

34

A-37-12-68

0.0605

0.0002 0.8620

0.0056 0.1033

0.0006 0.86

633

7

631

3

633

3

0.8

35

A-37-12-69

0.0626

0.0006 0.8766

0.0126 0.1018

0.0014 0.80

694

20

639

7

625

8

0.5

36

A-37-12-71

0.0606

0.0002 0.8635

0.0050 0.1034

0.0005 0.91

633

7

632

3

634

3

1.0

37

A-37-12-72

0.0605

0.0002 0.8413

0.0062 0.1009

0.0006 0.86

620

7

620

3

620

4

0.6

38

A-37-12-75

0.0609

0.0003 0.8566

0.0061 0.1020

0.0006 0.83

635

14

628

3

626

4

0.6

39

A-37-12-77

0.0607

0.0002 0.8442

0.0049 0.1009

0.0005 0.90

628

7

621

3

620

3

0.6

40

A-37-12-79

0.0620

0.0002 0.9026

0.0056 0.1056

0.0006 0.80

676

27

653

3

647

4

0.3

41

A-37-12-81

0.0610

0.0003 0.8762

0.0050 0.1041

0.0004 0.68

643

9

639

3

638

2

0.6

42

A-37-12-82

0.0613

0.0003 0.9027

0.0074 0.1068

0.0007 0.86

650

9

653

4

654

4

0.6

43

A-37-12-88

0.0609

0.0003 0.8716

0.0059 0.1037

0.0006 0.84

639

14

636

3

636

3

0.7

44

A-37-12-93

0.0611

0.0003 0.8877

0.0065 0.1053

0.0006 0.77

643

11

645

4

646

3

0.6

45

A-37-12-95

0.0614

0.0002 0.8757

0.0043 0.1035

0.0005 0.89

652

9

639

2

635

3

0.6

(continued on next page)

1582

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 Table 5 (continued) No.

Spot, sample no.

Isotope ratios 207

206

Pb/

Pb 1δ

Rho 207

Pb/

235

U 1δ

206

238

Pb/

Age, Ma 207

U 1δ

Th/U

206

Pb/

Pb 1δ

207

235

Pb/

U 1δ

206

238

Pb/

U 1δ

46

A-37-12-96

0.0610

0.0002 0.8630

0.0041 0.1025

0.0004 0.72

639

12

632

2

629

2

0.7

47

A-37-12-101

0.0607

0.0002 0.8571

0.0047 0.1023

0.0005 0.91

632

2

629

3

628

3

0.9

48

A-37-12-103

0.0609

0.0002 0.8705

0.0058 0.1037

0.0006 0.93

635

7

636

3

636

4

0.6

49

A-37-12-104

0.0610

0.0002 0.8517

0.0045 0.1012

0.0004 0.73

639

12

626

2

622

2

0.7

50

A-37-12-105

0.0604

0.0002 0.8421

0.0047 0.1010

0.0004 0.79

620

9

620

3

620

3

0.1

51

A-37-12-108

0.0602

0.0002 0.8339

0.0055 0.1004

0.0006 0.94

613

7

616

3

617

4

1.0

52

A-37-12-109

0.0605

0.0002 0.8352

0.0046 0.1001

0.0004 0.79

620

9

617

3

615

3

0.7

53

A-37-12-110

0.0617

0.0002 0.9184

0.0073 0.1080

0.0008 0.91

661

40

662

4

661

4

0.3

54

A-37-12-114

0.0612

0.0003 0.8834

0.0051 0.1046

0.0004 0.71

656

8

643

3

641

3

0.6

55

A-37-12-116

0.0614

0.0003 0.8961

0.0061 0.1059

0.0006 0.82

654

10

650

3

649

3

0.5

56

A-37-12-117

0.0614

0.0002 0.8814

0.0055 0.1042

0.0005 0.82

650

9

642

3

639

3

0.7

57

A-37-12-120

0.0613

0.0003 0.9085

0.0078 0.1076

0.0009 0.95

650

9

656

4

659

5

0.8

in metapelites to 0.25 in felsic metavolcanics. Biotite from these rocks exhibits variations in TiO2 (1.7–2.1 wt.%) and XFe (0.44–0.57). Muscovite from metapelites are celadonite-rich ((Mg + Fe)/(Mg + Fe + AlVI) = 0.21) and paragonite-poor (XNa = 0.05). Hornblende from metabasites of the Yudinka sequence and Yarlychikha massif has different TiO2 contents (0.8 and 1.3 wt.%) and K2O (1.5 and 0.4 wt.%) and XFe (0.55 and 0.4), respectively. The composition of plagioclase varies from XAn = 0.37 in metabasites of the Yudinka sequence to XAn = 0.45 in metabasites of the Yarlychikha massif. The maximum metamorphic pressures and temperatures for the garnet-containing metapelites and felsic metavolcanics were estimated using the calibration with appropriate activitycomposition models for the Grt-Bt geothermometer (Holdaway, 2000) and Grt-Bt-Pl-Qz geobarometer (Wu et al., 2004), Grt-Bt geothermometer (Ferry and Spear, 1978) and Grt-BtMs-Pl geobarometer (Ghent and Stout, 1981), Grt-Ms geothermometer and Grt-Ms-Pl-Qz geobarometer (Wu and Zhao, 2006). The Amp-Pl geothermometer (Blundy and Holland, 1990) and Amp-Pl-Qz geobarometer (Bhadra and Bhattacharya, 2007) were used to determine pressures and temperatures in garnet-free mineral assemblages from metabasites. The P-T estimates for these rocks were calculated for the combination of the geobarometers and geothermometers using the NullSpace procedure of the Mathematica 5.0 package (Korobeinikov et al., 2006; Wolfram, 2003). Uncertainties in temperature and pressure estimates obtained by the simultaneous use of geothermometers and geobarometers were calculated considering the contributions of analytical errors and errors in a reaction enthalpy as no higher than ±30 °C and ±1 kbar (Likhanov and Reverdatto, 2002, 2011). These values are similar to commonly accepted uncertainties of geothermobarometers (Kohn and Spear, 1991; Kontorovich et al., 1997). For an independent pressure control, these values were compared with the pressure estimates using four calibrations of the Al–Hrb geobarometer (Anderson and Smith, 1995; Hammarstrom and Zen, 1986; Hollister et al., 1987; Schmidt,

1992). The values obtained by different geobarometers and geothermometers are consistent within the commonly accepted uncertainties. The P-T estimates vary within 4.8 kbar/520 °C for felsic metavolcanics, 5.5–6 kbar/640–660 °C for metapelites of the Yudinka sequence and 4.6–5 kbar/640 °C for metabasites of the Yarlychikha massif, which correspond to epidote-amphibolite facies conditions. The higher P-T estimates are reported from epidote-amphibolite to amphibolite facies metabasites of this sequence (6.8–7.8 kbar/700 °C) (Table 5). These differences in metamoprhic P-T parameters can be explained by tectonic control in the Predivinsk and Yenisei shear zones along faults (Likhanov et al., 2011, 2015b). The parameters calculated in this study are consistent with the results of numerical modeling, indicating the development of tectonic overpressure (Schmalholz and Podladchikov, 2013) and heating of rocks in excess of lithostatic pressure in ductile shear zones at upper-mid crustal depths (Burg and Gerya, 2005; Burg and Schmalholz, 2008). The timing of metamorphism was constrained by Ar–Ar dating of hornblende separates from amphibolites (metabasites) in the island-arc rock suite of the Predivinsk terrane. The plateau ages of 606 ± 8 and 614 ± 8 Ma recorded by hornblende from the Yudinka (sample 116-78) and Predivinsk (sample 16) sequences (Fig. 6) suggest that metamorphism of volcaniclastic rocks at ca. 600–610 Ma was related to the Vendian accretion/collision event along the western margin of the Siberian craton (Nozhkin et al., 2007), which resulted in the accretion of the Predivinsk terrane to the Early Precambrian Angara–Kan block.

Discussion Reconstruction of the provenance and protoliths of metasedimentary rocks. The studied terrigenous metasedimentary rocks are classified using classifications diagrams of

Fig. 5. Histogram of U–Pb isotope ages calculated from probability.

U ratios of detrital zircons from garnet-bearing biotite-quartz-feldspar metasandstone (sample A-37-12). 1, number of grains, 2, relative

238

Pb/

206

1583 A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

1584

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 Table 6. Chemical compositions (wt.%), structural formulas, and P-T metamorphic conditions calculated using different geothermobarometers Component

332

40-12

Pl

Hbl

Pl

319 Hbl

Grt

324-1 Pl

Ms

Bt

Grt

Pl

Bt

SiO2

59.41

41.94

57.52

44.05

37.49

60.81

45.69

36.38

36.91

60.46

35.28

TiO2

–

0.80

0.02

1.25

–

–

0.92

2.05

–

–

1.65

Al2O3

25.48

11.75

27.21

12.35

20.92

24.90

34.02

18.45

20.40

23.73

18.99

FeO

0.04

18.74

0.05

13.11

26.27

0.08

2.99

16.92

38.65

0.10

20.64

MnO

–

0.38

0.10

0.02

9.70

0.01

0.02

0.11

0.18

–

0.02

MgO

–

8.59

–

11.25

3.83

–

0.83

12.13

1.79

–

8.64

CaO

7.70

11.58

9.45

11.57

2.03

6.78

0.04

0.01

2.36

5.30

0.06

Na2O

7.27

1.34

6.29

1.67

0.04

7.68

0.47

0.28

0.05

8.75

0.27

K2O

0.06

1.50

0.14

0.36

–

0.06

9.54

9.35

–

0.07

8.27

Total

99.96

96.62

100.1

95.64

100.3

100.3

94.53

95.70

100.3

98.41

93.83

(O)

(8)

(23)

(8)

(23)

(12)

(8)

(11)

(11)

(12)

(8)

(11)

Si

2.65

6.46

2.56

6.69

3.00

2.70

3.08

2.72

3.00

2.73

2.73

Ti

–

0.09

–

0.14

–

–

0.05

0.12

–

–

0.10

Al

1.34

2.13

1.43

2.18

1.97

1.30

2.70

1.63

1.96

1.26

1.73

Fe

–

2.41

–

1.64

1.76

–

0.17

1.06

2.63

–

1.33

Mn

–

0.05

–

–

0.66

–

–

0.01

0.01

–

–

Mg

–

1.97

–

2.51

0.46

–

0.08

1.35

0.22

–

1.00

Ca

0.37

1.91

0.45

1.85

0.17

0.32

–

–

0.21

0.26

0.01

Na

0.63

0.40

0.54

0.48

0.01

0.66

0.06

0.04

0.01

0.77

0.04

K

–

0.30

0.01

0.07

–

–

0.82

0.89

–

–

0.82

XAn/Fe

0.37

0.55

0.45

0.40

0.80

0.33

0.67

0.44

0.92

0.25

0.57

P/T1

7.8/698

4.9/638

–

–

P/T2

–

–

5.6/660

4.8/522

3

P/T

–

–

5.5/643

–

P/T4

–

–

6.0/654

–

1

P, kbar

6.8

4.6

–

–

P, kbar2

7.3

4.7

–

–

P, kbar3

7.1

5.0

–

–

4

7.1

5.0

–

–

P, kbar

Note. For plagioclase, anorthite content XAn = Ca/(Ca + Na + K); for the remaining minerals, XFe = Fe/(Fe + Mg). Total Fe is expressed as FeO. The blank means below the microprobe detection limit. The structural formulas of the minerals are calculated on the basis of a fixed number of oxygen atoms, denoted as n(O). P/T are the P-T estimates obtained using different modifications of geothermometers and geobarometers for garnet-free (1, (Bhadra and Bhattacharya, 2007; Blundy and Holland, 1990)) and garnet-containing assemblages (2, (Holdaway, 2000; Wu et al., 2004); 3, (Wu and Zhao, 2006); 4, (Ferry and Spear, 1978; Ghent and Stout, 1981)). P, kbar are pressures calculated using four calibrations of the Al–Hbl geobarometer: 1, (Hammarstrom and Zen, 1986); 2, (Schmidt, 1992); 3, (Hollister et al., 1987); 4, (Anderson and Smith, 1995).

Neelov (1980) and Herron (1988). The chemical data for the aleuroschistsand metasandstones of the Yudinka sequence are plotted in the field of shales and wackes in the first diagram and in the field of aleuropelites, polymictic and graywacke aleurolites (Fig. 7a, b). In these diagrams, aleuroschistsof the Predivinsk sequence are identified as shales and Fe-rich shales, graywacke aleurolites and aleuropelites. Quartzite schists and quartzites are classified as wackes in Herron’s diagram or as polymictic psammitolites in Neelov’s diagram. The terrigenous rocks of the Predivinsk terrane are characterized by a positive correlation between the titanium and femic modules (TM–FM) and a negative correlation between the hydrolysate and normalized alkalinity modules (HM–

NAM) (Fig. 8) (Yudovich and Ketris, 2011), which suggests that the studied sediments can be classified as the first cycle rocks. Composition and chemical maturity of eroded sediments. The normative mineralogy calculated using the MINLITH program (Rosen et al., 1999) provides preliminary estimates of the original premetamorphic mineralogical composition of metasedimentary rocks. Recalculations of silicate analyses to the normative mineral composition (Table 1) show that the original sediments are dominated by a clastic component, i.e., quartz (17–50%) and feldspar (14–56%), with minor amounts of acidic plagioclase and sometimes K-feldspar (up to 11%). The clay component is represented by normative illite

1585

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

(1–31%) and chlorite (up to 24%) in aleuroschists from both sequences, and only illite (3–31%) in quartzite schists. It should be taken in to account in the interpretation of the normative mineral composition that the normative mineralogy reflects the composition of mature sediments in which clasts of volcanic rocks and dark-colored minerals were totally destroyed by chemical weathering. A high proportion of chlorite indicates the presence of fragments of basic rocks and dark-colored minerals in the original sedimentary rocks. Micaor amphibole-rich felsic rocks are characterized by normative feldspar-quartz with minor illite at the expense of mica and normative montmorillonite at the expense of amphibole. The normative mineral composition indicates that greenschists of the Predivinsk sequence containing a high proportion of normative chlorite are weathering products of igneous rocks of basic and intermediate composition, whereas quartzite schists of the Predivinsk sequence and biotite-quartz-feldspar aleuroschists and metasandstones of the Yudinka sequence are weathering products of felsic and intermediate rocks. The presence of plagioclase, illite, and sometimes smectite (normative montmorillonite) and the absence of kaolinite in the primary composition of metasedimentary rocks point to a poorly differentiated character of these sediments. This is supported by low values of the chemical index of alteration (CIA) ranging from 47 to 67. The chemical data for the studied metasediments on a F1 vs. F2 plot (Roser and Korsch, 1988) indicate that the terrigenous rocks of the Yudinka sequence and quartzites of the Predivinsk sequence were derived from intermediate and felsic rocks, whereas the amphibole-plagioclase-quartz and greenschists were derived from intermediate and, to a lesser extent, basic rocks (Fig. 9a). It was also shown that the

Fig. 6. Ar–Ar age spectrum for hornblende from amphibolites of the Yudinka (sample 116-78) and Predivinsk (sample 16) sequences.

greenschists are relatively enriched in Ti, Fe, Ca, and Mg, which are typical of rocks of intermediate and basic composition, while the quartzite schists and metasandstones are enriched in alkalis and silica, which are typical of felsic magmatic rocks.

Fig. 7. Chemical compositions of metasedimentary rocks of the Yudinka sequence (1, mica-quartz-feldspar aleuroschist and metasandstone) and Predivinsk sequence (2, amphibole-plagioclase-quartz ± Bt ± Chl aleuroschist; 3, thinly laminated greenschist; 4, mica-feldspar quartzite and quartzite schist) plotted on the discrimination diagrams of (lg(SiO2/Al2O3) vs. lg(Fe2O3*/K2O) a (Herron, 1988) and Al/Si vs. (Fe + Mn + Ca + Mg) (Neelov, 1980) b. Fields in the diagram of Neelov, 1980: I, monomictic psammitolite; II, oligomictic psammitolite; III, polymictic psammitolite; IV, siltstone, polymictic (a), graywacke (b); V, aleuropelite (a), carbon- and iron-rich (b).

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

1586

Fig. 8. Correlation between petrochemical modules: TM–FM (a) and NAM–HM (b). TM = TiO2/Al2O3; FM = (Fe2O3 + FeO + MnO)/(TiO2 + Al2O3); NAM = (Na2O + K2O)/Al2O3; HM = (TiO2 + Al2O3 + Fe2O3 + FeO + MnO)/SiO2. Symbols are the same as in Fig. 7.

The distribution and concentrations of trace elements (REE, Th, Sc, La, Co, etc.) and their indicator ratios (e.g., Th/Co and La/Sc) provide important information on the provenance. Comparison of Th/Co and La/Sc ratios in the studied rocks with the composition of sediments derived from granitoids and basic rocks (Cullers, 2002) shows that the terrigenous sediments of the Predivinsk terrane were derived from felsic and intermediate and, to a lesser extent, basic sources. A plot of Th/Co vs. La/Sc shows that the analyzed terrigenous metasedimentary rocks define a common trend reflecting representative compositions of metavolcanic rocks (Table 2) and associated metasediments (Fig. 9b). The (La/Yb)n and Eu/Eu* ratios of terrigenous metasedimentary rocks and associated metavolcanics are characteristic

of the provenance of terrigenous debris. For example, micafeldspar-quartz aleuroschists and metasandstones ((La/Yb)n = 3–6; Eu/Eu* = 0.8–1.0) may have been derived from the weathering of the associated andesibasalt-andesite-dacite volcanics with REE patterns similar to those of sedimentary rocks ((La/Yb)n = 5–9; Eu/Eu* = 0.8–0.95) (Fig. 3a). The REE patterns of quartzite schists and quartzites of the Predivinsk sequence with a pronounced negative Eu anomaly (Eu/Eu* = 0.5–0.6) and low (La/Yb)n ratios (2.0–4.1) correspond to those of rhyodacite-rhyolite volcanics from the basalt-andesite-rhyolite suite of this sequence, which could be the primary sources of these rocks (Table 2, Fig. 3d). The REE distribution patterns of some quartzite samples (e.g., sample 225-78) exhibiting a general absence of Eu anomalies (Eu/Eu* = 0.87)

Fig. 9. Plots of F1 vs. F2 (Roser and Korsch, 1988) (a) and La/Sc vs. Th/Co (Cullers, 2002) (b) showing chemical compositions of metasedimentary rocks of the Predivinsk terrane. The associated volcanics (compositions are shown in Table 2) are given for comparison (1, Yudinka, 2, Predivinsk; the remaining symbols are the same as in Fig. 7). The fields correspond to the following igneous rocks: Bas, basic; An, intermediate; Gr, felsic rocks. F1 = –1.773TiO2 + 0.607Al2O3 + 0.76Fe2O3* – 1.5MgO + 0.616CaO + 0.509Na2O – 1.224K2O – 9.09, F2 = 0.445TiO2 + 0.07Al2O3 – 0.25Fe2O3* – 1.142MgO + 0.438CaO + 1.475Na2O + 1.426K2O – 6.861.

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Fig. 10. Plots of SiO2 vs. (K2O/Na2O) (Roser and Korsch, 1986) (a) and La–Th–Sc (Bhatia and Crook, 1986) (b) showing chemical compositions of metasedimentary rocks of the Predivinsk and Yudinka sequences. Fields: ARC, island arc; ACM, active continental margin; PM, passive margin; A, oceanic island arc; B, continental island arc; C, D, active and passive margins. Symbols are the same as in Fig. 7.

and elevated (La/Yb)n values (4.5) are similar to those of the associated tonalites ((La/Yb)n = 4.3; Eu/Eu* = 0.9). The REE patterns of amphibole-plagioclase-quartz aleuroschists and greenschists of the Predivinsk sequence suggest that basalts and andesites from the basalt-andesite-rhyolite suite of the Predivinsk sequence, which exhibit the poorly differentiated REE pattern with a slight negative Eu anomaly were subjected to weathering together with the rocks of rhyolitic composition. Therefore, elemental distributions indicate that the sedimentary rocks of the Predivinsk terrane were derived from local sources represented by subduction complexes of associated magmatic rocks. Various discrimination diagrams confirm the subduction character of terrigenous sediments of the Predivinsk terrane. On a plot of SiO2 vs. (K2O/Na2O) (Roser and Korsch, 1986), almost all chemical data for metasedimentary rocks of the Predivinsk terrane are plotted in the field of subduction settings, i.e., active continental margins and oceanic island arcs (Fig. 10a). Based on their elemental ratios (La–Sc–Th), the studied sedimentary rocks can be identified as island-arc graywackes (Bhatia and Crook, 1986) (Fig. 10b). The mostly positive εNd composition and similar TNd(DM) values of terrigenous rocks of the Predivinsk terrane suggest derivation from nearly coeval volcanic complexes (Table 3). The terrigenous metasediments of the Predivinsk terrane have a TNd(DM) model age ranging from 753 to 845 Ma (εNd(630) from +6.3 to +7.4), while metaandesite and metadacite from these sequences display TNd(DM) ages of 819–872 Ma and 630 Ma and εNd values of +6.5 and +6.6, respectively. At the same time, one sample (A-146-82a) with significantly older TNd(DM) age of 1565 Ma and a negative εNd value of –2.3 and elevated Th, Rb, and K contents (Table 1) may indicate involvement of a minor amount of the mature crustal materials in these mica-feldspar-quartz metasandstones. This mature crustal material could have been derived from the weathered products of granulite-gneiss and amphibolite-gneiss complexes

of the Angara–Kan block, which are significantly enriched in these elements (Nozhkin and Turkina, 1993; Nozhkin et al., 2012, 2016). This also agrees with the paleomagnetic reconstructions implying a spatial proximity of the Predivinsk island arc and the Siberian craton at the time of their accretion (Metelkin et al., 2004). The timing of formation and accretion of island arc complexes the Predivinsk terrane to the Siberian craton. The available geochronological data suggest that the age of the sources of clastic material in terrigenous sediments of the Yudinka sequence of the Predivinsk terrane must be in the range 610–640 Ma, as indicated by a predominance of these ages in the population of detrital zircons. These results are consistent with zircon U–Pb ages of 619 ± 4 Ma (this study) and 637 ± 5.7 (Vernikovsky et al., 2009) obtained for islandarc rhyolites from two different suites within the Yudinka and Predivinsk sequences. They clearly indicate that the island-arc volcanosedimentary sequences of the Predivinsk terrane formed during Early Vendian time. A major thermotectonic event provides an upper age limit of island-arc complexes. The Ar–Ar ages of hornblende from amphibolites (metabasites) (606 ± 8 and 614 ± 8 Ma) from two distinct volcanic suites of the Yudinka and Predivinsk sequences, respectively, suggest that this event took place at ca. 600–610 Ma during the Vendian as a result of an early accretion/collision stage along the western margin of the Siberianîãî craton (Nozhkin et al., 2007). These results are in close agreement with the our previous Ar–Ar data on biotite (603–605 Ma) from blastomylonites of the Yenisei regional shear zones and biotite (604 ± 5 Ma) from the basanite dike of the Isakovka terrane embedded in the sequence of intensely foliated flyschoid rocks of the accretionary belt (Likhanov et al., 2015a). The Vendian episode (590–620 Ma) is assumed to record the accretions of an island arc and ophiolitic thrust nappes of the Isakovka terrane to the Siberian craton (Vernikovsky et al., 1994). The data on the Yenisei segment of the

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accretionary belt are consistent with the ages of metamorphic rocks from the Northwestern Sayan region (Kan block and Arzybei terrane), which form part, together with the Yenisei Ridge, of the Sayan–Yenisei accretionary–collision belt (Nozhkin et al., 2003, 2007; Turkina et al., 2007). Previous studies show that the Vendian orogeny was manifested not only in the amalgamation of several terranes of different ages, but also in their collision with the Siberian continental margin, as recorded by synchronous thermotectonic events and emplacement of syn-collisional granitoids. Therefore, our results confirm that the Vendian accretion-collisional event resulted in the formation of the Sayan–Yenisei accretionary belt, the accretion of the continental crust to the margin of the Siberian craton and its subsequent thermotectonic reworking. Conclusions The distribution of major and trace elements shows that the protoliths of metasedimentary rocks in the Predivinsk terrane were predominantly mature terrigenous sediments derived from a local source, which was represented by island-arc magmatic rocks. The chemical data and paleogeodynamic reconstructions indicate that the studied terrigenous rocks were deposited in a subduction setting. The age of the sources of clastic material in terrigenous sediments of the Yudinka sequence of the Predivinsk terrane must be in the range 610–640 Ma, which is consistent with a zircon U–Pb age of ~620–640 Ma (this study) obtained for rhyolites from two different suites within the Yudinka and Predivinsk sequences. The geochronological constraints indicate that the terrigenous rocks were eroded from juvenile crustal sources represented primarily by magmatic rocks, which are similar to those of the Predivinsk terrane. This is supported by a similar range of model ages, positive εNd values of terrigenous and magmatic rocks, and U–Pb ages of detrital zircons and zircons from magmatic rocks. The P-T conditions for volcanosedimentary rocks of the Predivinsk terrane correspond to the epidote-amphibolite facies and the transition from epidote-amphibolite to amphibolite facies. The most likely age of metamorphism due to Vendian accretion/collision events is given by Ar–Ar dates of 600– 610 Ma. Acknowledgments. The authors are grateful to Yu.L. Ronkin for his assistance with the trace element analyses, E.N. Lepikhina for dating of zircons from rhyolites, A.I. Proshenkin and H. Geng for their assistance with dating of detrital zircons, A.V. Maslov and O.M. Turkina for their helpful discussion of the results. This study was supported by the Russian Foundation for Basic Research (project no. 12-05-00591) and the Presidium of the Siberian Branch, Russian Academy of Sciences (ONZ68). The study was performed as part of the base project of the Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences “Geodynamics and interplay of magmatic, sedimentary and accretion-collisional processes

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within the Central Asian Orogenic Belt and Siberian Platform”.

References Anderson, J.L., Smith, D.R., 1995. The effects of temperature and fO2 on the Al-in-hornblende barometer. Am. Mineral. 80, 549–559. Bayanova, T.B., 2004. Age of Reference Geologic Complexes in the Kola Region and Duration of Magmatism [in Russian]. Nauka, St. Petersburg. Bhadra, S., Bhattacharya, A., 2007.The barometer tremolite + tschermakite + 2 albite = 2 pargasite + 8 quartz: constraints from experimental data at unit silica activity, with application to garnet-free natural assemblages. Am. Mineral. 92, 491–502. Bhatia, M.R., Crook, A.W., 1986. Trace element characteristics of graywackes and tectonic setting discrimination of sedimentary basins. Contrib. Mineral Petrol. 921, 181–193. Blundy, J.D., Holland, T.J.B., 1990. Calcic amphibole equilibria and new amphibole-plagioclase geothermometer. Contrib. Mineral. Petrol. 104, 208–224. Boynton, W.V., 1984. Cosmochemistry of the rare earth elements: meteorite studies, in: Henderson, P. (Ed.), Rare Earth Element Geochemistry. Elsevier, Amsterdam, pp. 63–114. Burg, J.-P., Gerya, T.V., 2005. The role of viscous heating in Barrovian metamorphism of collisional orogens: thermomechanical models and application to the Lepontine Dome in the Central Alps. J. Metamorph. Geol. 23, 75–95. Burg, J.-P., Schmalholz, S.M., 2008. Viscous heating allows thrusting to overcome crustal-scale buckling: Numerical investigation with application to the Himalayan syntaxes. Earth Planet. Sci. Lett. 274, 189–203. Chernykh, A.I., 2001. Precambrian ophiolite and island-arc complexes of the Yenisei Ridge, in: Topical Problems of Geology and Minerageny of Southern Siberia [in Russian]. Novosibirsk, pp. 183–188. Cullers, R.L., 2002. Implications of elemental concentrations for provenance, redox conditions, and metamorphic studies of shales and limestones near Pueblo, CO, USA. Chem. Geol. 191, 305–327. Ferry, J.M., Spear, F.S., 1978. Experimental calibration of the partitioning of Fe and Mg between biotite and garnet. Contrib. Mineral. Petrol. 66, 113–117. Fleck, R.J., Sutter, J.F., Elliot, D.H., 1977. Interpretation of discordant 40 Ar–39Ar age-spectra of Mesozoic tholeiites from Antarctica. Geochim. Cosmochim. Acta 41, 15–32. Ghent, E.D., Stout, M.Z., 1981. Geobarometry and geothermometry of plagioclase-biotite-garnet-muscovite assemblages. Contrib. Mineral. Petrol. 76, 92–97. Goldstein, S.J., Jacobsen, S.B., 1988. Nd and Sr isotopic systematics of river water suspended material implications for crystal evolution. Earth Planet. Sci. Lett. 87, 249–265. Hammarstrom, J.M., Zen, E.-A., 1986. Aluminum in hornblende: an empirical igneous geobarometer. Am. Mineral. 71, 1297–1313. Herron, M.M., 1988. Geochemical classification of terrigenous sands and shales from core or log data. J. Sed. Petrol. 58, 820–829. Holdaway, M.J., 2000. Application of new experimental and garnet Margules data to the garnet-biotite geothermometer. Am. Mineral. 85, 881–892. Hollister, L.S., Grissom, G.C., Peters, E.K., Stowell, H.H., Sisson, V.B., 1987. Confirmation of the empirical correlation of Al in hornblende with pressure of solidification of calc-alkaline plutons. Am. Mineral. 72, 231–239. Jacobsen, S.B., Wasserburg, G.J., 1984. Sm–Nd evolution of chondrites and achondrites. Earth Planet. Sci. Lett. 67, 137–150. Kachevskii, L.K. (Ed.), 2002. Legend of the Yenisei Group of the State Geologic Map of the Russian Federation. Scale 1:200000 (second ed.) [in Russian]. Krasnoyarskgeols’emka, Krasnoyarsk. Khain, V.E., Volobuev, M.I., Khain, E.V., 1993. Riphean ophiolite belt of the western periphery of Siberian craton. Moscow Univ. Geol. Bull. 4, 22–28. Kohn, M.J., Spear, F.S., 1991. Error propagation for barometers. Am. Mineral. 76, 138–147.

1589

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590

Kontorovich, A.E., Khomenko, A.V., Burshtein, L.M., Likhanov, I.I., Pavlov, A.L., Staroseltsev, V.S., Ten, A.A., 1997. Intense basic magmatism in the Tunguska petroleum basin, eastern Siberia, Russia. Petrol. Geosci. 3, 359–369. Korobeinikov, S.N., Polyansky, O.P., Likhanov, I.I., Sverdlova, V.G., Reverdatto, V.V., 2006. Mathematical modeling of overthrusting fault as a cause of andalusite–kyanite metamorphic zoning in the Yenisei Ridge. Dokl. Earth Sci. 408 (4), 652–656. Kovalenko, V.I. (Ed.), 1987. Magmatic Rocks. The Evolution of Magmatism in the Earth’s History [in Russian]. Nauka, Moscow. Kozlov, P.S., Likhanov, I.I., Reverdatto, V.V., Zinov’ev, S.V., 2012. Tectonometamorphic evolution of the Garevka polymetamorphic complex (Yenisei Ridge). Russian Geology and Geophysics (Geologiya i Geofizika) 53 (11), 1133–1149 (1476–1496). Kuzmichev, A.B., 1987. Tectonics of the Isakovka Synclinorium of the Yenisei Ridge. Extended Abstract of Cand. Sci. (Geol.-Mineral.) Dissertation. Moscow. Likhanov, I.I., Reverdatto, V.V., 2002. Mass transfer during andalusite replacement by kyanite in Al- and Fe-rich metapelites in the Yenisei Range. Petrology 10 (5), 479–494. Likhanov, I.I., Reverdatto, V.V., 2007. Provenance of Precambrian Fe- and Al-rich metapelites in the Yenisey Ridge and Kuznetsk Alatau, Siberia: geochemical signatures. Acta Geol. Sinica (English Edition) 81, 409–423. Likhanov, I.I., Reverdatto, V.V., 2011. Lower Proterozoic metapelites in the northern part of the Yenisei Ridge: nature, age of protolith, and mass balance analysis during collisional metamorphism. Geochem. Int. 49 (3), 224–252. Likhanov, I.I., Reverdatto, V.V., Kozlov, P.S., 2011. Collision-related metamorphic complexes of the Yenisei Ridge: their evolution, ages, and exhumation rate. Russian Geology and Geophysics (Geologiya i Geofizika) 52 (10), 1256–1269 (1593–1611). Likhanov, I.I., Reverdatto, V.V., Kozlov, P.S., Zinov’ev, S.V., 2013a. The Neoproterozoic Trans-Angara dike belt, Yenisey Range, as an indicator of extension and breakup of Rodinia. Dokl. Earth Sci. 450 (2), 613–617. Likhanov, I.I., Reverdatto, V.V., Zinov’ev, S.V., Nozhkin, A.D., 2013b. Age of blastomylonites of the Yenisei regional shear zone as evidence of the Vendian accretionary–collision events at the western margin of the Siberian Craton. Dokl. Earth Sci. 450 (1), 489–493. Likhanov, I.I., Nozhkin, A.D., Reverdatto, V.V., Kozlov, P.S., 2014. Grenville tectonic events and evolution of the Yenisei Ridge at the western margin of the Siberian craton. Geotectonics 48 (5), 371–389. Likhanov, I.I., Reverdatto, V.V., Kozlov, P.S., Khiller, V.V., Sukhorukov, V.P., 2015a. P-T-t constraints on polymetamorphic complexes of the Yenisey Ridge, East Siberia: implications for Neoproterozoic paleocontinental reconstructions. J. Asian Earth Sci. 113, 391–410. Likhanov, I.I., Reverdatto, V.V., Kozlov, P.S., Zinoviev, S.V., Khiller, V.V., 2015b. P-T-t reconstructions of South Yenisei Ridge metamorphic history (Siberian Craton): petrological consequences and application to supercontinental cycles. Russian Geology and Geophysics (Geologiya i Geofizika) 56 (6), 805–824 (1031–1056). Liu, Y., Gao, S., Hu, Z., Gao, C., Zong, K., Wang, D., 2010. Continental and oceanic crust recycling-induced melt–peridotite interactions in the TransNorth China Orogen: U–Pb dating, Hf isotopes and trace elements in zircons of mantle xenoliths. J. Petrol. 51, 537–571. Ludwig, K.R., 1999. User’s Manual for Isoplot/Ex, Version 2.10. A geochronological toolkit for Microsoft Excel. Berkeley Geochronology Center Special Publication, No. 1. Ludwig, K.R., 2000. SQUID 1.00. A User’s Manual. Berkeley Geochronology Center Special Publication, No. 2. Ludwig, K.R., 2003. ISOPLOT 3.00: A Geochronological Toolkit for Microsoft Excel. Berkeley, Berkeley Geochronology Center, California. Metelkin, D.V., Vernikovsky, V.A., Belonosov, I.V., 2004. Paleomagnetism of volcanogenic complexes from the Predivinsk terrane of the Yenisei Ridge: Geodynamic implications. Dokl. Earth Sci. 399 (8), 1080–1084. Mironov, A.G., Nozhkin, A.D., 1978. Gold and Radioactive Elements in Riphean Volcanic Rocks and Their Metamorphic Products (Yenisei Ridge) [in Russian]. Nauka, Novosibirsk. Neelov, A.N., 1980. Petrochemical Classification of Metasedimentary and Volcanic Rocks [in Russian]. Nauka, Leningrad.

Nesbitt, H.W., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 299, 715–717. Nesbitt, H.W., Young, G.M., 1984. Prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations. Geochim. Cosmochim. Acta 48, 1523–1534. Nozhkin, A.D., 1985a. Early Precambrian trough complexes of the southwestern Siberian Platform and metallogeny, in: Precambrian Trough Structures of the Baikal–Amur region and Metallogeny [in Russian]. Nauka, Novosibirsk, pp. 34–46. Nozhkin, A.D., 1985b. Geochemical peculiarities of Early Precambrian trough complexes of the Yenisei Ridge, in: Geology and Radiogeochemistry of Middle Siberia [in Russian]. Nauka, Novosibirsk, pp. 118–140. Nozhkin, A.D., 1996. Composition and paleotectonic setting of the Precambrian volcanic complexes of the Predivinsk structural and formational zone (Yenisei Ridge), in: Magmatism and Geodynamics of Siberia [in Russian]. Tomsk. Gos. Univ., Tomsk, pp. 33–35. Nozhkin, A.D., 1997. Petrogeochemical typification of the Precambrian complexes of southern Siberia. Extended Abstract Doc. Sci. (Geol.-Mineral.) Dissertation [in Russian]. OIGGiM SO RAN, Novosibirsk. Nozhkin, A.D., Turkina, O.M., 1993. Geochemistry of Granulites of the Kan and Sharyzhalgai Complexes [in Russian]. OIGGM SO RAN, Novosibirsk. Nozhkin, A.D., Turkina, O.M., Bibikova, E.V., Ponomarchuk, V.A., Travin, A.V., Dmitrieva, N.V., 2003. Stages of metamorphism and granite formation in the Neoproterozoic accretionary–collision belt in the northwestern part of Eastern Sayan, in: Isotope Geochronology and Problems of Geodynamics and Ore Genesis. Proc. II Russian Conf. Isotope Geochrnology. St. Petersburg, pp. 339–342. Nozhkin, A.D., Turkina, O.M., Sovetov, Yu.K., Travin, A.V., 2007. The Vendian accretionary event in the southwestern margin of the Siberian craton. Dokl. Earth Sci. 415A (6), 869–873. Nozhkin, A.D., Maslov, A.V., Dmitrieva, N.V., Ronkin, Yu.L., 2012. Pre-Riphean metapelites of the Yenisei Range: Chemical composition, sources of eroded material, and paleogeodynamics. Geochem. Int. 7, 574–610. Nozhkin, A.D., Turkina, O.M., Likhanov, I.I., Dmitrieva, N.V., 2016. Late Paleoproterozoic volcanic associations in the southwestern Siberian craton (Angara–Kan block). Russian Geology and Geophysics (Geologiya i Geofizika) 57 (2), 247–264 (312–332). Ponomarchuk, V.A., Lebedev, Yu.N., Travin, A.V., Morozova, I.P., Kiseleva, V.Yu., Titov, A.T., 1998. Application of fine magnetic-separation 40 39 technology in K–Ar, Ar– Ar, and Rb–Sr methods of rock and mineral dating. Geologiya i Geofizika (Russian Geology and Geophysics) 39 (1), 55–64 (52–61). Reverdatto, V.V., Khlestov, V.V. (Eds.), 1986. Precambrian Crystalline Complexes of the Yenisei Ridge: Yenisei Field Trip Guide of the VII All-Union Petrographic Meeting [in Russian]. IGiG SO RAN, Novosibirsk. Rosen, O.M., Abbyasov, A.A., Migdisov, A.A., Bredanova, N.V., 1999. Mineral composition of sedimentary rocks: calculation based on petrochemical data (MINLITH program). Izv. Vyssh. Uchebn. Zaved., Geol. Razdev., No. 1, pp. 21–35. Roser, B.D., Korsch, R.J., 1986. Determination of tectonic setting of sandstone-mudstone suites using SiO2 content and K2O/Na2O ratio. J. Geol. 94, 635–650. Roser, B.D., Korsch, R.J., 1988. Provenance signatures of sandstone-mudstone suites determined using discriminant function analysis of major-element data. Chem. Geol. 67, 119–139. Rumyantsev, M.Yu., Turkina, O.M., Nozhkin, A.D., Gracheva, T.V., Shevchenko, D.O., 2000. New data on the age of the Shumikha paleoisland-arc complex (East Sayan): Late Riphean–Vendian crust formation of the southwestern margin of the Siberian Platform. Russian Geology and Geophysics (Geologiya i Geofizika) 41 (12), 1740–1748 (1790–1797). Schmalholz, S.V., Podladchikov, Y.Y., 2013. Tectonic overpressure in weak crustal-scale shear zones and implications for the exhumation of high pressure rocks. Geophys. Res. Lett. 40, 1984–1988. Schmidt, M.W., 1992. Amphibole composition in tonalite as a function of pressure: an experimental calibration of the Al-in-hornblende barometer. Contrib. Mineral. Petrol. 110, 304–310.

A.D. Nozhkin et al. / Russian Geology and Geophysics 57 (2016) 1570–1590 Taylor, S.R., McLennan, S.M., 1985. The Continental Crust: Its Composition and Evolution. Blackwell, Oxford. Turkina, O.M., Nozhkin, A.D., Bibikova, E.V., Zhuravlev, D.Z., Travin, A.V., 2004. Arzybei terrane: a fragment of Mesoproterozoic island-arc crust in the southwestern framing of the Siberian craton. Dokl. Earth Sci. 395 (2), 246–250. Turkina, O.M., Nozhkin, A.D., Bayanova, T.B., Dmitrieva, N.V., Travin, A.V., 2007. Precambrian terranes in the southwestern framing of the Siberian craton: isotopic provinces, stages of crustal evolution and accretion–collision events. Russian Geology and Geophysics (Geologiya i Geofizika) 48 (1), 61–70 (80–92). Vernikovsky, V.A., Vernikovskaya, A.E., Nozhkin, A.D., Ponomarchuk, V.A., 1994. Riphean ophiolites of Isakovka belt (Yenisei Ridge). Geologiya i Geofizika (Russian Geology and Geophysics) 35 (7–8), 169–180 (146– 156). Vernikovsky, V.A., Vernikovskaya, A.E., Sal’nikova, E.B., Kotov, A.B., Chernykh, A.I., Kovach, V.P., Berezhnaya, N.G., Yakovleva, S.Z., 1999. New U–Pb data on the formation of the Predivinsk paleoisland-arc complex (Yenisei Ridge). Geologiya i Geofizika (Russian Geology and Geophysics) 40 (2), 255–259 (256–261). Vernikovsky, V.A., Kazansky, A.Yu., Matushkin, N.Yu., Metelkin, D.V., Sovetov, Yu.K., 2009. The geodynamic evolution of the folded framing and the western margin of the Siberian craton in the Neoproterozoic: geological, structural, sedimentological, geochronological, and paleomag-

1590

netic data. Russian Geology and Geophysics (Geologiya i Geofizika) 50 (4), 380–393 (502–519). Whitney, D.L., Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. Am. Mineral. 95, 185–187. Williams, I.S., 1998. U–Th–Pb geochronology by ion-microprobe. McKibben, M.A., Shanks III, W.C., Ridley, W.I. (Eds.). Rev. Econ. Geol. 7, 1–35. Wolfram, S., 2003. The Mathematica Book, fifth ed. Wolfram Media Inc., Champaign IL. Wu, C.M., Zhao, G.C., 2006. Recalibration of the garnet–muscovite (GM) geothermometer and the garnet–muscovite–plagioclase–quartz (GMPQ) geobarometer for metapelitic assemblages. J. Petrol. 47, 2357–2368. Wu, C.M., Zhang, J., Ren, L.D., 2004. Empirical garnet–biotite–plagioclase– quartz (GBPQ) geobarometry in medium- to high-grade metapelites. J. Petrol. 45, 1907–1921. Xia, X.P., Sun, M., Geng, H.Y., Sun, Y.L., Wang, Y.J., Zhao, G.C., 2011. Quasisimultaneous determination of U–Pb and Hf isotope compositions of zircon by excimer laser-ablation multiple-collector ICPMS. J. Anal. Atom. Spectrom. 26, 1868–1871. Yudovich, Ya.Yu., Ketris, M.P., 2011. Geochemical Indicators of Lithogenesis (Litholgical Geochemistry) [in Russian]. Geoprint, Syktyvkar. Zablotskii, K.A., Nozhkin, A.D., Sopronchuk, V.P., 1986. Early Precambrian stratified units of the Yukseeva complex, in: Problems of Early Precambrian Stratigraphy of Siberia [in Russian]. Nauka, Moscow, pp. 5–14.

Editorial responsibility: V.V. Reverdatto