INTRODUCTION

The structure and composition of large Early Precambrian cratons, which form the basements of ancient platforms and are most often overlain by a Phanerozoic sedimentary cover, cannot be adequately understood without studying the drill-core materials of deep drillings. Studies of even single samples of these cores provides valuable information on the composition, age, and tectonic nature of the crustal segments and expand the knowledge about the buried Early Precambrian crust. Such studies are particularly important and highly demanded for the Siberian craton, whose inner parts are buried beneath thick sequences of Riphean sedimentary and Phanerozoic volcano-sedimentary rocks. Because of this, the age, composition and structure of this part of the craton still await their more accurate determination and adequate understanding. Currently available data on this part of the basement are mostly based on geophysics, with Sm−Nd isotopic data and U−Pb zircon ages of the Early Precambrian rocks nowadays available merely for single samples recovered by few drillholes (Fig. 1).

Fig. 1.
figure 1

Major tectonic structures of the Early Precambrian Siberian craton (slightly modified after Donskaya, 2020). Sites where rocks of the Siberian craton from beneath the sedimentary cover (drillhole core materials) were dated: Sm–Nd model ages (Kovach et al., 2000); U–Pb zircon SHRIMP ages (Bochkarev et al., 2011, 2013; Popov et al., 2015). Early Precambrian blocks: Anabar superterrane, including: (I) Magan, (II) Daldyn, and (III) Markha terranes; (IV) Berekta superterrane; Aldan superterrane, including (V) Olekma, (VI) Central Aldan, (VII) Eastern Aldan, and (VIII) Batomga terranes; (IX) Stanovoi superterrane; Tunguska superterrane, including: (X) Tunguska, (XI) Taseevskii, (XII) Angara–Lena, and (XIII) Biryusa terranes. Paleoproterozoic foldbelts: (1) Khapchan; (2) Akitkan; (3) Pre-Stanovoi; (4) Angara; and (5) Baikal–Taimyr. Outcrops of Early Precambrian rocks: (Al) Aldan and (An) Anabar shields; (B) Baikal, (K) Kan, (Ol) Olekma, (Sa) Sayan, (St) Stanovoi, (T) Tonod, and (Sh) Sharyzhalgai basement inliers.

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In the eastern part of the Siberian craton, Sm−Nd studies of drill cores (Fig. 1), considered together with data on adjacent outcropping territories of the Aldan and Anabar shields and data on crustal xenoliths and xenocrysts from the kimberlites (Skuzovatov et al., 2021 and references therein), make it possible to reasonably realistically reproduce the distribution of the Archean and Paleoproterozoic domains.

In the western part of the Siberian craton, Early Precambrian rocks were studied only in narrow inliers along the southern and southwestern margins, and data on the core materials of the few drillholes leave much freedom for tectonic speculations in interpreting the geophysical data. All earlier researchers of the western Siberian craton have distinguished its large block, the Tunguska superterrane (Fig. 1), whose inner structure was shown in much detail in some schematic tectonic maps on the basis of geophysical data (Mazukabzov et al., 2006; Glebovitsky et al., 2008; Bush, 2011; Donskaya, 2020). The Tunguska superterrane is bounded by the Paleoproterozoic Angara belt in the west, as was confirmed by data on territories in which the basement crops out in the southwestern Siberian craton (Rozen, 2003; Nozhkin et al., 2019; Donskaya, 2020 and references therein), studies of core samples recovered by a hole drilled in the Baikit uplift (Kovach et al., 2000; Bochkarev et al., 2011; Samsonov et al., 2021), and data on detrital zircon from the Late Precambrian sedimentary rocks (Priyatkina et al., 2020 and references therein). Most researchers believe that the Tunguska superterrane is bounded in the east by the Taimyr−Baikal collisional suture zone, which is completely overlain by sedimentary cover and was distinguished based on geophysics. Various schematic tectonic maps show notably different interpretations of the structure and location of the boundaries of the Taimyr−Baikal suture zone (Rozen, 2003; Mazukabzov et al., 2006; Glebovitsky et al., 2008; Isakov et al., 2008; Bush, 2011; Donskaya, 2020).

Ereminskaya-101 drillhole (Fig. 1) is of key importance as shedding light onto the nature of the central part of the Siberian craton, because this hole has recovered biotite granite-gneisses whose Sm−Nd model age TNd(DM) ranges from 2.30 to 2.37 Ga (Kovach et al., 2000) and thus confirms the local presence of juvenile Paleoproterozoic crust and constrains the field of the Neoarchean complexes of the Tunguska superterrane in the east. We attempted to more accurately determine the location of the eastern boundary of the Tunguska superterrane on the basis of core material of Kulidinskaya-1 drillhole, which was drilled through the top of the crystalline basement 20 km southwest of Ereminskaya-101 drillhole (Fig. 1).

METHODS

Samples were prepared to their analytical study and by magnetic and density separation of their monomineralic fractions at the Laboratory for Analysis of Mineral Composition at the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences, in Moscow.

Rocks were analyzed for major components by XRF in powdered samples on a PW-2400 sequential X-ray spectrometer at the same institute. The material was prepared for analysis by fusing 0.3 g of the powdered sample with 3 g of Li tetraborate in an induction furnace and then casting a homogeneous vitreous disc. The LOI values were determined by gravimetric techniques. The analysis was accurate to 1–5 relative % for elements whose concentrations were higher than 0.5 wt % and up to 12 relative % for elements whose concentrations were lower than 0.5 wt %. Concentrations of trace elements, including REE, were analyzed by ICP-MS at the Laboratory for Nuclear Physical and Mass-Spectral Analysis at the Institute of Technological Problems of Microelectronics and Superpure Materials, Russian Academy of Sciences, in Chernogolovka, Moscow oblast, using methods described in (Karandashev et al., 2007).

The Sm–Nd isotope study was carried out at the Laboratory of Isotope Geochemistry and Geochronology of the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry, Russian Academy of Sciences. The chemical processing of the samples was conducted preparatorily to their analysis according to (Larionova et al., 2007). The isotope ratios were analyzed on a Sector 54 (Micromass, UK) mass spectrometer in multicollector dynamic mode, using a three-filament ion source. The overall inaccuracy of the measured 143Nd/144Nd ratios was no higher than ±0.0022% with regard to the reproducibility of results on the Nd-IGEM in-laboratory standard: 0.512400 ± 11 (2σs, N = 24), which corresponds to the value of 0.511852 in the LaJolla isotope composition standard. The inaccuracy of the determined 147Sm/144Nd ratios was evaluated at ±0.3% (2σs) based on analysis of the BCR-1 standard.

The U–Pb isotope composition of zircon from the biotite granite (sample P48-K1-1a) was analyzed on a SHRIMP-II ion probe at the Isotope Research Center, Karpinsky Russian Geological Research Institute, in St. Petersburg, following the conventionally used technique (Williams, 1998; Larionov et al., 2004). Epoxy pellets with zircons to be analyzed and the 91500 (Wiedenbeck, 1995) and Temora (Black et al., 2003) zircon standards were polished to roughly half of the thicknesses of the grains and then sputter-coated with a ~100 Å layer of 99.999%-pure gold. The inner structure of the zircon grains was studied by optical and electron (CL, BSE) microscopy. Analysis was carried out at selected spots devoid of visually discernible cracks and inclusions, in euhedral crystals (see in Suppl. 1, ESM_1.pdfFootnote 1). The results were processed with the SQUID v. 1.12 and ISOPLOT/Ex software (Ludwig, 2005, 2008), using decay constants from (Steiger and Jäger, 1977). A correction for nonradiogenic Pb was introduced using the measured 204Pb/206Pb according to the model (Stacey and Kramers, 1975).

Cathodoluminescence (CL) images of zircon from the biotite gneiss (sample P48-K1-2) were taken at the IGEM-Analytic Center for Collective Use of Research Equipment in Moscow on a Cameca MS-46 microprobe equipped with a Videoscan 285 CCD high-resolution digital imager at 20 nA current and 200 s counting time. Regardless of the luminescence color in the polychromatic mode, the pale regions of the grains were those of low U concentrations, and the dark ones corresponded to elevated U contents, radiation-induced lattice disturbances, and/or regions with CL-suppressing admixtures.

The U–Pb dating of zircon from the biotite gneiss (sample P48-K1-2) by LA-ICP-MS was carried out at the Laboratory for Chemical Analytical Studies at the Geological Institute, Russian Academy of Sciences, in Moscow, using an Element 2 (Thermo Scientific) sector-field ICP-MS coupled to Elemental Scientific NWR-213 laser ablation system. The operation parameters for the U–Pb isotope dating were according to (Nikishin et al., 2020). U–Pb isotope ratios were calibrated against the GJ-1 primary zircon standard (Jackson et al., 2004; Horstwood et al., 2016). The quality of the analysis of zircon from sample P48-K1-2 was assayed by replicate measurements of the zircon standards 91 500 (Wiedenbeck et al., 1995) and Plešovice (Sláma et al., 2008), whose 206Pb/238U (±2σ) ages were 1068 ± 6 (n = 10) and 337 ± 6 Ma (n = 10), respectively. The time-resolved analytical signals were processed using the Glitter 4.4 software (Van Achterbergh et al., 2001; Griffin et al., 2008). The common lead was corrected using the ComPbCorr 3.18 software (Andersen, 2002; Andersen, 2008). The collected results have been processed with the Isoplot software (Ludwig, 2008). The histograms and probability curves of the age values were plotted with regard to the age estimates whose modulus of discordance coefficient was no higher than 2% {|D| = [100% × (age 206Pb/238U)/(age 207Pb/206Pb) – 1]}. The U and Th concentrations were calculated based on the measured U and Th signals from the 91500 standard (Wiedenbeck et al., 2004).

Petrography and Major-Component Chemistry

Kulindinskaya-1 drillcore revealed sections of the crystalline crust material at depths of 2550–2565 m. The lower portion of this depth range is made up of massive dark gray granite, and the upper one consists of biotite gneiss with numerous pegmatite veinlets and potassic feldspar porphyroblasts (Fig. 2). For this study, we selected three least weathered core samples, including two samples of biotite granite (samples P48-K1-1a and P48-K1-1b) from the depth range of 2565.0–2564.5 m and one of biotite gneiss (sample P48-K1-2) from a depth of 2558.8 m (Fig. 2).

Fig. 2.
figure 2

Photos of rocks recovered by Kulindinskaya-1 drillhole: biotite granite (sample P48-K1-1b) and biotite gneiss (sample P48-K1-2).

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The biotite granite of both samples is a dark fine-grained porphyritic rock (Fig. 2) with plagioclase and potassic feldspar crystals up to 3 mm in a fine-grained biotite–quartz–feldspar groundmass (Figs. 3a, 3b). The samples are similar in chemical composition: these are high-Al granite of normal alkalinity of the K–Na series (Table 1), with enriched LREE patterns and modestly fractionated HREE patterns, and negative Eu, Sr, and Nb and positive Zr anomalies (Fig. 4).

Fig. 3.
figure 3

PPL microphotographs of (a, b) the biotite granite (sample P48-K1-1a) and (c, d) the biotite gneiss (sample P48-K1-2) taken with (a, b) one polarizer and (c, d) crossed polarizers.

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Table 1. Chemical composition of biotite gneisses recovered by Kulindinskaya-1 drillhole
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Fig. 4.
figure 4

Primitive mantle (PM)-normalized (Wedepohl and Hartmann, 1994) trace-element patterns of the granite and gneiss recovered by Kulindinskaya-1 drillhole.

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The biotite gneisses are crosscut by numerous pegmatite quartz–feldspathic veinlets, which make the rock heterogeneous and patchy (Fig. 2). The gneiss consists of a fine-grained aggregate of biotite, chlorite, muscovite, quartz, feldspars, carbonate, and ore minerals (Figs. 3c, 3d). The feldspars are intensely pelitized and sericitized, and the biotite is partly replaced by chlorite. A notable compositional feature of the rock is that it is poor in SiO2 and strongly enriched in K2O at low Na2O and Sr concentrations and notably enriched in Fe-group elements, including Cr and Ni (Table 1). The REE, HFSE, and LILE concentrations and the trace-element patterns are close to those in the granites (Fig. 4).

U–Pb Zircon Geochronology

Granite (SIMS analysis). Zircon from the biotite granite (sample P48-K1-1a) is dominated by grains ranging from –0.15 to +0.05 mm, which are opaque or more rare semitransparent short-prismatic crystals with elongation coefficient close to 2. Rare crystals are long prismatic and have an elongation coefficient ≥3. As seen in their CL images, most of the crystals are heterogeneous and have pale inner and dark outer parts. They are 70 to 90 vol % metamict (Suppl. 1, ESM_1.pdf and Suppl. 2, ESM_2.exl), and only their cores include preserved relict domains with oscillatory zoning (Fig. 5a).

Fig. 5.
figure 5

Results of the isotope dating of zircon from rocks recovered by Kulindinskaya-1 drillhole: (a) biotite granite (sample P48-K1-1a) and (b, c) biotite gneiss (sample P48-K1-2). The figure shows CL images of the zircon grains.

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U–Pb isotope data on the central parts of the zircons, which show a preserved inner structure, are mildly discordant, and are approximated by a discordia corresponding to 2525 ± 10 Ma. One of the grains yielded an old subconcordant (D = –1%) age of 2614 ± 11 Ma (Fig. 5a).

Biotite gneiss (SIMS analysis). Zircon forms in the biotite gneiss (sample P48-K1-2) large grains, approximately 50% of which range from 0.25 to 0.1 mm. The zircons are gray opaque short- to long-prismatic crystals with elongation coefficient of 2–3.5 and rare ellipsoidal anhedral grains, which suggests that the detritus source was not distant. The apexes and edges of the crystals are variably smoothed, and many of the crystals contain more transparent cores, which are bright in CL images and are surrounded with darker opaque thick rims. Close to 40% of the examined grains did not show any internal heterogeneities, perhaps, because of their metamictization (Suppl. 3, ESM_3.pdf and Suppl. 4, ESM_4.exl). The other grains preserve their inner structures in irregularly shaped central zones, which show heterogeneous CL and are overgrown with thick CL-dark (i.e., with high U concentrations) rims or show oscillatory zoning relics with some metamict zones. Some of the grains have roundish cores with homogeneous or more rare diffuse oscillatory zoning.

The U–Pb analysis of various parts of the grains of different morphology (their preserved central parts and rims, cores and outer zones) indicates that they are highly discordant (D = 4.5–90%): only 13 of the 101 results are concordant (D < 1%, Table 1, Fig. 5b). These data are acquired from the inner (preserved) portions of the grains and show a wide scatter of the age values from 3284 to 2620 Ma, with two major peaks at 2717 and 2678 Ma (Fig. 5c).

Table 2. U–Pb SHRIMP-II analyses of zircon from biotite granites recovered by Kulindinskaya-1 drillhole (sample P48-K1-1a)
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Table 3. Results of U–Pb analysis (LA-ICP-MS) of zircon from the biotite gneiss recovered by Kulindinskaya-1 drillhole(sample P48-K1-2)
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Sm–Nd Isotope Geochemistry

Sm–Nd isotopic data on the studied biotite granites and gneisses are summarized at the Table 4. The granite has a model age of TNd(DM) = 2.77 Ga and positive εNd(T) = 1.0. The gneiss yielded an older age of TNd(DM) = 2.91 Ga and has a less radiogenic Nd isotopic composition, which recalculates to an age of 2.6 Ga [εNd(T) = – 0.2].

Table 4. Isotopic–geochemical data on rocks recoverd by Kulindinskaya-1 drillhole
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DISCUSSION

The results of our study allowed us to analyze the origin of the rocks and their tectonic settings in the structure of the basement of the central part of the Siberian Platform.

Origin of the Granites of the Kulinda Massif

The granites recovered by Kulindinskaya-1 drillcore are massive rocks, that do not show evidence of any significant deformations, preserve their primary porphyritic texture, and were likely produced during the posttectonic evolutionary stage of this part of the basement of the Siberian craton. Oscillatory magmatic zoning is seen mostly in the outer U-enriched parts of the zircon grains, as is typical of the CL images of zircons from granitoids and is explained by their metamictization. This process is likely also responsible for the inverse discordance of some of the zircon analyses.

The fine-grained porphyritic nature of the granites indicates that they crystallized at relatively shallow depths and likely make up apical parts of the larger Kulinda massif. The fractionation of HREE, considered together with deep negative Eu and Sr anomalies, suggests that the granitic melt was derived in equilibrium with garnet- and plagioclase-bearing residue, which in turn, argues that the melt was derived at pressures of 5 to 10 kbar (Gao et al., 2016). The fact that the zircon contains entrapped cores dated at 2.61 Ga indicates that the granite magma incorporated material of a crustal source. Therewith the highly radiogenic Nd isotope composition of the granite indicates that the crustal prehistory of this source was short, and it separated from the mantle reservoir no earlier than 2.77 Ga.

The composition of the source of the granitic melt is not self-evident. All petrochemical features of the Kulinda granites place them between the S and I types, although the moderate Al# of the rocks (A/CNK ≥ 1, Table 1) and their low P2O5 and normative corundum (<1 wt %) concentrations are more typical of I-type granites (Chappell, 1999). The liquidus temperature of the granite was evaluated by the Rhyolite-Melts program package (Gualda et al., 2012) for a pressure of 5 kbar, the QFM buffer, and 3−5 wt % H2O content at 900−930°C, which led us to classify the granites of the Kulinda massif with high-temperature I-type granites (Chappell et al., 1998). Lower temperature estimates were calculated from the saturation with Zr (Т = 835–845°C: Watson and Harrison, 1983; Т = 803–804°C: Boehnke et al., 2013) and indicate that the melt was, perhaps, undersaturated with Zr, and that the ancient zircon found in the granites is likely an undissolved xenocryst, which was entrapped by the melt at an upper crustal level. The affiliation of the Kulinda granites with I type also follows from data on their highly radiogenic Nd isotopic composition, which might have been caused by the melting of precursor juvenile granitoids with an age close to 2.7 Ga. Information on these rocks is provided by the detrital zircon of the metasedimentary rocks.

Genesis and Age of the Protoliths of the Biotite Gneisses

The biotite gneisses were intensely reworked at the emplacement of the Kulinda granites and have lost most features of their protolith. The rocks had not preserved any primary textural or structural features. Except the elevated concentrations of the Fe-group elements, all geochemical features of the gneisses seem to have been modified by the granites.

At the same time, zircon from the rocks does show evidence that the biotite granites have been derived from terrigenous sedimentary rocks. Most zircon grains from the biotite gneisses are significantly discordant because of the partial loss of radiogenic Pb. The few grains in which magmatic zoning was discerned yield discrete concordant age values within the range of 2.62 to 3.28 Ga, with most values falling within the narrower range of 2.68 to 2.72 Ga. These data indicate the dominance of Archean sources when the protoliths of the biotite gneisses were formed and a subordinate role of Meso- and Paleoarchean rock complexes. The minimum age obtained from the detrital zircon is 2.62 Ga, and it constrains the maximum age of sedimentation. The minimum limit is set at 2.53 Ga by the age of the crosscutting granites. Our data led us to suggest that the protoliths of the sedimentary rocks were produced during the collision stage and were intermountain molasse. This follows from two facts. First, sedimentation occurred shortly before the breakup of the collisional orogen to which the postcollisional Kulinda granites were likely related. Second, the large size and weak abrasion of the detrital zircon and the fact that its age values mostly lie within the range of 2.6–2.7 Ga suggest a proximal source of the detrital material, as is also typical of active tectonic environments (e.g., Cawood et al., 2012).

Rocks from Kulindinskaya-1 drillhole: Eastern Margin of the Neoarchean Tunguska Superterrane

The tectonic setting, age, Sm−Nd isotopic and geochemical features of the Kulinda granites are close to those of the postcollisional granitoids of the Yurubchen massif (Fig. 6) in the western part of the Tunguska superterrane.

Fig. 6.
figure 6

(a) Primitive mantle (PM)-normalized (Wedepohl and Hartmann, 1994) trace-element patterns of the biotite granites recovered by Kulindinskaya-1 drillhole and the postcollisional granitoids of the Yurubchen massif (Samsonov et al., 2021). (b) Age–εNd(Т) diagram for the granite and gneiss recovered by Kulindinskaya-1 drillhole in comparison with granitoids of the Yurubchen massif (Kovach et al., 2000; Samsonov et al., 2021). The depleted mantle is according to (Goldstein and Jacobsen, 1988). The fields of the Nd isotope composition evolution of gneisses from the Tunguska superterrane and Taimyr–Baikal suture zones were calculated using data from (Kovach et al., 2000).

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Similarities between the two massifs indicate that both were formed during the same stage of crust-building processes, which provides grounds to extend the Tunsguska superterrane eastward up to the site of Kulindinskaya-1 drillhole. At the same time, Ereminskaya-101 drillhole 20 km northeast of it recovered granite-gneisses with a model ages TNd(DM) = 2.30 to 2.37 Ga (Kovach et al., 2000). These juvenile Paleoproterozoic rocks are characterized by a crustal history that was contrastingly different from that of rocks in the Tunguska superterrane (Fig. 6b), and these rocks may belong to the marginal part of the Paleoproterozoic Taimyr−Baikal suture, which is distinguished by many researchers in the central part of the Siberian craton between the Tunguska and Magan superterranes. Such close neighborhood of the rocks with the contrast crustal history may be result of their tectonic combination that is an additional evidence for collision nature of the Taimyr−Baikal suture zone.

CONCLUSIONS

We have reconstructed the primary nature and age of the rocks recovered by Kulindinskaya-1 drillhole in the central part of the Siberian craton and correlated these rocks with complexes in the Tunguska superterrane and Taimyr−Baikal suture.

The biotite granites are not deformed, retain their primary porphyritic textures, and likely make up a shallow-depth apical portion of the Kulinda massif. According to the U–Pb zircon dates, the granites were emplaced at 2.53 Ga. The parental granitic melt was derived from a source with a brief crustal prehistory. The source involved acid material with an age of 2.6 Ga. All characteristics of the Kulinda granites, including their tectonic setting, age, geochemical and isotopic features, are analogous to those of the postcollisional granitoids of the Yurubchen massif, which was studied in the western part of the Tunguska superterrane.

The biotite gneisses have not preserved their primary structural features, but a complex of their characteristics indicates that these rocks are metamorphosed terrigenous sediments that were intensely recycled when the granitoids were emplaced. According to U–Pb zircon dates, the sedimentary protoliths of the gneisses were accumulated at 2.62–2.53 Ga and consisted of the eroded material of Neoarchean complexes, with minor contributions of Meso- and Paleoarchean sources.

The Neoarchean granite-gneiss complex penetrated by Kulindinskaya-1 drillhole in the Tunguska superterrane is bounded by juvenile Paleoproterozoic gneisses with TNd(DM) = 2.30 to 2.37 Ga, which have been studied in core samples recovered by Ereminskaya-101 drillhole (Kovach et al., 2000) and likely belong to the nearby Taimyr–Baikal suture zone. The contrastingly different crustal histories of the two neighboring complexes suggest that these complexes were combines by tectonics.