The results of U–Pb (ID-TIMS) geochronological studies of vesuvianite from ore-bearing metasomatites of Khopunvaara ore occurrence (Pitkyaranta ore district, Northern Ladoga region) are presented. The resulting age estimate (1550 ± 6 Ma) coincides within the error with the age of formation of ore-bearing skarns that are genetically related to the rapakivi granites of the Salmi batholith. This indicates the possibility of using vesuvianite as a U–Pb mineral-geochronometer, including for ore-bearing contact-reaction rocks.
An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X2305015X
The paper discusses possible immiscibility between fluoride salt (“cryolite”) and silicate liquids into which the parental melt of the Katugin massif exsolves, and the petrological implications of this phenomenon. Results of a detailed study of the cryolite and zircon are presented. Liquid immiscibility is demonstrated to have triggered the massive crystallization of zircon and, together with the processes of subsequent evolution of the cryolite melt, contributed to the formation of the large cryolite bodies. Data on mineral-hosted inclusions were used to estimate the crystallization temperatures of fluoride salt and silicate melts and outline the pathways of their evolution during the formation of the massif. It is shown that the granites of the Katugin and West Katugin massifs were most likely derived from distinct sources, that differed mainly in fluorine content. Data on the chemical composition of three zircon generations identified in the granites of the Katugin massif are presented.
Geochronological (U-Pb on zircons, ID-TIMS), isotope-geochemical (Nd, Sr, Pb), and geochemical studies of rocks of the Amanan and Amudzhikan intrusive complexes and volcanic rocks of the Ukurey Suite in the eastern part of the West Stanovoy superterrane of the Central Asian Fold Belt were performed. The belonging of granitoids of these complexes to high-potassium C-type adakites is substantiated. The cogeneticity of the studied rocks has been established, which makes it possible to unite them into one Amudzhikan volcano-plutonic association formed in the age range of 133±1–128±1 Ma. The igneous complexes of this association are part of the Stanovoy volcano-plutonic belt, which extends in the sublatitudinal direction from the Pacific Ocean deep into the North Asian continent for more than 1000 km subparallel to the Mongol-Okhotsk suture zone and stitches the tectonic structures of the Dzhugdzhur-Stanovoy and West-Stanovoy superterranes. The formation of the Stanovoy Belt is connected with the closure of the Mongolo-Okhotsk Ocean and the collision of the continental masses of the North Asian and Sino-Korean continents at the turn of ~140 Ma. The subsequent collapse of the collisional orogen, accompanied by large-scale lithospheric extension and delamination of the lower part of the continental lithosphere, led to upwelling of the asthenospheric mantle. This caused the melting of the lithospheric mantle and continental crust and, as a consequence, the formation of both mafic melts of the shoshonite type and anatectic crustal melts of the adakite type. The mixing of these melts led to the formation of the parent magmas of the Amudzhikan magmatic association. The crustal component in the source was of a heterogeneous nature and was finally formed as a result of the Early Cretaceous collision event. It is characterized by upper-crustal isotopic parameters: an increased Rb/Sr and U/Pb ratio and a decreased Sm/Nd ratio in the source. The mantle component is represented by the material of the enriched lithospheric mantle of the Central Asian fold belt, the formation of which is associated with subduction processes at the stage of closure of the Mongol-Okhotsk paleoocean. Metasomatic transformation of the mantle with the introduction of melts and fluids with isotopic parameters of an EMII-type source or upper crust occurred at this stage.
Geochemical, geochronological (U–Pb zircons, ID-TIMS) and isotope-geochemical (Sm–Nd) studies of the rocks of the Bambukoy volcano-plutonic association, which form the Zhanok-Bambukoy volcano-tectonic structure within the Anamakit–Muya terrane on the northern flank of the Barguzin–Vitim superterrane of the East Transbaikalian segment of the Central Asian orogenic belt. The association includes volcanic rocks of the Zhanok Suite (dacites and rhyolites mainly), as well as leucocratic and biotite granites of the Bambukoy Complex that cut through them. The granites of this complex host the Mokhovoe tin deposit, which is attributed to the tin-porphyry formation. Subvolcanic rocks of the Zhanok Suite are considered as ore-bearing. The geochemical features of the volcanic rocks of the Zhanok Suite and the granites of the Bambukoy complex bring them closer to S-type granites, and belonging to a single tin-bearing Bambukoy volcanic-plutonic association. The formation of this association is determined by the age interval 834 ± 23–818 ± 7 Ma. The isotopic data point to a source of parental magmas from the rocks of the Bambukoy volcano-plutonic association, formed as a result of mixing of the material of two crustal sources, the mature Early Precambrian and the juvenile Early Baikal. The geochemical data also point to an exclusively crustal source of the rocks of this association. Thus, the Bambukoy tin-bearing volcano-plutonic association was formed in the Neoproterozoic time (Tonian), most likely under lithospheric extension conditions due to a source with a complex and long crustal prehistory.
The results of geochemical and Nd isotopic studies of rocks and U–Th–Pb (LA-ICP-MS) geochronological and Hf isotopic studies of detrital zircon from metaterrigenous rocks of the Kodar Group of the Udokan Complex (Aldan Shield) are presented. It is established that the age of rocks of the Kodar Group is 1.99–1.91 Ga, whereas the age of rocks of the Chinei and Kemen groups of the Udokan Complex is 1.90–1.87 Ga (Kovach et al., 2018, 2023a). This allows us to raise the issue of recognition of the Kodar Group as an independent stratigraphic subdivision. The terrigenous rocks of the group were sourced from the Archean igneous and metamorphic rock of the Chara–Olekma Geoblock and probably the Kalar and Kurulta blocks of the Stanovoi suture zone, as well as the Paleoproterozoic (2.04–1.99, 2.08, 2.20, and 2.30 Ga) complexes of active continental margins or ensialic island arcs in the western–northwestern and southern (in the present-day coordinates) frame of the Chara–Olekma Geoblock, which are unidentified in the region at the current erosion level. Erosion of rocks of magmatic arcs and the continental slope led to the deposition of rocks of the Kodar Group in a retroarc foreland basin, whereas further collapse of the orogen and the formation of an intracontinental extension basin were responsible for the deposition of terrigenous rocks of the Chinei and Kemen groups. The obtained data indicate widespread previously unidentified Paleoproterozoic continental crust formation at about 2.04–1.97 Ga in the western part of the Aldan Shield.
The palingenic calc-alkaline granitoid massifs of the Olekminsky complex form a magmatic belt stretching within the Western-Stanovoy terrane in the northeastern direction for more than 700 km. New U-Pb LA-ICP-MS dates for zircons from the granodiorites of the Marekta-Bereinsky massif of the Olekminsky complex and the granodiorites of the Yamninsky massif of the Krestovsky complex were obtained, amounting to 371±4 Ma and 364±5 Ma, respectively. These geochronological data are well consistent with the 355–358 Ma ones, therefore suggesting the Late Carboniferous age of quartz-diorite-granodiorite-granite rocks of the Olekminsky complex. However, these dates are not correlated with the existing legends of geological maps covering the area of the Western-Stanovoy structural-formation zone or the Western-Stanovoy terrane, as the intrusive formations of the Olekminsky complex are dated as the Early Paleozoic. In addition, new geochronological data call into question distinguishing of a separate Early Paleozoic Krestovsky granitoid complex.
The results of U‒Th‒Pb (LA-ICP-MS) geochronological studies of detrital zircon from metagraywackes of the Kodar Group of the Udokan complex of the Aldan Shield are presented. It is established that the age of terrigenous rocks of the Kodar Group of the Kodar Subzone of the Kodar–Udokan Trough is 2.02−1.91 Ga. The accumulation of rocks of the Kodar Group was separated from the accumulation of rocks of the Chinei and Kemen groups of the Udokan complex and the formation of Cu mineralization of 1.90–1.87 Ga ago by a deformation and metamorphism stage. Our geochronological data allow us to raise a question on the recognition of the Kodar Group or, at least, its lower part as an individual complex. The rocks of the Kodar Group of the Kodar Subzone were sourced from the Archean ( 2.76–2.92 Ga) igneous and metamorphic complexes of the Chara–Olekma Geoblock of the Aldan Shield, as well as unidentified (at the present level of erosion) island arc or active continental margin complexes with an age of 2.02 Ga in the western–northwestern and southern (in the present-day coordinates) framework of the Chara–Olekma Geoblock.
The paper reports geochemical, geochronological (ID–TIMS zircon U–Pb) and isotope–geochemical (Nd, Pb) study of granitoids of the Kodar complex developed in the western part of the Aldan shield. It has been established that these rocks can be classified as postcollisional A–type rapakivi granites, which together with the mafic–ultramafic rocks of the Chinei complex compose a single magmatic association formed within 1876 ± 4–1859 ± 2 Ma. The massifs of this association are a part of the giant South Siberian magmatic belt over 2500 km in length, which was formed at the final stage (1.88–1.84 Ga) of evolution of the Paleoproterozoic orogen. Globally, this belt is the largest stitching suture, which marks the formation of the Siberian craton and its entrance into the Paleoproterozoic Nuna supercontinent. The formation of the initial magmas of the Kodar granitoids was related to the mantle–crustal interaction during the mixing of primary mafic mantle magmas or their derivatives with anatectic melts derived through partial melting of the Archean lower continental crust of the region under the thermal influence of mafic magma. The crustal component in the source clearly predominates and has a heterogeneous nature. The mantle component is mainly represented by ancient enriched mantle, with the possible contribution of the OIB–type component.
This paper investigates applicability of cassiterite to dating ore deposits in a wide age range. We report in situ LA-ICPMS U-Pb and Pb-Pb dating results (n = 15) of cassiterite from six ore deposits in Russia ranging in age from ~1.85 Ga to 93 Ma. The two oldest deposits dated at ~1.83–1.86 Ga are rare metal Vishnyakovskoe located in the East Sayan pegmatite belt and tin deposits within the Tuyukan ore region in the Baikal folded region. Rare metal skarn deposits of Pitkäranta ore field in the Ladoga region, Fennoscandian Shield are dated at ~1.54 Ga. Cassiterite from the Mokhovoe porphyry tin deposit located in western Transbaikalia is 810 ± 20 Ma. The youngest cassiterite was dated from the deposits Valkumei (Russian North East, 108 ± 2 Ma) and Merek (Russian Far East, 93 ± 2 Ma). Three methods of age calculations, including 208Pb/206Pb-207Pb/206Pb inverse isochron age, Tera-Wasserburg Concordia lower intercept age, and 207Pb-corrected 206Pb*/238U age were used and the comparison of the results is discussed. In all cases, the dated cassiterite from the ore deposits agreed, within error, with the established period of magmatism of the associated granitic rock.
Granitoids of the Uda complex are distributed within the southeastern marginal part of the Siberian craton and its folded framing. Geochemical, isotope (Nd, Sr), and geochronological (U–Pb ID TIMS) studies of two massifs (Chalbuk-Yakon and Uyan-Tavitchak) of this complex of the Dzhugdzhur Block of the Stanovoy suture were carried out; the results are presented in this paper. It is found that formation of these massifs took place in the Early Cretaceous (116 ± 1 Ma) in the geodynamic setting of lithospheric extension. The initial magma for these granitoids was formed from a mixed source: Early Precambrian lower crust and mantle, with a clear predominance of the crustal component. The granitoids of the Uda complex of the Dzhugdzhur block most likely represent the eastern end of the Udsko-Zeya (Stanovoy) post-collision magmatic belt, stretching for more than 1000 km along the southern framing of the Siberian craton parallel to the Mongol–Okhotsk suture zone and stitching various tectonic blocks of the northeastern part of the Central Asian fold belt. There is every reason to believe that, further to the west, the Udsko-Zeya (Stanovoy) belt passes into the West Transbaikal rift system, the formation of which took place in the interval of 170–110 Ma. In other words, it can be assumed that in the Mesozoic, in the southern framing of the Siberian craton, there was a giant unified rift system stretching for more than 2000 km.
U-Pb dating of cassiterite and zircon from the Yazov granite (Transbaikalia region, Eastern Siberia, Russia) and cassiterite from spatially associated tin mineralization in the Tuyukan ore district in the Tonod uplift was conducted using in situ laser ablation inductively coupled plasma mass spectrometry. These analyses allow comparison of isotopic systematics for both minerals, especially related to transport in granitic magma. These data are also useful for understanding possible genetic links between the granite and the tin mineralization. Most of the U-Pb zircon analyses define a 206Pb/238U age of 719 ± 15 Ma for the granite; in addition, several zircon cores define an inheritance age of 1839 ± 21 Ma. U-Pb data for 10 nearly concordant analyses of disseminated cassiterite from the same samples yield a 206Pb/238U age of 1838 ± 34 Ma. This is the first documented evidence of cassiterite inheritance in granitic magma. These data indicate the robust character of U-Pb isotope systematics in cassiterite, comparable to that in zircon. The presence of numerous inclusions of cassiterite in zircon from the Yazov granite (revealed by nanotomography) supports the interpretation of inherited cassiterite included during Neoproterozoic zircon crystallization. The data indicate that high tin concentrations in the Yazov granite are due to the incorporation of older cassiterite crystals from country rock, not coeval cassiterite crystallization. Cassiterite samples from two ore occurrences spatially associated with the Yazov granite yield Pb-Pb isochron ages of 1.86–1.82 Ga, indicating that tin mineralization occurred in the Paleoproterozoic, nearly 1 Ga before emplacement of the Yazov granite. Tin mineralization of the ore region is probably related to ~ 1.85 Ga Chuya-Kodar tin-bearing granitic rocks that host tin deposits. These results have broad implications for understanding how critical elements, such as tin, may become enriched in rare-metal granites and how they are related to regional to global geodynamic processes.
Granitoids of the Uda complex are developed within the southeastern marginal part of the Siberian craton and its folded framework. Geochemical, isotope–geochemical (Nd and Sr), and geochronological (U–Pb ID–TIMS) studies of a number of massifs of this complex were carried out for the Chogar granulite block of the Dzhugdzhur–Stanovoi superterrane. It was found that the massifs were formed during the Early Jurassic (181 ± 2 Ma) under the geodynamic conditions of the active continental margin. The initial magma of these granitoids originated from a mixed source consisting of the Early Precambrian lower crust and the mantle. There is a reason to believe that the granitoids of the Uda complex in the Chogar block constitute the southwestern edge of the Uda–Murgal magmatic arc formed under subduction, which extends along the border of the Paleo-Asian Ocean and the Siberian continent.
Abstract–Anorthosites of the Olonkhuduk pluton of the Central Asian Orogenic Belt are dated at 1772 ± 1 Ma (ID TIMS U-Pb zircon method). Similar age estimate (1784 ± 10 Ma) was previously obtained for anorthosite of the Khungilingol pluton from the Ider block of the Tarbagatai terrane. These data indicate a significant time gap (70–60 Ma) between the collision that formed the Early Precambrian blocks of the Baidaric and Tarbagatai terranes in the range 1860–1850 Ma and the emplacement of the anorthosites. The termination of accretion-collision processes and consolidation of the Early Precambrian block of the Baidaric terrain are marked by the postkinematic subalkaline granites with an age of 1825 ± 5 Ma. Geochemically, the anorthosites of the Olonkhuduk and Khungilingol plutons are similar to the typical anorthosites of ancient cratons. Sm-Nd isotopic data indicate a mixed source of these anorthosites: juvenile mantle component of Paleoproterozoic age and crustal component of Neoarchean age. It can be assumed that the primary mafic magma of the anorthosites experienced a significant crustal contamination. Based on the similar geologic setting, age, and composition, the anorthosites of the Olonkhuduk and Khungilingol plutons can be ascribed to a single within-plate complex. The age values obtained for the anorthosites coincide with the estimated age of rift magmatism in the North China craton at 1.8–1.75 Ga and the emplacement time of mafic dikes swarms at 1778 ± 3 Ma (SIMS U-Pb method). Thus, the considered Early Precambrian blocks by the end of the Paleoproterozoic (about 1900–1850 Ma) could be a part of the Columbia supercontinent (Rogers and Santosh, 2002).
Granite–porphyries of the Yazovka complex occur in the northern part of the Riphean Baikal–Patom fold-thrust belt within the Tonod Uplift of the Early Precambrian basement. The geochronological (U–Pb), isotope-geochemical (Sm–Nd), and geochemical studies have shown that the rocks of this complex belong to A-type tin-bearing granites of the age of 709 ± 7 Ma. Initial magma of these granites was formed from the mixed Early Precambrian crustal and mantle source in the intraplate geodynamic setting. This tectonic event was global in nature and manifested the Late Riphean impulse of the lithospheric extension, which was associated with breakup of the supercontinent Rodinia under the influence of a mantle superplume.