This study presents new whole rock major and trace element petrographic and geochronological data for three Permian granitoid intrusions of the northeastern Taimyr Peninsula (Chelyuskin Peninsula). U-Pb zircon ages (SIMS SHRIMP) define the crystallization age of the studied Taimyr intrusions as ranging from ca. 282 to 255 Ma, suggesting two magmatic pulses of Early Permian and Middle Permian age. We propose the adakitic geochemical composition of the Permian granites indicate their formation as the result of post-collisional slab melting.

Despite significant progress in Arctic geological studies, a number of principal questions concerning the Paleozoic collisional events remain unanswered. Therefore, the Taimyr Peninsula, representing the only outcropped high Arctic region where magmatic complexes, formed by Hercynian collision between the Siberian Craton and the Kara Block, are well exposed, is crucially important. In this paper we report new geochemical and geochronological data for intrusions in the poorly studied northeastern part of the Taimyr Peninsula. The obtained results in combination with published data show that supra-subduction magmatism at the southern active margin of the Kara Block continued from ca. 345 to 285 Ma (Early Carboniferous to Early Permian), and was followed by a post-collisional magmatic pulse that affected the whole Taimyr across terrane boundaries at ca. 280 Ma in the Early Permian. After cessation of the post-collisional magmatism at ca. 265 Ma, the Taimyr experienced extension, and voluminous magmatic series associated with a Siberian mantle plume were formed between 251 and 228 Ma during the Triassic. The studied post-collisional and plume-related intrusions of the Northeastern Taimyr are generally classified as evolved high-K I-type granites with adakitic affinity. The latter is a regional feature because the majority of the analyzed plume-related granitoids are geochemically similar to high potassium continental adakites. It is suggested that the adakitic geochemical characteristics of the plume-related granitoids resulted from melting of hydrated mafic lower crustal protoliths and were controlled by the source lithology. Comparison of the new results with data available for adjacent areas allows for correlation of terranes on a regional scale and sheds light on the evolution of the Arctic continental margins in general. In the Early–Middle Paleozoic, the Kara Block was part of a continental terrane that formed at the northern edge of Baltica as a result of Neoproterozoic Timanian orogeny. In the Early Carboniferous, the southern margin of Kara turned into an active margin, while its inferred continuation in the eastern Uralian margin of Baltica remained a passive margin until the Early Permian. This discrepancy can be explained by dextral displacement of Kara relative to Baltica that took place in the Early Carboniferous and was later accommodated by the formation of the Taimyr collisional belt in the course of the Early Permian collision between Kara and Siberia. After collision, the Taimyr was incorporated into the northern Eurasian margin as an uplifted block that experienced surface erosion and supplied clastic material in surrounding basins.

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070267

The studied plume-related intrusions of the NE Taimyr are generally classified as evolved high-K I type granites with adakitic affinity. The latter is a regional feature because majority of the analyzed plume-related granitoids are geochemically similar to high potassium continental adakites. It is suggested that adakitic geochemical characteristics of the plume-related granitoids resulted from melting of hydrated mafic lower crustal protoliths and were controlled by the source lithology.

The Taimyr Peninsula in the Russian High Arctic comprises a late Paleozoic-early Mesozoic collisional belt where several porphyry-type mineralization occurrences were identified during the last decade, making this area a potential exploration target for Cu-Mo deposits. In order to further evaluate the metallogenic potential of the poorly outcropped northeastern part of Taimyr, samples from seven granitoid intrusions were investigated in this study aimed to evaluate the granite fertility based on petrography, geochemistry, and composition of porphyry indicator minerals (zircon, apatite, and titanite). The studied intrusions represent small to moderate-sized bodies (40–800 km2) composed of biotite (±amphibole) quartz monzonites, granodiorites, granites, and biotite leucogranites that formed in the course of late Paleozoic-early Mesozoic tectono-magmatic events at the Siberian margins. The late Carboniferous Tessemsky massif represents suprasubduction granitoid series, while the Pekinskiy, Shirokinskiy, Dorozhinskiy, Kristifensenskiy, and Yuzhno-Lodochnikovskiy massifs are correlated with the early Triassic Siberian Traps LIP. The rocks of intrusions comprise a relatively uniform geochemically, predominantly magnesian, slightly peraluminous, calc-alkaline high-K amphibole-bearing I-type granitoid series with adakitic affinity, where Triassic plume-related granitoids inherit geochemical signatures of Carboniferous supra-subduction granitoids, and all rock types are marked by enrichment in LILE and negative Ta, Nb, and Ti anomalies. It is suggested that the adakitic geochemical characteristics of the Taimyr granites are a result of derivation from a relatively homogeneous mafic lower crustal source that formed at the stage of Carboniferous continental subduction and continued to produce granitic melts in the course of the early Mesozoic magmatic evolution. Whole rock geochemistry and composition of porphyry mineral indicators (zircon, apatite, and titanite) indicate that the Taimyr granites crystallized from oxidized water-saturated magmas at moderate temperatures, with the majority of samples showing characteristics typical for porphyry-fertile granites worldwide (fO2 = ΔFMQ +1 to +3 with zircon Eu/Eu* > 0.4 and apatite SO3 > 0.2 wt.%). Data from Dorozhinskiy, Kristifensenskiy, Pekinskiy, and Tessemskiy intrusions fully match geochemical criteria for porphyry-fertile granitoids, and these massifs are considered the most prospective for Cu-Mo mineralization. Granites from Shirokinskiy and Yuzhno-Lodochnikovskiy intrusions only partially match compositional constraints for fertile melts and can be considered as second-tier exploration targets. Finally, available data for the Simsovsky massif preclude its classification as a porphyry-fertile body. These conclusions are in line with previously developed exploration criteria for the northeastern Taimyr, showing that geochemical indicators of granite-fertility can be used on a regional scale in parallel with other exploration methods.

Gold-bearing mineral associations of gold-quartz and gold-sulfide-quartz occurrences of the Taimyr-Severnaya Zemlya Orogen (Nizhnelitkenskoe on Bolshevik Island, Vidimoe, Nerpichye, Konechninskoe in the myogeoclinal zone of the western Taimyr and Yasnenskoe, Malinovskoe in the accretion zone in the northern part of the Central Taimyr) have been studied. The data obtained indicate the possibility of identifying two new economic geological regions in the Central Sector of the Russian Arctic, comparable to the mineral resource potential of the Vitim-Patom Upland and the Yenisei Ridge.

Carbonatites of the Central Taimyr region, formed during the early Triassic (246.5 +/- 1.9 Ma), are coeval with other occurrences of alkaline-carbonatite magmatism of the Siberian LIP and related to the Siberian superplume activity. Petrological characteristics indicate that Central Taimyr carbonatites were derived from an alkaline-carbonatitic melt source with remarkably high concentrations of chloride-phosphate-fluoride-sulfate brines. Magmatic minerals (bearing F-Ba-Sr-REE ores), represented by calcite, fluorite, barite, bastnaesite-(Ce) and fluorapatite, were formed at a temperature range of 720-550 degrees C by brine-melts. Whereas, hydrothermal mineral assemblages (bearing F-Ba-Sr-REE ores), including magnetite, hematite, monazite-(Ce), parisite-(Ce), fluorite, roscoelite, rutile (Nb), barite, quartz, calcite, dolomite, as well as sulfides and uraninite, occur within a late-stage ore-forming processes, for which mineralized fluids of sulfate-fluoride-chloride-carbonate and chloride-hydrocarbonate compositions were responsible. Significant changes in the composition of fluid inclusions occurred as the homogenization temperature varied from 460 to 230 degrees C, and concentrations from 55 to 25 wt% NaCl-eq, respectively.

Research subject . Diamondiferous explosive detrital and sedimentary volcanoclastic rocks of the Carnian base of the Upper-Triassic confined to the west flank of the Bulkur Anticline in the north-eastern Siberian Platform. Aim . To identify diamondiferous features of Carnian rocks. Materials and methods . The materials collected by the authors while performing prospecting and evaluation works by the OOO Arctic Mining Company in 2022-2023 were used. The materials were represented by field observation results and mineral-petrographic studies. Rock types were defined by petrographic analysis in thin sections using a Leica DM2700P microscope and known classifications. Diamonds and accessory minerals were distinguished from steam sediment samples and described at the central analytical laboratory of the Vilyuysk Geosurvey Expedition, PJSC Alrosa. The estimation of diamond and pyrope content in core- and bulk samples (CPT) was performed considering their direct correlation. Results . The highest concentrations of diamonds were found to be localized in rocks in the west flank of the Bulkur Anticline. These formations were detected in lapilli tuffs, xenotuff breccia and orthotuffites. Paratuffites and tuff aleuro-sandstones exhibit a lesser diamond potential. Conclusions . The diamond potential of rocks of the Carnian base correlates well with the pyrope content and saturation of volcanoclastic materials. Tuff aleuro-sand-stones of the Bulkur member in the Osipay base and overlying shell deposits are considered potentially diamondiferous. Diamondiferous formations possess considerable thickness and productive efficiency, thus assuming a substantial increase in the diamond prospective potential in the Russian Arctic.

For the first time, based on the data of the study of fluid inclusions, the PTX parameters of the formation of gold mineralization of the Taimyr-Severozemelsky orogen were established. The temperature of formation of gold ores covers the range from 310 to 105°C, the pressure was not lower than 110–96 MPa. The ore-forming fluids were characterized by NaCl + KCl + H2O + CO2 + CH4 + N2 composition and salinity up to 9.7 wt. % in equiv. NaCl. The composition of native gold (fineness varies from 960 to 550‰) and minerals of productive mineral associations has been determined. Ore-forming fluids of gold-sulfide-quartz ore occurrences of the accretionary Schrenk-Fadeevskaya zone (Yasnenskoye and Malinovskoye in North-East Taimyr) are more oxidized and less saline compared to the gold-quartz occurrences of the orogenic type of the Mininsko-Bolshevitskaya myogeoclinal zone (Nizhnelitkenskoye, Vidimoe, Nerpichye).

We present a tectonothermal model for the late Paleozoic syncollisional formation stage of the Kara orogen in northern Taimyr in the Central Arctic. The model is based on new and published structural, petrological, geochemical, and geochronological data, as well as thermophysical properties obtained for the Kara orogen. The latter hosts a significant volume of granites formed as a result of the collision between the Kara microcontinent and the Siberian craton. Based on geological, geochemical, and U–Th–Pb isotope data, the granites were differentiated into syncollisional and postcollisional intrusions that were emplaced in the intervals 315–282 and 264–248 Ma, respectively. The presented tectonothermal model covers only the syncollisional formation stage of the Kara orogen, during which anatectic granites formed. The 2D models help to reconstruct the main tectonothermal processes of the syncollisional stage of formation of this structure, taking into account the local peculiarities of the thermal state of the Earth’s crust in the region. The model shows the mechanisms of increase in the lower crust temperature necessary for the formation of syncollisional anatectic granites. The estimates obtained from the model constrain the time interval between collision/tectonic stacking and the granite formation. The modeling also showed the general regularities typical for orogens on syncollisional stages.

The PTX parameters of the formation of gold mineralization in the Taimyr–Severnaya Zemlya orogen were established for the first time based on data from studies of fluid inclusions. The gold ore formation temperature ranges from 310 to 105°C; the formation pressure is not lower than 110–96 MPa. Ore-forming fluids were characterized by a NaCl + KCl + H2O + CO2 + CH4 + N2 composition and salinity up to 9.7 wt

In the Arctic zone of Siberia, large diamond occurrences have been discovered in volcaniclastic, sedimentary–volcaniclastic, volcanosedimentary, and sedimentary rocks of the upper Ladinian strata and the base of the Carnian (Triassic) strata. They are confined to the Primorye mineragenic zone, which is traced along the Laptev Sea water area from the western Verkhoyansk area to eastern Taimyr. We have first identified a specific range of diamonds in these deposits. Among the rounded crystals of varieties I, II, V, and VII, there are grains with a light carbon isotope composition and high nitrogen contents. They have no analogues in typomorphic features in the known primary deposits of Yakutia but are completely similar to diamonds in the Rhaetian, Early Jurassic, Late Jurassic, Early Cretaceous, Neogene, and Quaternary commercial placers and placer occurrences, which suggests their formation as a result of the erosion of Triassic sources.

Although irrefutable evidence for the presence of signs of diamondiferous kimberlite on the Taimyr Peninsula were obtained in the 1930s, it was only in 2020 that a macrodiamond (>1 mm) was first discovered in Eastern Taimyr. This was a colorless laminar crystal of a transitional shape from an octahedron to a rhombododecahedron. According to the set of features, the crystal is rare and atypical of the known primary and alluvial deposits of the Siberian Diamond Province. The find of this diamond indicates the presence of primary sources and the need for medium-scale geological survey and exploration over a large area from Anabar Bay (Pronchishchev Ridge) to the west to the Kiryaka–Tas and Tulai–Kiryaka highlands and to the northeast to Tsvetkov Cape.

This study utilized SHRIMP, LA MC–ICP–MS and ID-TIMS analytical techniques and presents for the first time U–Pb age, Lu-Hf-isotope features of zircon and the Nd-isotope composition of variously mineralized rocks from the ore-bearing Dyumtaley intrusion, one of the most promising targets for platinum-group element (PGE)-Cu–Ni ores within the Taimyr metallogenic province. 206Pb/238U ages of zircon from monzodiorite and gabbro of the Dyumtaley intrusion (250.9 ± 3.1 to 253 ± 1 Ma, respectively) indicate their close temporal relationship to a Permo-Triassic boundary and synchronism with a tholeiite-basaltic volcanism of the Siberian platform. Hafnium-neodymium isotope signatures (εHf(t) 6.9–8.5, εNd(t) 2.9–4.2) imply the significant role of the depleted mantle material in magma generation of the Dyumtaley intrusion.