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The results of studies of carbonaceous matter (CM) and the S isotopic composition of associated sulfides in metapelites of the Neoarchean banded iron formation of the Kostomuksha greenstone belt of Karelia (Karelian Craton of the Fennoscandinavian Shield) are presented. The petrographic observations show that the CM occurs inside and between silicates, in sulfides, or at the grain boundaries between the sulfide crystals and biotite or amphibole. The results of scanning electron and atomic force microscopy showed the presence of several CM types distinct in structure and C content. The analysis of Raman spectra of CM revealed the presence both of well-ordered graphite and weakly structured kerogene in samples. The isotopic composition of the total organic carbon is typical of biogenic processes. The δ13Corg values from –27.9 to –30.6‰ are consistent with the fixation of carbon by photo- or chemoautotrophs. The S isotopic composition of associated sulfides is characterized by a positive Δ33S anomaly (up to +0.94‰) and negative δ34S values (from –2.06 to –4.1‰). The positive Δ33S values indicate a genetic link with photochemical elemental sulfur (S8) from the atmosphere, whereas the negative δ34S values reflect the fractionation of isotopes during bacterial-related processes. Based on these observations, we suggest that the primary CM mostly has a biogenic origin. [ABSTRACT FROM AUTHOR]

The first data on the multi-isotopic S composition of sulfides of the Neoarchean banded iron formations (BIFs) of the Kostomuksha greenstone belt of Karelia (Karelian Craton of the Fennoscandian Shield) formed 2760–2740 Ma ago are presented in this paper. Pyrite associated with fine-grained magnetite has negative δ34S (to –7.8‰) and positive Δ33S (to +0.7‰) values. Pyrrhotite from stringer-disseminated ores associated with schists exhibits negative values of both δ34S (to –6‰) and Δ33S (to –0.46‰). Our data provide grounds to suggest that the BIF sulfides sourced photolitic elementary sulfur from the atmosphere, sulfate from seawater, and sulfur from magma. The S isotope ratios of sulfides reflect the interaction between abiotic (atmospheric, hydrothermal) and biotic (microbial dissimilation reduction) processes during the formation of iron deposits of the Kostomuksha greenstone belt of Karelia. [ABSTRACT FROM AUTHOR]

The Oleninskoe gold deposit is located in the northwestern part of the Kolmozero–Voron'ya greenstone belt (Kola Peninsula), in a sequence of amphibolite with granite porphyry sills. The sills are genetically connected with a big granodiorite- and granite-porhyry massif, which hosts the Pellapahk Cu–Mo porphyry deposit. The geochemical association of the Oleninskoe includes As, Pb, Ag, Cu, Sb, and Au; the Au/Ag ratio is less than 0.2. The ore is of very complex mineral composition (more than 50 mineral names of intermetallic compounds, sulfides, and sulfosalts are defined), with widespread Ag and Sb minerals. Fluid inclusions in quartz are of high salinity with anomalous concentration of minor elements. All these characteristics show that the deposit formed in an Early Precambrian porphyry-epithermal system. Then the deposit underwent metamorphism (lower amphibolite facies) in the Neoarchean and Paleoproterozoic, indicating the absence of chlorite and a scarcity of carbonates in metasomatic rocks, replacement of pyrite with pyrrhotite, and signatures of sulfide anatexis in ore. This is the first finding of this genetic type of gold deposits in the northern part of the Fennoscandian Shield. [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X23070152 [ABSTRACT FROM AUTHOR]

This work presents new U–Pb ID-TIMS geochronological data obtained for the rocks of the metagabbro–diorite–tonalite complex of the Olondo fragment of the Tokko–Khani greenstone belt of the Aldan Shield, Siberian Craton. Wide development of ultramafic and mafic volcanics associated with felsic volcanics has been recognized only within this fragment. It was established that the protoliths of metagabbro–diorite and quartz metadiorite intruding metavolcanic and metasedimentary rocks were crystallized at 3002 ± 5 and 3005 ± 7 Ma, respectively. The obtained age estimates determine the upper age boundary of the formation of the Olondo supracrustal rocks (3012–2997 Ma). The Nd model ages of the Olondo metaandesites and metadacites are close to 3.0 Ga, which, to the first approximation, determines the lower age boundary of their formation. Thus, the sedimentary–volcanogenic sequence of the Olondo fragment are about 3.0 Ga old, and their formation, including superimposed structural and metamorphic transformations, occurred within a short period (a few million years). [ABSTRACT FROM AUTHOR]

Data on the carbon and oxygen isotopic composition of carbonates from the rocks of the Giyani greenstone belt, Kaapvaal craton, South Africa are presented. This belt is immediately adjacent to the Hout River Shear Zone, along which the Southern Marginal Zone (SMZ) of the Limpopo granulite complex is overthrusted onto the Kaapvaal craton. The δ13C values are –2.1 and –2.2‰ for carbonates from two metapelite samples, –5.1‰ for a meta ultrabasite sample, and –7.1 and –7.7‰ for two metabasite samples, respectively. The δ18О values are 17.1 and 17.5‰ for carbonates from the metapelites, 14.3‰ for carbonates from the metaultrabasite, and 12.9 and 13.0‰ for carbonates from the metabasites. The comparison of the data obtained to the published data on the isotopic composition of carbonates from the rocks of the different greenstone belts indicates both hydrothermal (in the metabasites and the metaultrabasite) and sedimentary (in the metapelites) origins of the carbonate material in the rocks studied. Based on the comparison of these data to δ13C of magnesite that formed in ultrabasic granulites during the interaction of the Limpopo complex with the craton, the graphite and fluid inclusions in leucocratic garnet-bearing granitoids that transported fluids, and the carbon isotopic composition of graphite from metapelites of the SMZ, it is concluded that the carbon source was located outside the SMZ and represented a heterogeneous carbonate-bearing lithologies. It could be carbonate-bearing volcanogenic–sedimentary sequences of the greenstone belts of the Kaapvaal craton, which underwent prograde metamorphism during the interaction with the SMZ granulites. [ABSTRACT FROM AUTHOR]

Metarhyiolites are found along with metapelites and metabasites in sedimentary–volcanic sections of Archean greenstone belts of the Kursk block of the Eastern Sarmatia. The age of igneous protoliths of metarhyolites is about 3.12 Ga. A positive value of εNd(3122) = +0.9 for metarhyolite and a model age of TNd(DM) = 3.30 Ga, as well as the age of the inherited zircon grain (3250 Ma), testify to the contribution of a more ancient crustal component in the formation of rhyolite magmas. In terms of the geochemical characteristics, metarhyolites are quite similar to tonalites and trondhjemites of the TTG association of about 3 Ga in age within the framework greenstone belts of the Kursk block. These data confirm the hypothesis of the common geological history of the eastern part of the Ukrainian Shield and the Kursk block during the Mesoarchean. [ABSTRACT FROM AUTHOR]

Framing of the Archaean greenstone belts of the Kursk Block (KB) of the East Sarmatia preserves rocks of the TTG association: those do not form massifs with distinct boundaries, but occur as fields gradually transiting into gneisses and migmatites. According to Sm-Nd isotope-geochemical data, the TTG are characterized by positive values of εNd(2960) = +0.3+1.6 and protolith model ages of Nd(DM) = 3100-3200 Ma. Magmatic protoliths of the Kursk Block TTG were formed about 2960 Ma by melting from a juvenile basite source. These age estimates are significantly younger than heterochronous (3.19, 3.13 and 3.07 Ga) TTGs of the Middle Dnieper granite-greenstone terrane. On the other hand, the similarity of εNd(T) implies a single source of their protoliths. Consequently, the KB TTGs, apparently, are a result of transformation of an older sial crust preserved within the Middle Dnieper Block. [ABSTRACT FROM AUTHOR]

New U-Pb (SHRIMP II) data on the age (2661.8 ± 7.1 Ma) and isotopic (Sm-Nd) composition of the Patchemvarek gabbro-anorthosite massif located in the junction zone between the Neoarchean Kolmozero-Voron'ya greenstone belt and Keivy paragneiss structure are discussed. The established age and geological-tectonic position of gabbro-anorthosites allow the prognostic metallogenic estimate of Ti-V-Fe mineralization to be extended to the entire Kolmozero-Voron'ya-Keivy infrastructural zone of the Kola-Norwegian province of the Fennoscandian shield. [ABSTRACT FROM AUTHOR]

The article focuses on study on rare-metal pegmatites from the Vasin-Myl'k Deposit within the Kolmozero-Voron'ya greenstone belt. It mentions the problem of genetic relation of these rocks along with their solution. It adds views of researchers that pegmatites are related to plagiogranites and tonalites, amphibole-biotite granodiorites and microcline granites.

The article discusses the study conducted on granulite gneiss areas (GGA) and granite greenstone areas (GGSA) as important tectonic elements of the Archean time period to examine the reasons for the early evolution of the Earth. Topics discussed include Pobuzhie granulite complex (PGC) composed in the southwestern part of the Ukraine, information about Granulite UR132 as a glassy and gneissose rock with poor foliation and microbanding, and obtaining age of zircons during recrystallization.

The article presents study which investigates the isotope and age geochemistry of ore-hosting granodiorites of the Nyal'm-1 gold deposit at Kola Peninsula, Russia. It says that the Archean greenstone belts (GSBs) are localized in Paleoproterozoic volcanogenic-sedimentary complexes and are linked to the ore-metasomatic procedures in areas of shift deformations. It states that the investigation was done with the use of modern local isotope geochemical methods, along with the description of geological composition and structure of the volcanogenic-sedimentary complex of the GSB Kolmozero-Voron'ya (KV). Conclusion suggests that the age and genetic relationship of gold deposits enables the reconsideration of the concepts of the age of the gold formation.

The article presents a study which investigates the data, Baltic shield, and the significance of Archean rocks of the Vodlozero Domain for geodynamic reconstructions. It says that the marginal parts of the Vodlozero domain consists of greenstone belts which comprise primarily of metamorphosed komatiite or basaltic volcanic. It states that the basement rocks are compose of eastern part of the Palaya Lamba and comprise granitoid complexes which represent polymigmatites with a tonalitic prolith. It mentions that some of the rocks that were examined are tonalities, trondhjemites, vein granites, dike gabbroamphibolite, andesite, trondhjemite, granites, and gabbroamphibolite.

Zircons with an anomalously high content of Y and REEs in rims were first found in rocks of the Baltic shield (in a pegmatite vein in the Gridino eclogite-bearing melange and in quartz syenites of the North-Karelian greenstone belt); the total content reaching 17 wt %. The presence of such an amount of nonformula elements is caused by the isomorphic occurrence of them in zircon and is not associated with microinclusions of accessory minerals. The age of formation of these rims was determined as the Svecofennian, although the direct dating yields underestimated values of the age, which are void of geological sense. [ABSTRACT FROM AUTHOR]

The article offers information regarding Komatiite-tholeiitic metavolcanic rocks of Neoarchean greenstone belts. It states that formation is controlled by the conditions of intracontinental riftogenesis on the Mesoarchean granite-gneiss basement. It discusses understanding of the composition of the Archean subcontinental lithosphere and mechanisms of tectonic evolution of the Sarmat segment within the East European craton. It mentions that metakomatiites are represented by serpentinites, tremolite and hornblende amphibolites, and tremolite-serpentine and actinolite-tremolite schists. It concludes that the totality of the isotope and geochemical data allows us to suggest that the formation of komatiites is related to melting of the sublithospheric or asthenospheric mantle.

The article presents a study which analyzes the geology and geophysics of the discovery of apatite deposits in the Baltic Shield and its slopes. It says that greenstone belts are made of metamorphosed volcano-sedimentary rocks of the Lopian Complex (AR2 in the Karelian Craton. It states that metavolcanogenic rocks' spacious development areas determine their important mineragenic potential. It mentions the relation of the formation of regenerated riftogens to the final phase (N-Q) of tectono-magmatic activation of riftogenic structures and zones of tectonic faults in the Baltic Shield and adjacent regions of the Arctic Ocean. Results show basic revision of the apatite-bearing potential of the Baltic Shield and its slopes.

The article discusses the geological study conducted to examine the geological aspects of the industrial type of apatite and complex apatite-bearing ore deposits based on numerous and diverse genetic, formational, mineralogical, and technological feature. Topics discussed include metavolcanogenic complexes of the Saymagan greenstone depression, banding of the apatite calcite ores, and metavolcanogenic and metasomatic formations of greenstone complexes.