The volcanic rocks from Cenozoic Trans-Khamar-Daban volcanic zone (TKDVZ) in Russia and their xenocrysts and crust-mantle xenoliths were investigated by electron microprobe (EPMA) and laser-ablation inductively coupled mass-spectrometry (LA ICP MS) and other methods. They were used to show the composition and reconstructions of structure of the crust and mantle. Volcanism started from Central Part of ridge at 23 Ma and distributed to the shoulders (18–16 Ma) rift margins (13–16 Ma) and top of volcanoes (12–10 Ma), followed by rift valleys (5–2 Ma) and culminated in cinder cones volcanoes (0.8–0.15 Ma). Lavas evolved from sub-alkali to alkaline basalts and tephrites. Lherzolitic xenoliths are nearly primitive, having relics of garnets and simplectites which represent the material of mantle diapirs. The volcanics from Tunka and Dzhida valleys carry abundant cumulate xenoliths related to 2.0–1.0 GPa. The geothermal regimes reconstructed using electron probe (EPMA) mineral analyses and mineral thermobarometry is close to the South-Eastern Australian Geotherm (SEA). At the first stage, it shows heating to 1350 ◦C near Baikal Lake (Sukhoy volcano). The trace elements in the lherzolites are close to primitive mantle being more depleted near Tunka valley and showing ancient subduction related depletion and hydration in Dzhida. The cumulates show fractionation trends for pyroxenes, garnets amphiboles. The megacrysts show high La/Yb ratios increasing with Fe# for clinopyroxenes and garnets and LILE enrichments for amphiboles and Ti-biotites. The volcanism was caused by deep plume generated with the influence of the subduction from the Pacific and correlated with the events of India- Eurasia collision.

Minerals from heavy concentrates from two phases of the Aykhal kimberlite pipe, Yakutia, were analyzed with the EPMA, SEM, and ICP-MS. They were used to reconstruct the mantle sections and their evolution, and to determine the features of the protokimberlite melts and melt/fluid metasomatic agents responsible for the geochemistry. A high amount of garnets belong to the dunitic type. The clinopyroxenes, as well as amphiboles, are Mg-rich and highly vary in Al, Cr, Ti, Na. Micas are Ti-biotites derived from protokimberlites. The ilmenites and chromites show domination of Mg- and Cr-rich compositions. The mantle section of subcratonic lithospheric mantle (SCLM) for autholitic kimberlite breccia (AKB) reveals a long range of PT estimates for garnets from 8 GPa to Moho heated at the deeper part, showing in the P-Fe# plot sharp layering of 6 thick layers (subdivided to 2 sub-layers) visible by high Mg deviations and Ca fluctuations for garnets and grouping of PT points for other minerals. The lithosphere asthenosphere boundary (LAB) is marked by the ilmenite trend going from LAB to middle layer (4.5-3.5) GPa, traced by the Ti-augite and pyrope megacrysts. The minerals from tuffisitic kimberlitic breccia (TKB), show a similar division of the mantle section but amount of low-pressure pyrope and eclogite garnets is much higher.The geochemistry of lherzolitic garnets show rounded curves of depletion in light rare earth elements (LREE) allows to subdivide them into the enriched, depleted, and common lherzolitic types. The megacrystic and low-crust garnets show higher HREE levels. The dunitic garnets reveal S-shaped, harzburgitic depressions in HMREE and curved patterns. All peridotitic garnets demonstrate U, Nb, Zr enrichment in multicomponent spider diagram (MSD). The Cr-diopsides show small U enrichment and pyroxenites with higher Th peaks Pb, Ba depressions. Ilmenites display very high Ta-Nb and Zr-Hf peaks and very low REE level except for two samples. The Cr-spinels demonstrate Ta peaks on the MSD. The phlogopites reveal Eu peaks and W-shaped REE distributions and high LILE in MSD. Diamonds show low REE levels and Pb peaks. The differences in TKB and AKB geochemistry of garnets and diopsides are in the higher level of the Th-Nb and Zr-Hf levels, showing the influence of the carbonate and H2O-bearing melts that accompanied the interactions with the protokimberlite melts.Reconstructed with partition coefficients, parental melts reveal highly inclined lines up to 1000/PM (primitive mantle). Peridotites show U-Ba- enrichment typical for subduction related melts and high Nb also – due to super plume melts influence. Cr-diopsides and pyroxenites show dominating Th enrichment due to interaction with the carbonatite melt. The high diamond grade of the Aykhal pipe is determined by mixing of subduction-related Na-Mn-U and peridotitic high Mg-Cr with Ti-Nb-Th plume components and hybrid melt interaction with peridotite eclogitic material with the mixing of all components. Work was done on state assignments of IGM SB RAS FWZN-2026-0007. Russian Science Foundation Grant (24-27-00411).

The xenocrysts of studied Bulkur tuff site 1 (Skuzovatov et al.,2022; Grakhanov et al., 2024) with highest diamond grade are comparing with xenocrysts from new site 2 of phreatomagmatic Carnian (Lower Triassic) tuffs in Tuora Sis ridge. New set includes electron probe microanalyses (EPMA, 420 grains), scanning electron microscope (SEM, 1750 grains) and (laser ablation inductively coupled plasma mass spectrometry) LA ICP MS (180) analyses. Pyropes (0-13 wt.% Cr2O3), chromites (Cr-rich and Ti-Al rich varieties), micas (3.5-5% FeO and Cr2O3 to 3%) from site 2 reflect reactions of peridotites with K-rich melts, carbonatites and later protokimberlites which formed Mg rich ilmenites and T-augites. The Cr-diopsides divides to the Cr-Al and Fe- enriched types.The PTXFO2 diagram for mantle lithosphere site 2 show 8 layers similar to received for site 1 and long pyrope megacrysts trend P (6.5-2 GPa)-Fe# (0.11-0.15). The eclogitic inclined P- Fe# trend (Cr-bearing) 6.5-4 GPa is more typical to site 2, it corresponds to AFC reactions of partial eclogitic melts with peridotites going to Ca-rich layer in middle mantle pyroxenite-eclogite layer 4-5 GPa. Chromites show common Al-Cr and also ulvospinel trend starting from lithosphere base (TiO2 ∼12%).The geochemistry of almost all pyropes show high U-Th-Nb-Ta and extreme Zr-Hf peaks in multicomponent spiderdiagrams (MSD). Chromites reveal Nb and Ta peaks. Cr-phlogopites with peaks of large ion lithophile components show HFSE depressions like Cr-diopsides and megacrystic Cpx. The carbonatite debris in tuffs display high REE gently increasing up to Lan ∼ 5000/Cl (chondrite). The glasses in rock debris from tuffs vary from Ca- to Ca-Mg carbonatites to Mg-aillikites, orangeites (rarely lamproites) and kimberlites.The mantle column beneath Bulkur anticline (at Tuora Sis ridge) was reacted at first with silicate and adakite melts created refertilisation of peridotites, then with the K-rich melts created phlogopites and with HFSE rich carbonatite melts progressively increasing Zr, Hf, Nb, Ta. Studied phase (site 2) is later and reflect progressive enrichment of whole mantle column from lithosphere base (highest) in HFSE, 5 times higher then in site 1. The primary contamination of the lithospheric roots in K2O and HFSE was a result of the interaction with subduction-related melts contaminated in continental sediments.

Geochemistry and thermobarometry of mantle xenocrysts and xenoliths from Mir kimberlite pipe were studied using new EPMA, SEM and LA ICP MS analysesThe PTX plot for the Mir pipe (Malo-Botuobinsky field) (Ashchepkov et al., 2010; 2014; 2019; 2022; 2023) shows the large interval from 8 to 1.1 GPa. The garnets show rathe narrow PT and P-Fe# but very wide P-Ca plots starting from the middle pyroxenitic layer to LAB. The Cr-Cpx and Cr-Sp are coinciding in Fe# in general. But the eclogites show very wide range of compositions trend. Diamond inclusions (DIA) (Sobolev, et al., 1976; 1997; Bulanova et al., 2002; Logvinova et al., 2004) the DIA pyropes have an opposite trend. In the P (GPa)-CaO plot largest variations in CaO are in the lower part of the mantle section. The most magnesian dunite varieties form an interval from 6.5 to 5 GPa, and then above them, the harzburgitic garnets again appear in the middle part of SCLM. There is high proportion of peridotite Cr-bearing varieties of ortho-and clinopyroxenes in the middle SCLM, which suggests that pyroxenites originated from peridotite partial melts. Omphacites together with garnets form an ascending P-Fe# plot. The geothermal conditions traced by DIA also form two branches. Even Cr-garnets partly trace the convective branch, although this is not evident in the middle part. The Cr-garnets are found at higher temperature conditions at deeper part of the SCLM. However, most of them plot between the 35–40 mWm−2 geotherms. The Cr-pyroxenites and Cr-diopsides form the colder branches to 35 mWm−2 geotherms or even lower. In the P-fO2 diagram, the less oxidized conditions correspond to the eclogitic clinopyroxenes in middle SCLM. At high pressures, the Cr-rich garnets give the lowest fO2 conditions.The REE patterns of the pyropes show wide range of compositions from S-shaped dunitic to semi – rounded lherzolitic and flattened HREE harzburgitic and LREE enriched pyroxenitic. In multicomponent diagram they show peaks in Th-U and Pb and troughs in Sr and highly synchronously varying HFSE.The Cpx form Gar lherzolites are showing several groups commonly inclined La/Ybn ~100 (normalization to primitive mantle (McDonough and Sun, 1995) with the hump at Ce- to Nd. In MCD they show very wide variations even in LILE from peak in Ba Rb to deep troughs and the same for U, Th. Pb, Sr. The HFSE are mostly moderately depleted (Zr

Finding of the giant diamond in Ebelyakh of CLIPPIR type of IIa type (Moor, 2014) suggest that similar diamonds should be found in the source kimberlites in Anabar basing and nearest Northern fields located within collision Khapchan terrain. To predict the finding authors are using the method of 5E diagrams based on the principle of analogy of the compositions Fe/(Fe+Mg) – Cr/(Cr+Al) – (Mn,Na) (Mitchell, 1986) for satellite minerals (Gar, Cpx, Chr and Ilmenites) of diamond (DSM) comparing with the etalon diagram for Karowe pipe (reference) and any other pipe. The forecast is quantified by the probability of convergence of these compositions using the division to the cluster groups. It was shown that the convergence of the DSM compositions of the Karowe and Grib pipes is 74%, which can be regarded as an indicator of the possible presence of diamonds in the predicted CLIPPIR pipe (Zinchenko et al., 2021). The application of this technique to two weakly diamondiferous kimberlite pipes of the Anabar region is demonstrated that the Leningrad pipe (Lower Devonian) have probability (75%) and Malokuonamskaya (Lower Triassic) (20%). Methods of constructing 5E diagrams and complementary PTXfO2 diagrams by I.V. Ashchepkov (2010-2023) of reconstructed lithospheric mantle sections (SCLM) to predict the crystallization of CLIPPIR diamonds. The petrological meaning of such characteristic suggest diamond formation in pipe in permeable mantle within protokimberlite magmatic chamber located near the lithosphere boundary and connected with the asthenospheric source supplying by low oxidized magma, sulfides and extra pressure. The pipe should be surrounded by the low oxidized mantle eclogites rich C and dunites with the high pressure-temperature and Mg-rich ilmenite-chromite metasomatites. A. B.Fig.1. Mitchels’s diagram for minerals from Leningrad and Malokuhamskay (B) pipes in comporisond with the Karowe pipe (contur lines) Cr- pyropes, Cr-diopsides, Ilmenites, Cr -spinels together. B. Triangle Na-Mn-Ti and C. Triangle Na-Al-Cr for Cr-diopsides and pyropes. D. distributions of the cluster groups for different minerals. E. Correltions of diamond grade with TiO2 in garnest, Cr-diopsides and Cr-spinels and Fe2O3 in ilmenitesThe application of this technique to two weakly diamondiferous kimberlite pipes of the Anabar region is demonstrated that the Leningrad pipe (Lower Devonian) have probability (75%) and Malokuonamskaya (Lower Triassic) (20%). Methods of constructing 5E diagrams and complementary PTXfO2 diagrams by I.V. Ashchepkov (2010-2023) of reconstructed lithospheric mantle sections (SCLM) to predict the crystallization of CLIPPIR diamonds. The petrological meaning of such characteristic suggest diamond formation in pipe in permeable mantle within protokimberlite magmatic chamber located near the lithosphere boundary and connected with the asthenospheric source supplying by low oxidized magma, sulfides and extra pressure. The pipe should be surrounded by the low oxidized mantle eclogites rich C and dunites with the high pressure-temperature and Mg-rich ilmenite-chromite metasomatites.A.B. C.Fig.2. PTXFO2 diagram for all xenocrysts from Leningrad (A), Malokuonamskaya (B) and Karowe AK-6 pipes. Symboles see legendRussian Science Foundation grant 23-17-0003

The phreatomagmatic Carnian (Upper Triassic) kimberlitic tuff deposit of the Bulkur anticline at the right side of the Lena Mouth has the most high diamond grade in Russia (to 12 crt/t). Comparison of the thermobarometric reconstructions Ashchepkov ea 2001; Grakhanov ea., 2024) and geochemistry of pyropes (Skuzovatov et al., 2022) and presented here set of the EPMA (560), SEM (980) and LA ICP (140) analyses from tuffs at Olenek’s duct at Lena Mouth. Pyropes variations 0

The lower crust and Moho pyroxenites and xenocrysts from Cenozoic volcanoes studied with the EPMA, SEM and LA ICP MS for trace elements evidence about the structure and composition of the transitional zone from the crust to mantle in Cenozoic volcanic regions In Vitim (picrite basalts), Dzhida, (Bartoy volcanoes) and Tunka valley (Karierny volcano). For the comparisons the lower crust xenocrysts from the Angara Vitim batholite were studied. The calculated PT conditions show the PT estimates are localizing within the Moho –and just beneath giving the vast range of temperatures. Lower they trace 90 mw/m2 geotherm. Within the crust the variation of temperature regime are varying from the conductive to advective. Xenocrysts and pyroxenite xenoliths mainly trace 90 mw/m2 SEA plume geotherm the area of the intrusions is over heated to 1350oC.Fig.1 PT diagram for the xenoliths from Vitim Miocene Picrite basaltsFig.2 PT diagram for the xenoliths from Bartoy Pleistocene basaltsFig.3 PT diagram for the xenoliths from Tunka Pliocene basaltsFig.4 PT diagram for the xenocrysts from Magmas of Angara-Vitim batholiteThe granulites are typically represent the more colder conditions than SEA geotherm. Xenocrysts from Angara Vitim batholith magmas reveal more depleted material of lower crust than those found in Cenozoic lavas and possibly are skialites. The xenocrysts and granulate xenoliths in Cenozoic lavas are mainly basic cumulates. The lower crust became more acid to the upper part. The lateral variations in the lower crust sampled material show enrichment in K2O at the boundary with the Siberian craton in Tunka, more metasomatic and hydrous nature in Dzhida zone and more basic and CaO rich characteristic in Vitim area. These data give the evidence for the conditions of the creation of magmas of Angara-Vitim Batholiths. It was created by the hot spot created kimberlites and basalts in north and Center of Yakutia in Silurian- Devonian time and Ingashi lamproites, than it turned in Transbaikalia and after returned to central and Northern Siberia. Supported by Ministry of Science and Higher Education of the Russian Federation. Supported by Russian Science Foundation (23-17-00030). Work is done on state assignment of IGM SB RAS, Geological institute SB RAS Ulan Ude and Institute of Earth crust SB RAS, Irkutsk

Based on the analysis of the tectonophysical characteristics of the actual seismofocal zone (SFZ) in the lithosphere of the Kuril-Kamchatka region and adjacent Oceanic areas, we estimated the boundary conditions necessary for constructing the quantitative models of heat and mass transfer dynamics in compacted heterophase media under active volcanoes located over the mantle and crustal magmatic sources of the ocean–continent transition regions of the northwestern sector of the Pacific Ocean.The methodology of obtaining the information used for developing of the mathematical models of magmatogenic processes includes: 1) the study of individual porphyry deposits associated with active fluid volcanogenic systems; 2) the study of morphological structures using cosmic satellite images (Sharapov et al., 1980); 3) the study of mantle and crust xenoliths of volcanics (Kutyev, Sharapov, 1979; Sharapov et al., 2009, 2017, 2020); 4) parametric tectono-physical analysis of the modern SFZ of the studied region (Sharapov et al., 1984, 1992); 5) experimental modeling of the processes of deformation Earth's crust and lithospheric mantle rocks of modern SFZ (Sharapov et al., 1984, 1992); 6) construction of mathematical models of the petrogenesis under volcanoes (Sharapov et al., 2007, 2020)According to data on the structure of the Earth's crust under the Avacha volcano; (Koulakov et al., 2014), permeable zones are linear fractures 2-4 km wide, which are conductors of melts and magmatogenic fluids coming from magmatic systems (Koloskov et al., 2014).An analysis of the time characteristics of formation porphyric deposits in the active margins of the Pacific Ocean (Sharapov et al., 2013) showed that more than 70% of the described deposits are formed during the evolution of fluid mantle-crustal ore-magmatic systems. This study analyzes the data on the structure of the modern SFZ of Kamchatka and the Kuril Island arc, used in constructing a model of heat and mass transfer under volcanoes.Based on the analysis of the tectonophysical characteristics of the actual seismofocal zone (SFZ) in the lithosphere of the Kuril-Kamchatka region and adjacent Oceanic areas, we estimated the boundary conditions necessary for constructing the quantitative models of heat and mass transfer dynamics in compacted heterophase media under active volcanoes located over the mantle and crustal magmatic sources of the ocean–continent transition regions of the northwestern sector of the Pacific Ocean.TAn analysis of the time characteristics of formation porphyric deposits in the active margins of the Pacific Ocean (Sharapov et al., 2013) showed that more than 70% of the described deposits are formed during the evolution of fluid mantle-crustal ore-magmatic systems. This study analyzes the data on the structure of the modern SFZ of Kamchatka and the Kuril Island arc, used in constructing a model of heat and mass transfer under volcanoes.RNF grant 24-27-004

The influence of the hot spot for the AVB was assumed by (Kuzmin and Yarmolyuk, 2011). It may be the same hot spot that cause the creation of the kimberlites at 420 Ma at the north of Siberian craton (Sun et al,, 2014; 2018) than in the central part of Yakutian kimberlite province 350- 370 Ma. and transferred to the Prisayanie forming kimberlite fields covered by Carboni ferrous Permian sedimentary sequences in the basins of Tumanshet, Biryusa and Chuna rivers. Than it produced the Ingashi kimberlites - lamproites 310 -300 Ma (Kostrovitsly et al., 2022).Granites of Angara-Vitim batholith were caused and influenced by this huge thermal event. The A-type granitoid magmatism and acid and mafic magmatism accompanied by mingling between these magmas suggest influence of the mantle plume (Litvinovsky et al., 2002; Tsygankov et al., 2019). This explains the K-nature of the granitoid magmatism, corresponding to the selective melting of the K-feldspars (Litvinovsky et al., 2000). This is the reason of the alkaline magmatism widely distributed among the AVB magmas (Tsygankov et al., 2010-2021).The huge amount of the volatiles that accompany plumes are responsible for melting in the mantle and crust (White and McKenzie, 1995). But essential parts of plume volatiles are CO2 and CH gases (Marty and Tolstikhin, 1998).. The H2O fluxes correspond to the starting and final stages of plume impulses (Ivanov et al., 2013). The periods of such pulses are nearly close to 30- Ma what is regulated by the Cosmic forces (Abbott, and Isley, 2002). Boundaries of the geological periods correspond to plume events In Transbaikalia, the H2O-rich flux was designated by transition to more acid magmas at 270 Ma. The CO2-rich flux at the maximum was manifested by the generation of the Burpala alkali-carbonatite massif (Vladykin et al., 2017).Further, numerous already granitic and associated magmas and massifs were found in Eastern Sayan and Southern Pribaikalie. In Svyatoi Nos in Baikal 310 Ma (Kruk et al., 2023). The simultaneously and later the hot spot created the main massifs of the AVB at the time span 275 -320 Ma (Khubanov et al., 2016; 2021). The further continuation could be found in Khangai batholith (270-240 Ma) (Yarmolyuk et al., 2013).Than at the eastern margin, the plume turned to the NNW again and created the Siberian large igneous province- Permo-Triassic traps (Kuzmin and Yarmolyuk, 2011) 260-240 Ma. the development of the plume magmatism in Early Triassic and later in Jurassic time probably was transformed to the Island hot spot (Kuzmin and Yarmolyuk, 2010).RNF grant 23-17-00030Kostrovitsky S.I. ea 2021. Special Publications 513, 45 - 70.Khubanov V.B ea 2021. Russian Geology Geophysics. 62, 1331-1349.Kuzmin, M.I. , Yarmolyuk, 2014. Russian Geology and Geophysics, 55, 120-143.Kuzmin M.I. ea 2010. Earth-Science Reviews, 102, 29-59.Yarmolyuk V.V ea 2013, Petrologiya , 21/2, 115–142.

Beloziminsky alkaline ultramafic carbonatite massif (BZM) includes carbonatites, ijolites, meltegites, syenites (CIMS) layers and bodies and aillikites intrusions (∼ 645 - 621 Ma) within massif and Yuzhnaya pipe (YuP), locating in 16 km eastward. Comparisons of mineralogy and geochemistry of 19 CIMS samples (>1100 analyses) and > 16 aillikites (>2300 analyses) locating within the BZM and accounting aillikite minerals from pipes and dykes outside the massif (Ashchepkov et al., 2020) (all together >5400) reveal great difference for rock-forming minerals and less for the accessories. The analyses of the pyroxenes in aillikite correspond to mantle Cr-diopside xenocrysts and megacrystic augites. The low-Na Ti-augites and diopsides as well as aegirines prevail in carbonatites-ijolites-melteigites –syenites intrusive bodies (CIMS suit). Amphiboles show long trend from hornblendes to richterites.The in dolomitic carbonates include also admixtures of Na, K, Ba and Ca- carbonatites often contain Sr, The aillikitic carbonates are rich in Mg or Ca and CIMS rocks together with Ca-Mg carbonatites also often include siderites.Thermobarometry for YuP and Yuzhnaya pipe outside BZM containing Cr-diopsides, Cr-phlogopites, Cr-spinels (P ∼ 4–2 GPa, T ∼ 800–1250°C) and xenocrysts of augites with elevated HFSE, U, Th. Al-augites tracing 90 mW/m2 geotherm.The huge thermal impact of plume produced Rodinia breakdown series of ultramafic-alkaline-carbonatite massifs. Initially aillikites in mantle originated due to melting of carbonated metasomatites containing ilmenite, perovskites, apatites, amphiboles and phlogopites created by subduction related melts. Additional enrichment in ore components may occurred in low crust due to liquation. The aillikites inside BZM contain low-temperature clinopyroxenes tracing steep advective geotherm (0.4–1.5 GPa) and clots related to intermediate magma chambers together with CIMS pyroxenes and amphiboles. This suggests that the liquation of aillikites was accompanied later by density separation and AFC fractionation with the participation of crust material.Trace elements (especially REE) in silicate minerals, carbonates, apatites, and accessories (perovskites, pyrochlores, monazites, columbites zircons, ancylites etc). show general rise of the REE levels and La/Ybn rations from aillikites to ijolites and later to Fe-cabonatites. Presence of zircons, monazites, columbite- tantalites and other Zr-Hf and Ta-Nb minerals (perovskite, tantalites etc) in BZM aillikites occurred due to the mixing with the silicate melts with the carbonate-rich magmas in deep levels and later in massif. In aillikites any of them are of xenocrysts.Apatites and perovskites show high REE levels. The carbonate-silicate magmas passed through the system of polybaric magmatic chambers and liquated carbonatites. Late aillikites captured and mixed all varieties and xenocrysts.

Minerals from > 200 mantle xenoliths from Komsomolskaya kimberlite pipe were studied by electron microprobe and LA-ICP-MS. They are metasomatised garnet and spinel peridotites containing phlogopite, amphibole and ilmenite with garnets (up to 12.5 wt% Cr2O3) and clinopyroxenes (up to 5 wt% Na2O) or rarer Fe-pyroxenites and A, B, C eclogites.Thermobarometry indicates that the lithospheric mantle beneath the Komsomolskaya pipe is layered. Heated porphyroclastic, deformed peridotites at the lithosphere base (7-6 GPa) are enriched in Fe. The cold group at 6.0-5.5 GPa (34 mW/m2) are depleted peridotites with sub-Ca garnets. Cpx-fertilized varieties belong to the middle part of the mantle section. Amphiboles range from Cr-hornblendes to edenites (2-6 GPa), showing K-Ti enrichment. Picroilmenites yield two pressure intervals from 6.5 to 5.0 GPa and from 5.0 to 4.0 GPa, forming two differentiation branches. Eclogites mainly occur in the lower part of the section with a peak at pressures of 4-6 GPa.Trace elements of melts that formed harzburgitic garnets-pyroxenes refer to oceanic MORB like melt interaction with peridotites. The sub-calcic S-type garnets are similar to subduction-related melts (S-type REE) with troughs in HFSE. Adakite-like hybrid metasomatism formed Na, Al-rich pyroxenes with peaks in Sr and HFSE. K-bearing pyroxenes and amphiboles refer to shoshonitic metasomatism. Trace elements for Cpx of re-fertilized mantle peridotites reveal high LREE, Nb-Ta troughs and peaks in Zr, Th, Sr, U. They are reacted to carbonatite –alkaline melts. Protokimberlite (essentially carbonatitic) interaction produced HFSE-enrichment. Type B eclogites show more subduction-related features with HFSE troughs while type A eclogites are closer to hybrid and peridotitic signatures. We suggest six types of major metasomatic agents. The 40Ar/39Ar ages of phlogopites vary in the 440-690 Ma range, with some at 1.6 Ga, suggesting multistage metasomatism.

Preliminary studied lower crust and Moho of Baikal Rift (BR) was investigated using pyroxenite xenoliths and xenocrysts from Cenozoic volcanoes to determine the structure, thermal conditions and composition of the transitional zone from the crust to mantle and influence of plumes on it. Samples from Vitim Plateau (Miocene picrite basalts) SW part of BR, Dzhida River Basin (Bartoy volcanoes) located at SE of BR and Tunka axial Valley (Karierny volcanoes) to the West from Baikal were studied for major components using electron microprobe and electron microscope and for trace elements with the inductively connected mass-spectrometry with laser ablation. For the comparison, the lower crust xenocrysts from the Angara Vitim batholite were also included in this study. The PT estimates for minerals are mostly refer to the Moho boundary or are locating just beneath it giving the vast range of temperatures. Beneath the Moho, they trace 90 mw/m2 geotherm. Within the crust, temperature regime varies from the conductive to advective. Pyroxene xenocrysts and pyroxenite xenoliths mainly trace 90 mw/m2 SEA plume geotherm. The levels of the melt intrusions are overheated to 1350°C. The granulites are typically represent the colder conditions than SEA geotherm. Xenocrysts from Angara Vitim batholith magmas reveal more depleted material of lower crust than those found in Cenozoic lavas and possibly are skialites. The xenocrysts and granulite xenoliths in Cenozoic lavas are mainly basic cumulates. The rocks of the lower crust became more acid to the upper part.The lateral variations in the lower crust sampled material show enrichment in K2O at the boundary with the Siberian Craton in Tunka, more metasomatic and hydrous nature in Dzhida zone and more basic and CaO rich characteristic in Vitim area. These data give the evidence for the conditions of origin of the magmas of Angara-Vitim Batholith (AVP) (275-310 Ma), which was created due to interaction of hot spot with the crust in Baikal and Transbaikalia. Initially this hot generated kimberlites and basalts in northern (420-390 Ma) and central part of Yakutia (370-440 Ma) in time, migrated to – and eeastern Sayan Mountain formed Ingashi lamproites -kimberlites (310 Ma), than plume was spreading to south beneath the crust in Transbaikalia and created AVP. After it returned to central and northern Siberia, it generated Permo-Triassic Siberian trap province.

The finds of giant CLIPPIR-type diamonds in the placers hosted by the Ebelyakh River basin in the north of Yakutia suggest that similar diamonds can be found in the kimberlites of the Anabar region and the nearest northern deposits located within the collisional Khapchan and Daldyn terranes. To predict the discovery of such diamonds, the authors use the 5E diagram method based on the principle of similarity of the compositions of five oxides of satellite minerals (Grt, Cpx, Chr and Ilm) of diamond (DSM) with the reference diagrams for the Karowe pipe (K-6, Botswana) with the composition of those for any other pipe. It was previously shown that the convergence of the DSM compositions of the Karowe and V. Grib (Arkhangelsk diamond province) pipes is 74 %, which might indicate possible presence of CLIPPIR diamonds in the predicted pipe. The application of this technique to two kimberlite pipes of the Anabar region demonstrated that the probability of detecting such diamonds in the Leningrad pipe (Lower Devonian, medium diamond content potential) is 74 %, and in the Malokuonamskaya pipe (Lower Triassic, medium diamond content) is 20 %. A comparison of diagrams 5E and additional PTС – fO2 diagrams of reconstructed sections of the lithospheric mantle showed their efficiency in predicting favorable conditions of CLIPPIR-type diamond crystallization. It is assumed that formation of such diamonds may occur within the proto-kimberlite magmatic chamber located near the boundary of the lithosphere and associated with the asthenospheric source. It should be surrounded by low-oxidized carbon-rich mantle eclogites and dunites with high pressure and temperature, as well as magnesium-rich ilmenite-chromite metasomatites. The use of the 5E diagram method, as the approach to predict giant CLIPPIR diamonds in poorly diamondiferous kimberlites, might attract investing for exploration to audit the industrial potential of a series of such kimberlites in the Anabar region. Its implementation would significantly increase the efficiency of geological exploration and assessment of the potential of poorly diamondiferous pipes that have been suspended as subeconomic.

Mantle xenoliths from Zarnitsa pipe studied in gray eruptive breccias (early) brown autholitic breccia (BAB) and black macrocrystic kimberlites (last dike; BMK), include garnet and spinel dunites-harzburgites, pyroxenites, eclogites, glimmerites and megacrysts. PT reconstructions using xenoliths reveal sharply layered structure (8 levels), estimated with the single grain mineral estimates mark hot (Cpx, Ilm) and cold (OPx, Gar) inflected geotherm. The interaction with plume melts is found at the lithosphere asthenosphere boundary (LAB), pyroxenite layer (3-4 GPa), Gar-Sp transition and Moho. Eclogites reveal Fe# growth from LAB to middle pyroxenites layer. Clinopyroxenes and ilmenite estimates marks melt refertilisations in interlayers between coupled subduction slabs. Source of capture from first to third stage deepening to LAB and Cr- rich garnets (to 19.5 Cr2O3) are below the LAB.The grey erupted breccia (GEB) includes mainly depleted and deformed peridotites. The later BAB includes pyroxenites, eclogites, and refertilised, deformed, and veined peridotites in BMK. Geochemistry of minerals changes from primary mid ocean ridge basalts (MORB) and back arc peridotites with low REE and large ion lithophile elements (LILE) and deeps in high field strength elements (HFSE) to metasomatized by alkaline (high Na and LILE) and adakitic melts (high Al, Na, Sr, and elevated HFSE) varieties and refertilised lherzolites due to plume at last stage. Mantle column metasomatized with scattered phlogopites in early grey eruptive breccia to amphibole-phlogopite ilmenite veins at last stages. Amphiboles trace mantle from lithosphere – asthenosphere boundary to Moho.Growth of the diamond grade from early eruptive breccia to later kimberlite phases refer to decreasing of the crust material and deepening of the xenoliths capture level. Metasomatism dissolve the diamonds but growth of megacrystic diamond crystals increase diamond grade.

This contribution reports some 16,000 major and minor element analyses of garnet xenocrysts derived from 18 (out of the 21 known) kimberlite fields of the Yakutian Kimberlite Province (YaKP) on the Siberian craton in Russia. Using TiO2-in-garnet as an indicator of heterogeneity within the subcontinental lithospheric mantle (SCLM), as well as garnet mg# (mg#=Mg2+/(Mg2++Fe2+)*100), we distinguish three subpopulations of garnet: 1) high content of TiO2 (0.26-0.50 wt%) and high mg# (80.6-82.6) garnet xenocrysts are common in the southern diamondiferous kimberlite fields; 2) garnet xenocrysts with low content of TiO2 (0.06-0.26 wt%) and relatively high values of mg# (78.8-81.7), which prevail in the northern 'barren' kimberlite fields; and 3) three anomalous northern kimberlite fields (Chomurdakh, Ogoner-Yuryakh, Toluopka) characterized by the predominance of garnet xenocrysts with high TiO2 content (0.53-0.78 wt%) at relatively low mg# (76.9-78.3).It is reasonable to assume that relatively thin cratonic mantle lithosphere beneath the three anomalous kimberlite fields underwent intense metasomatic overprinting by melts and fluids injected from the underlying asthenosphere, which changed the compositions of peridotitic garnets significantly. An interpretation of the data presented in this study is that the generally high TiO2 contents of kimberlites in the northern YaKP (>1.5 wt% TiO2) are a primary magmatic feature of asthenospheric origin because the lithospheric mantle traversed by these kimberlite magmas is TiO2 depleted. We propose a model in which the relatively thin SCLM of the northern Siberian craton provided less opportunity for high-TiO2 asthenospheric kimberlite melts to interact and change compositions on their way to the Earth's surface. The high-TiO2 kimberlites of the northern YaKP may thus represent a good approximation of the primary compositions of natural kimberlite melts.pproximation of the primary compositions of natural kimberlite melts.(c) 2023 Published by Elsevier B.V. on behalf of International Association for Gondwana Research.

The article reports morphotectonic and petrological characteristics of Permo-Triassic trap basalts covering the major part of Siberian Craton and its surroundings. Lavas, sills, and dykes are distributed in Taimyr, in the crystalline basement and Mesozoic cover of the West Siberian Plate and in Kara sedimentary basin. Investigations include relief analysis, seismotomographic data, magnetic and gravitational anomalies. Four sectors of magma-permeable zones were distinguished along the perimeter of the Anabar Shield in the Siberian craton. The western sector is characterized by an intensive fracturing and stretching where the Tunguska syncline filled by the flood basalt was formed. A striking feature of volcanism is the meridional petrochemical trend corresponding to increasing the silica (decreasing pressure) of basic magmas in volcanic and intrusive rocks of the Siberian Craton from the impact center, located at the North near Norilsk, to South regions – Kuzbass and Angara-Taseev regions. It corresponds to the thinning of the mantle keel, which coincides with the reduction of the volumes of erupted melts. This trend was determined for volcanics referring to the two major time events 252–244 and 238–232 Ma.

Disentangling the physico-chemical evolution of the melts that give rise to kimberlites during their genesis, ascent through the sub-cratonic lithosphere and emplacement in the crust is challenging. This is because the extensive entrainment and assimilation of, and reaction with, mantle-derived material makes kimberlites mixtures of xenocrystic, magmatic components and alteration minerals, rarely preserving evidence of their original melt composition. Here, a detailed textural and compositional study of coherent and volcaniclastic kimberlite units from the Udachnaya–East pipe (Siberian craton) was performed to reconstruct the pressure–temperature–oxygen fugacity-compositional (P–T–fO 2 –X) path of kimberlite melts during their ascent through the sub-cratonic lithosphere. Routine and high-precision electron microprobe analyses of olivine, phlogopite and Fe–Ti oxides enabled to discriminate the mantle-derived cargo from the magmatic components, and thus make inferences on the liquid line of descent (LLD) of proto-kimberlite to kimberlite melts. Most of the olivine cores in Udachnaya–East kimberlite are xenocrystic and record conditions of last equilibration in the Siberian sub-cratonic lithospheric mantle at T–P ranging from 812–1227°C at 3.1–5.4 GPa, to 871–1170°C at 4.6–7.0 GPa, depending on the chosen model geotherm (35 mW/m 2 vs 40 mW/m 2 ). Based on their Ni, Cr, Mn, Al and P vs Mg/Fe systematics, olivine core populations were associated to the sheared, granular garnet-bearing or spinel-bearing cratonic peridotites. The occurrence of olivine Internal Zones (I) having the same composition as Fe-rich cores, as well as rare mantle-derived xenocrystic cores of phlogopite, bear witness of mantle metasomatism preceding kimberlite ascent. The assimilation of mantle material by initially H 2 O- and P-rich proto-kimberlitic melts is recorded by the cotectic formation of magmatic olivine Internal Zones (II) and phlogopite Internal Zones around resorbed xenocrystic cores. The LLD then evolved by inducing cotectic precipitation of olivine, phlogopite rims and Cr-spinel at P of 1.5–3.0 GPa, T of 1120–1250°C and fO 2 from −2.8 to −1.6 ΔFMQ. Ilmenite–magnetite pairs in the groundmass record the later conditions of crystallization that occurred at P of ~1.0 GPa, T from 1133°C down to 1000°C and fO 2 of +0.3 to +0.9 ΔFMQ. These results confirm the progressive oxidation of the melt that finally led to the formation of calcite, apatite and Mg-rich olivine and phlogopite rinds. The F-enrichment of phlogopite rinds reflects a late decrease of the H 2 O/CO 2 activity of the melt that evolved toward alkali-carbonated composition. Our results showed that the crystal cargo of kimberlites can be used to track all processes acting in between the melt-rock reactions in the mantle and the emplacement in the crust.

•PT conditions of diamond inclusions from Proterozoic, Paleozoic and Mesozoic kimberlites.•Pyroxenitic diamond inclusions tend to concentrate in the middle of the mantle.•Chromites and DIA trace the lithosphere-asthenosphere boundary.•Peridotitic inclusions are lower temperature than pyroxenes and eclogities.•Diamond inclusions in mobile belts and suture zones show higher T conditions.

<p>The Belo-Ziminsky alkaline-ultrabasic carbonatite massif contain dolomite, and calcite ankerite carbonatites essential part , syenites, melteigites and iolites cut by aillikite dikes of several generations (Ashchepkov et al., 2020; Doroshkevich et al., 2014-2021 etc). We analyzed  >4000 mineral grains by electron microscope in all types of rocks and >230 grains by  LA ICP MA  All rocks of the massif are derived from one type of mantle melt that was close to aillikite and formed at a level of >5 GPa in the mantle.</p> <p><img src="" alt="" width="536" height="499" /></p> <p><img src="" alt="" width="531" height="589" /></p> <p><img src="" alt="" /></p> <p><img src="" alt="" /></p> <p>According to the nature of the PGE spectra –  and by serpentinized xenoliths in aillikites, this melt drained metasomatized enriched peorvskites and hydrogenated mantle and was initially very rich in HFSE. Above, at the level of the crust and the upper part of the mantle, the melt began to separate under liquation. In the lower and middle crust, several (3) magmatic chambers were probably formed sequentially, which separated various carbonate and silicate melts, and from dolomite to ankerite melts, judging by the slope, the number of grains in the source decreased, that is, the melts became less deep and more fractionated.</p> <p><img src="" alt="" /><img src="" alt="" /></p> <p>These trends are reflected both in the composition of pyroxenes from aillikites  and in the PTX diagram . All this led to significant variations in rocks and their rare-earth spectra of all rocks</p> <p><img src="" alt="" /></p> <p><img src="" alt="" /></p> <p> </p>

<p>Peridotite xenoliths from kimberlites are useful tools for exploring the architecture and composition of the thick sub-cratonic lithosphere, and thus understanding the long-term evolution of the Earth’s mantle. However, the continuous infiltration of kimberlite-related melts and fluids prior to - and during - the transport of mantle-derived fragments towards the surface makes it difficult to extract information about the original texture and chemistry of the mantle rocks and the deep-seated metasomatic processes.</p> <p>In this study, fresh spinel- to garnet-bearing peridotite xenoliths from Udachnaya-East were studied to unveil the nature and composition of the lithospheric mantle beneath the Siberian craton. The studied samples have mostly harzburgitic to dunitic composition, even though lherzolites and rare wehrlites are also found. Occasionally, harzburgites are orthopyroxene-rich (up to 40 vol.%) or garnet-rich (up to 30 vol.%). The texture of the peridotites is extremely variable, ranging from protogranular to highly recrystallized and/or sheared. In spinel-bearing rocks, primary olivine is Mg- and Ni-rich (Fo<sub>90-93</sub>; NiO = 0.34-0.46 wt%), orthopyroxene has Mg# of 92-94 and Al<sub>2</sub>O<sub>3</sub> in the range of 0.3-3.0 wt%, while clinopyroxene is Mg-rich (Mg# 94-96), with Al<sub>2</sub>O<sub>3</sub> comprised between 1.0 and 3.5 wt%. In garnet-bearing peridotites, olivine ranges from Mg- and Ni-rich (Fo<sub>92</sub>; NiO = 0.45 wt%) to Fe-rich and Ni-poor (Fo<sub>87</sub>; NiO = 0.25 wt%), while pyroxenes have Mg# from 93 to 87-88 and comparatively low Al<sub>2</sub>O<sub>3</sub> contents (orthopyroxene: 0.5-1.1 wt%; clinopyroxene: 0.8-2.2 wt%). High-precision electron microprobe analyses complemented by thermo- and oxy-barometric models were used to reconstruct the thermo-chemical log of the Siberian sub-cratonic mantle, in comparison to what proposed by Liu et al. (2022). Textural-compositional studies of the reaction zones enabled to discriminate the secondary-formed minerals with composition ascribable to the liquid line of descent of kimberlite-related melts at Udachnaya (Casetta et al. 2023) from those formed during melt/fluid-rock reactions taking place in the mantle before xenoliths’ entrainment by the host kimberlites. Altogether, our results enable to trace the <em>P</em>-<em>T</em>-<em>X</em> evolution experienced by the Siberian mantle, opening a window onto the comprehension of the interactions between kimberlitic-related fluid/melts and the sub-cratonic lithosphere.</p> <p> </p> <p><em>Casetta, F., Asenbaum, R., Ashchepkov, I., Abart, R., & Ntaflos, T. (2023). Mantle-Derived Cargo vs Liquid Line of Descent: Reconstructing the P–T–fO<sub>2</sub>–X Path of the Udachnaya–East Kimberlite Melts during Ascent in the Siberian Sub-Cratonic Lithosphere. Journal of Petrology, 64(1), egac122. </em></p> <p><em> </em><em>Liu, Z., Ionov, D. A., Nimis, P., Xu, Y., He, P., & Golovin, A. V. (2022). Thermal and compositional anomalies in a detailed xenolith-based lithospheric mantle profile of the Siberian craton and the origin of seismic midlithosphere discontinuities. Geology.</em></p>