Inna Safonova | Institute for Philosophy and Law of the Siberian Branch of the Russian Academy of Sciences (original) (raw)
Papers by Inna Safonova
Episodes, 2016
The IGCP-Project #592 "Continental construction in the Central Asian Orogenic Belt compared to ac... more The IGCP-Project #592 "Continental construction in the Central Asian Orogenic Belt compared to actualistic examples from the western Pacific" funded by UNESCO-IUGS was launched in 2012 and catalysed an explosion of research activities in Central Asia itself and in other countries engaged in investigations on that region. The results, some of which can be highlighted as breakthrough advances in our understanding of geological processes, were published in ~60 articles in SCI peer-reviewed journals and reported at six scientific conferences. This paper summarizes main topics and scientific results of the 3 rd year of project activities. The meeting program included international conferences and workshops in China, Turkey and Russia and the educational program included nine lecture and field training courses and other capacity building activities in the United Kingdom, Kazakhstan, Russia, Turkey, China and Japan. In 2014, participants from more than 50 countries joined the research and meeting activities of IGCP#592, of which more than 35% were women and young scientists. The major scientific results come from the study of proportions of juvenile and recycled crust in the Central Asian Orogenic Belt (CAOB) with special focuses on the timing of granitoid and mafic magmatism, contribution of deep mantle processes, formation ages and genesis of major metal deposits, and comparison of the CAOB with the modern western Pacific.
International Geology Review, 1994
Results of research on the geological, petrochemical, and isotopic-geochronological charac- teris... more Results of research on the geological, petrochemical, and isotopic-geochronological charac- teristics of plagiogranites from the Chelyuskin ophiolitic belt, on the northern part of East Siberia's Taymyr Peninsula, are presented. Petro-geochemical features and REE distributions for this tonalite-trondhjemite series resemble those of plagiogranites from different ophiolitic complexes. The plagiogranites considered here belong to the low-potassium series of ophiolitic mafics—gabbro, gabbro-dolerite dikes,
International Geology Review
a Xinjiang Research Center for Mineral Resources, Chinese Academy of Sciences, Urumqi 830011, Chi... more a Xinjiang Research Center for Mineral Resources, Chinese Academy of Sciences, Urumqi 830011, China b State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China c Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China d Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090, Russia e State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and... more This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and whole-rock Nd and Hf-in-zircon isotope data from sandstones of the Char and Zharma zones of eastern Kazakhstan. Petrographically the sandstones represent greywackes. The U–Pb ages of detrital zircons show unimodal distributions peaked at 345–340 and 330–325 Ma indicating post-Early Carboniferous deposition. The sandstones have high CIA values (60–68), suggesting moderate to weak chemical weathering. Their high ICV values (1.1–1.3) and relatively high MgO and low Y, Nb indicate an immature probably mafic–intermediate igneous source (low La/Th, medium Hf). Positive whole-rock εNd(t) and zircon εHf(t) indicate dominantly juvenile character of igneous rocks in the provenance. In total, the unimodal character of U–Pb detrital zircon age patterns, the chemical composition of sandstones similar to that of associated volcanic rocks and the positive values of εNd(t) and εHf(t) suggest their deri...
Journal of Asian Earth Sciences
Lithos
has been submitted for publication in LITHOS in April, 2021. Please note that despite having unde... more has been submitted for publication in LITHOS in April, 2021. Please note that despite having undergone peer-review, the manuscript has not been formally accepted yet for publication and, therefore, it may be subject to some changes. Subsequent versions of the manuscript may include slightly different content. If accepted the final version of the manuscript will be available through the "PEER REVIEW PUBLICATION DOI" link.
Gondwana Research
Abstract The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Al... more Abstract The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Altai (Russia) in the west of Central Asian Orogenic Belt (CAOB) – the front part of the Altai convergent margin of the Siberian continent. Two geochemical types of subvolcanic rhyolites were emplaced synchronously with the bimodal rhyolite-basalt association, which began to form in the end-Emsian, and clearly manifested on the border of the Givetian and the Frasnian. The rhyolites yield zircon U-Pb ages of ca. 390 Ma (R1-type) and 380 Ma (R2- and R3-types), reflecting two peaks of the volcanic activity. Most of these rocks have extreme petrochemical characteristics of high SiO2 contents and have contrast Na/K ratios. Their compositions are transition between calc-alkaline and tholeiite series: (La/Yb)n ~ 2–7, Zr/Y ~ 4 (Zr 350 ppm), Zr (>250 ppm), and high Ga/Al (>2.6) values. The island-arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The generation of rift-like R2- and R3-rhyolites took place under non-equilibrium conditions, synchronously with the rise in the upper crust of Givetian-Frasnian basic magmas, as a result of the active lithospheric extension and high thermal input from the underlying hot mantle. We propose an extension regime in the transition area between the island-arc and back-arc basin for the origin of rhyolites. The study of the Devonian volcanism of the Rudny Altai gives important information about the processes that occurred at the initial stage of the formation of the Altai convergent margin.
Gondwana Research
Abstract The Itmurundy zone/belt is located in the northern Balkhash area of central Kazakhstan. ... more Abstract The Itmurundy zone/belt is located in the northern Balkhash area of central Kazakhstan. Geologically it belongs to the Kazakh orocline located in the western Central Asian Orogenic Belt (CAOB), north of the Tarim craton and west of the Junggar block. The Itmurundy belt, which surprisingly has remained unstudied in terms of up-to-date geochronological, geochemical and isotope methods compared to other regions of the CAOB, was revisited and reinvestigated. The belt possesses a very complicated geological structure and hosts rocks of mantle, orogenic and post-orogenic associations. This paper focuses on the orogenic association and presents original geological data, first U–Pb age and first up-to-date geochemical and Nd isotope data from igneous rocks. The orogenic association of the Itmurundy belt includes volcanic and sedimentary rocks of three formations, Itmurundy (O1-2), Kazyk (O2-3) and Tyuretai (O3–S1), and represents an accretionary complex. The most lithologically diverse Itmurundy Fm. (O1-2) consists of oceanic basalt, pelagic chert, hemipelagic siliceous mudstone and siltstone, and greywacke sandstones. Both sedimentary and igneous rocks were strongly deformed by syn- and post-accretion processes, which, in places, formed duplex structures. The igneous rocks are basalt/dolerite/gabbro, andesibasalt, trachybasalt and diorite. The diorite yielded a U–Pb age of ca. 500 Ma. The subalkaline volcanic and subvolcanic rocks belong to the tholeiitic series. Based on major oxides three groups of rocks can be distinguished: high-Ti, mid-Ti and low-Ti. The rocks of these three groups are variably enriched in LREE (LaN = 122, 23 and 2 in average, respectively) showing LREE enriched (high-Ti), LREE depleted (mid-Ti) and flat (low-Ti) REE patterns. The high-Ti group shows enrichment in Nb, Th, and Zr compared to the mid-Ti and low-Ti groups. The low-Ti group is special for the Nb troughs in primitive mantle normalized multi-element diagrams, which are typical of supra-subduction settings. The values of eNd are mostly positive for the mid-Ti and low-Ti groups, but negative for the high-Ti group. The geochemical features of the igneous rocks suggest their formation in oceanic (oceanic floor and oceanic island/seamount) and supra-subduction (intra-oceanic arc) settings. In general, the structural position, lithology and deformation styles of Itmurundy sedimentary and igneous rocks and the geochemical features of the igneous rocks all accord well with the models of Ocean Plate Stratigraphy (OPS) and Pacific-type orogeny. Thus, the Itmurundy belt at northern Balkhash represents an Ordovician-Silurian Pacific-type orogenic belt formed at a convergent active margin of the Paleo-Asian Ocean.
Gondwana Research
Abstract This paper presents new major and trace element data, Sr-Nd-Pb isotopic ratios and K-Ar ... more Abstract This paper presents new major and trace element data, Sr-Nd-Pb isotopic ratios and K-Ar ages from volcanic rocks of the Greater Khingan Range of NE China (Nuomin–Keluo and Arxan–Chaihe volcanic fields) and the Khangai volcanic province of Central Mongolia. These data are discussed in correlation with available in literature geological, geochronological, geochemical, isotopic, petrologic and geophysical data from intra-plate volcanic fields of Central and East Asia. All volcanic rocks possess geochemical affinities to intra-plate oceanic and continental basalts. The Nuomin-Keluo samples (2.75 and 0.41 Ma) show enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE; La/YbN = 43.6–91.5), as well as depletion in heavy REE (HREE), and Nb peaks relative to La and Th (Nb/Lapm = 0.61–1.24; Nb/Thpm = 0.96–1.70) in the multi-element spectra. The Arxan-Chaihe basalts (0.91 and 0.53–0.27 Ma) have lower K, less fractionated REE (La/YbN = 15.7–28.1), but higher Nb peaks (Nb/Lapm = 1.56–1.74; Nb/Thpm = 1.27–1.79), as well as higher epsilon Nd and 206Pb/204Pb, but lower Sr isotopic ratios. The Khangai volcanic province consists of central and peripheral areas, which are dominated by low–alkali and high–alkali varieties, respectively. The central Khangai have lower LREEs and LILEs, and lower Gd/YbN ratios compared to the peripheral Khangai. In the 143Nd/144Nd vs. 87Sr/86Sr diagram, the Nuomin-Keluo and Khangai samples plot close to EM1, whereas the Arxan-Chaihe samples possess less enriched compositions. In Pb isotope diagrams, the Nuomin-Keluo and peripheral Khangai samples plot between DM and EM1, whereas the Arxan-Chaihe and central Khangai samples plot near PREMA. Geochemistry-based melting modeling indicates that all the volcanic rocks were derived from garnet-bearing, probably enriched, mantle sources melted at variable degrees Based on the whole set of new and previous data we suggest that the Great Khingan and Khangai volcanic rocks were probably produced by hydrous mantle plumes generated in the MTZ and ascending from the subducted Pacific slab stored therein. In general, the late Cenozoic intra-plate volcanism in Central and East Asia can be triggered by the material, which has accumulated beneath the Asian continent and metasomatized the mantle underneath since the amalgamation of Laurasia and formation of the Central Asian Orogenic Belt at ca. 300–250 Ma.
Journal of Asian Earth Sciences
Tectonophysics, 2015
Abstract This paper presents a model for the generation of hydrous-carbonated plumes (HCPs) in th... more Abstract This paper presents a model for the generation of hydrous-carbonated plumes (HCPs) in the mantle transition zone (MTZ) linking (i) the Pacific-type convergent margins; (ii) melt generation in the MTZ under the influence of volatiles (water, carbon dioxide) and subducted granitic material and oceanic slabs and (iii) the Meso-Cenozoic intra-plate magmatism in Central Asia. The model is based on four groups of evidences obtained from geology, petrology, seismic tomography and numerical simulations. The double-sided subduction at the Pacific-type margins around post-Miocene Asia supplies hydrated-carbonated oceanic crust and continental crust materials down to the deep mantle, which accumulate in the MTZ at 410–660 km. The delivery of crustal material to the MTZ is provided by the direct subduction of intra-oceanic arcs in the Western Pacific and by the tectonic erosion of convergent margin hanging walls. The U-Th-K–enriched continental material accumulated in the MTZ can serve an additional source of heat. Evidence for the subduction of continental crust materials comes from seismic tomography and numerical modelling data. The subducting oceanic slab consisting of serpentinites, hydrated sediments, carbonates and carbonatized basalts can supply water and carbon dioxide to the deep mantle and metasomatize it. The presence of volatiles, which can reduce melting temperature, and the presence of the subducted crustal material, which may serve an additional heater, can synergistically trigger the generation of HCPs. Those HCPs can induce mantle upwelling, melting of the metasomatized mantle and subducted MORB slabs, ascent of melts, surface rifting and formation of mafic and bimodal volcanic series. In addition, they can contribute to the supercontinent cycle. The HCPs generated in the MTZ beneath Central and East Asia resulted in a shift of the tectonic regime from transpression to transtension and in the formation of numerous Meso-Cenozoic intra-plate volcanic fields.
Gondwana Research
Abstract The paper presents new petrographic, major element and Fourier transform infrared (FTIR)... more Abstract The paper presents new petrographic, major element and Fourier transform infrared (FTIR) spectroscopy data and PT-estimates of whole-rock samples and minerals of a collection of 19 relatively fresh peridotite xenoliths from the Udachnaya kimberlite pipe, which were recovered from its deeper levels. The xenoliths are non-deformed (granular), medium-deformed and highly deformed (porphyroclastic, mosaic-porphyroclastic, mylonitic) lherzolites, harzburgite and dunite. The lherzolites yielded equilibration temperatures (T) and pressures (P) ranging from 913 to 1324 °C and from 4.6 to 6.3 GPa, respectively. The non-deformed and medium-deformed peridotites match the 35 mW/m2 conductive continental geotherm, whereas the highly deformed varieties match the 45 mW/m2 geotherm. The content of water spans 2 ± 1–95 ± 52 ppm in olivine, 1 ± 0.5–61 ± 9 ppm in orthopyroxene, and 7 ± 2–71 ± 30 ppm in clinopyroxene. The amount of water in garnets is negligible. Based on the modal proportions of mineral phases in the xenoliths, the water contents in peridotites were estimated to vary over a wide range from
The Mongol–Okhotsk Belt, the youngest segment of the Central Asian Orogenic Belt, formed by the e... more The Mongol–Okhotsk Belt, the youngest segment of the Central Asian Orogenic Belt, formed by the evolution and closure of the Mongol–Okhotsk Ocean. The oceanic closure formed two volcanoplutonic belts: Selenge Belt in the north and Middle Gobi Belt in the south (in present day coordinates). However, the origin and tectonic evolution of the Mongol–Okhotsk Belt in general, the origin and formation age of the Middle Gobi Belt in particular, remain enigmatic. To better understand the history of the magmatic activity in the Middle Gobi Belt, we conducted geochemical, U–Pb geochronological, zircon Hf, whole-rock Nd isotopic analyses of volcanic and plutonic rocks of the Mandalgovi suite, the major component of the Middle Gobi Belt. Our results show that the Mandalgovi suite consists of (i) 265 ± 2 Ma biotite-granite; (ii) 250 ± 3 Ma hornblende-granitoids; (iii) their volcanic equivalents of both: and (iv) gabbro-diorites. The geochemical compositions indicate that their precursor magmas we...
Episodes, 2016
The IGCP-Project #592 "Continental construction in the Central Asian Orogenic Belt compared to ac... more The IGCP-Project #592 "Continental construction in the Central Asian Orogenic Belt compared to actualistic examples from the western Pacific" funded by UNESCO-IUGS was launched in 2012 and catalysed an explosion of research activities in Central Asia itself and in other countries engaged in investigations on that region. The results, some of which can be highlighted as breakthrough advances in our understanding of geological processes, were published in ~60 articles in SCI peer-reviewed journals and reported at six scientific conferences. This paper summarizes main topics and scientific results of the 3 rd year of project activities. The meeting program included international conferences and workshops in China, Turkey and Russia and the educational program included nine lecture and field training courses and other capacity building activities in the United Kingdom, Kazakhstan, Russia, Turkey, China and Japan. In 2014, participants from more than 50 countries joined the research and meeting activities of IGCP#592, of which more than 35% were women and young scientists. The major scientific results come from the study of proportions of juvenile and recycled crust in the Central Asian Orogenic Belt (CAOB) with special focuses on the timing of granitoid and mafic magmatism, contribution of deep mantle processes, formation ages and genesis of major metal deposits, and comparison of the CAOB with the modern western Pacific.
International Geology Review, 1994
Results of research on the geological, petrochemical, and isotopic-geochronological charac- teris... more Results of research on the geological, petrochemical, and isotopic-geochronological charac- teristics of plagiogranites from the Chelyuskin ophiolitic belt, on the northern part of East Siberia's Taymyr Peninsula, are presented. Petro-geochemical features and REE distributions for this tonalite-trondhjemite series resemble those of plagiogranites from different ophiolitic complexes. The plagiogranites considered here belong to the low-potassium series of ophiolitic mafics—gabbro, gabbro-dolerite dikes,
International Geology Review
a Xinjiang Research Center for Mineral Resources, Chinese Academy of Sciences, Urumqi 830011, Chi... more a Xinjiang Research Center for Mineral Resources, Chinese Academy of Sciences, Urumqi 830011, China b State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China c Department of Earth Sciences, The University of Hong Kong, Pokfulam Road, Hong Kong, China d Institute of Geology and Mineralogy, SB RAS, Novosibirsk 630090, Russia e State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and... more This paper presents first U–Pb detrital zircon ages, major and trace element geochemical data and whole-rock Nd and Hf-in-zircon isotope data from sandstones of the Char and Zharma zones of eastern Kazakhstan. Petrographically the sandstones represent greywackes. The U–Pb ages of detrital zircons show unimodal distributions peaked at 345–340 and 330–325 Ma indicating post-Early Carboniferous deposition. The sandstones have high CIA values (60–68), suggesting moderate to weak chemical weathering. Their high ICV values (1.1–1.3) and relatively high MgO and low Y, Nb indicate an immature probably mafic–intermediate igneous source (low La/Th, medium Hf). Positive whole-rock εNd(t) and zircon εHf(t) indicate dominantly juvenile character of igneous rocks in the provenance. In total, the unimodal character of U–Pb detrital zircon age patterns, the chemical composition of sandstones similar to that of associated volcanic rocks and the positive values of εNd(t) and εHf(t) suggest their deri...
Journal of Asian Earth Sciences
Lithos
has been submitted for publication in LITHOS in April, 2021. Please note that despite having unde... more has been submitted for publication in LITHOS in April, 2021. Please note that despite having undergone peer-review, the manuscript has not been formally accepted yet for publication and, therefore, it may be subject to some changes. Subsequent versions of the manuscript may include slightly different content. If accepted the final version of the manuscript will be available through the "PEER REVIEW PUBLICATION DOI" link.
Gondwana Research
Abstract The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Al... more Abstract The paper presents new original data on the Devonian felsic volcanism of the NW Rudny Altai (Russia) in the west of Central Asian Orogenic Belt (CAOB) – the front part of the Altai convergent margin of the Siberian continent. Two geochemical types of subvolcanic rhyolites were emplaced synchronously with the bimodal rhyolite-basalt association, which began to form in the end-Emsian, and clearly manifested on the border of the Givetian and the Frasnian. The rhyolites yield zircon U-Pb ages of ca. 390 Ma (R1-type) and 380 Ma (R2- and R3-types), reflecting two peaks of the volcanic activity. Most of these rocks have extreme petrochemical characteristics of high SiO2 contents and have contrast Na/K ratios. Their compositions are transition between calc-alkaline and tholeiite series: (La/Yb)n ~ 2–7, Zr/Y ~ 4 (Zr 350 ppm), Zr (>250 ppm), and high Ga/Al (>2.6) values. The island-arc-like R1-rhyolite formed immediately after the beginning of rifting due to widespread crustal melting under reduced conditions. The generation of rift-like R2- and R3-rhyolites took place under non-equilibrium conditions, synchronously with the rise in the upper crust of Givetian-Frasnian basic magmas, as a result of the active lithospheric extension and high thermal input from the underlying hot mantle. We propose an extension regime in the transition area between the island-arc and back-arc basin for the origin of rhyolites. The study of the Devonian volcanism of the Rudny Altai gives important information about the processes that occurred at the initial stage of the formation of the Altai convergent margin.
Gondwana Research
Abstract The Itmurundy zone/belt is located in the northern Balkhash area of central Kazakhstan. ... more Abstract The Itmurundy zone/belt is located in the northern Balkhash area of central Kazakhstan. Geologically it belongs to the Kazakh orocline located in the western Central Asian Orogenic Belt (CAOB), north of the Tarim craton and west of the Junggar block. The Itmurundy belt, which surprisingly has remained unstudied in terms of up-to-date geochronological, geochemical and isotope methods compared to other regions of the CAOB, was revisited and reinvestigated. The belt possesses a very complicated geological structure and hosts rocks of mantle, orogenic and post-orogenic associations. This paper focuses on the orogenic association and presents original geological data, first U–Pb age and first up-to-date geochemical and Nd isotope data from igneous rocks. The orogenic association of the Itmurundy belt includes volcanic and sedimentary rocks of three formations, Itmurundy (O1-2), Kazyk (O2-3) and Tyuretai (O3–S1), and represents an accretionary complex. The most lithologically diverse Itmurundy Fm. (O1-2) consists of oceanic basalt, pelagic chert, hemipelagic siliceous mudstone and siltstone, and greywacke sandstones. Both sedimentary and igneous rocks were strongly deformed by syn- and post-accretion processes, which, in places, formed duplex structures. The igneous rocks are basalt/dolerite/gabbro, andesibasalt, trachybasalt and diorite. The diorite yielded a U–Pb age of ca. 500 Ma. The subalkaline volcanic and subvolcanic rocks belong to the tholeiitic series. Based on major oxides three groups of rocks can be distinguished: high-Ti, mid-Ti and low-Ti. The rocks of these three groups are variably enriched in LREE (LaN = 122, 23 and 2 in average, respectively) showing LREE enriched (high-Ti), LREE depleted (mid-Ti) and flat (low-Ti) REE patterns. The high-Ti group shows enrichment in Nb, Th, and Zr compared to the mid-Ti and low-Ti groups. The low-Ti group is special for the Nb troughs in primitive mantle normalized multi-element diagrams, which are typical of supra-subduction settings. The values of eNd are mostly positive for the mid-Ti and low-Ti groups, but negative for the high-Ti group. The geochemical features of the igneous rocks suggest their formation in oceanic (oceanic floor and oceanic island/seamount) and supra-subduction (intra-oceanic arc) settings. In general, the structural position, lithology and deformation styles of Itmurundy sedimentary and igneous rocks and the geochemical features of the igneous rocks all accord well with the models of Ocean Plate Stratigraphy (OPS) and Pacific-type orogeny. Thus, the Itmurundy belt at northern Balkhash represents an Ordovician-Silurian Pacific-type orogenic belt formed at a convergent active margin of the Paleo-Asian Ocean.
Gondwana Research
Abstract This paper presents new major and trace element data, Sr-Nd-Pb isotopic ratios and K-Ar ... more Abstract This paper presents new major and trace element data, Sr-Nd-Pb isotopic ratios and K-Ar ages from volcanic rocks of the Greater Khingan Range of NE China (Nuomin–Keluo and Arxan–Chaihe volcanic fields) and the Khangai volcanic province of Central Mongolia. These data are discussed in correlation with available in literature geological, geochronological, geochemical, isotopic, petrologic and geophysical data from intra-plate volcanic fields of Central and East Asia. All volcanic rocks possess geochemical affinities to intra-plate oceanic and continental basalts. The Nuomin-Keluo samples (2.75 and 0.41 Ma) show enrichment in large ion lithophile elements (LILE) and light rare earth elements (LREE; La/YbN = 43.6–91.5), as well as depletion in heavy REE (HREE), and Nb peaks relative to La and Th (Nb/Lapm = 0.61–1.24; Nb/Thpm = 0.96–1.70) in the multi-element spectra. The Arxan-Chaihe basalts (0.91 and 0.53–0.27 Ma) have lower K, less fractionated REE (La/YbN = 15.7–28.1), but higher Nb peaks (Nb/Lapm = 1.56–1.74; Nb/Thpm = 1.27–1.79), as well as higher epsilon Nd and 206Pb/204Pb, but lower Sr isotopic ratios. The Khangai volcanic province consists of central and peripheral areas, which are dominated by low–alkali and high–alkali varieties, respectively. The central Khangai have lower LREEs and LILEs, and lower Gd/YbN ratios compared to the peripheral Khangai. In the 143Nd/144Nd vs. 87Sr/86Sr diagram, the Nuomin-Keluo and Khangai samples plot close to EM1, whereas the Arxan-Chaihe samples possess less enriched compositions. In Pb isotope diagrams, the Nuomin-Keluo and peripheral Khangai samples plot between DM and EM1, whereas the Arxan-Chaihe and central Khangai samples plot near PREMA. Geochemistry-based melting modeling indicates that all the volcanic rocks were derived from garnet-bearing, probably enriched, mantle sources melted at variable degrees Based on the whole set of new and previous data we suggest that the Great Khingan and Khangai volcanic rocks were probably produced by hydrous mantle plumes generated in the MTZ and ascending from the subducted Pacific slab stored therein. In general, the late Cenozoic intra-plate volcanism in Central and East Asia can be triggered by the material, which has accumulated beneath the Asian continent and metasomatized the mantle underneath since the amalgamation of Laurasia and formation of the Central Asian Orogenic Belt at ca. 300–250 Ma.
Journal of Asian Earth Sciences
Tectonophysics, 2015
Abstract This paper presents a model for the generation of hydrous-carbonated plumes (HCPs) in th... more Abstract This paper presents a model for the generation of hydrous-carbonated plumes (HCPs) in the mantle transition zone (MTZ) linking (i) the Pacific-type convergent margins; (ii) melt generation in the MTZ under the influence of volatiles (water, carbon dioxide) and subducted granitic material and oceanic slabs and (iii) the Meso-Cenozoic intra-plate magmatism in Central Asia. The model is based on four groups of evidences obtained from geology, petrology, seismic tomography and numerical simulations. The double-sided subduction at the Pacific-type margins around post-Miocene Asia supplies hydrated-carbonated oceanic crust and continental crust materials down to the deep mantle, which accumulate in the MTZ at 410–660 km. The delivery of crustal material to the MTZ is provided by the direct subduction of intra-oceanic arcs in the Western Pacific and by the tectonic erosion of convergent margin hanging walls. The U-Th-K–enriched continental material accumulated in the MTZ can serve an additional source of heat. Evidence for the subduction of continental crust materials comes from seismic tomography and numerical modelling data. The subducting oceanic slab consisting of serpentinites, hydrated sediments, carbonates and carbonatized basalts can supply water and carbon dioxide to the deep mantle and metasomatize it. The presence of volatiles, which can reduce melting temperature, and the presence of the subducted crustal material, which may serve an additional heater, can synergistically trigger the generation of HCPs. Those HCPs can induce mantle upwelling, melting of the metasomatized mantle and subducted MORB slabs, ascent of melts, surface rifting and formation of mafic and bimodal volcanic series. In addition, they can contribute to the supercontinent cycle. The HCPs generated in the MTZ beneath Central and East Asia resulted in a shift of the tectonic regime from transpression to transtension and in the formation of numerous Meso-Cenozoic intra-plate volcanic fields.
Gondwana Research
Abstract The paper presents new petrographic, major element and Fourier transform infrared (FTIR)... more Abstract The paper presents new petrographic, major element and Fourier transform infrared (FTIR) spectroscopy data and PT-estimates of whole-rock samples and minerals of a collection of 19 relatively fresh peridotite xenoliths from the Udachnaya kimberlite pipe, which were recovered from its deeper levels. The xenoliths are non-deformed (granular), medium-deformed and highly deformed (porphyroclastic, mosaic-porphyroclastic, mylonitic) lherzolites, harzburgite and dunite. The lherzolites yielded equilibration temperatures (T) and pressures (P) ranging from 913 to 1324 °C and from 4.6 to 6.3 GPa, respectively. The non-deformed and medium-deformed peridotites match the 35 mW/m2 conductive continental geotherm, whereas the highly deformed varieties match the 45 mW/m2 geotherm. The content of water spans 2 ± 1–95 ± 52 ppm in olivine, 1 ± 0.5–61 ± 9 ppm in orthopyroxene, and 7 ± 2–71 ± 30 ppm in clinopyroxene. The amount of water in garnets is negligible. Based on the modal proportions of mineral phases in the xenoliths, the water contents in peridotites were estimated to vary over a wide range from
The Mongol–Okhotsk Belt, the youngest segment of the Central Asian Orogenic Belt, formed by the e... more The Mongol–Okhotsk Belt, the youngest segment of the Central Asian Orogenic Belt, formed by the evolution and closure of the Mongol–Okhotsk Ocean. The oceanic closure formed two volcanoplutonic belts: Selenge Belt in the north and Middle Gobi Belt in the south (in present day coordinates). However, the origin and tectonic evolution of the Mongol–Okhotsk Belt in general, the origin and formation age of the Middle Gobi Belt in particular, remain enigmatic. To better understand the history of the magmatic activity in the Middle Gobi Belt, we conducted geochemical, U–Pb geochronological, zircon Hf, whole-rock Nd isotopic analyses of volcanic and plutonic rocks of the Mandalgovi suite, the major component of the Middle Gobi Belt. Our results show that the Mandalgovi suite consists of (i) 265 ± 2 Ma biotite-granite; (ii) 250 ± 3 Ma hornblende-granitoids; (iii) their volcanic equivalents of both: and (iv) gabbro-diorites. The geochemical compositions indicate that their precursor magmas we...