Far East Geological Institute

This paper discusses the modes of occurrence of critical elements and their origins in the studied coal and associated rock samples (partings and roof strata) from the Datanhao coal mine, Daqingshan Coalfield, Inner Mongolia, northern China. The studied coals are enriched in trace elements including Zr, Hf, Th, Be, F, Zn, Ga, Nb, Mo, Cd, In, Sn, Ta, Hg, W, Pb, and rare earth elements and Y (REY). Zirconium, Nb, Ta, and Hf are largely associated with anatase in the studied coal and non-coal samples. The main carriers of REY, Th, and U in both coal and non-coal samples are Ca-bearing REE-phosphate minerals, most likely monazite, although U is partly associated with organic matter. Fluorine in the Datanhao coals is mainly associated with kaolinite. Most partings identified as volcanic ash-derived tonsteins from the Datanhao Mine exhibit negative Eu anomalies that, along with the common presence of equant-shaped euhedral volcanic quartz (beta-quartz), indicate a felsic volcanic source located in the Xing'an-Mongolia Orogenic Belt. Other probable sources of clastic material into the basin include the pre-Cambrian granites from the adjacent uplands, which may be responsible for the light rare earth element enrichment of the studied deposits, and associated metamorphic rocks from the adjacent uplands. Owing to acidic hydrothermal fluids, which are most likely related to the Yanshanian (Jurassic to Early Cretaceous) intrusive activity and/or low-temperature basinal waters circulating within the coal-bearing unit during the epigenetic stage, most of the coal benches from the Datanhao mine are also relatively enriched in middle rare earth elements. On the other hand, some coal and non-coal bench samples from the middle Datanhao section are enriched in heavy REE. This, along with the presence of abundant syngenetic or early diagenetic carbonate minerals, indicates deposition in an episodic alkaline environment, the origin of which is mostly probably attributed to evaporation and/or saline water inputs resembling a playa lake environment. As the concentrations of Zr, Hf, Nb, and Ta are all close to or higher than the respective industry cut-off grades or standards for these critical elements, the Datanhao coal seam has potential economic significance for these as an important by-product of the coal mining.

The Qinshui Basin is the largest reservoir of commercial coalbed methane in China. The No. 15 seam, one of the major coal seams for coalbed methane exploration in the Jincheng Coalfield, SE Qinshui Basin, has recently been found to be enriched in the critical element Li. This study further investigates the inorganic geochemistry of the No. 15 coal and associated rocks and reveals the enrichment origin of critical elements in these horizons. The Jincheng No. 15 coal is rich in Li, Mo, U, Se, Re, and rare earth elements and Y (REY). Concentrations of Mo, U, Se, and Re are higher in the two topmost coal benches, probably due to marine transgression in the early diagenetic stage after the peat had been established. The enrichment of Li and REY in a few lowermost coal benches is suggested to be derived from hydrothermal fluids that were related to magmatic activity (110–140 Ma) during the Yanshanian Orogeny (Late Jurassic-Early Cretaceous), or a Late Triassic-Early Jurassic abnormal thermal event occurring at 190–215 Ma. Light REY (La, Ce, Pr, and Nd) in the Jincheng No. 15 coal are predominantly associated with phosphate minerals. Heavier REY (Sm to Lu) show a mixed phosphate and organic affinity in the studied coal samples. Non-coal samples are characterized by light REY- and HREY-enrichment, which is probably inherited from the source material in the Trans North China Orogen. Trace elements in the coal can be highly enriched in the ash if the coal is combusted due to the low to medium ash yield of the coal. Critical elements, including Li, Ga, and REY, in the Jincheng No. 15 coal are considered as promising material for industrial recovery and have been previously under-estimated. On the other hand, environmentally sensitive elements including As, Hg, and Pb, while having concentrations within the normal range compared with average worldwide coals, can be highly enriched in the coal combustion residues if the coal is combusted, and thus careful consideration needs to be given to the utilisation of such coals.

ABSTRACT Heavy-mineral analyses of fifty Quaternary sediments from the North Sea, Red Sea, East China Sea, South China Sea, and Vancouver Island area (western seaboard of Canada) supplemented by over 1000 published analyses of sediments from many other sites in the world define accessory clastic mineral assemblages indicative of the principal plate-tectonic settings (excluding transform plate boundaries) associated with continental margins. Assemblages of all continental margins studied differ significantly from those of the intraoceanic, island-arc, and deep marginal-sea assemblages by possessing relatively high contents of zircon, tourmaline, garnet, epidote, amphibole (as well as other less common minerals), derived chiefly from metamorphic and sialic intrusive rocks. This suite is accompan ed by olivine, iddingsite, and brown (titanium-rich) clinopyroxene in regions containing rifting-type volcaniclastic sediments (i.e., near divergent plate boundaries), and with orthopyroxene, green clinopyroxene, and green-brown hornblende in arc-type volcaniclastic deposits (areas near convergent plate boundaries). On passive continental margins, both volcaniclastic suites are absent or present in negligible amounts.

Abundances, modes of occurrence, enrichment, and origin of critical elements in coal and coal-bearing sequences have attracted much attention in recent years. Previous investigations have attributed REE-Y-Nb-Ta-Zr-Hf mineralization in coals and in intra- and inter-seam tuffs in coal-bearing sequences to alkali volcanic ash eruptions and subsequent hydrothermal alteration. In this study, two major minable coal seams (D101 and W407) that are located in the lowermost and uppermost Wuchiapingian Longtan Formation in the Liupanshui Coalfield, Guizhou, southwestern China, were investigated in order to better understand the mechanism of REE-Y-Nb-Ta-Zr-Hf enrichment in these coals. Elevated concentrations of REE-Y-Nb-Ta-Zr-Hf in the D101 coal are dominantly due to the alkaline volcanic material forming the top of the Emeishan Large Igneous Province (ELIP), which served as a terrigenous source region for the coal basin and to airborne volcanic ash, which occurs as an intra-seam tonstein within the coal seam. Both of the two source materials were subsequently subjected to groundwater leaching, resulting in redistribution of the rare earth elements and Y (REY), leading to an uneven distribution of REY and Zr along the studied coal-seam sections. The average REY oxides in the D101 and W407 coals are 2682 and 1260 ppm (both on ash basis), respectively, and the outlook coefficients are 0.79 and 1.15 respectively, indicating that both ashes from the two coals are potential raw sources for REY.

Abstract. The Eurasian (née European) Modern Pollen Database (EMPD) was established in 2013 to provide a public database of high-quality modern pollen surface samples to help support studies of past climate, land cover, and land use using fossil pollen. The EMPD is part of, and complementary to, the European Pollen Database (EPD) which contains data on fossil pollen found in Late Quaternary sedimentary archives throughout the Eurasian region. The EPD is in turn part of the rapidly growing Neotoma database, which is now the primary home for global palaeoecological data. This paper describes version 2 of the EMPD in which the number of samples held in the database has been increased by 60 % from 4826 to 8134. Much of the improvement in data coverage has come from northern Asia, and the database has consequently been renamed the Eurasian Modern Pollen Database to reflect this geographical enlargement. The EMPD can be viewed online using a dedicated map-based viewer at https://empd2.github.io and downloaded in a variety of file formats at https://doi.pangaea.de/10.1594/PANGAEA.909130 (Chevalier et al., 2019).

Terrigenous materials from sediment-source regions are important controls on the types and concentrations of inorganic components in coal. The Kangdian Upland (dominated by the Emeishan basalts) is the dominant terrigenous supplier for most of the Late Permian coals, as well as for their associated host rocks (roof and floor strata) in southwestern China. The high volatile bituminous coals (Nos. 3 and 6 coals) are the two major minable coal seams in the Tucheng coal deposit in southwestern China. Unlike most Late Permian coals in this region that are characterized by elevated concentrations of the element assemblage Sc-V-Cr-Co-Ni-Cu-Zn-Se, these two coals are not enriched in this assemblage although Se is slightly concentrated. The mineralogical (e.g., relatively abundant quartz and mixed-layer illite/smectite) and elemental distribution patterns (e.g., spider diagrams of rare earth elements, discrimination diagrams of Al2O3-TiO2 and Zr/TiO2-Nb/Y, and elemental assemblages) indicate that the inorganic components in the two coal seams were mainly derived from unidentified volcanic arc and/or distal orogens, while the clastic components in the roof and floor strata of the two coal seams were mainly supplied by the high-Ti Emeishan basalts. The two partings in the two coal seams, identified as tonsteins, were probably derived from the final (rejuvenated) activity of the Emeishan plume. Critical elements in the two coals and associated non-coal horizons (partings, roof and floor strata) are economically unpromising, indicating that prospecting for Late Permian coal-hosted critical metal ore deposits in the vicinity of the Emeishan plume in southwestern China, should not be focused on coals with inorganic components derived mostly from distal volcanic arcs and orogens and high-Ti Emeishan basalts, and a minor contribution of volcanic ashes resulting from the final rejuvenated activity of the Emeishan plume.

Geological data and about 300 precision geochronological and geochemical determinations are analyzed to identify the Albian–Cenomanian continental-margin orogenic belt and simultaneous igneous province of Pacific Asia. The orogenic belt represents a newly formed region of continental lithosphere that resulted from the deformation of mainly Jurassic–Early Cretaceous epioceanic terranes. The igneous province is made up of volcanic and intrusive complexes of mostly Albian age, which are syn-orogenic within the belt and post-orogenic beyond it. The igneous rocks include A-, I-, and S-type granitoids; adakites; and VAB- and OIB-type basalts and their intrusive analogues. Both the orogenic belt and the igneous province were formed in a tectonic setting of a transform continental margin between 110 and 95 Ma. The interval of 103–97 Ma became the peak of orogenic and magmatic activity caused by upwelling of the hot asthenospheric mantle through destructed stagnant slabs of the pre-Albian subduction. The Albian–Cenomanian age of the large gold, copper, tungsten, tin, and other ore deposits argues in favor of recognition of the corresponding metallogenic province. The first age data (100–97 Ma) are reported for the granite from the Malmyzh deposit within the Sikhote-Alin Ridge.

Although the geochemical and mineralogical characteristics and provenance of Permian-Triassic boundary (PTB) widespread volcanic ashes from southern China have been well investigated, the volcanic ashes just prior to the end-Permian mass extinction (EPME) have rarely been studied. This paper presents the mineralogical and geochemical compositions of volcanic ashes from the latest Permian coal-bearing strata of southwest China. Based on the relative abundances of kaolinite and mixed-layer illite/smectite (I/S), the volcanic ashes in the present study can be divided into tonsteins and K-bentonites, which are dominated by kaolinite and I/S, respectively. The I/S in K-bentonites formed during burial diagenesis in a non-marine environment, indicated by their low contents of sulfur and low ratios of Sr/Ba. Based on the general geothermal gradient and vitrinite reflectance of coals, the I/S was deduced to have formed under a temperature less than 100 °C. Collectively, the occurrence of vermicular kaolinite, as well as high-temperature quartz and euhedral primary zircon identified in tonstein samples indicate an intermediate-felsic pyroclastic origin for the volcanic ashes, while rounded quartz and mica grains both in tonsteins and K-bentonites reflect the products of erosion from sediment source regions. The negative Eu anomalies, rare earth elements (REY) distribution patterns, low contents of Sc, V, Cr, Co, Ni and Zn, and Al2O3/TiO2 values, suggest that the tonsteins and K-bentonites are related to felsic volcanic eruptions. The relationship between Al2O3/TiO2 vs. Nb/Yb and Al2O3/TiO2 vs. Zr/TiO2 ratios indicate that the tonsteins and K-bentonites were derived from at least two felsic sources: (1) some distal volcanic arc(s) and (2) the top of the Kangdian Upland exposing the alkaline-felsic volcanic rocks formed during the waning activity of the Emeishan plume and the basement of the Kangdian Upland exposing older felsic rocks.

Comprehensive research on the concentrations, modes of occurrence, and origin of critical elements in coal is significant from an economic point of view. Several previous investigations have attributed the host of critical elements such as Li, Ga, Nb, Ta, Zr, and Hf in coals to aluminosilicate minerals derived from terrigenous input, while Li of hydrothermal origin has rarely been found in coals. The Late Triassic coal of the Caotang mine, northeastern Sichuan Basin, China of this study is a high-ash, medium-sulfur, low volatile bituminous coal. The dominant minerals in these coals are illite, calcite, kaolinite, and quartz, with minor chlorite, sulfate minerals, paragonite, pyrite, and anatase, along with traces of phosphate minerals. In comparison with the world hard coals and Chinese common coals, the critical element Li is ∼20-times higher in the Caotang coal. The Li concentrations (range 89.1–520 μg/g, 291 μg/g on average) and the abundance of chlorites in coal low-temperature ashes (LTAs) show a strong correlation (r = 0.88), indicating that chlorites are the dominant host of Li in the coal. The chlorite minerals in this study belong to three types: cookeite, chamosite, and a chlorite mineral of intermediate composition between them. Both the kaolinite-cookeite assemblage with a vermicular texture and Li-bearing chlorite occurring as fracture-fills, indicate that they formed by interaction of kaolinite with Li-rich solutions or directly precipitated from Li-bearing solutions during diagenetic or epigenetic processes. Based on geochemical indicators such as Al2O3/TiO2 ratios, rare earth elements and yttrium (REY) distribution patterns, and the relationship between Al2O3/TiO2 and Zr/TiO2 and Nb/Yb ratios, the source-area compositions of Caotang coals are felsic-intermediate igneous rocks from the southeast Qinling thrust system, Longmenshan thrust belt, Hannan Upland, and Micangshan-Dabashan Uplift. The kaolinite-paragonite assemblage with authigenic minerals such as chamosite, anatase, calcite, barite, pyrite, quartz, and REY-rich minerals, as well as the REY enrichment patterns, suggest that the Caotang coals may have been subjected to a multi-stage injection of hydrothermal fluids. The Caotang coal is considered to be a promising source of the critical element Li. Furthermore, the concentrations of the critical elements Ga, Nb, and Ta in the coal increase its potential economic significance even further.

The Qinshui Basin, the largest reservoir of commercial coalbed methane in China, has attracted much attention and several studies have focused on the mineralogy and element geochemistry of coals in this basin. However, the sources of minerals and elements, particularly those of high-ash coals in the northeastern basin were yet unidentified. This study investigated mineralogy and geochemistry of the Pennsylvanian No. 8 Coal (including the roof strata and partings) from the Xinjing mine, northeastern Qinshui Basin, Shanxi Province, China. The Xinjing Coal is a low-ash, medium‑sulfur semi-anthracite. The minerals in the studied coals are mainly represented by kaolinite, illite, calcite, ankerite, siderite, dolomite, and pyrite. The Xinjing Coal is characterized by enriched Li, Zr, and Hg, and slightly enriched F, Ga, Ge, Se, Sr, Mo, Hf, and Pb. The diagrams of Al2O3-TiO2, Zr/TiO2-Nb/Y, as well as the REY (rare earth elements and Y) distribution patterns show that the sediment source region of the studied deposit is represented by the old granitoides, sedimentary rocks and bauxites of the Yinshan Upland located to the north of Qinshui Basin. In this study, three geological factors (sediment source regions, injections of hydrothermal fluids, and seawater) are identified as the dominant influences on geochemical and mineralogical compositions. Elevated concentrations of critical elements such as Li and Ga are dominantly derived from the sediment source region. Authigenic minerals including sulfides, quartz, carbonates, phosphates, and clausthalite, as well as the significant variations of Se-Mo-Pb-Hg assemblage across the coal seam, indicate that the Xinjing coal probably has been subjected to a multi-stage hydrothermal activities. Relatively high total sulfur contents (2.3% on average), framboidal pyrite, Sr/Ba (3.3) and Th/U values (2.2) suggest that seawater is another important geological factor affecting the Xinjing coal.

Research Article| June 01, 2001 Oxygen isotope and trace element zoning in hydrothermal garnets: Windows into large-scale fluid-flow behavior Douglas E. Crowe; Douglas E. Crowe 1Department of Geology, University of Georgia, Athens, Georgia 30602, USA Search for other works by this author on: GSW Google Scholar Lee R. Riciputi; Lee R. Riciputi 2Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6365, USA Search for other works by this author on: GSW Google Scholar Sandra Bezenek; Sandra Bezenek 3Department of Geology, University of Georgia, Athens, Georgia 30602, USA Search for other works by this author on: GSW Google Scholar Alexander Ignatiev Alexander Ignatiev 4Russian Academy of Science, Far East Geological Institute, 159, Prospect 100-letya, Vladivostok 690022, Russia Search for other works by this author on: GSW Google Scholar Geology (2001) 29 (6): 479–482. https://doi.org/10.1130/0091-7613(2001)029<0479:OIATEZ>2.0.CO;2 Article history received: 28 Aug 2000 rev-recd: 05 Feb 2001 accepted: 12 Feb 2001 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Douglas E. Crowe, Lee R. Riciputi, Sandra Bezenek, Alexander Ignatiev; Oxygen isotope and trace element zoning in hydrothermal garnets: Windows into large-scale fluid-flow behavior. Geology 2001;; 29 (6): 479–482. doi: https://doi.org/10.1130/0091-7613(2001)029<0479:OIATEZ>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Single garnet crystals from a large, multicyclic hydrothermal system in Far East Russia are strongly growth zoned. Microscale ion microprobe analysis reveals consistent intracrystalline patterns in oxygen isotope composition and boron and iron contents, reflecting evolution of the hydrothermal system from magmatic- to meteoric-dominated conditions, and repetitive influx of magmatic fluids. Large intracrystalline variations in oxygen isotope composition (>12‰ δ18O) delimit temporal evolution of magmatic and meteoric fluid input within different portions of the hydrothermal system, and suggest that fluid-flow regimes differed between central and distal portions of the system. These results provide compelling evidence that microanalytical data can be extrapolated from intracrystalline scales to study macroscale processes in complex, large-scale fluid-rock systems. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

As a critical element, lithium plays an important role in a wide range of modern industries and in particular, battery storage and new energy technologies. Lithium in coal has attracted much attention in recent years because some coals are highly enriched in this element and consequently their corresponding coal combustion products may provide anm alternative source for this element. Previous studies showed that highly enriched Li in coals is generally associated with chlorite group minerals and in most cases attributed to the action of hydrothermal solutions. This paper provides mineralogical and geochemical data on the No. 9 Coal, the major minable coal from the Antaibao Surface Mine, Ningwu Coalfield, Shanxi Province, northern China, and focuses on the modes of occurrence and source of Li in this coal. The No. 9 Coal is a medium ash, medium sulfur, high volatile bituminous coal. The mineralogy of the No. 9 Coal is dominated by kaolinite, calcite, and pyrite, with minor amounts of anatase, rutile, goyazite, quartz, illite, boehmite, and bassanite, and traces of orthoclase, zircon and galena. The studied coal samples are characterized by high contents of Al2O3 (39.80% on average) in comparison with average Chinese coals, and high concentrations of Li, Ga, Se, Zr, Nb, Ta and Th compared with world hard coals. In addition to Li and Al, the critical elements Nb, Ta, Zr, Hf, and Ga in this coal also have a potential economic significance. The geochemical indicators (high Al2O3/TiO2, low Nb/Yb ratios and the specific rare earth element distribution patterns) and the mineral compositions (e.g., very low content of boehmite) indicate that the mineral matter in most coal benches and host rocks is dominantly derived from the Precambrian calc-alkaline granites of the Yinshan and northern Trans North China Orogens, and possibly from the bauxite of the Benxi Formation. Additionally, the geochemical and mineralogical characteristics of the intra-seam partings and some coal benches (quartz-free, kaolinite-dominated mineralogy, high Al2O3/TiO2 and Nb/Yb values) indicate that they were derived from an alkaline intermediate-felsic volcanic source. The highly enriched Li in the studied samples mainly occurs in kaolinite and is attributed to the input of material from sediment-source regions, rather than hydrothermal fluids. In addition, interaction of terrestrial and marine waters may have promoted the Li enrichment process in the partings.

The Maizuru Belt in southwest Japan and the Khanka Massif in Far East Russia include both Siluro–Devonian and Permo–Triassic granitoids. In order to elucidate the simultaneity of granitoid magmatism in the Maizuru Belt and the Khanka Massif, we investigated zircon U–Pb ages using LA–ICP–MS for granitoid samples from the Maizuru area in the northern zone of the Maizuru Belt and from the Vladivostok area in the southernmost part of the Khanka Massif. Five granitoid samples from the Vladivostok area yielded ages of 422.2 ± 2.5 Ma, 260.7 ± 3.1 Ma, 301.7 ± 2.4 Ma, 249.7 ± 3.5 Ma, and 431.9 ± 2.7 Ma. Additionally, a porphyry sample yielded an age of 423.7 ± 3.2 Ma. Four granitoid samples from the Maizuru area yielded ages of 291.6 ± 4.3 Ma, 443.8 ± 4.1 Ma, 279.7 ± 2.4 Ma, and 259.0 ± 3.0 Ma. In reference to the coexistence of the Triassic sedimentary sequence and Siluro–Devonian and Permo–Triassic granitoids across the Sea of Japan, it seems that there were strong relationships between the northern zone of the Maizuru Belt and the southernmost part of the Khanka Massif. Our data provide additional evidence to support a geological connection between southwest Japan and the Vladivostok area before the Miocene opening of the Sea of Japan.

Determination of the geochemical and mineralogical characteristics of coal can provide useful information on the geological setting and evolution of coal basins and assist in identifying factors that control the distribution of the minerals and elements of interest. The Late Permian coals of southwestern China have received much attention because some of these coals are usually considered to be potential sources of some critical metals and have high concentrations of potentially toxic elements. Mineralogical and geochemical analyses were carried-out on the Late Permian coals from the Kulishu and Sijichun mines of the Zhijin-Nayong Coalfield, Western Guizhou, China. The diagram of Al2O3/TiO2-Nb/Yb shows that the sediment source of the Kulishu and Sijichun coals is dominantly the Emeishan magmatic province with a smaller contribution from a Neoproterozoic metamorphic-granite complex, both of which are the two major components of the Kangdian Upland. The sediment source of the roof and floor rocks is dominantly basaltic volcanics in the Emeishan large igneous province (ELIP), while the partings were probably derived from eruptions of the Emeishan felsic-alkaline magmas and a mixture of ashes derived from a distal volcanic arc. Highly elevated total sulfur contents (dominated by pyritic and organic sulfur), abundant framboidal pyrite, as well as disseminated fine-grained pyrite provide evidence for input of seawater during the peat and coal formation. Paragonite mineralization with enrichment of Li, Nb (Ta), Zr (Hf), REY and Pb in the Sijichun coals and partings of the Kulishu coal are attributed to the intrusion of alkaline magma. The pyrite, quartz, albite, anatase and gypsum occurring as veins-, cleat-fillings and separate well-crystallized aggregates of epigenetic origin in the studied coals are indicative of the influence of hydrothermal fluids from a magmatic source.

Abstract Ophiolites are divided into lherzolite-type (L-type) and harzburgite-type (H-type) by the lithology of their mantle peridotites. Rare depleted harzburgite-type (DH-type) is distinguished from the normal H-type by the more refractory nature of its mantle peridotite and the occurrence of orthopyroxene-type cumulate rocks including iron-rich harzburgite and orthopyroxenite. The Shelting (Sakhalin) and Krasnaya (Koryak Mountains) ophiolites in Far East Russia, which have both depleted harzburgite and orthopyroxene-type cumulate rocks, belong to this newly defined DH-type. The ophiolites in SW Japan-Primorye, NE Japan-Sakhalin, and the Koryak Mountains in the northwestern Pacific margin have diverse ophiolite types ranging from L- to DH-types. The wide petrological diversity, the common occurrence of DH-type, and the presence of thick crustal sections in these ophiolites suggest regionally inhomogeneous, commonly very high degrees of mantle melting over subduction zones, as in the modern Mariana forearc environment. The ophiolites of Japan and Far East Russia range in age from Early Palaeozoic to Cenozoic and are tectonically underlain by younger blueschists and accretionary complexes. The spatial association of these ophiolites with blueschists is analogous to the ophiolite-blueschist assemblages recovered from the Mariana forearc. This association might have formed in a period of non-accretion at an oceanic subduction zone that was followed by voluminous accretion of sediments, facilitating subsequent uplift of the ophiolites and blueschists.

Data are presented on the purity (concentrations of metal oxides), morphology (particle size and shape), specific surface, pore diameter, density, and water solubility of amorphous silicas prepared from rice husk, rice straw, and oat husk. It is shown that rice and oat processing wastes can be used as raw materials for the production of high-purity amorphous silica ranging in particle size from 0.02 to 100 μm.

The uppermost Permian and Lower Triassic are completely exposed in Mt. Pingdingshan and Mt. Ma jiashan , Northwest Chaohu City, Anhui Province, East China, where the Lower Triassic is well developed and composed of the alternations of mudrock and limestone deposited on a deep part of the Lower Yangtze carbonate ramp, containing rich ammonoid fossils. 37 genera and 60 species are recognized from the uppermost Permian and Lower Triassic at the North Pingdingshan Section, West Pingdingshan Section and South Majiashan Section. In addition, many specimens were also collected from the North Majiashan Section and the Guimengguan Section in South Chaohu. A complete Lower Triassic ammonoid zonation can be retrieved in ascending order: Ophiceras Lytophiceras Zone, Gyronites Prionolobus Zone, Flemingites Euflemingites Zone, Anasibirites Zone, Columbites Tirolites Zone and Subcolumbites Zone. The base of the Flemingites Euflemingites Zone is very close to the FAD of conodont Neospathodus waageni at the West Pingdingshan Section, which was proposed as the GSSP of the Induan Olenekian boundary. This paper describes some better preserved ammonoid fossils of biostratigraphic importance with emphasis on those around the Induan Olenekian boundary, plus a few specimens from the uppermost Permian Tapashanites Pleuronodoceras Zone.

Newly obtained precise analytical data on trace elements and radiogenic Sr, Nd, and Pb isotopes testify to anomalous geochemical characteristics of mafic and intermediate Quaternary lavas in Paramushir (in the north of the Kuril arc), Kunashir and Iturup (in the south) islands, which are the largest three islands of the Kuril island arc. The high K and LREE concentrations in the volcanic products in Paramushir Island resulted from the southward expansion of the mantle thermal anomaly of the Kamchatka Peninsula and the involvement of melts related to the melting of oceanic sediments in magma generation. The depleted characteristics of the mafic volcanics are explained by the relatively young tectono-magmatic events during the opening of the Kuril backarc basin. The Kuril island-arc system developed on a heterogeneous basement. The northern islands are a continuation of the volcanic structures of southern Kamchatka, which were formed above an isotopically depleted and hot lithospheric mantle domain of composition close to that of the Pacific MORB type. The southern islands were produced above an isotopically enriched and cold lithospheric domain of the Indian-Ocean MORB type, which was modified in relation to relatively young backarc tectono-magmatic processes. Although issues related to the genesis of the transverse geochemical zoning were beyond the originally formulated scope of our research, the homogeneous enough isotopic composition of the rear-arc lavas in the absence of any mineralogical and geochemical lines of evidence of crustal contamination suggests an independent magmatic source.

The Qinshui Basin is one of the largest coal-bearing basins and the largest reservoir of commercial coalbed methane in China. Recent studies have also reported a potential coal-hosted Li deposit in the Pennsylvanian coal seam of the Jincheng Coalfield, Qinshui Basin. This study further investigates the mineralogy and inorganic geochemistry of the Permian No. 3 coal and associated rocks of the Jincheng Coalfield, to reveal the modes of occurrence and enrichment origins of critical elements including Li, Ga, and rare earth elements and yttrium (REY). The mineralogy of the coal is dominated by two groups of mineral assemblages, kaolinite/NH4/illite/paragonite and ankerite/chamosite/siderite. At least one intra-seam altered volcanic ash layer was identified in the coal seam. The No. 3 coal is highly enriched in Li, with the Li2O content in the coal ashes averaging 0.11 %, which is above the common cut-off grade of 0.1 % Li2O in claystone deposits. The primary host of Li in the coal seam is cookeite, the presence of which is confirmed by ToF-SIMS analysis, which is of hydrothermal origin. Rare earth elements and yttrium are also enriched in the coal (REY oxides average 919 μg/g, ash basis), occurring mainly as phosphate minerals (florencite and crandallite). The concentration of Ga in the coal (58.3 μg/g on average, ash basis) exceeds the suggested cut-off grade in coal (50 ppm, ash-basis), with diaspore and kaolinite being the primary hosts. Diaspore, mainly occurring as fracture infillings, appears to be of late-stage hydrothermal origin. Lithium, Ga, and REY in the No. 3 coal are highly enriched and the coal is a potential source of these critical metals, making it a target for more comprehensive exploration and potential development. The enrichment origin of Li and REY in the Early Permian coal is similar to that in the Pennsylvanian no. 15 coal of the same coalfield, both of which are likely due to hydrothermal fluids originating from magmatic activity during the Yanshanian movement.

A new approach to the use of rice straw as a difficult-to-recycle agricultural waste was proposed. Potassium aluminosilicate was obtained by spark plasma sintering as an effective material for subsequent immobilization of 137Cs into a solid-state matrix. The sorption properties of potassium aluminosilicate to 137Cs from aqueous solutions were studied. The effect of the synthesis temperature on the phase composition, microstructure, and rate of cesium leaching from samples obtained at 800–1000 °C and a pressure of 25 MPa was investigated. It was shown that the positive dynamics of compaction was characteristic of glass ceramics throughout the sintering. Glass ceramics RS-(K,Cs)AlSi3O8 obtained by the SPS method at 1000 °C for 5 min was characterized by a high density of ∼2.62 g/cm3, Vickers hardness ∼ 2.1 GPa, compressive strength ∼231.3 MPa and the rate of cesium ions leaching of ∼1.37 × 10−7 g cm−2·day−1. The proposed approach makes it possible to safe dispose of rice straw and reduce emissions into the atmosphere of microdisperse amorphous silica, which is formed during its combustion and causes respiratory diseases, including cancer. In addition, the obtained is perspective to solve the problem of recycling long-lived 137Cs radionuclides formed during the operation of nuclear power plants into solid-state matrices.