MINERALOGICAL AND GEOCHEMICAL FEATURES OF APATITE-FLUORITE ROCKS OF THE BURPALA MASSIF IN THE NORTHERN BAIKAL REGION

The Burpala massif located in the Northern Baikal region contains ore-bearing pegmatites, carbonatites and apatite-fluorite rocks with Zr-Nb-REE-rare-metal mineralization. Considering their petrological, geochemical, geological and thermobarochemical features, it was established that apatite-fluorite rocks were formed from a residual fluid melt containing minor CO2, increased P2O5 and F. Apatite-fluorite rocks of the Burpala massif are similar to the foscorite formations of most carbonatite complexes distinguished by the presence of fluorite.The mineral composition of these rocks was for the first time studied in details. In addition to apatite and fluorite, the following minerals are present: zircon, baddeleyite, barite-celeistine, barite, thorianite, ilmenite, magnetite, hematite, biotite, potassium feldspar, pyroxene, as well as rare minerals with high Ta, Nb and Pb content

SOURCES AND MECHANISMS OF FORMATION OF ALKALINE RARE-METAL GRANITES AT THE ZASHIKHINSKY MASSIF BASED ON GEOCHEMICAL AND Nd ISOTOPE DATA

The intraplate alkaline-granite magmatism essentially contributes to formation of rare-metal strategic raw materials. In the Major Sayan Fault of the East Sayan Mountains, the rocks of the Zashikhinsky (Pz3) massif were studied through the isotope-geochemical analysis to identify probable sources of alkaline-granite magma and mechanisms of their evolution resulting in ore accumulations, up to the formation of Nb-Ta deposits. The Nd isotopic characteristics of its alkaline granites were obtained for the first time. Together with the results of mineralogical and geochemical studies, they were applied for modeling its formation, in which crystallization differentiation of alkaline granite melts proceeds simultaneously with their assimilation of the enclosing granite-metamorphic formations

МИНЕРАЛОГО-ГЕОХИМИЧЕСКИЕ ОСОБЕННОСТИ АПАТИТ-ФЛЮОРИТОВЫХ ПОРОД БУРПАЛИНСКОГО МАССИВА (СЕВЕРНОЕ ПРИБАЙКАЛЬЕ)

The Burpala massif located in the Northern Baikal region contains ore-bearing pegmatites, carbonatites and apatite-fluorite rocks with Zr-Nb-REE-rare-metal mineralization. Considering their petrological, geochemical, geological and thermobarochemical features, it was established that apatite-fluorite rocks were formed from a residual fluid melt containing minor CO2, increased P2O5 and F. Apatite-fluorite rocks of the Burpala massif are similar to the foscorite formations of most carbonatite complexes distinguished by the presence of fluorite.The mineral composition of these rocks was for the first time studied in details. In addition to apatite and fluorite, the following minerals are present: zircon, baddeleyite, barite-celeistine, barite, thorianite, ilmenite, magnetite, hematite, biotite, potassium feldspar, pyroxene, as well as rare minerals with high Ta, Nb and Pb content.Бурпалинский массив, расположенный в Северном Прибайкалье, содержит рудоносные пегматиты, карбонатиты и апатит-флюоритовые породы с Zr-Nb-REE-редкометалльной минерализацией. В результате изучения петролого-геохимических, геологических и термобарохимических особенностей апатит-флюоритовых пород установлено, что они образовались из остаточного флюид-расплава, который содержал незначительное количество СО2 и повышенное – Р2О5 и F. Апатит-флюоритовые породы Бурпалинского массива во многом аналогичны фоскоритам большинства карбонатитовых комплексов и отличаются присутствием флюорита.Впервые был детально изучен минеральный состав данных пород. Установлено, что, кроме апатита и флюорита, в них содержатся следующие минералы: щелочной пироксен, биотит, калиевый полевой шпат, титаномагнетит, ильменит, бадделеит, циркон, торианит, а также редкие минералы с высоким содержанием Ta, Nb, Pb

ИСТОЧНИКИ И МЕХАНИЗМЫ ФОРМИРОВАНИЯ ЩЕЛОЧНЫХ РЕДКОМЕТАЛЛЬНЫХ ГРАНИТОВ ЗАШИХИНСКОГО МАССИВА НА ОСНОВЕ ГЕОХИМИЧЕСКИХ И Nd ИЗОТОПНЫХ ДАННЫХ

The intraplate alkaline-granite magmatism essentially contributes to formation of rare-metal strategic raw materials. In the Major Sayan Fault of the East Sayan Mountains, the rocks of the Zashikhinsky (Pz3) massif were studied through the isotope-geochemical analysis to identify probable sources of alkaline-granite magma and mechanisms of their evolution resulting in ore accumulations, up to the formation of Nb-Ta deposits. The Nd isotopic characteristics of its alkaline granites were obtained for the first time. Together with the results of mineralogical and geochemical studies, they were applied for modeling its formation, in which crystallization differentiation of alkaline granite melts proceeds simultaneously with their assimilation of the enclosing granite-metamorphic formations.При формировании месторождений редкометалльного стратегического сырья значимая роль принадлежит проявлениям внутриплитового щелочно-гранитного магматизма. С целью изучения вероятных источников щелочно-гранитных магм и механизмов их эволюции, приводящих к рудным накоплениям, вплоть до образования Nb-Ta месторождений, было проведено изотопно-геохимическое изучение пород Зашихинского массива (Восточно-Саянская зона, Главный Cаянский разлом). Впервые получены Nd изотопные характеристики щелочных гранитов массива, которые в совокупности с результатами проведенных ранее минералогических и геохимических исследований позволили предложить модель его формирования, в которой кристаллизационная дифференциация щелочно-гранитных расплавов происходит одновременно с ассимиляцией ими вмещающих гранитных и гранитно-метаморфических комплексов

Reconstruction of mantle sections beneath Yakutian kimberlite pipes using monomineral thermobarometry

<p>Four original monomineral methods for mantle peridotite associations are used to reconstruct <em>P</em>–<em>T</em> conditions beneath the kimberlite pipes of Yakutia. The clinopyroxene Jd–Di method gives the closest coincidence with Opx barometry in accord with all physico-chemical boundaries. Garnet thermometers calibrated using Opx, Gar–Cpx and Ni-garnet thermometers and two variants of barometers were developed separately for pyroxenites and peridotites. A Cr–Sp thermobarometer uses the monomineralic version of the Ol–Sp thermometer and a newly calibrated Cr–Sp barometer. A picroilmenite method uses the Ol–Sp thermometer and a pressure-calibration of the geikielite component. Each mantle column is divided into two (upper and lower) sections by a pyroxenite layer located near 40 kbar. Below the pyroxenite layer, the lower section comprises 3–4 lithologically distinct horizons, with a thermally perturbed layer at the base. Above the pyroxenite layer are 3–5 lithologically distinct horizons, which are more fertile than the lower sections. Splitting of the geotherms characterizes most <em>P</em>–<em>T</em> diagrams and is ascribed to multistage melt percolation processes typical for the mantle beneath kimberlite pipes. The largest pipes are diamond-bearing and have a highly depleted peridotite lens above the asthenospheric layer. </p

Immunopathogenic and Antibacterial Effects of H3N2 Influenza A Virus PB1-F2 Map to Amino Acid Residues 62, 75, 79, and 82▿

The influenza A virus protein PB1-F2 has been linked to the pathogenesis of both primary viral and secondary bacterial infections. H3N2 viruses have historically expressed full-length PB1-F2 proteins with either proinflammatory (e.g., from influenza A/Hong Kong/1/1968 virus) or noninflammatory (e.g., from influenza A/Wuhan/359/1995 virus) properties. Using synthetic peptides derived from the active C-terminal portion of the PB1-F2 protein from those two viruses, we mapped the proinflammatory domain to amino acid residues L62, R75, R79, and L82 and then determined the role of that domain in H3N2 influenza virus pathogenicity. PB1-F2-derived peptides containing that proinflammatory motif caused significant morbidity, mortality, and pulmonary inflammation in mice, manifesting as increased acute lung injury and the presence of proinflammatory cytokines and inflammatory cells in the lungs compared to peptides lacking this motif, and better supported bacterial infection with Streptococcus pneumoniae. Infections of mice with an otherwise isogenic virus engineered to contain this proinflammatory sequence in PB1-F2 demonstrated increased morbidity resulting from primary viral infections and enhanced development of secondary bacterial pneumonia. The presence of the PB1-F2 noninflammatory (P62, H75, Q79, and S82) sequence in the wild-type virus mediated an antibacterial effect. These data suggest that loss of the inflammatory PB1-F2 phenotype that supports bacterial superinfection during adaptation of H3N2 viruses to humans, coupled with acquisition of antibacterial activity, contributes to the relatively diminished frequency of severe infections seen with seasonal H3N2 influenza viruses in recent decades compared to their first 2 decades of circulation