The 40Ar/39Ar method determined the age of sanidine from high-potassium trachyte fragments of pipe fluid-explosive breccia. Fluid-explosive breccia breaks through the basalts of the Early Devonian Kanino-Timan complex. The established age of sanidine is 369.7±4.0 million years. Trachytic magmatism is the final stage of the formation of an alkaline igneous province of potassium specialization in Middle Timan.

Rare-metal and thorium mineralization (uranium pyrochlore, niobaeschynite-(Ce), aeschynite-(Ce), thorite, and thorianite) was studied in the dike complex of fluid-explosive rocks of the Middle Timan. The source of thorium and rare-metal-rare-earth elements was carbonate-alkaline solutions of carbonatites, paragenetically associated with the formation of dike rocks.

The alkaline-carbonate fluid-explosive structure in the Middle Timan includes carbonatites, carbonatized fluidexplosive dikes, and fenitized terrigenous-carbonate rocks of the Riphean. Phosphates, represented by monazite and apatite, are formed in all rocks. The chemical composition of the minerals testifies to the multiphase formation of this structure and a single source of fluids involved in its formation.

Сыктывкарский государственный университет, СыктывкарАннотация.Во флюидно-экспозивных фемических дайках Среднего Тимана, парагенетически связанных с карбонатитовым магматизмом, кристаллизовались бариево

Fluid-explosive rocks of the dike complex are identified in the Middle Timan. The rocks have convergent properties due to a combination of explosive and metasomatic processes. The study of the petrographic features of the rocks revealed their explosive nature. Further study of the chemical composition of rock-forming minerals established the source of the mantle material and the paragenetic relationship with carbonatite magmatism. The fluid-explosive rocks of the dyke complex have a long-term multistage formation history. The fluids caused fenitization of the host strata and its disintegration. Solid-gas material of the mantle-crustal compound fills the cracks. At the last stage of formation of fluid-explosive rocks, the rare-metal, rare-earth, and sulfide mineralization took place.

This work presents the summarization of U–Pb (SIMS, TIMS) zircon dates and petrogeochemical signatures of granitoids of the north of the Urals (Polar, Subpolar, and Northern Urals) obtained over the last decade. Granitе melts were formed from melting of different substrates, highly heterogeneous in composition and age, at all geodynamic stages distinguished in the studied area. Preuralides include island arc–accretionary (735–720 Ma, 670 Ma), collisional (650–520 Ma), and rift-related (520–480 Ma) granitoids. Uralides includes primitive island-arc granitoids (460–429 Ma), mature island-arc granitoids (412–368 Ma), early collisional (360–316 Ma) and late collisional (277–249 Ma) granitoids. As a result, the general trend of variations of oxygen (δ 18 O Zrn , ‰), neodymium (εNd (t)wr ), and hafnium (εHf (t)Zrn ) isotope compositions identified in time. Mantle isotope compositions (δ 18 O Zrn (+5.6), εNd (t)wr (+1.7), εHf (t)Zrn (+8.7...+10.6)), common for island arc granitoids (Preuralides) are changed by crustal–mantle ones (δ 18 O Zrn (+7.2...+8.5), εNd (t)wr (–4.8...+1.8), εHf (t)Zrn (+2.1 to +13)), typical of collisional granites. According to this, the crustal matter played a significant role during the formation of the latter. The crustal-mantle isotope compositions are changed by the mantle ones, characteristic of rift-related (δ 18 O Zrn (+4.7...+7), εNd (t)wr (+0.7...+5.6), εHf (t)Zrn (–2.04...+12.5)) and island-arc (Uralides; δ 18 O Zrn (+4.2...+5.7), εNd (t)wr (+4.1...+7.4), εHf (t)Zrn (+12...+15.2)) granitoids.

Fenitized Precambrian carbonate rocks (Middle Timan) are parent rocks for bauxite — phosphate weathering crusts. Therefore, the mineral composition of fenites, characterized by rich and varied mineralization, is of great interest. Titanium minerals especially attract attention, since their high concentrations are noted in bauxite-phosphate weathering crusts. For example, in the bauxites of the Verkhne-Shchugorsk area, the amount of rutile may reach 6000—7000 g/t. Titanium mineralization is represented by titanite, rutile, anatase, and cassite.

Хромшпинелиды флюидо-эксплозивных даек Среднего ТиманаГолубева И.И. 1 , Мокрушин А.В. 2 , Филиппов В.Н. 1 , Бурцев И

The results of a comprehensive study of a slag-like sideritolite, a representative of a previously unknown genetic type of rock, are summarized. The nano- microstructural features, chemical composition, trace elements, the constitution and the spectroscopic properties of the pore-forming and accessory minerals were investigated. Using the mineralogical and ontogenetic method, the history of rock formation was defined. Penoliths, the slag-like sideritolite, may be identified as a new genetic type of endogenous rocks formed directly in the bubbly foam.

ХРОМШПИНЕЛИДЫ -КАК ИНДИКАТОР ТИПИЗАЦИИ УЛЬТРАМАФИТОВ СПОРНОГО ГЕНЕЗИСАГолубева И.И

ÂâåäåíèåÏîðîäû, ñîäåðaeàùèå óãëåðîäèñòîå âåùåñòâî, â ëþáîé ãåîëîãè÷åñêîé ñèòóàöèè ïðèâëåêàþò íàó÷íûé è ïðà-êòè÷åñêèé èíòåðåñ.Ýòî îáúÿñíÿåòñÿ íåîäíîçíà÷íîé òðàêòîâêîé ïðèðîäû óãëåðîäèñòîãî âåùåñòâà è åãî ñïîñîáíîñòüþ êîíöåíòðèðîâàòü îïðåäåëåííûå ýëåìåíòû.Îáúåêòîì íàøåãî èññëåäîâàíèÿ ïîñëóaeèëè äîêåìáðèéñêèå óãëåðîäèñòûå êâàðöèòû Ïîëÿðíîãî Óðàëà ñ íàäêëàðêîâûì óðîâíåì ôîñôîðà.Ïîðîäû íå áûëè äîñòàòî÷íî õîðîøî èç

Dedicated to V.N. Okhotnikov and L.V. Makhlaev -known researchers of geology of Russian polar areasThe paper presents new data on the petrography and geochemistry of granitic bodies from the north-eastern part of Gerdizsky massif.The genesis of gneissic structure of granites from this massif is still controversial.Researchers assume autochthonous origin by granitisation processes, and others -intrusive genesis.The study of the granite body of north-eastern part of Gerdizsky massif revealed that granites, interpreted as ultrametamorphogenous autochthonous formations, are intrusive A-granites and the characteristic gneissic structure of rocks is formed by tectonic effects.

Совокупность геологических, геохронологических, петрографических и минералого-геохимических данных свидетельствует об участии в образовании бразильских алмазоносных конгломератов эндогенного, предположительно мантийного по происхождению, вещества. Не исключено, что алмазоносные породы из формации Сопа-Брумадиньо в Восточной Бразилии являются не вторичными (коллекторами), как это традиционно считается, а первичными источниками алмазов в современных россыпях, поиски которых ведутся здесь уже около 200 лет. Изучение бразильских, уральских и якутских алмазов подтверждает существование в природе единого бразильско-уральского типа округлых алмазов, характерных для особого флюидизатного типа коренных алмазных месторождений. По данным фотогониометрических исследований устанавливается, что кривогранная форма алмазов является результатом длительного мантийного процесса растворения, сочетающегося с механическим истиранием и химическим травлением, происходящими преимущественно в эндогенных условиях. Впервые получены количественные данные о морфологических различиях округлых алмазов в кимберлитовых и некимберлитовых месторождениях. Результаты спектроскопических исследований указывают на принципиальные особенности бразильских алмазов – очень широкие вариации по параметрам ИК-поглощения, преобладание среди алмазов подтипа IаВ1, высокую степень агрегации структурной примеси азота и, в частности повышенную концентрацию плейтелетс, обогащение водородными центрами и центрами систем Н3 и Н4, часто преобладающими над центрами N3, повышенную (1150–1200°С) температуру и значительную длительность мантийного посткристаллизационного отжига. Вариации спектроскопических свойств свидетельствуют о кристаллизации бразильских алмазов в неустойчивой термодинамической обстановке.

It is established that the meteorite Chelyabinsk LL refers to a group of low-iron olivine ordinary chondrites. The mineral composition of the meteorite is defined moderate-ferrous olivine (Fa24-36), iron-magnesium and calcium pyroxene, anorthoclase, high-chromium Cr-spinels, monosulfide series geksapirrotin-troilite-makkinavit, pentlandite, samorodnometallicheskimi phases (nickel-iron, iron-nikelil, copper), apatite, dolomite hibbingitom. In thermogenic rims installed presumably enstatite glass with inclusions of magnetite. Content was determined in the debris of the meteorite and its carbon isotopic composition.

Data on the age of gneissic granites from the Precambrian Kharbei Complex (Polar Urals) have been obtained for the first time. Local U-Pb dating was carried out using a SHRIMP-II ion microprobe. Zircons were taken from three granitic bodies close in petrographic and petrochemical parameters. The formation of gneissic granites was implemented in two stages: during the Late Ediacarian (556 ± 2.2 Ma) and in the Late Cambrian (497 ± 3 and 487.1 ± 2.1 Ma). The rocks formed owing to rheomorphic flow of granitic material, caused by tectonic events related to Timanian (Baikalian) tectogenesis and epicontinental riftogenesis, which occurred prior to the appearance of the Paleouralian Ocean.