Research subject. The composition, properties, and connection of the lattice defects in the disordered s tructure of quartz with the conditions of its formation. Materials and methods. The quartz of the gold deposits of the Darasun ore field – Darasun, Teremkinskoye, and Talatuy – were studied. For the purpose of comparative analysis, gold-ore quartz from the deposits of Northern Kazakhstan was used. Registration of centers in quartz samples was carried out by the EPR method. When interpreting the obtained results, genetic information consisting in the distribution of substitutional Ge and Ti impurities in quartz was used. Results. Two groups of paramagnetic centers were identified in the quartz under study. One of them is associated with substitutional Al, Ti, and Ge impurities in quartz zones with an ordered crystal structure, while the other is associated with the lattice defects localized in the disordered crystal structure of quartz. The latter group includes several types of E'-centers formed in quartz glass and Al-X-centers caused by Al3+ ions associated with oxygen vacancies. In the case of stable thermodynamic conditions of mineral formation, a linear relationship was established between the concentrations of Al-X-centers (CAl-X) and E'-centers (CEs). Under a change in thermodynamic conditions, a deviation of the points from the CEs(CAl-X) dependence was observed. Conclusions. The type of CEs(CAl-X) dependence is determined by the thermodynamic conditions of mineral formation and can be used to identify cases of non-equilibrium solidification of quartz.

The distributions of trace elements in pyrite were studied in samples of high-grade gold ores from the Talatui, Teremkyn, and Darasun deposits. The paper presents LA-ICP-MS data on concentrations of trace elements in pyrite in gold ores from mineral deposits of the Darasun goldfield, which were produced by a single fluid–magmatic system at various temperatures. The high-temperature pyrite was found to be enriched in Co, Se, and W, whereas the medium-temperature pyrite was enriched in Cu, Zn, Ag, Te, As, and In. The behaviors of some elements (Ni, Au, Bi, Sb, and Pb) seem to be independent of temperature. The identified trends and relations in the behaviors of elements can be used in studying the Au-Bi mineralization of the intrusion-related type.

Research subject. The distribution regularities of Al and Li impurities in gold-ore quartz. Materials and methods. The quartz of the Darasun, Teremkinskoye and Talatuy gold deposits of the Darasun ore field was studied. The gross contents of Al and Li impurities in quartz were determined by the LA-ICP-MS method; substitutional Al impurity concentrations were studied by the EPR method. The forms of Al impurity in quartz were determined based on the results of studying its behavior during material recrystallization. The genetic significance of Al and Li impurities in quartz was estimated taking into account the genetic information obtained during the study of the distribution of substitutional Al and Ti impurity concentrations. Results. It was found that Al is present in quartz in two main forms, i. e., as a substitutional Al impurity and Al complexes localized in the areas of high mineral defectiveness. Li+ ions are located in the structural channels of the mineral, serving as compensating ions for both Al impurity forms. The composition of Al complexes is assumed to include three Al 3+ ions and one H + or Li + ion. Two stages of quartz recrystallization occurring at different temperatures of mineral formation were identified. The first, low-temperature stage leads to quartz enrichment with substitutional Al impurities. The second, high-temperature stage causes the decomposition of Al complexes. The recrystallization stages can be identified by the type of relationship between the gross concentrations of Al and Li. The increased content of Al impurity in ore quartz was found to be related to the presence of a large number of Al complexes. An assumption is made that these complexes formed during mineral crystallization from solutions with a high content of metal ions. Conclusions. The results obtained indicate that high Al impurity concentrations can serve as a genetic sign of ore quartz. At the same time, the decomposition of Al complexes during quartz recrystallization should be taken into account. A method for estimating the initial concentration of Al complexes is proposed, which is a more reliable genetic indicator.

Quartz samples taken from the ore veins of the Darasun gold deposit (Eastern Transbaikalia, Russia) were studied using electron paramagnetic resonance (EPR) and laser ablation (LA) methods. The purpose of the research was to clarify the behavior of the Al impurity during quartz crystallization and its subsequent recrystallization. The results of the research were used to determine the genetic informativeness of the Al impurities concentration in ore quartz. A separate study of the regularities of the distribution of Al impurity in the regions of crystalline structure and in the zones of crystal lattice distortions was carried out. In the regions of crystalline structure, the Al impurity concentration NAL was determined by the concentration of paramagnetic Al–O–-centers associated with the presence of substitutional Al3+ ions. The content of the Al impurity in the zones of crystal lattice distortions was judged by the difference between the gross concentrations of aluminum CAl and the values of NAL. It was taken into account that the intensity and direction of the studied processes can be influenced by the temperature of quartz formation and the degree of its recrystallization. The temperature of quartz formation was estimated by the values of Ti impurity concentration, and the degree of recrystallization was estimated by the content of Li impurity CLi in the mineral. It was found that the amount of Al impurity localized in the zones of crystal lattice distortions is an order of magnitude higher than that present in the zones of crystalline structure. It is shown that this phenomenon is explained by the high ability of the zones of crystal lattice distortions to capture of Al impurity during quartz crystallization. The amount of Al impurity trapped by quartz increases sharply with an increase in the temperature of the mineral formation. In areas of regions of crystalline structure, a different picture is observed − impurity capture during crystallization proceeds with low intensity and is not so critically dependent on temperature. It was found that the Al impurity in the considered zones behaves differently during quartz recrystallization. If Al impurity capture continues in the regions of crystalline structure, then Al impurity removal from quartz can occur in the zones of crystal lattice distortions at high CAl values. Based on the data obtained, the areas of use of aluminum impurity contents as a typomorphic feature of ore quartz were determined. The Al impurity concentrations proved to be suitable for use in cases of low ore formation temperatures, and its gross CAl contents have the prospect of wider use. It is noted that a characteristic feature for quartz from high productivity zones is a negative angle of slope of the CAl(CLi) dependence plot.

Gold concentration in natural pyrite from the high-grade sulfide ores of the Darasun gold district and pyrite synthesized from the solution saturated in gold has been studied using laser ablation inductively coupled plasma mass-spectrometry. Parameters and composition of the solution from which pyrite was grown were chosen according to the data obtained in the study of the natural pyrite formation. The experiments were carried out at 350°С/1000 bar and 490°С/1000 bar with synthetic troilite FeS or hydrotroilite FeOHHS as a precursor. Concentration of NaCl was 0, 15, and 35 wt

Методом электронного парамагнитного резонанса исследовано распределение изоморфных примесей Al, Ti и Ge в образцах кварца из месторождений золота Дарасун, Теремкинское и Талатуй, входящих в состав Дарасунского рудного поля. На основе изучения кварца методами оптической и растровой электронной микроскопии рассмотрена связь изоморфизма с процессами динамической рекристаллизации минерала. Показано, что анализ графиков зависимостей между концентрациями разных изоморфных примесей (изоген) в кварце позволяет проследить закономерности развития изоморфизма. Обнаружены две стадии изоморфизма, одна из которых связана с кристаллизацией минерала, а вторая – с его последующей динамической рекристаллизацией. На первой стадии наблюдается вхождение примеси Al в кристаллическую структуру кварца, а на второй – примеси Ti. Примесь Ge играет роль катализатора изоморфизма, и ее концентрации варьируют в широких пределах. Отмечается, что вторая стадия играет решающую роль, поскольку с ней связано образование основной части изоморфных примесей. Ее реализация осуществляется благодаря динамической рекристаллизации кварца. На Дарасунском рудном поле обнаружено 4 генетические группы кварца, описываемые индивидуальными изогенами. Две из них отвечают кварцу, образованному из флюида магматического происхождения или переотложенного с его участием, а две другие группы – кварцу, возникшему в среде измененного флюида. Показано, что при переотложении кварца в нем сохраняется концентрация изоморфного Al, но резко уменьшается содержание структурного Ti. Рассмотрены процессы минералообразования на каждом золоторудном месторождении. На месторождении Дарасун установлены две температурные зональности – прямая и обратная. Каждая из них характеризуется своей генетической группой кварца и степенью закрытости системы минералообразования. На месторождениях Дарасун и Талатуй обнаружены генетически близкие образцы магматогенного кварца, что указывает на единство процесса минералообразования на Дарасунском рудном поле. Выявленные закономерности изоморфизма в кварце могут быть использованы при изучении рудообразования на месторождениях золота и других полезных ископаемых. Ключевые слова: месторождения Дарасун, Теремкинское и Талатуй Дарасунского рудного поля, минералообразование, золоторудный кварц, динамическая рекристаллизация, изоморфные примеси, генетический анализ, изогены, стадии изоморфизма, переотложение кварца, температурная зональность, метод ЭПР, растровая электронная микроскопия.

The composition and diffusion mobility of the compensating ions in the quartz structural channels of the gold fields in the Darasun, Teremkinskoye, and Talatuy gold fields of the Darasun ore field were examined using the electron paramagnetic resonance method. The assessment of the properties and peculiarities of the ion distribution in quartz was based on their ability to participate in the neutralization of the electric charges of the structural defects occurring in the minerals. In this regard, the ion composition was evaluated by the ratio of the concentrations of the Ti-centers using various compensators. Their mobility was determined by the center formation rate during the quartz radiation exposure. The research demonstrated the availability of two major compensating ions, H+ and Li+, in the quartz structural channels of the gold fields in the Darasun ore field. The diffusion mobility of the H+ ions in the channels was observed to be 1–2 orders of magnitude higher than that of Li+. The correlation link between the compensating ions in the mineral and fluid compositions was not obtained based on the data analysis. A difference was identified between the ratio of the H+ and Li+ concentrations in the quartz structural channels of different fields. Further, the highest concentration of H+ ions and the lowest concentration of Li+ ions were recorded for the quartz in the Darasun field; the inverse correlation was observed for the quartz in the Talatuy field, which can be attributed to the mixing of the fluid gas component during the ore formation process. The electron paramagnetic resonance method can be used for the quantitative assessment of the degree of quartz dynamic recrystallization.

The distribution of substitutional Al, Ti, and Ge impurities in quartz samples from the Darasun, Teremkinskoe and Talatui gold deposits, located in the Darasun orefield, were studied using the electron paramagnetic resonance method. Relationship between the isomorphic substitution and the dynamic recrystallization of quartz was studied by optical and scanning electron microscopy. Analysis of the plots of interdependency between the concentrations of various substitutional impurities in quartz (isogens) provided an opportunity to detect isomorphic substitution development trends. Two isomorphic substitution stages were recognized, one associated with mineral crystallization and the other, with its subsequent dynamic recrystallization. The first stage leads to Al impurity incorporation into the quartz crystal lattice, and the second, to Ti impurity incorporation. The Ge impurity is the isomorphic substitution catalyst, and its concentrations vary widely. It is noted that the second stage plays a decisive role, because it accounts for the incorporation of the larger part of substitutional impurities. This process is facilitated by the dynamic recrystallization of quartz. Four quartz genetic groups, which are described by individual isogens, have been recognized in the Darasun orefield. Two of them correspond to the quartz crystallized from a magmatogenic fluid directly or redeposited with its participation, and the other two correspond to the quartz crystallized from an altered fluid. The facts that substitutional Al concentrations are retained in quartz after redeposition, whereas substitutional Ti impurity concentrations fall dramatically, are demonstrated. Mineral formation processes at each gold deposit are discussed. Two types of temperature zoning, the normal and the reverse, have been recognized at the Darasun deposit. Each zoning is characterized by an individual quartz genetic group and the extent of mineralization system closedness. The genetically similar magmatogenic quartz samples found at the Darasun and Talatui deposits attest to the uniformity of mineralization process in the Darasun orefield. The established trends of isomorphic substitution in quartz are applicable in the studies of ore formation histories of gold and other ore deposits. Keywords: Darasun; Teremkinskoe; and Talatui deposits of the Darasun orefield; mineral formation; auriferous quartz; dynamic recrystallization; substitutional impurities; genetic analysis; isogens; isomorphic substitution stages; quartz redeposition; temperature zoning; EPR method; scanning electron microscopy

This article presents the new mineralogical, fluid inclusion, and isotopic data for ores of the Novoshirokinsky base metal–gold deposit. Mineralogical sequence is supplemented and specified. The mineral assemblages containing native gold are studied. Morphology, grain size and chemical composition of native gold are described. Major parameters and composition of mineralizing fluids of the main ore stages at the deposit are estimated: main base metal (mid-temperature conditions, fluid salinity 3.1–13.1 wt % equiv NaCl) and carbonate–base metal (low-temperature conditions, fluid salinity 1.0–12.9 wt % equiv. NaCl). Sulfur isotopic composition of sulfides from commercial mineral assemblages has been studied. The δ 34 S value (+10.5 ± 1‰) of mineralizing fluid has been calculated. The Novoshirokinsky deposit is similar to epithermal deposits and is spatially related to the Late Jurassic porphyry system. Evidence is provided on carbonate rocks of basement involved in the ore-forming process.

Bosiite, NaFe33+(Al4Mg2)(Si6O18)(BO3)(3)(OH)(3)O, is a new mineral species of the tourmaline supergroup from the Darasun gold deposit (Darasun mine), Vershino-Darasunskiy, Transbaikal Krai, Eastern-Siberian Region, Russia (52 degrees 20'24 '' N, 115 degrees 29'23 '' E). Bosiite formed as a hydrothermal phase in a gold-bearing quartz-vein spatially related to the Amudzhikan-Sretensky subvolcanic K-rich granodiorite-porphyry intrusion. Ores of this deposit are enriched in sulfides (up to 60%). Bosiite is intimately associated with other tourmalines. The first tourmaline generation is bosiite, which is followed by a second generation of oxy-dravite and a third generation of dravite. Bosiite also coexists with quartz and pyrite; further associated minerals in the vein are gangue minerals (quartz, calcite, and dolomite), sulfides (pyrite, arsenopyrite, chalcopyrite, pyrrhotite, tetrahedrite, sphalerite, and galena) and native gold. Crystals of bosiite are dark brown to black with a pale-brown streak. Bosiite is brittle and has a Mohs hardness of 7; it is non-fluorescent, has no observable parting and cleavage. It has a measured density of 3.23(3) g/cm(3) (by pycnometry) and a calculated density of 3.26(1) g/cm(3). In plane polarized light, it is pleochroic, O = yellow-brown, E = red-brown. Bosiite is uniaxial negative, omega = 1.760(5), epsilon = 1.687(5). The mineral is trigonal, space group R3m, a = 16.101(3), c = 7.327(2) angstrom, V = 1645.0(6) angstrom(3). The eight strongest X-ray diffraction lines in the (calculated) powder pattern [d in angstrom(1)hkl] are: 2.606(100)(50-1), 8.051(58)(100), 3.008(58)(3-1-2), 4.025(57)(4-20), 3.543(50)(10-2), 4.279(46) (3-11), 2.068(45)(6-1-2), 4.648(28)(300). Analysis by a combination of electron microprobe (EMPA), inductively coupled plasma mass spectrometry (ICP-MS), Mossbauer spectroscopic data and crystal-structure refinement results in the empirical structural formula:(X)(Na0.73Ca0.23 square(0.04))(Sigma 1.00)(Y)(Fe1.473+Mg0.80Fe0.592+Al0.13Ti0.014+)(Sigma 3.00)(Z)(Al3.23Fe1.883+Mg0.89)(Sigma 6.00)(T)(Si5.92Al0.08O18)(Sigma 6.00)(BO3)(3)(V)(OH)(3)(W)[O-0.85(OH)(0.15)](Sigma 1.00)According to the IMA-CNMNC guidelines, the dominant valence at the Y site is Fe3+ and the dominant cation is Fe3+. To accommodate the disorder and allocating cations to the Z and Y sites, the recommended procedure leads to the optimized empirical formula (based on 31 O): (X)(Na0.73Ca0.23 square(0.04))(Y)(Fe2.403+Fe0.592+Ti0.014+)(Z)(Al3.36Mg1.69Fe0.953+)(T)(Si5.92Al0.08O18)(BO3)(3)(V)(OH)(3)(W)[O-0.85(OH)(0.15)] Bosiite, ideally NaFe33+(Al4Mg2)(Si6O18)(BO3)(3)(OH)(3)O, is related to end-member povondraite, ideally NaFe33+(Fe43+Mg2)(Si6O18)(BO3)(3)(OH)(3)O, by the substitution Al-Z(4) -> Fe-Z(4)3+. Further, bosiite is related to oxy-dravite, ideally Na(Al2Mg)(Al5Mg)(Si6O18)(BO3)(3)(OH)(3)O, by the substitutions Fe-[6](3)3+ -> Al-[6](3).Bosiite is named after Dr. Ferdinando Bosi, researcher at the University of Rome La Sapienza, Italy, and an expert on the crystallography and mineralogy of the tourmaline-supergroup minerals and the spinels.

We studied the mineralogic and geochemical features of metasomatic rocks and ores from the Pogromnoe gold deposit, which is unconventional for Transbaikalia. The deposit, which formed in the Early Cretaceous, at the rifting stage of the regional evolution, is localized in the dynamoclastic strata of the Mongol-Okhotsk suture, along which the Siberian continent joined the Mongolia-China continent in the Early-Middle Jurassic. Gold mineralization occurs as two morphologic types of ores: stockwork quartz-carbonate-arsenopyrite-pyrite ores in altered volcanics (orebody no. 1) and veinlet-vein quartz ones (with disseminated sulfides) in altered carbonaceous shales (orebody no. 10). The host rocks of the deposit are the highly altered volcanosedimentary rocks of the Butorovskii Formation (Shadoron Group, J(2-3)), which transformed into metasomatic (by composition) and dynamoclastic (by texture and structure) rocks. It has been found that the formation of the metasomatic rocks and mineralization proceeded in several stages. Propylites formed at the preore stage (J(3)); tectonic schists and albitophyres, at the late preore stage; and sericitolites and albite-carbonate-sericite-quartz metasomatic rocks (quartzites), at the synore stage. The Ar-40/Ar-39 age of the stockwork system of ore-bearing fractures and metasomatic rocks which formed at the late preore stage is estimated as 139.5 +/- 1.8 Ma. The gold-bearing rocks at the deposit are the late preore and synore metasomatic rocks formed after volcanics with sulfide mineralization (gold concentrators are pyrite II and III and arsenopyrite I and II) and after altered carbonaceous shales (gold concentrators are vein quartz and arsenopyrite II). Gold grade is completely consistent with silicification, saturation with quartz-sulfide and sulfide microveinlets, and fine sulfide dissemination. By genesis, the Pogromnoe deposit belongs to objects which formed in shear zones with the contribution of gold-bearing mantle fluids. The authors presume that the sources of mineralization are the ore-producing granitoids of the Amudzhikan-Sretensk intrusive assemblage within the Aprelkovo ore-magmatic system (OMS) (Os'kina and Urguchan plutons). This is confirmed by Pb isotope compositions (Pb-207/Pb-204 and Pb-206/Pb-204) for the pyrite and arsenopyrite of the Pogromnoe gold-bearing ores, which testify to the widespread occurrence of "mantle" Pb isotope signatures. The Ar-40/Ar-39 age of the ore-producing granitoids of the Aprelkovo OMS is 131.0 +/- 1.2 Ma. Gold in the orebodies occurs in native form and is fine and very fine. By gold grade, the Pogromnoe deposit deserves very close attention as a new commercial type of gold mineralization in Transbaikalia. (C) 2015, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

Дарасунское золоторудное поле, расположенное в южной части Западно-Станового террейна вблизи Монголо-Охотского сутурного шва, включает месторождения коренного золота Дарасун (более 100 т Au), а также Талатуй (около 38.2 т Au) и Теремкинское (3 т Au). Rb-Sr и K-Ar методами датированы гранодиорит-порфиры амуджиканского комплекса, с которыми, согласно данным многих исследователей, пространственно и парагенетически связано месторождение Дарасун и метасоматиты (“березиты”). Rb-Sr методом анализировались валовые пробы гранодиорит-порфиров, мономинеральные фракции плагиоклаза, калишпата и биотита, а также серицит из березитов (всего 26 проб). K-Ar методом датированы 8 проб биотита и серицита. Минеральные Rb-Sr изохроны, полученные по индивидуальным пробам гранодиорит-порфиров, выявляют неоднородность начального изотопного отношения 87Sr/86Sr, которое варьирует в пределах 0.70560–0.70591. Хорошо согласующиеся данные обоих методов позволяют принять значения возраста гранодиорит-порфиров и березитов соответственно 160.5 ± 0.4 и 159.6 ± 1.5 млн лет. Датировка гранодиорит-порфиров амуджиканского комплекса 160.5 ± 0.4 млн лет отвечает границе нижней и поздней юры. Эта дата маркирует время завершения коллизии Восточно-Сибирского и Монголо-Китайского континентов и связанной с ней орогении и отмечает вступление территории Восточного Забайкалья в посторогенный (внутриплитный) этап развития, с которым связано образование значительных по масштабу месторождений золота, урана и других металлов.

When prospecting ore deposits in Trans-Baikal region the endogenous geochemical fields (EGF) are taken as the main search element, as was proposed by L.V. Tauson (1983). Such fields are classified into: geochemical fields of dispersion (GFD), concentration (GFC) and removal (GFR). With regard to their formation conditions they are subdivided into magmatic (associated with magmatic chambers), intratelluric (associated with activity of intratelluric emanations), hydrothermal-metamorphic (vadose-thermal solutions), metamorphogenic, and sedimentary-metamorphogenic ones. Magmatic EGFs are divided into three groups: magmatic, pneumatolytic, and hydrothermal stages. This study identified their polygenetic origin and association with ore-magmatic systems. The geochemical fields of ore zones, fields, and deposits result from the late and post-magmatic processes; they also include the EGF of host rocks and those which altered at pre-ore stage of the natural system development.At ore deposits the EGFs are responsible for supply and redistribution of elements through the entire ore formation process. The fields were divided into EGF of poor concentration (contrast coefficient CC normalized after background to 10), mean (CC > 10-100), and intense (CC >> 100). The EGF intensity progressively increases at the hierarchy stage: "host rock-pre-ore metasomatite-syn-ore hydrothermalite-ore body-ore pillar".To summarize, the fields, ore districts, zones, and deposits are characterized by diverse patterns of dispersion, concentration, and removal.The specific features of composition, structure, and zonal distribution of elements in geochemical fields are exemplified by some gold-bearing zones of the Trans-Baikal region. The paper reports new approaches to investigating these natural formations. The authors promote transition from the generally accepted evaluation of a halo separation to the volumetric survey of endogenous geochemical fields (GFD, GFC, and GFR included) of ore deposits and ore-magmatic systems, in general. The acquired evidence supports the assumption that endogenous geochemical fields should be regarded as a complete system differentiated in space and time preserving specifics and pattern of the internal structure. (C) 2014, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

The Darasun ore field situated in the southern West Stanovoi Terrane near the Mongolia-Okhotsk Suture comprises the Darasun (>100 t Au), Talatui (∼38.2 t Au), and Teremki (3 t Au) lode gold deposits. In the opinion of many researchers, the Darasun deposit is spatially and paragenetically linked to granodiorite porphyry of the Amudzhikan Complex and related metasomatic rocks (beresites). Whole-rock samples of granodiorite porphyry, monomineralic fractions of plagioclase, K-feldspar, and biotite, as well as sericite from beresite (26 samples in total), were analyzed by the Rb-Sr method. Eight biotite and sericite samples were analyzed by the K-Ar method. The Rb-Sr mineral isochrons obtained for individual granodiorite porphyry samples yielded initial 87Sr/86Sr ratios varying from 0.70560 to 0.70591. The consistent results of both methods allowed us to accept the ages of granodiorite porphyry and beresite as 160.5 ± 0.4 and 159.6 ± 1.5 Ma, respectively. The age of granodiorite porphyry of the Amudzhikan Complex of 160.5 ± 0.4 Ma corresponds to the boundary between the Early and Middle Jurassic and marks the completion of collision between the East Siberian and Mongolia-China continents and related orogeny. Since that time, the eastern Transbaikal region has been involved in the postorogenic (within-plate) stage of evolution, characterized by the formation of large gold, uranium, and other ore deposits.