Nadezhda A. Krivolutskaya

The Amount of Recycled Crust in Sources of Mantle-Derived Melts

One proposed strategy for controlling the transmission of insect-borne pathogens uses a drive mechanism to ensure the rapid spread of transgenes conferring disease refractoriness throughout wild populations. Here, we report the creation of maternal-effect selfish genetic elements in Drosophila that drive population replacement and are resistant to recombination-mediated dissociation of drive and disease refractoriness functions. These selfish elements use microRNA-mediated silencing of a maternally expressed gene essential for embryogenesis, which is coupled with early zygotic expression of a rescuing transgene.The phosphoinositide phosphatase PTEN is mutated in many human cancers. Although the role of PTEN has been studied extensively, the relative contributions of its numerous potential downstream effectors to deregulated growth and tumorigenesis remain uncertain. We provide genetic evidence in Drosophila melanogaster for the paramount importance of the protein kinase Akt [also called protein kinase B (PKB)] in mediating the effects of increased phosphatidylinositol 3,4,5-trisphosphate (PIP3) concentrations that are caused by the loss of PTEN function. A mutation in the pleckstrin homology (PH) domain of Akt that reduces its affinity for PIP3 sufficed to rescue the lethality of flies devoid of PTEN activity. Thus, Akt appears to be the only critical target activated by increased PIP3 concentrations in Drosophila.Using genomic and mass spectrometry-based proteomic methods, we evaluated gene expression, identified key activities, and examined partitioning of metabolic functions in a natural acid mine drainage (AMD) microbial biofilm community. We detected 2033 proteins from the five most abundant species in the biofilm, including 48% of the predicted proteins from the dominant biofilm organism, Leptospirillum group II. Proteins involved in protein refolding and response to oxidative stress appeared to be highly expressed, which suggests that damage to biomolecules is a key challenge for survival. We validated and estimated the relative abundance and cellular localization of 357 unique and 215 conserved novel proteins and determined that one abundant novel protein is a cytochrome central to iron oxidation and AMD formation.

Petrology of the Parental Melts and Mantle Sources of Siberian Trap Magmatism

Based on the investigation of olivine phenocrysts and melt and spinel inclusions in them from the picrites of the Gudchikhinsky Formation and olivine phenocrysts and the whole-rock geochemistry from the Tuklonsky and Nadezhdinsky formations of the Noril’sk region, the compositions and conditions of formation and evolution of the parental melts and mantle sources of Siberian trap magmatism were evaluated. Olivine phenocrysts from the samples studied are enriched in Ni and depleted in Mn compared with olivines equilibrated with the products of peridotite melting, which suggests a considerable role of a nonperidotitic component (olivine-free pyroxenite) in their mantle source. The onset of Siberian trap magmatism (Gudchikhinsky Formation) was related to the melting of pyroxenite produced by the interaction of ancient recycled oceanic crust with mantle peridotite. During the subsequent evolution of the magmatic system (development of the Tuklonsky and Nadezhdinsky formations), the fraction of the pyroxenite component in the source region decreased rapidly (to 40 and 60%, respectively) owing to the entrainment of peridotite material into the melting zone. The formation of magmas was significantly affected by the contamination by continental crustal material. The primitive magmas of the Gudchikhinsky Formation crystallized under near-surface conditions at temperatures of 1250–1170°C and oxygen fugacities 2.5–3.0 orders of magnitude below the Ni-NiO buffer. Simultaneously, the magmas were contaminated by continental silicic rocks and evaporites. The parental magmas of the Gudchikhinsky rocks corresponded to tholeiitic picrites with 11–14 wt % MgO. They were strongly undersaturated in sulfur, contained less than 0.25 wt % water and carbon dioxide, and were chemically similar to the Hawaiian tholeiites. They were produced by melting of a pyroxenite source at depths of 130–180 km in a mantle plume with a potential temperature of 1500–1580°C. The presence of low melting temperature pyroxenite material in the source of Siberian trap magmas promoted the formation of considerable volumes of melt under the thick continental lithosphere, which could trigger its catastrophic collapse. The contribution of pyroxenite-derived melt to the magmas of the Siberian trap province was no less than 40–50%. This component, whose solid residue was free of sulfides and olivine, played a key role in the origin of high contents of Ni, Cu, and Pt-group elements and low sulfur contents in the parental trap magmas and prevented the early dispersion of these elements at the expense of sulfide melt fractionation. The high contents of Cl in the magmas resulted in considerable HCl emission into the atmosphere and could be responsible for the mass extinction at the Paleozoic-Mesozoic boundary.

Geochemical specifics of massifs of the drusite complex in the central Belomorian Mobile Belt: II. Sm-Nd isotopic system of the rocks and the U-Pb isotopic system of zircons

First isotopic-geochemical data were obtained on basite-ultrabasite rocks from the southern Kovdor area that were previously provisionally ascribed to the drusite (coronite) complex based on the occurrence of drusite (coronite) textures. The mineral and whole-rock Sm-Nd isochron age determined for five rock samples from the Sorkajoki and Poioiva massifs and the massif of Elevation 403 m turned out to be close (within the error): 2485 ± 51, 2509 ± 93, and 2517 ± 75 Ma, respectively. The crystallization age was evaluated for the two massifs (Poiojovski and Mount Krutaya Vostochnaya) by the U-Pb system of zircons. Our samples contained both magmatic and xenogenic crustal zircons, whose age was estimated at 2700 Ma. The crystallization age of the massifs themselves (data on the magmatic zircons) is 2410 ± 10 Ma. The undepleted character of the mantle source (ɛNd = +0.9) and the much younger age of the massifs than that of other known manifestations of ultrabasic magmatism in the territory of Karelia and the Kola Peninsula (including the layered pluton classic drusite massifs) suggest that the central part of the Belomorian Mobile Belt hosts one more independent intrusive rock complex, which has never been recognized previously and which is different from typical drusites.

Structure and geochemical characteristics of trap rocks from the Noril’sk Trough, Northwestern Siberian craton

Modern analytical methods (XRF and ICP-MS) were employed for the first time to investigate the geochemical characteristics of rocks from the Noril’sk Trough. It differs from other folded structures of the region in the presence of massifs with high-grade Pt-Cu-Ni ores at relatively high levels in the section of the platform cover, in the middle part of the tuff-lava sequence. This provides an opportunity of directaions of observe geologic relationships between the extrusive and intrusive rocks of the Siberian Traps and more reliably test the possibility of their comagmatic origin, because other intrusions with massive ores occur at a deeper stratigraphic level in the Devonian sequences (Kharaerlakhsky and Talnakhsky massifs in the Kharaerlakhsky Trough). A comparison of the volcanic sections of the Noril’sk Trough and other parts of the region suggests that the tectonic structures were initiated before or simultaneously with trap development. By the example of the sill of the Maslovsky intrusion, it was shown that the ore-bearing gabbro-dolerites were formed in post-Nadezhdinsky time. The geochemical characteristics of the rocks of the Noril’sk 1 and Maslovsky intrusions were compared with those of the supposedly comagmatic rocks of the Gudchikhinsky, Tuklonsky, Nadezhdinsky, and Morongovsky formations. It was found that the Gudchikhinsky picritic basalts show higher Gd/Yb values compared with the picritic gabbro-dolerites (on average, 2.5 and 1.5, respectively) and higher nickel and calcium contents in olivine (0.44 and 0.22 wt % NiO and 0.30 and 0.12 wt % CaO for Fo82, respectively). The high-magnesium rocks of the Tuklonsky Formation are depleted in U and enriched in Eu relative to their intrusive analogues and also differ with respect to NiO and CaO contents in olivine (0.11 and 0.21 wt % NiO and 0.21 and 0.12 wt % CaO for Fo78, respectively). The rocks of the Nadezhdinsky Formation show strongly enriched incompatible trace element patterns, especially for LREE. Although the Morongovsky Formation is geochemically similar to the intrusions of the Noril’sk complex, it shows a lower weighted mean MgO content (6–7 wt % as compared with 11–12 wt % for the gabbro-dolerites). Thus, it was shown by the example of the geologic setting and compositional features of the Maslovsky intrusion that the massifs with high-grade mineralization are not analogues of volcanic complexes, but were produced by an independent magmatic stage.

Geochemical Features of the Drusite Massifs, the Central Part of the Belomorian Mobile Belt: I. Distribution of Major and Trace Elements in the Rocks

The comparative-geochemical study was first conducted for the ultrabasic-basic massifs of the central part of the Belomorian mobile belt, which were previously ascribed to the drusite complex on the basis of the presence of coronal textures. The studied magmatic bodies are geochemically heterogeneous and can be subdivided into three groups: (1) high-Mg rocks (MgO > 20 wt %) with elevated Cr content, enriched trace element patterns, and deep negative Ta-Nb anomaly (Sorkajoki Massif). Intrusions of this group are geochemically close to the layered plutons of Northern and Eastern Karelia (Kivakka, Burakovsky) and to the intrusions of the Kola Peninsula (Monchepluton and others); (2) low-Mg intrusions (MgO < 10 wt %) with elevated contents of Fe, Ti, and P (403-m Height Massif). The rocks composing these intrusions are characterized by subhorizontal trace element patterns and weak Ta-Nb anomaly; (3) intrusions with intermediate MgO contents (10–20 wt %), flat, occasionally depleted REE patterns, and lack of Ta-Nb anomaly (Mt. Grob Tundra). The identified geochemical differences do not depend on the degree of metamorphic transformations, but were presumably caused by differences in phase and chemical composition of parental magmas, as well as by conditions of their crystallization. It was substantiated that ultrabasic-basic massifs presently united into the drusite complex are genetically diverse and acquired similar textural appearance due to regional metamorphism. Thus, the presence of coronal textures is insufficient to ascribe the intrusions to the drusite complex, their mineralogical and geochemical composition should be taken into account.

Inner Structure, Composition, and Genesis of the Chineiskii Anorthosite-Gabbronorite Massif, Northern Transbaikalia

The Chineiskii anorthosite-gabbronorite massif is the most typical layered intrusion in Russia, which is accompanied by large V and Cu deposits. This massif is first considered to be a component of the Proterozoic volcanic-plutonic system of the Kodar-Udokan district, whose largest massifs are Chineiskii and Lukturskii. This system also comprises numerous dikes (including the Main gabbronorite dike at the Udokan deposit, whose thickness reaches 200 m), which are likely the magmatic feeders of ancient volcanism. An intermediate position in the vertical section of the magmatic system is occupied by gabbroids, whose exposures occur in the peripheral part of the Lurbunskii granite massif. The intrusive rocks were proved to be genetically interrelated and show certain similar geochemical features: they bear elevated TiO2 concentrations and have similar trace element patterns and (La/Sm)N and (Gd/Yb)N ratios (1.5–2.3 and 1.87–2.06, respectively). The Chineiskii Massif is thought to have been formed by the successive emplacement of genetically similar basic magmas, which produced four rock groups with fine and coarse layering and cyclicity of variable rank (microrhythms, rhythms, units, and series). The results of cluster analysis indicate that the rocks can be classified into 13 petrochemical types. The phase and chemical characteristics of the parental melts of these compositions were simulated with the use of the COMAGMAT-3.5 computer model, which was also applied to evaluate the composition of the most primitive initial magma of the whole Chineiskii Massif. Our results indicate that the primitive magma was heterogeneous (olivine + plagioclase ± titanomagnetite + melt) at a temperature of approximately 1130°C. The initial melt had a ferrobasaltic composition and was close to saturation with magnetite at ∼NNO ± 0.5

Mantle origin of heavy isotopes of sulfur in ores of the Noril’sk deposits

When solving the problems regarding the forma� tion of sulfide ores at deposits of various genetic types, one of the key factors is the isotopic composition of sulfur. Such an approach implies definition of either the mantle or the crustal source of sulfur. This problem becomes especially topical when considering igneous copper–nickel deposits localized in ultrabasite–basite complexes. The mantle origin of the melts that formed these deposits and the ores proper is usually recog� nized by most geologists and is based mostly on the

The Problem of Subdivision of Volcanic Rocks of the Trappean Formation of the Norilsk Region

The evolution of magmatism within the large trap� pean provinces both in time and in space is one of the most important aspects of their formation on Earth. Reconstruction of the history of the evolution of vol� canism in the Norilsk region is an important task for determination of regularities of the formation of the Siberian province as a whole, since this region differs from its other parts by the higher thickness (up to 3.7 km) and significant diversity of effusive rocks com� posing it, as well as by the presence of unique Pt–Cu– Ni deposits. We obtained principally new data on the structure and composition of some formations in the Norilsk region, which allows us to specify the history of tectonomagmatic evolution of this territory in the Early Triassic. Basalts of the Norilsk region have been studied by many researchers for several decades [2, 3, 7]. The

Geochemical aspects of the assimilation of host rocks by basaltic magmas during the formation of Noril’sk Cu-Ni ores

In models for the genesis of the Noril’sk Pt-Cu-Ni ore deposits, much importance is attached to the processes of assimilation of host rocks by basaltic melts. This idea is based on unusual relations between the silicate and sulfide constituents of this type of ore deposits and also on the heavy sulfur isotopic composition of the sulfide ores. The reason for this unusual composition is thought to be the assimilation of anhydrite from the host rocks. However, no other factors able to influence this process have ever been analyzed in the literature. We were the first to thoroughly analyze the inner structure of contact aureoles of the intrusions hosted in various rocks: the Maslovsky intrusion in Early Triassic basalts of the Ivakinsky and Nadezhdinsky formations and the Talnakh intrusion in Devonian anhydrite-bearing carbonate-terrigenous rocks. The distributions of trace elements, the 87Sr/86Sr isotopic ratio, and Sm and Nd isotopes indicate that host rocks were either not assimilated at all, or their effect is perceptible only within a very narrow (1 m) zone in the eastern apophyse in the southern portion of the Maslovsky intrusion. The Sr, Nd, and particularly, Pb isotopic composition indicate that the anhydrite could not be the source of isotopically heavy sulfur for sulfides at Noril’sk deposits. The ores of the Maslovsky and Talnakh intrusions have similar sulfur isotopic composition of their sulfides (the maximum δ34S values of these sulfides reach +10.8 and +14.2‰, respectively), in spite of the significant differences in the rocks hosting these intrusions. Our newly obtained data indicate that assimilation was insignificant and could not affect the origin of the ores.

Unique zoned olivines from an ultrabasic—Basic massif in the Noril’sk disitrict

The specifics of the morphology, internal structure, and composition of olivine, one of the major rock� forming minerals of ultrabasic and basic rocks, contains valuable information on the conditions of its formation and are widely used in petrology [11, 8, 3, 7, 12]. One of its important characteristics is zoning, which is most pronounced in lunar [8] and Martian [2] meteorites. Olivine exhibits both normal and reverse zoning, with the core–rim difference reaching 25 mol % forsterite. However, this phenomenon is uncommon in the ter� restrial intrusive rocks, because subsolidus diffusion usually “smoothes out” the initial compositional het� erogeneities of the mineral. At present, the available data are reduced to scarce olivine grains with zoned distribution of major (Fe and Mg with Fo gradient of 8–10 mol % [1, 4, 5]) and trace elements Ca, Ni, as well as Al, Cr, and P [4, 9]. Therefore, the find of zoned olivines with the core–rim difference more than 20 mol % Fo in the magmatic rocks of the Noril’sk district is a unique phenomenon not only for this region but also for ultrabasite–basite complexes around the world. The Noril’sk district is located in the NW Siberian trap province. It consists of the rocks of the crystalline basement and platform cover represented by the Early Cambrian–Late Permian terrigenous–carbonate rocks and Early Triassic basalts. Numerous ultrabasite– basite hypabyssal massifs in the forms of chonoliths and bodies of irregular shape are localized among the sedimentary and volcanic rocks of the area. Distinctly differentiated intrusions are combined into the pro� ductive Noril’sk complex, which is characterized by an elevated average weighted MgO content (10–12 wt %) relative to tholeiitic basalts predominant in the section (6–7 wt %). Some of them contain superlarge Pt– Cu–Ni deposits (Talnakh, Oktyabr’skoe, Noril’sk�1), whereas others are either weakly mineralized or bar� ren. Their age relations with volcanic rocks were not established exactly, because in most cases the intru� sions are localized in the underlying sedimentary rocks. One of the representatives of this type of magmatic complexes is the massif studied by us in the eastern part of the area, in the Mikchangda River basin. It is located in the Devonian carbonate–terrigenous rocks