Kukisvumchorr Deposit: Mineralogy of Alkaline Pegmatites and Hydrothermalites.: By Igor V. Pekov and Alexander S. Podlesnyi. Association Ecost and Ocean Pictures Limited, Moscow (Russia) and Denver (Colorado), 2004 (translated from Russian). 168 pages, softbound, US$45. ISBN 5-900395-53-7. Available from Terry Huizing, 5341 Thrasher Drive, Cincinnati, Ohio 45247, U.S.A. (http://webcenter.ru/ minbooks).
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The word “KUKISVUMCHORR”, written across the cover, reads like a magic spell. I know I would want to pull this book off a stand and peek inside at least to learn the story behind the title. Actually, this thirteen-letter loan from Lapp translates roughly as “Long Wooded Range”, and the bookKeywords:
Pegmatite
Gabal El Urf region is located in the northern Egyptian Eastern Desert and overlain essentially by older and younger granitoids of Late Proterozoic age. These granitoids contain numerous outcrops of pegmatites, mostly occurring as dikes and veins or huge separated masses. In the contrary, pegmatites form lens-like bodies enclosed within the younger granites along their margins. Previous radiometric surveys showed anomalous concentrations of radioactivity on pegmatite body, located to the south of the study region. The younger granites and the associated radioactive pegmatite are studied in details with the aim to describe this pegmatite, petrogenesis and its relation with the encolsing granite. The younger granites are monzogranite and syenogranite according to mineralogical and chemical classification. Petrographically, the two younger granitic phases are strikingly similar. Both consist of potash feldspar, plagioclase and biotite with some hornblende in the earlier phase. Gabal El Urf younger granites are categorized as highly fractionated I-type granites with metaluminous to mildly peraluminous characters, which emplaced at 600 ± 11 Ma in post-collisional environment. The radioactive pegmatite is located within the syenogranite and enriched with Zr, Nb, Ta, Y, Th, U and REEs; accordingly it was classified as NYF-type rare-elements pegmatite. Metal-bearing generations of minerals within the rare-elements pegmatite include zircon, uranothorite, betafite, aeschynite, fluorite, pyrite and ilmenite.
Pegmatite
Leucogranite
Petrogenesis
Hornblende
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Pegmatite
Muscovite
Orthoclase
Petrogenesis
Spodumene
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The Dahongliutan rare-metal pegmatite deposit, associated with the pegmatite dikes hosted by Dahongliutan pluton and metasedimentary rocks, is a new discovered Li–Be deposit in the the West Kunlun orogen, Northwest China. The Dahongliutan pegmatite is a classic and typical example of a highly fractionated Li-Ce-Ta (LCT) type pegmatite, with distinct regional zonation composed of well-developed garnet-tourmaline-microcline (GTM), beryl-tourmaline-muscovite (BTM) and spodumene-albite (SA) pegmatites from the barren core inward to outer zone. Detailed field studies, together with B-isotope studies of tourmaline and the chemistry of feldspar, muscovite and tourmaline, were undertaken to investigate the differentiation processes in a pegmatite magma and the different mineralizing episodes of the Dahongliutan rare-metal pegmatite deposit. Alkali metal fractionation trends (Rb, Cs and K/Rb) in the pegmatitic K-feldspar and muscovite define a primitive to evolved magmatic evolution. From low to high degrees of evolution, the mineralization stages of Dahongliutan pegmatite field are metal barren in centre, Be-rich in the intermediate and Li-rich in the outer zone. Furthermore, besides the magmatic tourmaline in the GTM pegmatite dikes, the fine-grained euhedral magmatic BTM-I type and subhedral to anhedral coarse-grained magmatic-hydrothermal BTM-II type in the BTM pegmatite dikes have been identified. The average δ11B values of the magmatic tourmalines in the GTM-type is −8.82, BTM-I type is −8.53‰, and BTM-II type is −7.85‰. Combined with petrography and chemical data, we suggest that the Dahongliutan pegmatite dikes were derived from metasedimentary source within the continental crust and the BTM-II type tourmaline is correlated with separation of an immiscible B-rich fluid during the magmatic-hydrothermal evolution. Consequently, highly fractional crystallization, albite alteration and liquid immiscibility were the main factors controlling the spatial and temporal decoupling of rare element mineralization in the Dahongliutan pegmatite deposit.
Pegmatite
Tourmaline
Dike
Muscovite
Spodumene
Igneous differentiation
Cassiterite
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Pegmatite
Petrogenesis
Geochronology
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Pegmatite
Cassiterite
Muscovite
Dike
Columbite
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Pegmatite
Petrogenesis
Geochronology
Igneous differentiation
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The Jiajika Li-Be Polymetallic District is located in the Songpan-Ganze Orogenic Belt, Southwestern China. The Li-Be mineralization is genetically, temporally, and spatially, related to pegmatites in the Jiajika District. Hundreds of pegmatite dikes were emplaced surrounding the adjacent Majingzi granite pluton. Drill core samples from the 3,200 m deep scientific drilling project (JSD-1) were acquired to determine the vertical extent and the petrogenesis and metallogeny of the granites, and the pegmatites, respectively, and to obtain a better understanding of their genetic relationship. The vertical zonation of the pegmatites from shallow to deep is as follows: shallow albite pegmatites; albite-microcline pegmatites; microcline pegmatites; and deeper more albite pegmatites. Spodumene occurs mainly in the shallow albite pegmatites (55–105 m), and disseminated beryl, columbite-tantalite, and cassiterite, mainly occur in pegmatites at depths less than 700 m. Eight samples were selected for monazite U-Pb geochronology and trace element geochemistry from pegmatites and granites at different depths. LA-ICPMS monazite U-Pb geochronology for the pegmatites indicate two episodes of magmatic activity; one at 210–205 Ma (2σ, 523–2,568 m depth) and another at 193–192 Ma (2σ, 3,170–3,211 m depth). The crystallization age of the older pegmatites is in good agreement with the monazite U-Pb geochronology of the adjacent Majingzi granite (209–205 Ma) within analytical uncertainty, indicating their close temporal relationship. The younger albite pegmatite (193–192 Ma) is associated with the columbite-tantalite Nb-Ta rare-metal mineralization. Compared to those in the deep pegmatites (excluding the younger albite pegmatite in 3,170–3,211 m depth), and the adjacent granites, monazites in the shallow pegmatites and the adjacent granites are relatively enriched in Li, Th, and U, indicating the continuous evolution of a felsic magmatic system; with the residual melt more enriched in various incompatible rare metal elements. Hence, the monazite U-Pb geochronology and trace element geochemistry indicate that a highly evolved felsic magma plays an important role in the petrogenesis of the Jiajika Li-Be pegmatites.
Pegmatite
Geochronology
Leucogranite
Columbite
Microcline
Cassiterite
Dike
Metallogeny
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Paragenetic sequences observed in ore-bearing and barren pegmatites associated with alkalic ultramafic rocks are described. The Afrikanda massif is located in the western part of the Kola peninsula and is represented by nepheline pyroxenite. In its central part are ore-bearing pegmatites containing concentrations of titanomagnetite, knopite, schorlomite garnet, nepheline, pyroxene, and phlogopite. Processes of replacement are described and a comparison is made of geochemical features of these pegmatites as compared to granitic pegmatites, nepheline syenite pegmatites, and gabbroic pegmatites. --M. Russell.
Pegmatite
Massif
Nepheline
Nepheline syenite
Ultramafic rock
Pyroxene
Kola peninsula
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