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Astrophyllite–alkali amphibole rhyolite, an evidence of early Permian A-type alkaline volcanism in the western Mongolian Altai

The result's identifiers

  • Result code in IS VaVaI

    <a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00025798%3A_____%2F16%3A00000126" target="_blank" >RIV/00025798:_____/16:00000126 - isvavai.cz</a>

  • Result on the web

    <a href="http://www.jgeosci.org" target="_blank" >http://www.jgeosci.org</a>

  • DOI - Digital Object Identifier

    <a href="http://dx.doi.org/10.3190/jgeosci.205" target="_blank" >10.3190/jgeosci.205</a>

Alternative languages

  • Result language

    angličtina

  • Original language name

    Astrophyllite–alkali amphibole rhyolite, an evidence of early Permian A-type alkaline volcanism in the western Mongolian Altai

  • Original language description

    A dyke of alkali rhyolite intrudes the Tsetseg and Zuun Nuruu volcanosedimentary sequence of Ordovician–Silurian age (Hovd Zone, Central Asian Orogenic Belt) at the Botgon Bag, Mankhan Soum, Hovd District in Western Mongolia. The rock consists of quartz and K-feldspar phenocrysts set in fine-grained groundmass composed of quartz, K-feldspar, albite, blue alkali amphibole (riebeckite–arfvedsonite containing up to 1.94 wt. % ZrO2), tiny brown radial astrophyllite, annite and accessory zircon, ilmenite, fluorite, monazite, hematite, chevkinite and bastnäsite. Astrophyllite has unusual, highly ferroan composition and occurs as two sharply bound zones of astrophyllite I and II with the average empirical formulae: (K1.71 Na0.01Rb0.08Cs0.01) (Na0.93Ca0.07) (Fe2+6.52Mn0.31Zn0.06) (Ti0.84Zr0.50Nb0.55) Si7.68Al0.32 O26 (OH)3.78 F0.66 (astrophyllite I, Zr-Nb-rich); (K1.52Rb0.07) (Na0.81Ca0.19) (Fe2+6.31 Mn0.28Zn0.06) (Ti1.28Nb0.30Zr0.28) Si7.68Al0.32 O26 (OH)2.85 F0.67 (astrophyllite II). Geochemically, the rhyolite corresponds to strongly fractionated silicic alkaline A-type (ferroan) magmatic rock with 75.5–75.9 wt. % SiO2, 4.4 wt. % K2O, 3.9–4.3 wt. % Na2O and 1.98–2.23 wt. % Fe2O3t, poor in CaO (0.26–0.37 wt. %), MgO (0.01–0.11 wt. %), and P2O5 (0.01 wt. %). The rock is enriched in Zr, Nb, Ta, Ga, Sn, Y, Rb, Cs, U and Th, depleted in V, Sr, Ba, Sc, and exhibits a pronounced negative Eu anomaly, (Eu/Eu* = 0.03–0.05). The conventional whole-rock K–Ar geochronology yielded an age of 299.9 ± 9.1 Ma (1σ), which indicates latest Carboniferous or early Permian extension associated with the A-type alkaline volcanic activity.

  • Czech name

  • Czech description

Classification

  • Type

    J<sub>x</sub> - Unclassified - Peer-reviewed scientific article (Jimp, Jsc and Jost)

  • CEP classification

    DB - Geology and mineralogy

  • OECD FORD branch

Result continuities

  • Project

  • Continuities

    V - Vyzkumna aktivita podporovana z jinych verejnych zdroju

Others

  • Publication year

    2016

  • Confidentiality

    S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Data specific for result type

  • Name of the periodical

    Journal of Geosciences

  • ISSN

    1802-6222

  • e-ISSN

  • Volume of the periodical

    61

  • Issue of the periodical within the volume

    jaro

  • Country of publishing house

    CZ - CZECH REPUBLIC

  • Number of pages

    11

  • Pages from-to

    93-103

  • UT code for WoS article

    000372458600006

  • EID of the result in the Scopus database