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Rock textures and mineral zoning – A clue to understanding rare-metal granite evolution: Argemela stock, Central-Eastern Portugal

The result's identifiers

  • Result code in IS VaVaI

    <a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985831%3A_____%2F22%3A00550728" target="_blank" >RIV/67985831:_____/22:00550728 - isvavai.cz</a>

  • Alternative codes found

    RIV/00216305:26310/22:PU147188

  • Result on the web

    <a href="https://www.sciencedirect.com/science/article/pii/S0024493721006058" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0024493721006058</a>

  • DOI - Digital Object Identifier

    <a href="http://dx.doi.org/10.1016/j.lithos.2021.106562" target="_blank" >10.1016/j.lithos.2021.106562</a>

Alternative languages

  • Result language

    angličtina

  • Original language name

    Rock textures and mineral zoning – A clue to understanding rare-metal granite evolution: Argemela stock, Central-Eastern Portugal

  • Original language description

    The small leucocratic strongly peraluminous P, F, Li-rich granitic system at Argemela, central-eastern Portugal, is an ideal object for the study of relations between chemical composition of granitic rocks, rock-forming minerals androck and mineral textures, and the associated Sn, Ta and W mineralization. To define the rock and mineral composition and to formulate an evolutionary model, traditional methods of bulk-rock chemical analyses, and EMPA and LA ICP-MS analyses of rock-forming minerals were combined with the study of macrotextures, TIMAautomated mineralogical mapping of typical rock samples, and CL study of internal texture of quartz and mica crystals. The Argemela stock forms a steep cylindrical body 1 km deep, with an elliptical outcrop 250 × 180 m in size, crosscutting Cambrian schists. The stock comprises two intrusions: a geochemically moderately evolved equigranular facies (0.3 wt% F, 1.2 wt% P2O5, 1850 ppm Li, 310 ppm Sn, 24 ppm Ta, 5 ppm W) composed of albite, quartz, muscovite and minor montebrasite followed by a rather inhomogeneous, more evolved porphyritic facies (0.25–1.2 wt% F, 1.3–1.8 wt% P2O5, 1600–4900 ppm Li, 600–1000 ppm Sn, 40–85 ppm Ta, 3–6 ppm W) composed of quartz, mica and subordinate K-feldspar phenocrysts embedded in an albite-quartz-mica-amblygonite matrix. The later facies is rimmed by stockscheider at the contact with slates, and with an up to 1 m thick layered zone with unidirectional solidification textures along contact with the equigranullar facies. The NE-part of the stock is crosscut by numerous thin quartz veinlets ±K-feldspar, phosphates and wolframite, while several aplitic dikes and thicker quartz+phosphate veins were found in two boreholes NW of the granite. Porphyritic facies, the most voluminous part of the system, contains strongly zoned phenocrysts of mica (phengite→lepidolite) and quartz (Tienriched to Al, Rb-enriched) indicating crystallization in two magmatic stages, while the equigranular facies and extragranitic aplitic dikes crystallized in one magmatic stage only. Hydrothermal muscovite enriched in Sn and Ta forms late overgrowths on some mica flakes in the porphyritic facies and in aplitic dikes. Based on a combination of chemical and textural observations, a four-stage evolutionary model of the Argemela stock was formulated: (i) an early magmatic stage comprises intrusion and in situ crystallization of aplitic dikes and the equigranular facies, and crystallization of quartz and mica cores in the deeper reservoir prior to intrusion of the porphyritic facies, (ii) in the late magmatic stage, crystal mush + evolved residual melt from the reservoir intruded upwards crystallizing the porphyritic facies including the stockscheider and layered zone. A small part of evolved melt formed rounded enclaves crystallizing as a phenocrysts-free ball facies. (iii) In the early (high-temperature) hydrothermal stage, magmatic fluid caused weak pervasive muscovitization of the porphyritic facies and aplitic dikes accompanied by the crystallization of disseminated cassiterite and columbite. After the transition from ductile to brittle deformation, quartz veinlets also developed, mainly in the NE part of the body. (iv) In the late, low-temperature stage, schistderived fluid enriched in Ca, Sr and Ba caused local alteration of granite, forming crandallite–goyazite–gorceixite solid solution.

  • Czech name

  • Czech description

Classification

  • Type

    J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database

  • CEP classification

  • OECD FORD branch

    10504 - Mineralogy

Result continuities

  • Project

    <a href="/en/project/GA19-05198S" target="_blank" >GA19-05198S: Greisenization and albitization - geological processes potentially concentrating some critical raw materials for modern technologies</a><br>

  • Continuities

    P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Others

  • Publication year

    2022

  • Confidentiality

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

Data specific for result type

  • Name of the periodical

    Lithos

  • ISSN

    0024-4937

  • e-ISSN

    1872-6143

  • Volume of the periodical

    410-411

  • Issue of the periodical within the volume

    February

  • Country of publishing house

    NL - THE KINGDOM OF THE NETHERLANDS

  • Number of pages

    25

  • Pages from-to

    106562

  • UT code for WoS article

    000762448200002

  • EID of the result in the Scopus database

    2-s2.0-85121650151