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Magmatic episodes in the Holy Cross Mountains, Poland – a new contribution from multi-age zircon populations

Krzemińska Ewa, Krzemiński Leszek

Biuletyn Państwowego Instytutu Geologicznego

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2019

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nr 474

43--57

EN

This contribution reports on new U-Pb zircon age data from magmatic rocks from the Holy Cross Mountains (HCM) of Poland. The analyzed samples were taken from lamprophyre and diabase veins of Podkranów and Janowice-2 as well as from tuff horizon of Kielce Beds (Ludlow). Internal morphologies have been investigated by SEM-BSE and cathodoluminescence images and they have been used as a guide for the selection of genetically various type of grains, e.g. potential auto-, ante- and xenocrysts, that were analyzed by ion microprobe. The U-Pb age of the magmatic events at 414.2 ±6.6 Ma (Kielce tuff), 322 ±12 Ma (Podkranów, lamprophyre), and 300±10 Ma (Janowice-2, diabase) confirmed the time frame of known magmatic activity reported within the HCM, as determined by 40Ar/39Ar geochronology in previous studies. The zircon investigation revealed also multiple populations with record of an earlier pulse of magma system (antecrysts), as well as abundant xenocrysts.

PL

W artykule przedstawiono nowe oznaczenia wieku U-Pb cyrkonu w skałach magmowych z obszaru Gór Świętokrzyskich (HCM). Próbki pobrano z żył lamprofiru i diabazu z Podkranowa i Janowic-2 oraz z poziomu tufu w warstwach kieleckich (ludlow). Morfologię i wewnętrzne cechy budowy ziaren zbadano za pomocą obrazów SEM-BSE i katodoluminescencji SEM, stosując je jako przewodnik do selekcji genetycznie różnych typów ziaren, potencjalnych auto-, ante- i ksenokryształów, które były analizowane na mikrosondzie jonowej. Wiek U-Pb epizodów magmowych, 414,2 ±6,6 Ma (Kielce, tuf), 322 ±12 Ma (Podkranów, lamprofir) i 300 ±10 Ma (Janowice-2, diabaz), potwierdza znane z wcześniejszych publikacji ramy czasowe aktywności magmowej na obszarze HCM oznaczone metodą 40Ar/39Ar. Badania wieku U-Pb cyrkonu ujawniły także szereg populacji z zapisem wcześniejszych impulsów magmowych (antekryształy) i licznych ksenokryształów.

2

Petrological implications of the Early Mesozoic lamprophyre dikes and related Tarkhata syenites (SE Altai and NW Mongolia)

Vasyukova E. A., Borisenko A. S.

Mineralogia

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2013

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Vol. 44, iss. 1/2

13--30

EN

This paper presents new data derived from field sampling and from a thorough description of lamprophyres located in southeastern Altai and northwestern Mongolia in terms of their mineralogy, textures, and chemical composition. The swarms of alkaline mafic dikes in the area coexist with granosyenite-monzodiorite and gabbro-dolerite intrusions and spatially coincide with an ore district of Sb-Hg, Ag-Sb, Ni-Co-As, Cu-Mo-W, and CaF2 hydrothermal mineralization. All lamprophyres belong to the Early Mesozoic Chuya complex formed in an intracontinental enviroment. Their distribution and orientation is controlled by two large fault zones. The Chuya dikes were investigated at two localities, namely, Yustyd and South-Chuya. The Yustyd lamprophyres intrude Middle-Upper Devonian black shale of the Yustyd depression. At South Chuya, lamprophyres, together with the Tarkhata granosyenite-monzodiorite complex, are hosted by Cambrian and Ordovician metamorphic rocks of the South-Chuya Range. Ar-Ar (phlogopite) and U-Pb (SHRIMP, zircon) ages of the lamprophyre dikes indicate long and continuous period of the formation of the Chuya complex (250-235 Ma). Major- and trace-element compositions of the lamprophyres from both localities and of the syenite indicate their origin from the same magma source. The textures and structures of the lamprophyre and plutonic rocks, their mineral assemblages and the chemistry of the rock-forming minerals provide clues to the evolution of the parental alkaline mafic magma and fluid regime.

3

Potassium-rich dyke rock of Rogówek (Sudetes, Poland)

Wierzchołowski B.

Archiwum Mineralogiczne

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2001

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T. 54

77-97

EN

Vogesites, microsyenites and alkaline microsyenites have been found to occur within the Kłodzko – Złoty Stok granitoid massif. Trace elements identified in these rocks have been used to construct spider diagrams. In vogesites, metamorphic and mag-matic amphiboles have been identified, the co-occurrence of which suggests that these rocks have been formed due to mechanical and chemical contamination of syenitic mag-ma with material rich in metamorphic amphiboles. In the Rogówek dyke rocks, the am-phiboles crystallized from melt represent winchite, richterite and magnesio-arfvedsonite in composition. Geochemical data suggest that this magma was generated in within-plate continental environment.