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2 Acta Geologica Polonica

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Kozłowski Andrzej, Matyszczak Witold

Acta Geologica Polonica

2022

Vol. 72, no. 1

9--31

Fluorite mineralization was studied in the Variscan granitoid Karkonosze pluton in the northern part of the Bohemian massif (Lower Silesia, Poland). Fluid inclusions in fluorite and quartz were investigated by the following methods: heating and freezing on an immersion microscope stage, spectrophotometric and electron probe analysis, calcination and water leachate. The parent fluids of fluorite were of the Na-Ca-Cl type with a low CO₂ content. The fluoride ions had sources in the pluton and in its host rocks. Fluid inclusion observations provide evidence of various post-formation alteration. such as refilling, partition, cracking, migration, expulsion or vacuole modification from irregular to cubic habit. A final model of fluorite origin and parent fluid evolution is presented.

Th-U-total Pb timing constraints on the emplacement of the granitoid pluton of Stolpen, Germany

Lisowiec K., Budzyń B., Słaby E., Schulz B., Renno A. D.

Acta Geologica Polonica

2014

Vol. 64, no. 4

457--472

Monazite from the Stolpen monzogranite (SE Germany) was studied to constrain the Th-U-total Pb age of pluton formation. Monazite grains demonstrate subtle to distinct patchy zoning related to slight compositional variations. Textural and compositional characteristics indicate that the monazite formed in a single magmatic event in a slightly heterogeneous system, and was only weakly affected by secondary alteration, which did not disturb the Th-U-Pb system. Chemical dating of the monazite gave a consistent age of 299 ± 1.7 Ma. The current study presents the first geochronological data for the Stolpen granite. It provides evidence that Stolpen is the youngest Variscan granitic intrusion in the Lusatian Granodiorite Complex and indicates that magmatic activity related to post-collisional extension in this region lasted at least 5my longer than previously assumed.