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Permsko-karboński wulkanizm w Sudetach

Awdankiewicz Marek

Przegląd Geologiczny

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2025

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Vol. 73, nr 9

795--803

EN

Post-orogenic, post-collisional, intracontinental Permian-Carboniferous volcanism in the Sudetes, Central Europe, marked the transition from the Variscan Orogeny to the continental rifting in the eastern central Pangea. The volcanic rocks are part of volcano-sedimentary successions found in the Intra-Sudetic and North-Sudetic synclinoria. Between 313-287 Ma and culminating around 299 Ma, magmas originated from subduction-modified mantle sources and evolved in crustal magma chambers yielding rhyolitic ignimbrites and lavas with less widespread rocks of andesitic and trachyandesitic compositions. The older volcanic rocks reveal supra-subduction geochemical characteristics, while the younger ones show more pronounced within-plate signatures. Several tens of volcanic centres formed in the region, including lava fields, shield volcanoes, large rhyolite extrusions, ignimbrite caldera, maars and tuff rings, and numerous laccoliths and sills. Volcanic edifices underwent substantial erosion and supplied volcanogenic detritus into local depositional systems, while the caldera acted as an intrabasinal depositional centre. The volcanic rocks are significantly affected by post-volcanic and, mostly, diagenetic alteration. In recent years the extinct Permian-Carboniferous volcanoes became more widely recognized as regional nature attraction and part of the UNESCO Global Geoparks network.

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A Permian andesitic tuff ring at Rožmitál (the Intra-Sudetic Basin, Czech Republic) : evolution from explosive to effusive and high-level intrusive activity

Awdankiewicz M., Awdankiewicz H., Rapprich V., Stárková M.

Geological Quarterly

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2014

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Vol. 58, No. 4

759–-778

EN

Mafic, monogenetic volcanism is increasingly recognized as a common manifestation of post-collisional volcanism in late Variscan, Permo-Carboniferous intramontane basins of Central Europe. Although identification of individual eruptive centres is not easy in these ancient successions, the Permian Rožmitál andesites in the Intra-Sudetic Basin (NE Bohemian Massif) provide an exceptionally detailed record of explosive, effusive and high-level intrusive activity. Based on field study and petrographic and geochemical data on pyroclastic and coherent rocks, the Rožmitál succession is interpreted as the proximal part of a tuff ring several hundred metres in diameter. Initial accumulation of pyroclastic fall and surge deposits occurred during phreatomagmatic eruptions, with transitions towards Strombolian eruptions. Gullies filled with reworked tephra document periods of erosion and redeposition. Andesitic blocky lavas capped the volcaniclastic succession. Invasion of lavas into unconsolidated sediments and emplacement of shallow-level intrusions in near-vent sections resulted in the formation of jigsaw- and randomly-textured peperites. Most geochemical differences between coherent andesites and pyroclastic rocks can be linked to incorporation of quartz-rich sediments during the explosive eruptive processes and to later cementation of the volcaniclastic deposits by dolomite. The Rožmitál tuff ring could have been one of several phreatomagmatic centres in a monogenetic volcanic field located on an alluvial plain.

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Fractional crystallization, mafic replenishment and assimilation in crustal magma chambers: geochemical constraints from the Permian post-collisional intermediate-composition volcanic suite of the North-Sudetic Basin (SW Poland)

Awdankiewicz M.

Geologia Sudetica

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2006

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Vol. 38

39-61

EN

The Permian intermediate-composition lavas of the North-Sudetic Basin represent a high-K calc-alkaline suite emplaced in an extensional, intracontinental, post-collisional setting in the eastern part of the European Variscan belt. The lavas, in a total volume of over 100 km3, erupted from fissure vents or small shield-type volcanoes in several episodes separated by repose and sedimentation periods. An idealised eruptive episode comprised basaltic trachyandesites (plagioclase- phyric, clinopyroxene lavas) followed by predominant, main-series basaltic andesites (weakly porphyrytic, two-pyroxene microcrystalline lavas) and evolved basaltic andesites (weakly porphyrytic, two-pyroxene fine-grained lavas). This volcanic suite originated in magmatic systems where differentiation processes evolved with time from (I) fractional crystallization, producing the basaltic trachyandesites, through (II) fractional crystallization coupled with mafic replenishment, resulting in the main series basaltic andesite lavas, to (III) fractional crystallization, mafic replenishment and minor crustal contamination, producing the evolved basaltic andesites. The fractionating mineral assemblages changed during the successive stages and, apart from plagioclase, olivine, clinopyroxene and Fe-Ti oxides, included ortho- pyroxene (stage II and III) and apatite with zircon (stage III). The general trace element characteristics of the volcanic rocks (enrichment in Th, LILE, Nb and Zr, but with high Th/Nb and La/Nb ratios) are transitional between those of extension-related within-plate lavas and active continental margin lavas. These characteristics are inherited from enriched lithospheric mantle sources carrying a crustal signature related to subduction processes during the earlier stages of the Variscan orogeny.