Niemcza diorites and moznodiorites (Sudetes, SW Poland): a record of changing geotectonic setting at ca. 340 Ma

Granites sensu lato in the Sudetes intruded in several episodes during the Variscan orogeny recording different stages of crust and mantle evolution. Correlating precise ages with geochemistry of the Variscan granites provides information on the evolution of these sources within the Variscan orogen. The Variscan intrusive rocks from the Niemcza Zone (Bohemian Massif, Sudetes, SW Poland) include undeformed dioritic to syenitic rocks and magmatically foliated granodiorites. In this study we analysed low SiO2 (48–53 wt.%) monzodioritic rocks from Przedborowa and Koźmice. The monzodiorites contain late-magmatic zircons with ages of 341.8 ± 1.9 Ma for Przedborowa and 335.6 ± 2.3 Ma for Koźmice, interpreted as emplacement ages of the dioritic magmas. Older Przedborowa rocks are lower in K, Mg, Rb and Ni than the Koźmice rocks and similar compositional trend is also observed in the Central Bohemian Plutonic Complex. The implication is that the mantle underlying the Niemcza Zone became more enriched from ca. 342 to ca. 336 Ma, probably following the collision of the Saxothuringian and Moldanubian/Lugian domains. The magmatism related to the collision occurred ca. 12 Ma later than that in the Central Bohemian Plutonic Complex, but was accompanied by a similar change in magma chemistry from high-K (Przedborowa) to shoshonitic (Koźmice, Kośmin enclaves) and probably to ultrapotassic (Wilków Wielki)

Contrasting sources of Late Paleozoic rhyolite magma in the Polish Lowlands:evidence from U–Pb ages and Hf and O isotope composition in zircon

International audienceThe Polish Lowlands, located southwest of the Teisseyre–Tornquist Zone, within Trans-European Suture Zone, were affected by bimodal, but dominantly rhyolitic, magmatism during the Late Paleozoic. Thanks to the inherited zircon they contain, these rhyolitic rocks provide a direct source of information about the pre-Permian rocks underlying the Polish Lowland. This paper presents zircon U–Pb geochronology and Hf and O isotopic results from five drill core samples representing four rhyolites and one granite. Based on the ratio of inherited vs. autocrystic zircon, the rhyolites can be divided into two groups: northern rhyolites, where autocrystic zircon is more abundant and southern rhyolites, where inherited zircon dominates. We suggest that the magma sources and the processes responsible for generating high silica magmas differ between the northern and southern rhyolites. Isotopically distinct sources were available during formation of northern rhyolites, as the Hf and O isotopes in magmatic zircon differ between the two analysed localities of northern rhyolites. A mixing between magmas formed from Baltica-derived mudstone–siltstone sediments and Avalonian basement or mantle can explain the diversity between the zircon compositions from the northern localities Daszewo and Wysoka Kamieńska. Conversely, the southern rhyolites from our two localities contain zircon with similar compositions, and these units can be further correlated with results from the North East German Basin, suggesting uniform source rocks over this larger region. Based on the ages of inherited zircon and the isotopic composition of magmatic ones, we suggest that the dominant source of the southern rhyolites is Variscan foreland sediments mixed with Baltica/Avalonia-derived sediments

Provenance and paleoenvironmental context of the Late Pleistocene thin aeolian silt mantles in southwestern Poland – A widespread parent material for soils

Thin loess deposits are widespread soil parent materials and important archives for paleoenvironmental reconstruction. The origin of loess in SW Poland is attributed to the Great Odra Valley (GOV), following the general concept that large rivers play a major role in regional silt supply. Yet, the precise provenance (glacier sources and/or local rocks) of silts, possibly deflated from dry GOV braided riverbeds, is not clear. Our study of thin and thick loess mantles in SW Poland for the first time indicates the provenance of thin loess based on mineralogical (MLA-SEM) and isotopic analyses (143Nd/144Nd, 87Sr/86Sr). Luminescence ages of five localities point to thin loess mantle formation during and shortly (23.0 to 17.7 ka yr) after the Last Glacial Maximum (LGM). Our isotopic data indicate that thin loess deposits in SW Poland are the mixtures of two main components – local Sudetic and Scandinavian, the latter delivered by the Fennoscandian ice sheet (FIS). Also, detailed analyses of heavy minerals show that a single mineral (e.g., hornblende) may come from both Sudetic and Scandinavian sources. This research highlights the role of the (Pleistocene) GOV in collecting and homogenizing materials, while supplying the region with fine particles to be deflated by paleowinds from open surfaces. Anomalies in mineralogy and isotopic composition are connected with influence of Sudetic mountain rivers and locally blowing silt material by katabatic winds. Regional grain size differentiation of thin loess mantles explains transport distance and altitude. © 2021 The Author

Dating zircon from the Gęsiniec Intrusion by LA-ICPMS Laser Ablation — Inductively Coupled Plasma Mass Spectrometry

New U-Pb ages for zircon from the dominating quartz diorite type in the Gęsiniec Intrusion were obtained using LA ICPMS laser ablation inductively coupled plasma mass spectrometry. The concordant age for a tight population of 11 grains is 294.1 ± 2.0 Ma, which is similar to the other ages of this intrusion reported in literature.Nowe datowania U-Pb dla cyrkonu z dominującego typu diorytu kwarcowego występującego w intruzji Gęsinica zostały uzyskane za pomocą LA ICPMS ablacji laserowej sprzężonej ze spektrometrem mas z jonizacją w plazmie indukcyjnie sprzężonej. Konkordantny wiek został uzyskany dla 11 ziarn i wynosi 294.1 ± 2.0 milionów lat i tym samym jest podobny do innych wieków tej intruzji opublikowanych w literaturze naukowej.New U-Pb ages for zircon from the dominating quartz diorite type in the Gęsiniec Intrusion were obtained using LA ICPMS laser ablation inductively coupled plasma mass spectrometry. The concordant age for a tight population of 11 grains is 294.1 ± 2.0 Ma, which is similar to the other ages of this intrusion reported in literature.Nowe datowania U-Pb dla cyrkonu z dominującego typu diorytu kwarcowego występującego w intruzji Gęsinica zostały uzyskane za pomocą LA ICPMS ablacji laserowej sprzężonej ze spektrometrem mas z jonizacją w plazmie indukcyjnie sprzężonej. Konkordantny wiek został uzyskany dla 11 ziarn i wynosi 294.1 ± 2.0 milionów lat i tym samym jest podobny do innych wieków tej intruzji opublikowanych w literaturze naukowej

Editors' foreword

Editor's forewor

Evaluation of the development of mineralogical sciences in Poland in the first decades of the 21st century

The Mineralogical Sciences Committee of the Polish Academy of Sciences and Polish Mineralogical Society analysed the scientific output and achievements of Polish geochemists, mineralogists, and petrologists (collectively termed mineral scientists)between 2012 and 2021. In Poland, there are 212 researchers who declare themselves as mineral scientists. According to SciVal analyses they published 2530 articles between 2012 and2021 in 829 topic clusters. Mineralogical investigations in Poland have become increasingly interdisciplinary. Polish mineral scientists have changed their way of doing research from single-authorship to ever increasing national and international collaboration involving large research groups. Unlike during the previously evaluated period between 1995 and 2011, Polish mineral scientists have increasingly contributed to solving major problems of mineral and environmental sciences. There has been increasing involvement of young researchers in achievements of Polish mineral scientists

Plagioclase transfer from a host granodiorite to mafic microgranular enclaves: diverse records of magma mixing

Chemical and structural zoning in plagioclase can develop in response to a number of different magmatic processes. We examine plagioclase zonation formed during the transfer of plagioclase from a granodioritic host to a monzodioritic enclave to understand the development of different zonation patterns caused by this relatively simple magma mixing process. The transferred plagioclase records two stages of evolution: crystallization of oscillatory plagioclase in the host granodioritic magma and crystallization of high An zones and low An rims in the hybrid enclave magma. High An zones (up to An72) are formed only in the hybrid enclaves after plagioclase transfer. Plagioclase from a primitive enclave, showing no or only minimal interaction with the host, is An30–43. The implication is that high An zones crystallize only from the hybrid magma and not from the primitive one, probably because of an increase in water content in the hybrid magma. Complex interactions between the two magmas are also recorded in Sr content in plagioclase, which indicates an initial increase in Sr concentration in the melt upon transfer. This is contrary to what is expected from the mixing of low Sr enclave magma with a high Sr granodiorite one. Such Sr distribution in the plagioclase implies that the transfer of the plagioclase took place before the onset of plagioclase crystallization in the enclave magma. Therefore, the mixing between high Sr granodiorite magma and low Sr enclave magma was recorded only in plagioclase rims and not in the high An zones