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

Stopování alpské mědi-analýzy depotu měděných ingotů z pozdní doby bronzové z Jižních Čech

We present the results of a complex archaeometric study of Late Bronze Age copper ingots from the Stare Hodejovice hoard (South Bohemia). In order to understand the origin of the copper and describe the metallurgical process, we use modern analytical methods (metallography analyses, major/trace element and lead isotope analyses) to describe the samples. Within this study, a representative dataset of trace element composition and lead isotope ratios of non-alloyed and non-recycled corpus of copper ingots from the Late Bronze Age was created. We assume that most of the ingots were not altered by alloying, mixing or recycling. Based on lead isotope ratios and major/trace element composition, we suppose that the origin of the copper could be mostly Alpine ores from the Trentino and Mitterberg regions and possibly the Valais region. By this study, it was proved that copper smelted by a matte smelting process was transported in the form of flat or plano-convex ingots from multiple sources to South Bohemia, where it was subsequently refined and alloyed. Obtained analytical results refute the idea of prevailing copper recycling in the Late Bronze Age.Článek prezentuje výsledky komplexního archaeometrického studia měděných ingot z pozdní doby bronzové z depotu ze Starých Hodějovic (Jižní Čechy). Za účelem určení geografického původu mědi a porozumění používaným metalurgickým procesům byly ke studiu vzorků použity nejmodernější analytické metody (metalografické analýzy, analýzy příměsových a stopových prvků a izotopové analýzy olova). V rámci analýz byla vytvořena reprezentativní databáze koncentrací stopových prvků a izotopových poměrů olova pro nelegovaný a nerecyklovaný soubor měděných ingotů pocházející z pozdní doby bronzové. Z výsledků vyplývá, že většina ingotů nebyla ovlivněna legováním, mixováním nebo recyklací. Na základě izotopových poměrů olova a koncentrací hlavních a stopových prvků předpokládáme, že původ mědi je převážně z Alpských ložisek z oblasti Trentino a Mitterberg a případně i oblasti Valais. Studií bylo prokázáno, že měď tavená ze sulfidických rud technologií tavení na kamínek a následně byla transportována ve formě plochých nebo plano-konvexních ingotů z několika zdrojů do oblasti Jižních Čech, kde byla následně rafinována a legována. Získané analytické výsledky neprokázaly domněnku převažující recyklace mědi v pozdní době bronzové

Mg, Ca and Sr isotope dynamics in a small forested catchment underlain by paragneiss: The role of geogenic, atmospheric, and biogenic sources of base cations

Knowledge of the origin of magnesium (Mg) and calcium (Ca) in soil solutions and catchment runoff helps to predict forest ecosystems’ vulnerability to deficiencies in essential nutrients in an era of climate change, environmental pollution and bark-beetle calamities. Here we discuss isotope aspects of Mg, Ca and strontium (Sr) cycling in a spruce-forested headwater catchment in a relatively unpolluted part of Central Europe. We investigated to what extent Mg and Ca isotope signatures of runoff reflect the isotope compositions of specific Mg- and Ca-rich minerals that easily dissolve during the weathering of paragneiss, and compared the isotope variability of Mg and Ca in fresh bedrock minerals, soils and other ecosystem reservoirs. We also compared conclusions from Mg and Ca isotope systematics with inferences from catchment input–output mass budgets. Long-term input–output monitoring in the studied catchment situated near the Czech–German border (Central Europe) revealed 3.5–7 times higher outputs of Mg, Ca, and Sr via surface runoff relative to their present-day atmospheric inputs. It follows that hydrological exports of recent atmospheric Mg, Ca and Sr are minor. Release of geogenic base cations into the runoff results from the interplay between mineral abundances, concentrations of the studied elements in the minerals, and their dissolution rates. Chemical depletion fractions for the studied elements from bedrock to the soil were 50–70 %, and the losses of dominant soluble minerals in the soil were 30–80 %. Exports of residual Mg, Ca and Sr following partial incorporation of these elements into secondary phyllosilicates are probably low because newly-formed clay minerals are not abundant in the soil. Residual Ca following preferential incorporation of isotopically light Ca into growing tree biomass may contribute to the isotopically heavy runoff Ca. Isotope ratios of base cations were obtained for six minerals (plagioclase, orthoclase, biotite, muscovite, apatite, and ilmenite). Mineral fractions differ greatly in δ²⁶Mg and δ⁴⁴Ca values and ⁸⁷Sr/⁸⁶Sr ratios. 80–97 % of each of the three studied base cations are present in the bedrock in a single relatively easily dissolvable mineral: Mg in biotite, and Ca and Sr in plagioclase. The isotope composition of Mg in biotite was similar to the isotope composition of Mg in runoff. The isotope compositions of Ca and Sr in plagioclase were also similar to Ca and Sr isotope compositions in runoff. Thus, the dominant geogenic source of each of the studied elements (Mg, Ca and Sr) in the investigated paragneiss catchment can be represented by one relatively soluble mineral.ISSN:0016-7061ISSN:1872-625