Quaternary, Volume 7, Issue 2 (June 2024) – 5 articles

The analysis of tephra layers in maar lake sediments of the Eifel shows 14 well-visible tephra during the last glacial cycle from the Holocene to the Eemian (0–130,000 yr b2k). These tephra were analyzed for their petrographic composition, which allows us to connect several tephra to eruption sites. All tephra were dated by application of the ELSA-20 chronology, developed using the late Pleistocene infilled maar lake of Auel and the Holocene lake Holzmaar (0–60,000 yr b2k). We extend the ELSA-20 chronology with this paper for the millennia of 60,000–130,000 yr b2k (ELSA-23 chronology), which is based on the infilled maar lake records from Dehner, Hoher List, and Jungferweiher. The evaluation of the tephra from the entire last glacial cycle shows that all 14 tephra were close to interstadial warming of the North Atlantic sea surface temperatures. In particular, phreatomagmatic maar eruptions were systematically associated with Heinrich events or C-events. These events represent times of warming of the Southern Hemisphere, global sea level rise, and CO₂ increase, which predate the abrupt interstadial warming events of the Northern Hemisphere. This synchroneity indicates a physical relationship between endogenic and exogenic processes. Changes in the lithospheric stress field in response to changes in continental ice loads have already been suggested as a potential candidate to explain the exogenic forcing of endogenic processes. The chronology of volcanic activity in the Eifel demonstrates that intraplate mantle plumes are also affected by the exogenic forcing of endogenic processes. Full article

Our work presents an updated overview of the Italian Middle Pleistocene records of hippopotamuses, including the two species Hippopotamus antiquus and Hippopotamus amphibius. In addition to reviewing several well-known fossils in the literature, a large number of samples are described herein for the first time. Following the recent results published in the literature, where the skull from the Middle Pleistocene of Cava Montanari (ca. MIS 13) was confirmed to belong to H. amphibius, one of the aims of this work was to investigate the H. antiquus–H. amphibius transition. A morphological analysis applied to a large sample confirmed the validity of the arrangement of the enamel ridges of the external surfaces of the lower canines as a diagnostic character for specific identifications. Finally, biometric analyses allowed us to test the size variability during the Middle Pleistocene, which confirmed that H. antiquus was generally larger than H. amphibius. Nevertheless, the remains of H. antiquus dated to ca. 600 ka show a reduced size when compared to older fossils of the same taxon, probably as a response to severe glacial conditions that occurred during MIS 16. Full article

Ombrotrophic suboceanic bogs are distinguished by a high diversity of complex microlandscapes within the bog massif. Each complex microlandscape is a separate intrabog ecosystem with a specific set of parameters and relationships. This study aims to assess the specifics of the characteristics and parameters of the complex microlandscapes as part of an ombrotrophic suboceanic Sphagnum bog and as stages of bog morphogenesis, and to establish the internal relationships and their relationship with external environmental factors. A comprehensive multidisciplinary approach was used to assess the functioning of the complex microlandscapes. It was found that the relationship with the air temperature is closer than with the bog water table dynamics. It was shown that the morphometric parameters of perennial dwarf shrubs can serve as indicators of the stages of development of bogs. The processes of the self-regulation of complex microlandscapes are weakened with the age of the complex microlandscape, as evidenced by an increase in the amplitude of temperature fluctuations and the level of bog waters, as well as the key physicochemical parameters of the peat deposit. This leads to a gradual, slow reorientation of the physicochemical processes occurring in the deposit, from the deposition of organic matter to the decomposition of peat biomass. Full article

Pollen deposition in small lakes and peatlands is composed of local pollen deposition arriving from the nearby vegetation and of regional pollen deposition arriving from farther away. The LOVE model aims to reconstruct past vegetation on a small local scale by extracting only the local pollen signal. To this end, pollen deposition from small sites is related to pollen deposition from large lakes with predominantly regional pollen deposition. We here present a new implementation of the LOVE model in the R environment for statistical computing that is more user friendly than existing implementations. It allows more readily application with fossil pollen data and facilitates extensive testing of the approach in simulated landscapes. The LOVE model derives from critical mathematical assumptions that strongly limit its application. We additionally present LOVEoptim as an adjusted approach to local-scale reconstructions. Other than in LOVE, past local plant abundances are approximated using numerical optimization. Tests in a simulated landscape, which is based on true landscape patterns from digital maps, show that both approaches are valid. Due to fewer mathematical assumptions, LOVEoptim is more widely applicable. The modeling results help to better interpret the spatial scale of vegetation reflected in LOVE/LOVEoptim reconstructions. Full article

We analyzed mineralogical characteristics, and major as well as rare earth element concentrations, from a cryptotephra layer in sediments of the infilled maar of Auel (Eifel, Germany). The results of detailed geochemical analyses of clinopyroxenes and their glassy rims from the Auel cryptotephra layer showed that they are similar to those from the thick Campanian Ignimbrite tephra occurrence in a loess section at Urluia (Romania). Both tephras show idiomorphic green clinopyroxenes and formation of distorted grains up to millimeter scale. The cryptotephra in the Auel core has a modelled age of around 39,940 yr b2k in the ELSA-20 chronology, almost identical to the latest ⁴⁰Ar/³⁹Ar dates for the Campanian Ignimbrite/Y-5 (CI/Y-5) eruption. These observations suggest that parts of the CI/Y-5 ash cloud were transported also northwestward into Central Europe, whereas the main branch of the CI/Y-5 ash plume was transported from southern Italy towards the NE, E, and SE. Based on pollen analyses, we conclude there was no direct effect on vegetation from the CI/Y-5 fallout in the Eifel area. Trees, shrubs, and grasses remained at pre-tephra-airfall levels for roughly 240 years, but changed around 39,700 yr b2k when thermophilic woody plants (e.g., Alnus and Carpinus) disappeared and Artemisia spread. This change in vegetation was well after the Laschamp geomagnetic excursion and also after the GI9 interstadial and quite probably represents the onset of the Heinrich Event 4 (H4) cold spell, when climatic conditions over the North Atlantic, and apparently also in Central Europe, deteriorated sharply. Full article