Multiple Quaternary erosion and infill cycles in overdeepened basins of the northern Alpine foreland

The cumulative effect of repeated extensive glaciations represents a poorly constrained component in the understanding of landscape evolution in mid-latitude mountain ranges such as the Alps. Timing, extent, and paleo-climatic conditions of these glaciations are generally poorly understood due to the often-fragmentary character of terrestrial Quaternary records. In this context, the sedimentary infills of subglacial basins may serve as important archives to complement the Quaternary stratigraphy over several glacial–interglacial cycles. In this study, sedimentary facies, valley-fill architecture, and luminescence dating are used to describe nine erosional and depositional cycles (Formations A–I) in the Lower Glatt valley, northern Switzerland. These cycles can be related to the ‘Birrfeld’ Glaciation (~ MIS2), the ‘Beringen’ Glaciation (~ MIS6), and up to three earlier Middle Pleistocene glaciations that can be tentatively correlated to the regional glaciation history. Evidence suggests that deep bedrock trough incision and/or partial re-excavation last occurred mainly during the ‘Beringen’ and ‘Habsburg’ Glaciations. Second-order, ‘inlaid’ glacial basins document separate glacier re-advances during the Beringen Glaciation. The arrangement of subglacial basins in the Glatt valley with different sub-parallel or bifurcating bedrock troughs, re-excavated segments, and inlaid basins document changes in the magnitude and the spatial focus of subglacial erosion over time. The Glatt valley may thus serve as a key example for the glacial landscape evolution in many other repeatedly glaciated forelands.     

Reducing landscape heterogeneity for improved land use and land cover (LULC) classification across the large and complex Ethiopian highlands

This paper presents a land use and land cover (LULC) classification approach that accounts landscape heterogeneity. We addressed this challenge by subdividing the study area into more homogeneous segments using several biophysical and socio-economic factors as well as spectral information. This was followed by unsupervised clustering within each homogeneous segment and supervised class assignment. Two classification schemes differing in their level of detail were successfully applied to four landscape types of distinct LULC composition. The resulting LULC map fulfills two major requirements: (1) differentiation and identification of several LULC classes that are of interest at the local, regional, and national scales, and (2) high accuracy of classification. The approach overcomes commonly encountered difficulties of classifying second-level classes in large and heterogeneous landscapes. The output of the study responds to the need for comprehensive LULC data to support ecosystem assessment, policy formulation, and decision-making towards sustainable land resources management.     

Mineralogy,nucleation and growth of dolomite in the laboratory and sedimentary environment: A review

Dolomite [CaMg(CO₃)₂] forms in numerous geological settings, usually as a diagenetic replacement of limestone, and is an important component of petroleum reservoir rocks, rocks hosting base metal deposits and fresh water aquifers. Dolomite is a rhombohedral carbonate with a structure consisting of an ordered arrangement of alternating layers of Ca²⁺ and Mg²⁺ cations interspersed with anion layers normal to the c‐axis. Dolomite has symmetry, lower than the (CaCO₃) symmetry of calcite primarily due to Ca–Mg ordering. High‐magnesium calcite also has symmetry and differs from dolomite in that Ca²⁺ and Mg²⁺ ions are not ordered. High‐magnesium calcite with near‐dolomite stoichiometry (≈50 mol% MgCO₃) has been observed both in nature and in laboratory products and is referred to in the literature as protodolomite or very high‐magnesium calcite. Many dolomites display some degree of cation disorder (Ca²⁺ on Mg²⁺ sites and vice versa), which is detectable using transmission electron microscopy and X‐ray diffractometry. Laboratory syntheses at high temperature and pressure, as well as studies of natural dolomites show that factors affecting dolomite ordering, stoichiometry, nucleation and growth include temperature, alkalinity, pH, concentration of Mg and Ca, Mg to Ca ratio, fluid to rock ratio, mineralogy of the carbonate being replaced, and surface area available for nucleation. In spite of numerous attempts, dolomite has not been synthesized in the laboratory under near‐surface conditions. Examination of published X‐ray diffraction data demonstrates that assertions of dolomite synthesis in the laboratory under near‐ambient conditions by microbial mediation are unsubstantiated. These laboratory products show no evidence of cation ordering and appear to be very high‐magnesium calcite. Elevated‐temperature and elevated‐pressure experiments demonstrate that dolomite nucleation and growth always are preceded by very high‐magnesium calcite formation. It remains to be demonstrated whether microbial‐mediated growth of very high‐magnesium calcite in nature provides a precursor to dolomite nucleation and growth analogous to reaction paths in high‐temperature experiments.     

Engineering geomorphology: A novel professional profile to face applied challenges in earth surface dynamics in mid-Europe

Engineering geomorphology is concerned with the assessment of surface processes, sediment dynamics, landform changes and geomorphological hazards, which are related to civil engineering and construction. As an important planning component, it contributes significantly to the solution of societal problems on a dynamic earth surface. Unlike in the UK and other countries where it has become an independent sector within geotechnical engineering, the discipline has found little attention up to now in mid-European applied geosciences. This ESEX commentary discusses the under-representation and proposes an advancement of professional engineering geomorphology within the German-speaking countries. The relation to neighbouring disciplines and the history of the field are illustrated from the academic and practical perspectives. A brief outline of potential fields of activity, recent professional practice and requirements for academic training are presented to provide aspiring practitioners with an idea of their future prospects as engineering geomorphologists. As part of their qualification, teamwork with geologists and engineers must be considered a key aspect, involving mutual knowledge of methods, techniques and interfaces for the propagation of uncertainty. The discussion demonstrates ways engineering geomorphology could be implemented as an established profession/academic discipline in mid-Europe as part of physical geography, geosciences and neighbouring engineering disciplines.     

Using legacy data to reconstruct the past? Rescue,rigour and reuse in peatland geochronology

There is a growing interest in the rescue and reuse of data from past studies (so-called legacy data). Data loss is alarming, especially where natural archives are under threat, such as peat deposits. Here we develop a workflow for reuse of legacy radiocarbon dates in peatland studies, including a rigorous quality assessment that can be tailored to specific research questions and study regions. A penalty is assigned to each date based on criteria that consider taphonomic quality (i.e., sample provenance) and dating quality (i.e., sample material and method used). The weights of quality criteria may be adjusted based on the research focus, and resulting confidence levels may be used in further analyses to ensure robustness of conclusions. We apply the proposed approach to a case study of a (former) peat landscape in the Netherlands, aiming to reconstruct the timing of peat initiation spatially. Our search yielded 313 radiocarbon dates from the 1950s to 2019. Based on the quality assessment, the dates—of highly diverse quality—were assigned to four confidence levels. Results indicate that peat initiation for the study area first peaked in the Late Glacial (~14,000 cal years BP), dropped during the Boreal (~9,500 cal years BP) and showed a second peak in the Subboreal (~4,500 cal years BP). We tentatively conclude that the earliest peak was mostly driven by climate (Bølling–Allerød interstadial), whereas the second was probably the result of Holocene sea level rise and related groundwater level rise in combination with climatic conditions (hypsithermal). Our study highlights the potential of legacy data for palaeogeographic reconstructions, as it is cost-efficient and provides access to information no longer available in the field. However, data retrieval may be challenging, and reuse of data requires that basic information on location, elevation, stratigraphy, sample and laboratory analysis are documented irrespective of the original research aims.     

Ancient charcoal as a natural archive for paleofire regime and vegetation change in the Mayumbe,Democratic Republic of the Congo

Charcoal was sampled in four soil profiles at the Mayumbe forest boundary (DRC). Five fire events were recorded and 44 charcoal types were identified. One stratified profile yielded charcoal assemblages around 530 cal yr BP and > 43.5 cal ka BP in age. The oldest assemblage precedes the period of recorded anthropogenic burning, illustrating occasional long-term absence of fire but also natural wildfire occurrences within tropical rainforest. No other charcoal assemblages older than 2500 cal yr BP were recorded, perhaps due to bioturbation and colluvial reworking. The recorded paleofires were possibly associated with short-lived climate anomalies. Progressively dry climatic conditions since ca. 4000 cal yr BP onward did not promote paleofire occurrence until increasing seasonality affected vegetation at the end of the third millennium BP, as illustrated by a fire occurring in mature rainforest that persisted until around 2050 cal yr BP. During a drought episode coinciding with the ‘Medieval Climate Anomaly’, mature rainforest was locally replaced by woodland savanna. Charcoal remains from pioneer forest indicate that fire hampered forest regeneration after climatic drought episodes. The presence of pottery shards and oil-palm endocarps associated with two relatively recent paleofires suggests that the effects of climate variability were amplified by human activities.     

Formation of weathering-derived magnesite deposits in the New England Orogen, New South Wales, Australia: Implications from mineralogy, geochemistry and genesis of the Attunga magnesite deposit

Nodular, cryptocrystalline, weathering-derived magnesite deposits in the New England Orogen, Australia, provide a significant source of high-purity magnesite. Common textural features and related isotopic fingerprints indicate a close genetic relationship between weathering-derived magnesite deposits hosted by ultramafic rocks at Attunga and by sediments at Kunwarara while silica-carbonate rock alteration and rare hydrothermal magnesite vein deposits reflect contrasting conditions of formation. Localised weathering of carbonates in a soil environment shifts stable isotopic composition towards low δ ¹³C and high δ ¹⁸O typical for weathering-derived magnesites while intrusion-related fluids do not significantly change the isotopic composition of affected carbonates. At Attunga, magnesite consists of irregular, nodular veins and masses filling faults and cracks in the weathered serpentinite host rock as well as soft powdery magnesite in pervasive serpentinite alteration zones. The high-grade magnesite at Attunga can be contaminated by amorphous silica and serpentine relicts but does not contain dolomite or ferroan magnesite as observed for its hydrothermal equivalent, the Piedmont magnesite deposit, or other widespread deposits of silica-carbonate rock in the Great Serpentinite Belt. Heavy δ ¹⁸O values are compatible with a supergene formation from meteoric waters while low δ ¹³C suggests C3-photosynthetic plants as the predominant source of carbon for the Attunga magnesites. We infer that weathering-derived, nodular magnesite deposits hosted in ultramafic rocks like the Attunga magnesite deposit have formed in a two-step process involving the hypogene formation of a pre-cursor magnesite deposit and complete supergene overprinting by meteoric waters that acquired carbon from percolation through soil.     

Problems associated with extrapolating ecological traits to higher-than-species level exemplified in the description of the larvae of Potamophylax haidukorum Malicky, 1999, Potamophylax winneguthi (Klapálek, 1902) and Melampophylax austriacus Malicky, 1990

Functional diversity, e.g. based on feeding types, is frequently used for assessment procedures. By using Trichoptera genera Potamophylax and Melampophylax as examples, we demonstrate that functional diversity, based on mandible morphology, is low in the former, but high in the latter. When using functional feeding types for assessment procedures, this strictly questions identification at higher than species level and underlines the importance of providing taxonomic information by describing hitherto unknown larvae.Based on mandible morphology, the close species pair Potamophylax haidukorum and P. winneguthi, both endemics of the Dinaric Western Balkan, are omnivorous shredders, a character shared with all other known larvae of genus Potamophylax. In existing keys, P. haidukorum and P. winneguthi may be separated from morphologically close species (e.g. Allogamus spp., Micropterna spp., Potamophylax spp., Leptotaulius gracilis Schmid and Parachiona picicornis (Pictet)) by the lack of a large posterior sclerite at the lateral protuberance, by the lack of additional face setae at mid and hind femora, by the absence of numerous black spines at the pronotal surface and by the shape of metanotal sclerites. Melampophylax austriacus, an endemic of the Eastern Alps, has spoon-shaped scraper mandibles lacking teeth. This character is shared with M. mucoreus (Hagen) and M. nepos (McLachlan), whereas in M. melampus (McLachlan) teeth are present at the mandibles as it is common for omnivorous shredders. Such intra-generic functional diversity questions trait classifications on higher taxonomic units like genus or family.     

The earliest occurrence of peltasperms in the basal Permian strata of the North China Block and the radiation of this group

The peltasperm foliage Autunia naumannii (Gutbier) Kerp and possible peltasperm fructifications are for the first time described from the uppermost Taiyuan Formation of earliest Permian age near Wuda, Inner Mongolia. This is the oldest record of this group on the North China Block (Sino‐Korean Platform), indicating an early migration into this area. Data of other occurrences in China demonstrate independent radiations of the group in Cathaysia. All known records indicate that peltasperms probably originated in the tropical extrabasinal areas of Euramerica, and subsequently migrated within the tropical belt and experienced independent regional radiations in Europe, the southwestern United States and on the North China Block. The present discovery of Autunia naumannii (Gutbier) Kerp in China adds a common floral component between the Euramerican and Cathaysian floras, providing more evidence indicating mutual migration of floral elements between Cathaysia and Euramerica. Copyright © 2013 John Wiley & Sons, Ltd.