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Refining the timing of Middle Pleistocene ( MIS 12 to MIS 6) ice advances into northern central Europe:Sedimentological analysis and single‐grain luminescence dating of glaciotectonic complexes and tunnel‐valley fills
Get PDFThe timing of the Middle Pleistocene ice advances into northern central Europe is still disputed. In this study, we summarize the current state of knowledge on the age of the Middle Pleistocene Saalian and Elsterian ice advances into northern central Europe and provide new single‐grain luminescence ages of related meltwater deposits. Twenty‐five samples for luminescence dating were taken from five different Saalian ice‐marginal positions and (upthrusted) Elsterian tunnel‐valley fills in northern Germany. The sampled Elsterian deposits mainly comprise subaqueous fan and delta sediments, which were deposited in glacial lakes that formed in underfilled tunnel valleys and their marginal areas. The estimated luminescence ages range between >578 and 346±98 ka, probably correlating with Marine Isotope Stage (MIS) 12, although an older and/or younger age (MIS >14 to MIS 8) cannot be excluded. During MIS 6, four different ice advances are recorded from the study area. During the maximum extent of the first and second Saalian Drenthe ice advances, large ice‐dammed lakes formed along the Fennoscandian ice sheets, which catastrophically drained during ice‐margin retreat. Further north, glaciofluvial fans and/or larger glaciofluvial distributive systems formed along the ice sheets. The first Saalian Drenthe ice advance probably occurred during MIS 6e‐d. However, the estimated luminescence ages range between 293±59 and 209±37 ka, and therefore, we cannot rule out an earlier Saalian pre‐Drenthe ice advance into the north‐eastern part of the study area. After a phase of ice‐sheet retreat, fluvial erosion and soil formation, the second Saalian Drenthe ice advance probably occurred during late MIS 6c. The estimated luminescence ages range between 172±38 and 123±18 ka. Meltwater deposits that are related to the third Saalian Drenthe (Hondsrug ice stream) and/or Warthe ice advances have luminescence ages of 128±19 to 123±22 ka, correlating with MIS 6b‐a. The glaciotectonic complexes partly have a multiphase development related to the different Saalian ice advances. Smaller composite ridge systems with shallow detachments (20–60 m deep) evolved in areas with tunnel‐valley fills, probably controlled by the rheological contrasts between sandy meltwater deposits and underlying fine‐grained deposits of the uppermost Elsterian tunnel‐valley fills (Lauenburg Clay Complex). In contrast, larger glaciotectonic complexes with deep detachments (>100 m deep) formed further south (‘Rehburg line’) where large tunnel valleys are absent
Uniformity of heating across sample holders during luminescence measurements
Get PDFFor luminescence research, samples are often heated prior to and/or during measurement to measure the thermoluminescence (TL) signal or to remove charge from shallow traps. The reproducibility and repeatability of luminescence measurements will be influenced by how consistently and uniformly the samples are heated, both within a single aliquot and between different readers or sample positions. While the effects of temperature lag during heating have been intensively studied, the spatial uniformity of temperature across samples has received less attention. This study presents spatially-resolved measurements of the temperature of the heating strip, a steel cup and an aluminium single grain disc in a Risø TL/OSL DA20 reader. Temperature is calculated using black body emissions from the three materials, detected with an Electron Multiplying Charge Coupled Device (EMCCD). The results show that temperature is not spatially uniform across any of the three materials, although the degree of variation differs between them. The largest temperature variation is observed across the steel cup (∼18 % at a temperature of 500 °C), followed by the heating strip (∼8 % at a temperature of 500 °C), and then the single grain disc (∼2 % at a temperature of 250 °C). The steel cup also has greater anisotropy in temperature compared to the single grain disc. This study suggests that spatial variation in temperature can be minimised by using sample holders made of materials with high thermal conductivity (e.g. aluminium or silver), and that the impact of thermal variation can be reduced by restricting samples to the central portion of a sample holder (e.g. the central 2 mm of a sample holder (i.e. ‘small aliquots’)).</p
COMPASS Guidelines for Conducting Welfare-Focused Research into Behaviour Modification of Animals
No full textResearchers are increasingly engaged in studies to determine and correct negative welfare consequences of animal husbandry and behaviour modification procedures, not least in response to industries’ growing need to maintain their social licence through demonstrable welfare standards that address public expectations. To ensure that welfare recommendations are scientifically credible, the studies must be rigorously designed and conducted, and the data produced must be interpreted with full regard to conceptual, methodological, and experimental design limitations. This commentary provides guidance on these matters. In addition to, and complementary with, the ARRIVE guidelines that deal with animal studies in general, there is a need for additional specific advice on the design of studies directed at procedures that alter behaviour, whether through training, handling, or restraint. The COMPASS Guidelines offer clear direction for conducting welfare-focused behaviour modification research. They stand for the following: Controls and Calibration, emphasising rigorous design, baseline measures, equipment calibration, and replicability; Objectivity and Open data, ensuring transparency, validated tools, and data accessibility; Motivation and Methods, with a focus on learning theory, behavioural science, and evidence-based application of positive reinforcers and aversive stimuli; Precautions and Protocols, embedding the precautionary principle, minimising welfare harms, listing stop criteria, and using real-time monitoring; Animal-centred Assessment, with multimodal welfare evaluation, using physiological, behavioural, functional, and objective indicators; Study ethics and Standards, noting the 3Rs (replacement, reduction, and refinement), welfare endpoints, long-term effects, industry independence, and risk–benefit analysis; and Species-relevance and Scientific rigour, facilitating cross-species applicability with real-world relevance and robust methodology. To describe these guidelines, the current article is organised into seven major sections that outline detailed, point-by-point considerations for ethical and scientifically rigorous design. It concludes with a call for continuous improvement and collaboration. A major purpose is to assist animal ethics committees when considering the design of experiments. It is also anticipated that these Guidelines will assist reviewers and editorial teams in triaging manuscripts that report studies in this context
