Search results for "RIO"
showing 10 items of 19845 documents
Does glacial environment produce glacial mineral grains? Pro- and supra-glacial Icelandic sediments in microtextural study
2022
Abstract Mineral grains from proglacial and supraglacial sedimentary settings in central south-eastern Iceland are considered in this study and analysed with the use of scanning electron microscope (SEM) techniques. By applying this, it is attempted to answer the key research question of whether quartz grains that come from a glacial-related sedimentary environment are indeed of glacial origin. The study also attempts to provide a linkage between microtextures produced on coarser and finer grains and to verify whether mineral grains from adjacent cryconite holes are similar or different. The preliminary assumption was that the more intense glacial grain record was based on several glacial a…
Paleoclimatic evolution of the Uvs Nuur basin and adjacent areas (Western Mongolia)
2000
Abstract The investigations presented in this paper focus on the shifts in Pleistocene glaciations and the geomorphic changes in landforms, as well as lake level changes and aeolian deposits of the last glacial–interglacial cycle, including the Holocene. Geomorphic evidence and high lake levels show that the climate was more humid before the last glacial maximum (LGM); however, at least one arid phase also occurred. During the second half of the LGM the climate was dry and cold, turning to wet and cold during the Late Glacial of the last Ice Age. Fluctuations in humidity and temperature occurred during the Holocene. Since about 2000 yr BP the impact of human activity has increased.
Seismites resulting from high-frequency, high-magnitude earthquakes in Latvia caused by Late Glacial glacio-isostatic uplift
2016
Abstract Geologically extremely rapid changes in altitude by glacial rebound of the Earth crust after retreat of the Scandinavian Ice Sheet at the end of the last Weichselian glaciation influenced the palaeogeography of northern Europe. The uplift of the Earth crust apparently was not gradual, but shock-wise, as the uplift was accompanied by frequent, high-magnitude earthquakes. This can be deduced from strongly deformed layers which are interpreted as seismites. Such seismites have been described from several countries around the Baltic Sea, including Sweden, Germany and Poland. Now similarly deformed layers that must also be interpreted as seismites, have been discovered also in Latvia, a…
Warming or cooling in the Pragian? Sedimentary record and petrophysical logs across the Lochkovian–Pragian boundary in the Spanish Central Pyrenees
2016
Abstract High-resolution petrophysical correlation methods were applied, for the first time, to mid-Paleozoic rocks of the Pyrenees. The methods included magnetic susceptibility measurements (MS), gamma-ray spectrometry (GRS), and alignment of MS logs using the dynamic time-warping (DTW) algorithm. Conodont biostratigraphy provided the basic framework necessary for work with the GRS and MS logs. Despite differences in the sediment patterns and accumulation/erosion rates, the logs from two selected sections in the Spanish Central Pyrenees show a striking symmetry that correlates well with the previously published logs from the Barrandian area in the Czech Republic. The high similarity betwee…
Different parts of the same plants. Charcoals and seeds from Cova de les Cendres (Alicante, Spain)
2018
Abstract The analysis of archaeobotanical macroremains from Cova de les Cendres (Teulada-Moraira, Alicante, Spain) allows a better understanding of the dynamic of the vegetation during the Upper Palaeolithic in the region. The anthracological sequence shows that Pinus type nigra/sylvestris dominates in the area during the Upper Palaeolithic, while more open formations of Juniperus and Fabaceae spread in Upper Solutrean and Early-Middle Magdalenian. The carpological analysis that has been carried out in the Middle Magdalenian level has brought to light different species of Juniperus (J. sabina, J. communis and J. oxycedrus). This information indicates that during the period, Cova de les Cend…
Benefits for nurse and facilitated plants emerge when interactions are considered along the entire life-span
2019
The structure of plant communities is often influenced by facilitative interactions where ‘facilitated’ plants benefit from growing associated with ‘nurse’ plants. Facilitation has been mostly studied from the facilitated plant's perspective, and bidirectional effects between nurse and facilitated plants have received less attention. We hypothesized that reciprocal benefits in plant-plant interactions may emerge when interactions are considered along the life-span of the plants involved. Over one spring, we selected five species with similar life-form and growth strategy, and using a full factorial design, we compared different fitness components along the plants’ life-span (seedling establ…
Plankton assembly in an ultra-oligotrophic Antarctic lake over the summer transition from the ice-cover to ice-free period: A size spectra approach
2017
Abstract Lakes from the Antarctic maritime region experience climate change as a main stressor capable of modifying their plankton community structure and function, essentially because summer temperatures are commonly over the freezing point and the lake's ice cap thaws. This study was conducted in such seasonally ice-covered lake (Lake Limnopolar, Byers Peninsula, Livingston Is., Antarctica), which exhibits a microbial dominated pelagic food web. An important feature is also the occurrence of benthic mosses ( Drepanocladus longifolius ) covering the lake bottom. Plankton dynamics were investigated during the ice-thawing transition to the summer maximum. Both bacterioplankton and viral-like…
Current and Future Influence of Environmental Factors on Small Pelagic Fish Distributions in the Northwestern Mediterranean Sea
2020
Managing for the Future: Understanding the Relative Roles of Climate and Fishing on Structure and Dynamics of Marine Ecosystems.-- 20 pages, 15 figures, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2020.00622/full#supplementary-material
Effect of simulated faunal impoverishment and mixture on the ecological structure of modern mammal faunas: Implications for the reconstruction of Mio…
2011
15 pages; International audience; The strong link between environment and the ecological diversity of communities is often used for drawing palaeoenvironmental inferences from fossil assemblages. Here we focus on the reliability of fossil samples in comparison to original communities when inferring palaeoenvironments from the ecological diversity of fossil mammal faunas. Taphonomic processes and sampling techniques generally introduce two kinds of biases in fossil samples: 1) the directional impoverishment of communities, i.e. the absence of some specific categories of bones, individuals or species; and 2) the mixture of several communities, temporally (timeaveraging) and/or spatially (spac…
Food availability and temperature optima shaped functional composition of chironomid assemblages during the Late Glacial–Holocene transition in North…
2021
Abstract Non-biting midges (Chironomidae) are the most diverse and abundant invertebrate group in boreal lakes and are strongly responsive to climate change, thus they are a valuable palaeoecological proxy for studying aquatic biodiversity response in the face of climate change. Here, we aim to decipher the influence of climate-induced changes on temporal patterns in chironomid assemblages. We apply a novel approach combining traditional taxon-based analysis and species-trait framework to subfossil chironomid assemblages in a sediment core covering the Late Glacial–Holocene transition in Northern Europe. We produce pollen-based July and January temperature reconstructions to characterize pa…