Etudier les archives fluviales : de la diversité à la multidisciplinarité

Cordier, Stéphane; Bridgland, David R.; Benito, Gerardo

doi:10.4000/quaternaire.7119

Cited by 3 publications

(1 citation statement)

References 61 publications

(42 reference statements)

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“…Fluvial deposits have long been a reliable tool for the reconstruction of the history and basin evolution of river systems at various timescales (Ejarque et al 2015). There are preserved remains of organisms continuously accumulated for a long timescale in fluvial sediments, which can be a source of evidence about environmental and hydro-climatic changes of lotic systems (Cordier et al 2015). Amongst the various proxies preserved in sediments, diatoms represent one of the more powerful bioindicators to trace recent and past environmental changes because they thrive over a wide range of environmental conditions, respond quickly to physical, chemical and biological variations in aquatic ecosystems, preservation and show a well-defined taxonomy (Battarbee et al 2001;Espinosa and Beilinson 2019).…”

Section: Introductionmentioning

confidence: 99%

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

2021

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Dryland river systems support a diverse aquatic biota in semi-arid and arid landscapes, but they are increasingly vulnerable to natural and human impacts. This study provides the first modern diatom training set (n = 38) from three dryland rivers in northern Patagonia, Argentina. The relationship between surface-sediment diatoms and contemporary environmental variables was explored using multivariate analyses. The results showed that surface-water chemistry varies among rivers in accordance with local-scale factors such hydro-climatic variability and anthropic activities. A total of 378 diatom taxa were identified but only 45 taxa occurred with relative abundances higher than 2% in at least one sediment sample. The Colorado and Negro rivers were characterized by high abundances of small tychoplanktic fragilarioids whereas the Chubut River was dominated by epiphytic and planktic taxa. The canonical correspondence analyses (CCA) showed that conductivity, pH and HCO 3 − were the main environmental variables governing diatoms distributions. A transfer function was developed for water conductivity using unimodal methods because of partial CCA and λ 1 /λ 2 ratio revealed that this variable had the largest unique effect on diatom variance. A weighted averaging (WA) model with tolerance downweighting and classic deshrinking provided a reasonably robust model (r 2 jack = 0.94 and RMSEP = 0.249 log 10 μS cm −1 ). However, the diatom-inferred conductivity values should be carefully interpreted because of the uneven distribution of sampling sites and the dominance of small araphid diatoms belonging to the genera Staurosira, Pseudostaurosira and Punctastriata. By their benthic habitat, the distribution of these taxa could be influenced by other factors as light and substrate in addition to water chemistry. The autoecological information achieved through this study will provide the basis for a better insight into the hydrological responses of the dryland rivers in northern Patagonia to climate and environmental changes.

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Section: Introductionmentioning

confidence: 99%

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

2021

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The past in dust: current trends and future directions in Pleistocene geoarcheology of European loess

Chu

Nett

2021

J Quaternary Science

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Loess is a main archive of Pleistocene landscapes and environments and therefore has an important connection to the preservation and interpretation of Paleolithic sites. In Europe, anthropogenic sites have been found in loess because of past local occupation. At one extreme, sites are well preserved with minimal disturbance often accompanied by embedded proxies to estimate ecological parameters. On the other hand, loess deposits have undergone post‐depositional alterations such as weathering, pedogenesis or bioturbation due to changing environmental conditions or other disturbances that obscure anthropogenic sites. We outline the current state of research and connections between Paleolithic archeology and loess research while introducing a series of subsequent regional case studies as part of a special issue. We also make recommendations for future work to incorporate a wider variety of methods to create more robust inferences on hominin and environmental evolution and their connections.

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Late-Middle Pleistocene Sedimentary Environment and Climate Variation in North Hebei Plain, China: Evidence from the SHBZK-1 Core

et al. 2023

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Thick Quaternary alluvial and floodplain sediments in north Hebei Plain provide important information for understanding local paleoenvironmental and paleoclimatic variations. A 120.8 m drilled core (SHBZK-1) was recovered to determine the late Pleistocene climatic fluctuations, sedimentary environment and their coevolutionary relationship. Laboratory analysis, including grain size distribution, magnetic susceptibility, and optical stimulated luminescence dating, was carried out. Lithofacies and grain size showed that the sediments are of fluvial origin and contain two subfaces: river sand bar and flood plain. The good correlation between magnetic susceptibility and grain size show that climate change is the main factor controlling the variation of sedimentary environment in Hebei Plain, rather than tectonic factors. Furthermore, variations of the magnetic susceptibility and lithofacies reflect the intensity and fluctuations of Asian monsoons and couple well with glacial-interglacial cycles, suggesting that the variation of ice volume in the Northern Hemisphere drives climate change in the Hebei Plain, which, in turn, regulates the variation of the sedimentary environment and facies through controlling precipitation changes, as well as the input amount of magnetic minerals. This research provides a useful continental archive for understanding the late Pleistocene environmental and climatic variation and suggests the prevalence of climate-driven environmental change.

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Etudier les archives fluviales : de la diversité à la multidisciplinarité

Cited by 3 publications

References 61 publications

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

The past in dust: current trends and future directions in Pleistocene geoarcheology of European loess

Late-Middle Pleistocene Sedimentary Environment and Climate Variation in North Hebei Plain, China: Evidence from the SHBZK-1 Core

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