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This paper addresses the surface and Holocene aeolian deposits in the southeastern Mu Us Desert, N. China, systematically analysing the evolution of the geochemical characteristics of aeolian sand-palaeosol sequences and their environmental significance. Our results indicate that the geochemical components of the Holocene aeolian deposits and surface deposits had the similar material sources, sediment transport and deposition processes in the study region, which were dominated by SiO2, Al2O3, and Na2O. In the weathering process of the Jinjie (JJ) profile, the Na, K, and Si presented the slight leaching and migration in general, while the other elements were relatively accumulated. The Holocene aeolian deposits and surface deposits incurred weaker geochemical weathering under cold and dry conditions and were only weakly leached, which implies a relatively arid environment in the Holocene epoch and the modern era. The weathering degree was controlled by the regional temperature and precipitation, and was probably more sensitive to the precipitation changes. In the sedimentary profile, the geochemical parameters and migration of elements demonstrated that there have been several alternating warm-wet and cold-dry intervals in the Mu Us Desert in the Holocene epoch; there were relatively warm and wet conditions prior to 4.6 ka, and it has been cold and dry since then. Six millennial-scale dry events were recorded during the Holocene, which were not only accordant with the history of palaeoclimatic changes in the different latitudes and archives of the Northern Hemisphere, but also correspond to the millennial-scale variation of cosmic radiation and solar activity during that period. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Geochemistry, sediment provenance, and the Holocene paleoenvironmental evolution of the Southern Po River coastal plain (Italy) were examined based on the geochemical analysis of 279 sediment samples from 35 cores. The Holocene succession is subdivided into four major facies associations: back‐barrier, transgressive barrier, shallow‐marine, and beach‐ridge deposits. Bulk chemical composition shows remarkable differences between facies associations, and the poly‐modal behavior in the related frequency curves suggests distinct sources of sediment. Using MgO and Ni as geochemical tracers, changes in sediment provenance were assessed with the aim to reconstruct the Holocene paleoenvironmental evolution of the area. The Po River and the Apenninic rivers represented the main sources of sediment during the early stages of transgression and highstand sea‐level conditions, whereas transgressive barrier and early shallow‐marine facies associations exhibit a clear North Adriatic river (eastern Alpine) provenance. The Holocene paleoenvironmental evolution of the study area, between about 10 ky and the present, indicates the presence of a bypass zone in front of the Po River mouth between 9 and 6 ky BP. At that time, sediment supplied by the North Adriatic rivers was transported southward by the longshore drift, bypassed the weak Po River influx and accumulated close to the Apennines. Comparison between Holocene facies associations and current back‐barrier and shallow‐marine sediments confirms that the present‐day basin circulation is similar to the one that acted during the last episode of sea‐level rise. [ABSTRACT FROM AUTHOR]

Results of analyses of a shallow marine sediment vibrocore from the Atlantic seafloor just west of the Aran Islands, western Ireland, are presented. The sediments range from ~16,000 to younger than 9,000 cal BP in age, based on 14C dating of foraminifers and molluscs. One sample within the core is dated at 12804 ± 125 cal BP and lies a very short distance stratigraphically below a conspicuous horizon containing isolated pebbles and sand‐size clasts, in what is an otherwise fine‐grained sequence of sediment. These outsized clasts are interpreted to be ice‐rafted debris. Approximately coeval with this horizon, the diversity and abundance of foraminifers decrease significantly and the foraminifer Nonionellina labradorica makes its first appearance in the core sediment. Stable isotope analysis shows a significant increase in values of δ18O approaching the horizon containing ice‐rafted debris. These results show the effects of a relatively sudden cooling of this part of the Atlantic Ocean at middle latitudes coincident with, or just after, the onset of the Younger Dryas event and demonstrate the extent of floating icebergs and probable later pack ice as a result of this temperature decrease. [ABSTRACT FROM AUTHOR]