Search results for "Glacial period"
showing 10 items of 196 documents
Depositional model in subglacial cavities, Killiney Bay, Ireland. Interactions between sedimentation, deformation and glacial dynamics
2012
Subglacial meltwater drainage and sedimentary processes play a major role in ice-sheet dynamic but there is a lack of study of subglacial environment because modern ice-sheet beds remain inaccessible. Previous authors already intended to provide diagnostic criterion and recent investigations suggest that fluid pressure variations are a key factor in subglacial environment. This paper investigated the late Devensian sedimentary record in order to describe subglacial sedimentological facies associations and deformation features related to fluid overpressures. We used an integrated approach, based on stratigraphy, sedimentology and deformations styles to demonstrate a subglacial depositional m…
Multi-proxy dating of Holocene maar lakes and Pleistocene dry maar sediments in the Eifel, Germany
2013
Abstract During the last twelve years the ELSA Project (Eifel Laminated Sediment Archive) at Mainz University has drilled a total of about 52 cores from 27 maar lakes and filled-in maar basins in the Eifel/Germany. Dating has been completed for the Holocene cores using 6 different methods (210Pb and 137Cs activities, palynostratigraphy, event markers, varve counting, 14C). In general, the different methods consistently complement one another within error margins. Event correlation was used for relating typical lithological changes with historically known events such as the two major Holocene flood events at 1342 AD and ca 800 BC. Dating of MIS2–MIS3 core sections is based on greyscale tunin…
Paleoclimate variability during the Blake geomagnetic excursion (MIS 5d) deduced from a speleothem record
2014
To evaluate possible connections between climate and the Earth's magnetic field, we examine paleoclimate proxies in a stalagmite (PA-8) recording the Blake excursion (∼112–∼116.4 ka) from Cobre cave (N Spain). Trace element, δ13C, δ18O, δ234U, fluorescent lamination, growth rate, and paleomagnetic records were synchronized using a floating lamina-counted chronology constrained by U–Th dates, providing a high-resolution multi-proxy paleoclimate record for MIS 5d. The alpine cave setting and the combination of proxies contributed to improve the confidence of the paleoclimatic interpretation. Periods of relatively warm and humid climate likely favored forest development and resulted in high sp…
The Jura glaciers: palaeogeography in the Würmian circum-Alpine zone
2008
Since the first studies on the glacial formations of the Jura mountains there have been two concepts concerning type of glaciation and ice origin during the Wurmian glaciation. Some authors believed that the Jura was totally inundated by ice of Alpine origin, while others believed that the Jura had its own glaciers, originating from a single ice-cap. Several recent studies on both the NW and SE slopes of the range define the problem more accurately. This paper presents a synthesis of the new results from mapping the moraine systems and studying the stratigraphic relationships between Alpine and Jura tills. It is concluded that even the highest level of Alpine glaciers could not lead to a pe…
Implications for paleomobility studies of the effects of quaternary volcanism on bioavailable strontium: a test case in North Patagonia (Argentina)
2020
Strontium isotopes (⁸⁷Sr/⁸⁶Sr) are used as geochemical tracers for paleomobility studies because they display predictable and stable patterns in ecosystems primarily controlled by the underlying geological regimes. While bedrock geology is stable over thousands of years, geomorphological processes can influence the ⁸⁷Sr/⁸⁶Sr in ecosystems over archeologically relevant timescales. Among these geomorphological processes, the deposition and reworking of volcanic sediments over Quaternary timescales are little studied but could be an important control of ⁸⁷Sr/⁸⁶Sr variations in many archeological regions. North Patagonia is a key archeological region to address animal and human movements, and a…
A 350,000-year climatic record from the loess sequence of Achenheim, Alsace, France
2008
Up to now the best Quaternary climatic sequences come from oceanic isotope studies, but terrestrial sequences are also well known, usually for pollen or ice core data. A new sequence providing climatic information for the last 500,000 years has been studied in the loess series of Achenheim (Alsace), using the mollusc record in relation to other stratigraphical data. Mollusc assemblages are analysed using a multivariate method. The correspondence analysis used here allows us to explain, in ecological terms, the general variability of the Achenheim set. Most Pleistocene mollusc species have the advantage that modem individuals live in the same assemhlages. So, the known ecology and distributi…
Subglacial bed deformation and dynamics of the Apriķi glacial tongue, W Latvia
2011
Saks, T., Kalvans, A. & Zelcs, V. 2012 (January): Subglacial bed deformation and dynamics of the Apriķi glacial tongue, W Latvia. Boreas, Vol. 41, pp. 124–140. 10.1111/j.1502-3885.2011.00222.x. ISSN 0300-9483. We evaluate the glacial dynamics and subglacial processes of the Apriķi glacial tongue in western Latvia during the Northern Lithuanian (Linkuva) oscillation of the last Scandinavian glaciation. The spatial arrangement of glacial bedforms and deformation structures are used to reconstruct the ice dynamics in the study area. The relationship between geological structures at the glacier bed and the spatial distribution of drumlins and glacigenic diapirs, on the one hand, and the permeab…
Freshening of the Alaska Coastal Current recorded by coralline algal Ba/Ca ratios
2011
Arctic Ocean freshening can exert a controlling influence on global climate, triggering strong feedbacks on ocean‐atmospheric processes and affecting the global cycling of the world’s oceans. Glacier‐fed ocean currents such as the Alaska Coastal Current are important sources of freshwater for the Bering Sea shelf, and may also influence the Arctic Ocean freshwater budget. Instrumental data indicate a multiyear freshening episode of the Alaska Coastal Current in the early 21st century. It is uncertain whether this freshening is part of natural multidecadal climate variability or a unique feature of anthropogenically induced warming. In order to answer this, a better understanding of past var…
Distribution patterns, floristic structure and habitat requirements of the alpine river plant community Stuckenietum amblyphyllae ass. nova (Potamete…
2012
This paper discusses the floristic structure, distribution and habitat requirements of a new aquatic syntaxon, <em>Stuckenietum a</em><em>m</em><em>b</em><em>l</em><em>y</em><em>p</em><em>h</em><em>ylla</em><em>e </em>ass. nova. Patches of the <em>Stuckenietum amblyphyllae </em>association occur in the Pamir Alai Mountains in Middle Asia (Tajikistan). The biotope of this community represent high mountain rivers and ponds at the bottom of glacial river valleys situ- ated at elevations between 1900 and 3800 m. Patches of the <em>Stuckenietum amblyphyllae </em>ass…
Microremains from El Mirón Cave human dental calculus suggest a mixed plant/animal subsistence economy during the Magdalenian in Northern Iberia
2015
Abstract Despite more than a century of detailed investigation of the Magdalenian period in Northern Iberia, our understanding of the diets during this period is limited. Methodologies for the reconstruction of Late Glacial subsistence strategies have overwhelmingly targeted animal exploitation, thus revealing only a portion of the dietary spectrum. Retrieving food debris from calculus offers a means to provide missing information on other components of diet. We undertook analysis of human dental calculus samples from Magdalenian individuals (including the “Red Lady”) at El Miron Cave (Cantabria, Spain), as well as several control samples, to better understand the less visible dietary compo…