Search results for "Arche"

Anthropogenic soils are the golden spikes for the Anthropocene

2011

We propose that the Anthropocene be defined as the last c. 2000 years of the late Holocene and characterized on the basis of anthropogenic soils. This contrasts with the original definition of the Anthropocene as the last c. 250 years (since the Industrial Revolution) and more recent proposals that the Anthropocene began some 5000 to 8000 years ago in the early to mid Holocene (the early-Anthropocene hypothesis). Anthropogenic soil horizons, of which several types are recognized, provide extensive terrestrial stratigraphic markers for defining the start of the Anthropocene. The pedosphere is regarded as the best indicator of the rise to dominance of human impacts on the total environment b…

Decadal climate variability of the North Sea during the last millennium reconstructed from bivalve shells (Arctica islandica)

2014

Uninterrupted, annually resolved paleoclimate records are crucial to contextualize the current global change. Such information is particularly relevant for the Europe realm for which weather and climate projections are still very challenging if not virtually impossible. This study presents the first precisely dated, annually resolved, multiregional Arctica islandica chronologies from the North Sea which cover the time interval ad 1040–2010 and contain important information on supra-regional climatic conditions (sea surface temperature (SST), ocean productivity, wind stress). Shell growth varied periodically on timescales of 3–8, 12–16, 28–36, 50–80, and 120–240 years, possibly indicating a…

The limits of freely-available tree-ring chronologies

2020

OSL dating of Middle Weichselian age shallow basin sediments in Western Latvia, Eastern Baltic

2012

Abstract This paper presents the results of the first attempt to date the Quaternary sediments of western Latvia in the southeast Baltic region, using luminescence. The analyses have been carried out on sandy sediments of the Jurkalne Formation that are located between upper and lower Scandinavian sourced tills. Previous publications on the origin of the Quaternary sediments in the region are reviewed and it is found that there are a wide range of explanations for their processes of formation and their age of formation. It is concluded that although the sandy sediments were deposited in freshwater environment although they contain both marine and freshwater fauna and flora, a property that …

Alternative chronologies for Late Quaternary (Last Interglacial–Holocene) deep sea sediments via optical dating of silt-sized quartz

2003

Abstract We summarize the results of a test on the potential of optical dating for the age assessment of Late Quaternary deep-sea sediments. Our approach combines a single aliquot regeneration (SAR) protocol for equivalent dose ( D e ) estimation on fine silt-sized quartz with a time-dependent evaluation of supported and unsupported long-lived radioisotopes within the deposited sediment matrix. For this purpose nine samples from two independently dated deep-sea cores from the Indian Ocean were obtained. The SAR analysis resulted in mean D e estimates with precisions ranging from 0.9% to 3.7%. Combination of these data with measured radioisotope concentrations resulted in stratigraphically s…

Rectilinear evolution in arvicoline rodents and numerical dating of Iberian Early Pleistocene sites

2014

Abstract Lozano-Fernandez et al. (2013a) have recently published a method intended for numerical dating of Early Pleistocene sites, which is based on the assumption of uniform, constant rate increase through time of mean lower molar tooth length of water voles ( Mimomys savini ) in a number of levels sampled in the stratigraphic sequence of Atapuerca TD site. They suggest that the regression equation obtained in this local section for site chronology on tooth size could be useful for estimating the numerical age of other localities from southwestern Europe. However, in our opinion this biostratigraphic approach has severe conceptual and methodological problems, which discourage its use as a…

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…

The seasonal water temperature cycle in the Arctic Dicksonfjord (Svalbard) during the Holocene Climate Optimum derived from subfossil Arctica islandi…

2015

Future climate change will have significant effects on ecosystems worldwide and on polar regions in particular. Hence, palaeo-environmental studies focussing on the last warmer-than-today phase (i.e. the early Holocene) in higher latitudes are of particular importance to understand climate development and its potential impact in polar systems. Molluscan bivalve shells constitute suitable bio-archives for high-resolution palaeo-environmental reconstructions. Here, we present a first reconstruction of early Holocene seasonal water temperature cycle in an Arctic fjord based on stable oxygen isotope (δ18Oshell) profiles in shells of Arctica islandica (Bivalvia) from raised beach deposits in Di…

Neanderthal firewood management: Evidence from Stratigraphic Unit IV of Abric del Pastor (Eastern Iberia)

2015

This paper presents anthracological data from Abric del Pastor (Alcoi, Spain), a Middle Paleolithic rock shelter site. Analysis of 1077 wood charcoal remains from Stratigraphic Unit IV (S.U. IV), collected within archaeological combustion structures and from loose sediment outside of structures, allowed us to characterise the local landscape, as well as to approach the interaction between Neanderthal groups and their local environment. Taxonomic identification suggests that firewood was gathered from nearby sources, with predominance of juniper (Juniperus sp.) followed by thermophilous shrubby taxa. Additional analysis focussing on post-depositional processes affecting charcoal have shown f…

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…