Search results for "dating"

Transcranial direct current stimulation over the right DLPFC selectively modulates subprocesses in working memory

2018

Background Working memory, as a complex system, consists of two independent components: manipulation and maintenance process, which are defined as executive control and storage process. Previous studies mainly focused on the overall effect of transcranial direct current stimulation (tDCS) on working memory. However, little has been known about the segregative effects of tDCS on the sub-processes within working memory. Method Transcranial direct current stimulation, as one of the non-invasive brain stimulation techniques, is being widely used to modulate the cortical activation of local brain areas. This study modified a spatial n-back experiment with anodal and cathodal tDCS exertion on th…

Millennial-scale phase relationships between ice-core and Mediterranean marine records: insights from high-precision 40Ar/39Ar dating of the Green Tu…

2013

International audience; With the advent of annually-resolved polar ice records extending back to 70 ka, marine and continental paleoclimate studies have now matured into a discipline where high-quality age control is essential for putting on an equal pace layer-counted timescale models and Late Quaternary sedimentary records. High-resolution U-Th dating of speleothem records and 40Ar/39Ar dating of globally recorded geomagnetic excursions have recently improved the time calibration of Quaternary archives, reflecting the cross-disciplinary effort made to synchronize the geologic record at the millennial scale. Yet, tie-points with such an absolute age control remain scarce for paleoclimatic …

Last Glacial Human Settlement in Eastern Cantabria (Northern Spain)

2002

While the excavation of individual sites remains fundamental to the creation of the Palaeolithic archeological record, increasingly the focus of prehistoric research is on human adaptations to and within natural regions. Such a reorientation implies viewing sites and occupations as samples of different suites of activities in various habitats across space and time; it is dependent on the use of radiocarbon to date and relate occupation residues among sites; and it necessitates the application of methods to uncover patterns of human mobility as an integral aspect of subsistence economy, demographic arrangements and social relations. This paper contributes to the regional study of Last Glacia…

Precise chronology of Polynesian temple construction and use for southeastern Maui, Hawaiian Islands determined by 230Th dating of corals

2015

International audience; Emergent archaic states in pre-contact Hawai'i used a ritual control hierarchy implemented through a system of temples to manage production, extract tribute, and reinforce the legitimacy of the ruling elites. Based on a limited sample of precise 230Th dates from coral offerings on Maui Island temples it had been hypothesized that this temple system rapidly expanded during the period from A.D. 1580–1640. We tested this hypothesis by obtaining an expanded sample of 39 new 230Th coral dates from temples in Kahikinui District, and one sample from the summit of a cinder cone that likely had ritual significance. Combined with seven coral dates previously obtained, this yie…

Illuminating Intcal During the Younger Dryas

2020

As the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any…

Mas d’Is (Penàguila, Alicante): farms and Early Neolithic causewayed camps in the Serpis valley

2003

In this paper, results from recent archaeological field work carried out in the Neolithic village of Mas d’Is (Penaguila, Alicante) are presented. We focus on an important set of domestic and monumental architectural structures. Integration of data from the site in a regional context allows us to rethink the social relations of the first farmers in the area. At the same time, radiocarbon data from our excavations show a finer chronology of the neolithization in Western Mediterranean, and what is more important to approach its historical process.

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…

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…

2017

Ranking among the largest volcanic eruptions of the Common Era (CE), the ‘Millennium Eruption’ of Changbaishan produced a widely-dispersed tephra layer (known as the B-Tm ash), which represents an important tie point for palaeoenvironmental studies in East Asia. Hitherto, there has been no consensus on its age, with estimates spanning at least the tenth century CE. Here, we identify the cosmogenic radiocarbon signal of 775 CE in a subfossil larch engulfed and killed by pyroclastic currents emplaced during the initial rhyolitic phase of the explosive eruption. Combined with glaciochemical evidence from Greenland, this enables us to date the eruption to late 946 CE. This secure date rules out…