Search results for "IGRA"
showing 10 items of 4940 documents
Environmental and climatic controls of the clay mineralogy of Albian deposits in the Paris and Vocontian basins (France)
2020
18 pages; International audience; High-resolution clay mineral analyses were performed on lower and middle Albian deposits from the Paris and Vocontian basins in order to specify the weathering conditions that prevailed at that time. The clay mineral assemblages are composed of small proportions of chlorite and vermiculitic clays associated with abundant illite, R0 type illite-smectite mixed-layers (smectite) and kaolinite. Clay minerals originated from the physical alteration and chemical weathering of rocks and soils outcropping on the Variscan massifs bordering the studied areas. In the Paris Basin, the covariation of illite and kaolinite suggests the reworking of these latter minerals f…
Ancient DNA from European early neolithic farmers reveals their near eastern affinities.
2010
The first farmers from Central Europe reveal a genetic affinity to modern-day populations from the Near East and Anatolia, which suggests a significant demographic input from this area during the early Neolithic.
Neolithic fish remains from the freshwater shell midden Riņņukalns in northern Latvia
2016
The Neolithic site Riņņukalns in the Lake Burtnieks/River Salaca area in northern Latvia is the only freshwater shell midden in the eastern Baltic Sea area. An excavation carried out in 2011 revealed an intact stratigraphy with alternating layers of unburnt and burnt mussel shells and yielded various kinds of archaeological finds, among them several thousand fish remains. To gain an understanding of the fish species and specimens caught by the Neolithic settlers, and to discern any temporal development in the fish species composition, we analysed fish remains from different sections and layers. Results from both the archaeozoological and stable isotope data, give evidence for a change in th…
Annual 14C Tree-Ring Data Around 400 AD: Mid- and High-Latitude Records
2019
ABSTRACTTwo tree-ring series, one from a high-latitude pine tree (located in northern Scandinavia) and one from a mid-latitude oak tree (located in eastern Germany) were analyzed for radiocarbon (14C) at annual resolution. The new records cover the calendar date ranges 290–460 AD and 382–486 AD, respectively, overlapping by 79 yr. The series show similar trends as IntCal13. However, some significant deviations around 400 AD are present with lower Δ14C (higher 14C ages). An average offset between the two new series and IntCal13 of about 20 years in conventional 14C age is observed. A latitudinal 14C offset between the tree sites in central and northern Europe, as would be expected due to the…
Entorno 3D para el análisis y la recreación virtual de las actuaciones arqueológicas en Cueva de la Cocina (Dos Aguas, Valencia, España)
2017
Con este trabajo pretendemos presentar nuestro procedimiento de digitalización de información de campo (gestión de datos) y su imbricación en la reconstrucción estratigráfica virtual (virtualización) de la Cueva de la Cocina (Dos Aguas, Valencia, España). La herramienta principal para la implementación del Sistema de Información Geográfica (SIG) ha sido OpenJUMP, mientras que para la recreación tridimensional (3D) del entorno virtual de la cueva se han utilizado MeshLab, ParaView, CloudCompare y R. De acuerdo con los datos recuperados durante las excavaciones de los últimos años en la cueva -2015 y 2016-, se presenta el estado actual de la virtualización de la estratigrafía en los sectores …
Clay resources and technical choices for neolithic pottery (Chalain, Jura, France): chemical, mineralogical and grain-size analyses
2007
Many authors have considered pottery manufacturing constraints and sociocultural elements as factors in change in past civilizations over time. The main issue of this research is to better understand the reasons for changes, or choices, in pottery raw materials. The very precise and detailed stratigraphy and cultural succession of occupations is based on dendrochronological data from the lake-dwelling sites of Chalain (Jura, France). Petrographic, palaeontological and chemical analyses were used to determine the nature and origins of the raw materials used by the Neolithic potters. Stratigraphy and dendrochronological data were used to reconstruct in detail the evolution dynamics of fabric …
Through diachronic discontinuities and regionalization: The contribution of the analysis of the lithic industries from Grotta della Serratura (Strata…
2019
Abstract Within the evolutionary dynamics of post-Gravettian techno-complexes, one can observe an intense regionalization phenomenon, both on a European scale, with the creation of two main provinces, and within the Italian peninsula. To date, typological studies have led to the recognition of several Italian Epigravettian facies, identifying trends, similarities, and differences in the lithic complexes. An important contribution was made by the technological method which in recent years has allowed us to identify the evolutionary processes of the lithic industries in numerous deposits of northern Italy. It is the intent of this reporting to add information which contributes to the debate o…
Ammonoids and quantitative biochronology - A unitary association perspective
2015
Ammonoid evolutionary changes have long been recognized to be excellent time markers. They are the major macrofossil group to date and correlate Paleozoic and Mesozoic marine strata. Originations and extinctions of ammonoid species are commonly used to define GSSPs and build high resolution biozonations. Biochronology is now an advanced field with the recent development of computerized, quantitative methods yielding robust biochronological schemes. It has been demonstrated that such quantitative biochronological methods are very efficient to resolve (often complex) biostratigraphic contradictions and produce accurate and high resolution biozonations, thus enabling precise dating and correla…
Causes and consequences of past and projected Scandinavian summer temperatures, 500-2100 AD
2011
Tree rings dominate millennium-long temperature reconstructions and many records originate from Scandinavia, an area for which the relative roles of external forcing and internal variation on climatic changes are, however, not yet fully understood. Here we compile 1,179 series of maximum latewood density measurements from 25 conifer sites in northern Scandinavia, establish a suite of 36 subset chronologies, and analyse their climate signal. A new reconstruction for the 1483–2006 period correlates at 0.80 with June–August temperatures back to 1860. Summer cooling during the early 17th century and peak warming in the 1930s translate into a decadal amplitude of 2.9°C, which agrees with existin…
The global bio-events at the Cenomanian-Turonian transition in the reduced Bahloul Formation of Bou Ghanem (central Tunisia).
2010
In central Tunisia, the thickness of the Bahloul Formation varies generally between 20 to 40 m such as for example, respectively, at wadi Smara near Kalaat Senan and at wadi Bahloul near Maktar. The thickness is also of several tens metres at Koudiat el Azreg near Jerissa and at Tajerouine. In these sites where the thickness of the Bahloul Formation is dilated, in addition to five geochemical events (d13C), nine bio-events were defined near the Cenomanian-Turonian transition, successively in ascending order: 1. LO Rotalipora cushmani, 2. Heterohelix bio-event, 3. FO Pseudaspidoceras pseudonodosoides, 4. LO P. pseudonodosoides, 5. LO Thalmanninella multiloculata, 6. “filaments” bio-event, Ce…