SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Scheel-Ybert,Rita; Macario,Kita; Buarque,Angela; Anjos,Roberto M.; Beauclair,Mariana.

This paper presents unexpectedly early dates for a Tupiguarani settlement in Southeastern Brazil. One radiocarbon dating of 1740 ± 90 yr BP (1820-1390 cal yr BP) was already available for the Morro Grande site (Araruama, southeastern coast of Rio de Janeiro State). Two new dates, obtained from charcoal samples, are reported here. An age of 2920 ± 70 yr BP (3220-2790 cal yr BP) was obtained from a specialized hearth, probably used for cooking ceramics; a funerary hearth at the same archaeological locus was dated at 2600 ± 160 yr BP (3000-2150 cal yr BP). Both measurements were made independently, indifferent laboratories, arguing for their validity. These results considerably age the arrival time of Tupiguarani populations to the coastal region of...

A paleomagnetic approach toward refining Holocene radiocarbon-based chronologies: Paleoceanographic records from the north Iceland (MD99-2269) and east Greenland (MD99-2322) margins

Palavras-chave: Radiocarbon dating; Prehistoric occupation; Archaeology; Tupiguarani; Brazil.

Ano: 2008

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000400015

Stoner, Joseph S.; Jennings, Anne; Kristjansdottir, Greta B.; Dunhill, Gita; Andrews, John T.; Hardardottir, Jorunn.

We report the intercalibration of paleomagnetic secular variation (PSV) and radiocarbon dates of two expanded postglacial sediment cores from geographically proximal, but oceanographically and sedimentologically contrasting settings. The objective is to improve relative correlation and chronology over what can be achieved with either method alone. Core MD99-2269 was taken from the Hunafloaall Trough on the north Iceland shelf. Core MD99-2322 was collected from the Kangerlussuaq Trough on the east Greenland margin. Both cores are well dated, with 27 and 20 accelerator mass spectrometry (14)C dates for cores 2269 and 2322, respectively. Paleomagnetic measurements made on u channel samples document a strong, stable, single-component magnetization. The...

Tipo: Text

Palavras-chave: Holocene; Paleomagnetic secular variation; Radiocarbon dating.

Ano: 2007

URL: https://archimer.ifremer.fr/doc/00233/34436/32934.pdf

Australian Summer Monsoon variability in the past 14,000 years revealed by IODP Expedition 356 sediments

Ishiwa, Takeshige; Yokoyama, Yusuke; Reuning, Lars; Mchugh, Cecilia M.; De Vleeschouwer, David; Gallagher, Stephen J..

The International Ocean Discovery Program (IODP) Expedition 356 Site U1461 cored a Miocene to Holocene sedimentary sequence in the upper bathyal carbonate offshore northwestern Australia (NWA). The siliciclastic component of these strata is primarily derived from the Australian continent. Radiocarbon dating on macrofossils and planktonic foraminifera shows that the upper 14 m section at Site U1461 preserves Holocene sediments, recording regional climate variability. K/Ca ratios determined by X-ray fluorescence elemental analyses and %K determined by shipboard natural gamma ray analysis are interpreted as indicators of riverine run-off from the Australian continent. We document the consequences of the variability of the Australian Summer Monsoon (ASM) on...

Tipo: Text

Palavras-chave: International Ocean Discovery Program Expedition 356; Australian Summer Monsoon; Radiocarbon dating; Holocene climate variability; Northwestern Australia.

Ano: 2019

URL: https://archimer.ifremer.fr/doc/00496/60780/65034.pdf

Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation

Callard, S. Louise; Cofaigh, Colm O.; Benetti, Sara; Chiverrell, Richard C.; Van Landeghem, Katrien J. J.; Saher, Margot H.; Gales, Jenny A.; Small, David; Clark, Chris D.; Stephen, J. Livingstone; Fabel, Derek; Moreton, Steven G..

During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BITS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we...

Tipo: Text

Palavras-chave: British-Irish Ice Sheet; Glacimarine; Last glacial maximum; Radiocarbon dating; Ice-sheet retreat; Grounding-zone wedges.

Ano: 2018

URL: https://archimer.ifremer.fr/doc/00504/61588/65891.pdf

Mid- to Late-Holocene estuarine infilling processes studied by radiocarbon dates, high resolution seismic and biofacies at Vitoria Bay, Espirito Santo, Southeastern Brazil

Bastos,Alex C.; Vilela,Claudia G.; Quaresma,Valéria S.; Almeida,Fabiana K..

Vitoria Bay is a 20 km long estuary, morphologically narrow, with a microtidal regime and, as other modern estuaries, was formed during the last post-glacial transgression. The estuarine bed morphology is characterised by a main natural channel limited by tidal flats with developed mangroves. Original radiocarbon dates were obtained for the site. Five radiocarbon ages ranging from 1,010 to 7,240 years BP were obtained from two sedimentary cores, which represent a 5 m thick stratigraphic sequence. The results indicate that, until about 4,000 cal. yrs BP, environmental conditions in Vitoria Bay were still of an open bay, with a free and wide connection with marine waters. During the last 4,000 yrs, the bay has experienced a major regression phase, by...

Pedochronology and development of peat bog in the environmental protection area pau-de-fruta - Diamantina, Brazil

Palavras-chave: High-resolution seismic; Holocene estuarine evolution; Radiocarbon dating; Vitoria Bay; Biofacies.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000300022

Rev. Bras. Ciênc. Solo

Campos,José Ricardo da Rocha; Silva,Alexandre Christófaro; Vasconcellos,Leandro Lara; Silva,Daniel Valladão; Romão,Rafael Vitor; Silva,Enilson de Barros; Grazziotti,Paulo Henrique.

In the region of the Serra do Espinhaço Meridional, peat bog is formed in hydromorphic environments developed in sunken areas on the plain surfaces with vegetation adapted to hydromorphic conditions, favoring the accumulation and preservation of organic matter. This pedoenvironment is developed on the regionally predominant quartzite rocks. Peat bog in the Environmental Protection Area - APA Pau-de-Fruta, located in the watershed of Córrego das Pedras, Diamantina,Brazil, was mapped and three representative profiles were morphologically characterized and sampled for physical, chemical and microbiological analyses. The organic matter was fractionated into fulvic acid (FA), humic acids (HA) and humin (H). Two profiles were sampled to determine the radiocarbon...

Radiocarbon age of late glacial deep water from the equatorial Pacific

Palavras-chave: Organosols; Soil organic matter; Humic substances; Microbial activity; Radiocarbon dating; Δ13C.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832010000600021

Tectonic control on the stratigraphic framework of Late Pleistocene and Holocene deposits in Marajó Island, State of Pará, eastern Amazonia

Broecker, Wallace; Clark, Elizabeth; Barker, Stephen; Hajdas, Irena; Bonani, Georges; Moreno, Eva.

Radiocarbon age differences for pairs of coexisting late glacial age benthic and planktic foraminifera shells handpicked from 10 sediment samples from a core from a depth of 2.8 km in the western equatorial Pacific are not significantly different from that of 1600 years calculated from measurements on prenuclear seawater. This places a lower limit on the depth of the interface for the hypothetical radiocarbon-depleted glacial age seawater reservoir required to explain the 190% drop in the (14)C/C for atmospheric CO(2), which occurred during the mystery interval (17.5 to 14.5 calendar years ago). These measurements restrict the volume of this reservoir to be no more than 35% that of the ocean. Further, (14)C measurements on a single Last Glacial Maximum age...

Tipo: Text

Palavras-chave: Ocean circulation; Mystery interval; Radiocarbon dating.

Ano: 2007

URL: https://archimer.ifremer.fr/doc/00233/34449/32884.pdf

Rossetti,Dilce F..

The traditional view that the Brazilian Amazonia is located in a tectonically stable area since the Cretaceous is changing in front of the increasing documentation of fault reactivations even during the Holocene. How the sedimentary record has responded to these events is an issue that remains to be approached with basis on field data. This work focuses on the stratigraphic correlation of late Quaternary deposits from eastern Marajó Island, with the goal of demonstrating the role of fault reactivation on the origin and preservation of these deposits. Despite the location in a stable platform of a continental passive margin, three studied stratigraphic units display significant vertical offsets that define two depocenters that are better explained through...

The Last Scottish Ice Sheet

Palavras-chave: Amazonia; Tectonics; Quaternary; Stratigraphic framework; Radiocarbon dating; Sedimentation.

Ano: 2010

URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652010000200020

Ballantyne, Colin K.; Small, David.

The last Scottish Ice Sheet (SIS) expanded from a pre-existing ice cap after ∼35 ka. Highland ice dominated, with subsequent build-up of a Southern Uplands ice mass. The Outer Hebrides, Skye, Mull, the Cairngorms and Shetland supported persistent independent ice centres. Expansion was accompanied by ice-divide migration and switching flow directions. Ice nourished in Scotland reached the Atlantic Shelf break in some sectors but only mid-shelf in others, was confluent with the Fennoscandian Ice Sheet (FIS) in the North Sea Basin, extended into northern England, and fed the Irish Sea Ice Stream and a lobe that reached East Anglia. The timing of maximum extent was diachronous, from ∼30–27 ka on the Atlantic Shelf to ∼22–21 ka in Yorkshire. The SIS buried all...

Tipo: Text

Palavras-chave: British-Irish Ice Sheet; Deglaciation; Dimlington Stade; Flowsets; Ice streams; Late Devensian; Lithostratigraphy; Radiocarbon dating; Readvances; Terrestrial cosmogenic nuclide dating.

Ano: 2019

URL: https://archimer.ifremer.fr/doc/00505/61627/65539.pdf

The Late Holocene upper montane cloud forest and high altitude grassland mosaic in the Serra da Igreja, Southern Brazil

SCHEER,MAURICIO B.; CURCIO,GUSTAVO R.; RODERJAN,CARLOS V..

Many soils of the highlands of Serra do Mar, as in other mountain ranges, have thick histic horizons that preserve high amounts of carbon. However, the age and constitution of the organic matter of these soils remain doubtful, with possible late Pleistocene or Holocene ages. This study was conducted in three profiles (two in grassland and one in forest) in Serra da Igreja highlands in the state of Paraná. We performed δ13C isotope analysis of organic matter in soil horizons to detect whether C3 or C4 plants dominated the past communities and 14C dating of the humin fraction to obtain the age of the studied horizons. C3 plants seem to have dominated the mountain ridges of Serra da Igreja since at least 3,000 years BP. Even though the Serra da Igreja may...