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Registros recuperados: 48 | |
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Freitas,Aline Gonçalves de; Carvalho,Marcelo de Araujo; Mendonça,Claudia Barbieri Ferreira; Gonçalves-Esteves,Vania. |
Here, we describe pollen grains extracted from a Pleistocene-Holocene sediment core (BU-91-GL-05; 22°48'45"S; 41°54'13"W) taken from the Albacora Slope (22°48'45"S; 41°54'13"W), located in the Campos Basin of the northern region of the state of Rio de Janeiro, Brazil. The analysis resulted in the identification and morphological description of 46 types of pollen: one of a gymnosperm genus (Podocarpus); and 45 of angiosperm taxa across 27 families-one family of monocotyledons (Poaceae) and 26 families (30 types) of dicotyledons. The most common angiosperm families were Amaranthaceae (Chenopodium, Amaranthus and Gomphrena); Fabaceae (Fabaceae type, Bauhinia, Inga and Canavalia); Malpighiaceae (Tetrapteris, Heteropteris and Peixotoa); Malvaceae (Sida,... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Palynology; Pollen descriptions; Paleovegetation; Quaternary; Campos Basin. |
Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062013000400016 |
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Sá,Natália de Paula; Absy,Maria Lúcia; Soares,Emílio Alberto Amaral. |
ABSTRACT The core PD-67 of 160 cm depth was collected from the delta of Lake Cabaliana situated on the Solimões River. Seventeen samples were removed for palynological and sedimentological analysis and three for radiocarbon analysis. Two dry periods, both in the Late Holocene, were observed (2800-2550 cal yr BP, 1450-550 cal yr BP) separated by a wetter phase (2550-1450 cal yr BP). In 2800-2550 cal yr BP, varzea forests of Alchornea, Symmeria, Cecropia, Alternanthera and Asteraceae were predominant. Beginning in 2,550-1450 cal yr BP, the varzea was characterized by pioneer elements, such as Cassia, Laetia, Mabea, Symmeria and Cecropia, and by the expansion of Poaceae, Cyperaceae, Sagittaria, Montrichardia and Asteraceae. In 1450-550 cal yr BP the... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Amazon; Pollen; Quaternary; Rainfall; Terra firme forest. |
Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0102-33062016000300473 |
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Nova,Patricia Villa; Avilla,Leonardo S.; Oliveira,Édison V.. |
The present study acknowledges the diversity of fossil marsupials from the Gruta dos Moura cave, as well as environmental and climatic aspects during the Quaternary. The results show that this is the largest diversity of Pleistocene marsupials recorded in a single cave: Didelphis albiventris, D. aurita, Gracilinanus agilis, G. microtarsus, Marmosa murina, Monodelphis brevicaudata, M. domesticaand Sairadelphys tocantinensis. Furthermore, the described specimens are also part of the only fossil assemblage unequivocally referable to the late Pleistocene. Paleontological studies suggest an intimate association with dry and open environments with high abundance of water sources. Since most of the identified taxa are characteristic of open forests and gallery... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Mammals; Didelphidae; Marsupials; Northern Brazil; Quaternary; Late Pleistocene. |
Ano: 2015 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652015000100193 |
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SOUZA,LENA S.B.; ROSSETTI,DILCE F.; ELIAS,VAGNER R.; PRADO,RENATO L.. |
Studies suggest that the Marajó Island has experienced neotectonic activity during its latest evolution. However, there are no data demonstrating the presence of tectonic structures in its shallow subsurface. This work integrates vertical electric sounding, morphostructural lineaments, and geological data aiming to show fault control on the Late Pleistocene-Holocene sedimentation of this area. Resistivity values were related to mud (< 90 Ωm), clayey sand (90 and 200 Ωm), sand (200 and 500 Ωm), as well as Fe-bearing sand and laterite (> 500 Ωm). The latest values were related to the unconformity with lateritic paleosol at the top of the Barreiras Formation. Despite the values ≤ 500 Ωm of both the Barreiras Formation and the Late Pleistocene-Holocene... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Vertical electric sounding; Faults; Quaternary; Marajó Island; Remote sensing. |
Ano: 2013 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652013000100073 |
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Mahiques,Michel M.; Sousa,Silvia H.M.; Burone,Leticia; Nagai,Renata H.; Silveira,Ilson C.A.; Figueira,Rubens C.L.; Soutelino,Rafael G.; Ponsoni,Leandro; Klein,Daniel A.. |
The aim of this work was to generate an inventory of the data on radiocarbon datings obtained from sediments of the São Paulo Bight (southern Brazilian upper margin) and to analyze the data in terms of Late Quaternary sedimentary processes and sedimentation rates. A total of 238 radiocarbon datings from materials collected using differents ampling procedures was considered for this work. The sedimentation rates varied from less than 2 to 68 cm.kyr-1. The highest sedimentation rate values were found in a low-energy (ría type) coastal system as well as in the upwelling zones of Santa Catarina and Cabo Frio. The lowest rates were found on the outer shelf and upper slopes. Our results confirm the strong dependency of the shelf currents, with an emphasis to the... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Continental margin; Quaternary; Radiocarbon; Sea-level; Sedimentation. |
Ano: 2011 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652011000300006 |
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Rossetti,Dilce F.; Góes,Ana M.. |
Marajó Island shows an abundance of paleochannels easily mapped in its eastern portion, where vegetation consists mostly of savannas. SRTM data make possible to recognize paleochannels also in western Marajó, even considering the dense forest cover. A well preserved paleodrainage network from the adjacency of the town of Breves (southwestern Marajó Island) was investigated in this work combining remote sensing and sedimentological studies. The palimpsest drainage system consists of a large meander connected to narrower tributaries. Sedimentological studies revealed mostly sharp-based, fining upward sands for the channelized features, and interbedded muds and sands for floodplain areas. The sedimentary structures and facies successions are in perfect... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Remote sensing; Sedimentology; Paleochannel; Marajó Island; Quaternary. |
Ano: 2008 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652008000300017 |
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FERREIRA,THAIS M.F.; OLIVARES,ADRIANA ITATI; KERBER,LEONARDO; DUTRA,RODRIGO P.; AVILLA,LEONARDO S.. |
ABSTRACT Echimyidae (spiny rats, tree rats and the coypu) is the most diverse family of extant South American hystricognath rodents (caviomorphs). Today, they live in tropical forests (Amazonian, coastal and Andean forests), occasionally in more open xeric habitats in the Cerrado and Caatinga of northern South America, and open areas across the southern portion of the continent (Myocastor). The Quaternary fossil record of this family remains poorly studied. Here, we describe the fossil echimyids found in karst deposits from southern Tocantins, northern Brazil. The analyzed specimens are assigned to Thrichomys sp., Makalata cf. didelphoides and Proechimys sp. This is the first time that a fossil of Makalata is reported. The Pleistocene record of echimyids... |
Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Caviomorphs; Echimyidae; Fossil record; Quaternary; South America. |
Ano: 2016 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0001-37652016000300829 |
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Berben, Sarah M.p.; Dokken, Trond M.; Abbott, Peter M.; Cook, Eliza; Sadatzki, Henrik; Simon, Margit H; Jansen, Eystein. |
Understanding the dynamics that drove past abrupt climate changes, such as the Dansgaard-Oeschger (DO) events, depends on combined proxy evidence from disparate archives. To identify leads, lags and synchronicity between different climate system components, independent and robust chronologies are required. Cryptotephrochronology is a key geochronological tool as cryptotephra horizons can act as isochrons linking disparate and/or distant records. Here, we investigated marine sediment core MD99-2284 from the Norwegian Sea to look for previously identified Greenland ice core cryptotephra horizons and define time-parallel markers between the archives. We explored potential secondary transport and depositional mechanisms that could hamper the isochronous... |
Tipo: Text |
Palavras-chave: Quaternary; Paleoclimatology; Paleoceanography; North Atlantic; Sedimentology; Marine cores; Ice cores; Cryptotephrochronology; DO-Events; Synchronization. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00622/73391/72606.pdf |
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Cabioch, G; Correge, T; Turpin, L; Castellaro, C; Recy, J. |
In New Caledonia, core data indicate that the fringing reefs grew during the last interglacial and the Holocene, while the barrier reefs developed during several high sea level stands of the Quaternary. These growth periods are archived in a 128-m-long core from Ilot Amedee, offshore of Noumea. Directly upon the peridotitic substrate (reached at 126.50 m), a basal unit comprising abundant rhodoliths, molluscs and rare corals is characteristic of the pioneer stage of barrier reef development. Above it, a severely calcitized unit contains corals, molluscs and abundant micritic levels. Then, a sequence punctuated by several minor discontinuities and by a downward increase in diagenetic alteration is found. At 47 m core depth, a unit, which is thought to be... |
Tipo: Text |
Palavras-chave: Croissance récifale; Néotectonique; Nouvelle-Calédonie; Quaternaire; Reef growth; Neotectonics; New Caledonia; Quaternary. |
Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/00325/43582/44021.pdf |
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Bassetti, Maria-angela; Berne, Serge; Jouet, Gwenael; Taviani, M; Dennielou, Bernard; Flores, J; Gaillot, Arnaud; Gelfort, R; Lafuerza, S; Sultan, Nabil. |
Thick forced regressive units on the wide continental shelf of the Gulf of Lions (western Mediterranean) recorded the composite effect of sea level changes during the Quaternary. They are mostly composed of coastal siliciclastic and bioclastic wedges showing clinoform geometry. These deposits have been intensively explored through high-resolution seismic investigations, but only recently it was possible to ground truth seismic interpretations, based on a long (100 m) borehole that crossed the succession and recovered a large part of the mainly sandy deposits (similar to 84% recovery). A multiproxy analysis of the sedimentary succession shows that (1) the stratal architecture of the shelf margin is defined by major bounding surfaces that are polygenic... |
Tipo: Text |
Palavras-chave: Paleoclimate; Mediterranean; Quaternary; Shoreface. |
Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4929.pdf |
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Berger, A.; Crucifix, M.; Hodell, D. A.; Mangili, C.; Mcmanus, J. F.; Otto-bliesner, B.; Pol, K.; Raynaud, D.; Skinner, L. C.; Tzedakis, P. C.; Wolff, E. W.; Yin, Q. Z.; Abe-ouchi, A.; Barbante, C.; Brovkin, V.; Cacho, I.; Capron, E.; Ferretti, P.; Ganopolski, A.; Grimalt, J. O.; Hoenisch, B.; Kawamura, K.; Landais, A.; Margari, V.; Martrat, B.; Masson-delmotte, V.; Mokeddem, Zohra; Parrenin, F.; Prokopenko, A. A.; Rashid, H.; Schulz, M.; Riveiros, N. Vazquez. |
Interglacials, including the present (Holocene) period, are warm, low land ice extent (high sea level), end-members of glacial cycles. Based on a sea level definition, we identify eleven interglacials in the last 800,000years, a result that is robust to alternative definitions. Data compilations suggest that despite spatial heterogeneity, Marine Isotope Stages (MIS) 5e (last interglacial) and 11c (similar to 400ka ago) were globally strong (warm), while MIS 13a (similar to 500ka ago) was cool at many locations. A step change in strength of interglacials at 450ka is apparent only in atmospheric CO2 and in Antarctic and deep ocean temperature. The onset of an interglacial (glacial termination) seems to require a reducing precession parameter (increasing... |
Tipo: Text |
Palavras-chave: Interglacials; Review; Quaternary. |
Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00340/45150/44547.pdf |
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Schmitt, A.; Elliot, M.; Thirumalai, K.; La, C.; Bassinot, F.; Petersen, J.; Movellan, A.; Jorry, Stephan; Borgomano, J.. |
The ratio of magnesium to calcium (Mg/Ca) in foraminiferal shells is commonly used as a proxy for past ocean temperature. Recent advances in elemental analyses now enable single-specimen measurements of planktic foraminifera and thus, can provide information on past seasonal and interannual variability, owing to the near-monthly lifespan of foraminifera. In this study, we explore the temperature variance recorded by Mg/Ca in tests of foraminifera Globigerinoides ruber, a planktic species that occurs throughout the year in tropical waters. Using LA-ICP-MS, we characterize Mg/Ca variability in single specimens of two morphotypes of G. ruber picked from a sediment core retrieved offshore New Caledonia. We provide an estimate of the range of calcification... |
Tipo: Text |
Palavras-chave: Globigerinoides ruber; Mg/Ca ratio; Sea surface temperature; LA-ICPMS; Seasonality; Quaternary. |
Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00472/58336/60890.pdf |
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Registros recuperados: 48 | |
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