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Registros recuperados: 3
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Caractéristiques physiques et chimiques fines des cendres volcaniques : application à la téphrostratigraphie ArchiMer
Jouannic, Gwénolé.
The challenge of this work was to carry out several tephrostratigraphic studies in various sedimentary environments in order to test the efficiency of classical detection methods of tephra layers. First, analysis has been focused on tephra keys, previously studied in known sites, in Belgium and in the Jura Mountains, in order to update data with current analytical techniques. This work was later expanded to sites from eastern French Massif Central, an area with unexploited tephrostratigraphic potential, which offers the possibility to precise the source of cryptotephras identified in the Jura and Switzerland whose origin was uncertain. This work has been carried out in tephras sampled in loess, carbonate maris and peat allowing to discuss conservation...
Tipo: Text Palavras-chave: Téphra; Jura; Massif Central; Belgique; Diatomées; Imagerie scanner; XRF; Susceptibilité magnétique; Pyroclastites -- Jura (massif); Pyroclastites; Pyroclastites -- Liège (Belgique; Région); Stratigraphie; Téphrochronologie; Tephra; French Massif Central; Belgium; Diatoms; CT Scan; Magnetic susceptibility.
Ano: 2015 URL: https://archimer.ifremer.fr/doc/00506/61720/65688.pdf
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Changes in magnetic susceptibility and grain size of Holocene sediments of the Pearl River estuary and climate changes reflected by them. OceanDocs
Cao, Linglong; Wang, Ping; Wang, Jianhua; Wang, Xiaojing; Yang, Jie.
Through the Pearl River Estuary Wan Qing-sha W2 core AMS 14C dating of sediments, combining with paleomagnetic test, pollen analysis, and comprehensive comparison with other relevant records, the regional framework of Holocene age was established. Using the combined feature grain size and magnetic susceptibility proxies for the environment, climate change information in the area since about 6 000 cal yr BP was obtained. The result showed the area since the middle Holocene had experienced three stages climate changes of warm and dry - cool and wet temperature and humidity. South area of China in the late Holocene climate (especially rainfall) had important changes, corresponding to the Northern Hemisphere solar radiation reducing, air temperature...
Tipo: Journal Contribution Palavras-chave: Grain size; Magnetic susceptibility; Holocene; Palaeoclimate.
Ano: 2012 URL: http://hdl.handle.net/1834/5851
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Magnetic and spectral signatures of Cerrado soils in the state of Goiás, Brazil PAB
Fernandes,Kathleen Lourenço; Ribon,Adriana Aparecida; Marques Junior,José; Bahia,Angélica Santos Rabelo de Souza; Tavares Filho,João.
Abstract: The objective of this work was to estimate the iron oxide contents (hematite and goethite) and to characterize the color and the spectral and magnetic signatures of Cerrado soils in the state of Goiás, Brazil. Six Oxisols and one Inceptisol were studied. Spectral and magnetic signatures were determined by diffuse reflectance spectroscopy (DRS) and magnetic susceptibility, respectively. Then, the spectral curves and the second derivative calculations were used to determine hematite and goethite contents, as well as soil color after conversion into tristimulus values. Hematite and goethite contents were also obtained by x-ray diffractometry, and soil color was also defined in the field (Munsell color chart). The values for the isomorphic...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Diffuse reflectance spectroscopy; Goethite; Hematite; Magnetic susceptibility; Oxisols.
Ano: 2017 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-204X2017001000923
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