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17. The use of quantitative mineralogy linked to palynological studies in palaeoenvironmental reconstruction; the case study of the 'Lagoa Campestre' lake, Salitre, Minas Gérais, Brazil

Author

Bertaux, J., Marie-Pierre Ledru, Soubies, F., and Sondag, F.

Subjects
QUATERNAIRE, PALEOENVIRONNEMENT, SEDIMENTATION LACUSTRE, PALYNOLOGIE, MINERALOGIE
Abstract

La comparaison des contenus minéraux déterminés par spectroscopie IRTF et polliniques de sédiments lacustres de la région de Salitre (Brésil) montre que les variations des teneurs en phases minérales répercutent des changements régionaux ou locaux de l'environnement. Une évolution inverse entre couvert forestier et charge détritique des sédiments est observée pendant la phase lacustre pleistocène. La méthode utilisée permet la détection d'un hiatus sédimentaire marqué par un changement brutal du contenu minéral, ainsi que l'évaluation du caractère abrupt de certains changements du couvert végétal qui, en l'absence de datation, pourraient être confondus avec un hiatus sédimentaire. (Résumé d'auteur)

18. Hydrology in the humid tropic environment

Author

Seyler, P., Guyot, J. L., Laurence Maurice, Sondag, F., Elbaz-Poulichet, F., Etcheber, H., Quintanilla, J., Johnson, A.I. (ed.), and Fernandez-Jáuregui, C.A. (ed.)

Subjects
EAU DE SURFACE, ECHANTILLONNAGE, CHIMIE DE L'EAU, ANALYSE EN COMPOSANTES PRINCIPALES, MINE, EVAPORITE, MATIERE EN SOLUTION, ELEMENT CHIMIQUE MAJEUR, FACTEUR ANTHROPIQUE, SCHISTE, OLIGOELEMENT, SUBSTRAT, ELEMENT EN TRACE, COURS D'EAU, GEOCHIMIE, LITHOLOGIE, ANALYSE STATISTIQUE
Abstract

The geochemistry of dissolved trace elements (V, Mn, Co, Ni, Cu, Zn, As, Rb, Sr, Mo, Cd, Sb, Cs, Ba, Pb and U) in the Upper Madeira basin, which constitutes the Bolivian part of the Amazon basin have been investigated. Using a statistical method (principal component analysis), the combined use of these geochemical data together with geological information on each watershed demonstrated the fundamental control of the substrate lithology on the trace chemistry of unpolluted surface waters within the catchment, at least in the Andean part of the basin. Three factors account for 87% of the variance. The first factor represents the influence of solution of evaporite and associated deposits occurring in the Andean Palaeozoic and Cretaceous sections; the second represents the influence of the mining activities being carried out in the Taquesi basin; and the third, the influence of black shale products and arenaceousargillaceous rocks. In spite of the occurrence of evaporite rocks in the Upper Madeira watershed which tend to mask the trace-metal signatures of other lithological formations, it has been possible to discriminate the sources of trace metals present in the Andean and Amazonian Plain rivers.

19. Selective extraction procedures applied to geochemical prospecting in an area contaminated by old mine workings.

Author

Sondag F. and Sondag F.

Abstract

Soil samples were collected from an ore body at Lontzen (Belgium). Selective extraction with ammonium acetate or hydroxylamine hydrochloride discriminates better against contaminated samples, hydroxylamine hydrochloride gives a slightly better contrast between anomalous and background values than other digestions. Samples also underwent non- sequential selective extractions. The calculations of the difference between non-sequential and sequential extractions leads to the localisation of two highly contrasted peaks which correspond exactly with galena-sphalerite veins., Soil samples were collected from an ore body at Lontzen (Belgium). Selective extraction with ammonium acetate or hydroxylamine hydrochloride discriminates better against contaminated samples, hydroxylamine hydrochloride gives a slightly better contrast between anomalous and background values than other digestions. Samples also underwent non- sequential selective extractions. The calculations of the difference between non-sequential and sequential extractions leads to the localisation of two highly contrasted peaks which correspond exactly with galena-sphalerite veins.

20. The use of geochemical methods to characterise the metamorphic domain in the Belgian Ardennes.

Author

Sondag F., Duchesne J.C., Sondag F., and Duchesne J.C.

Abstract

In the Adrennes anticline, the area of low-grade metamorphism is marked by a widespread regional Ti anomaly in stream sediment sampling (Ti contents over 0.17%), due to the appearance of ilmenite in the metamorphosed rocks and its concentration in the sediments. Outside the metamorphosed area, Ti is associated with illite and is not concentrated in stream sediments., In the Adrennes anticline, the area of low-grade metamorphism is marked by a widespread regional Ti anomaly in stream sediment sampling (Ti contents over 0.17%), due to the appearance of ilmenite in the metamorphosed rocks and its concentration in the sediments. Outside the metamorphosed area, Ti is associated with illite and is not concentrated in stream sediments.

21. Selective chemical extraction of uranium from mineral, soil and stream sediment samples at Horta da Vilarica, Northeastern Portugal.

Author

Bolle J.N., Cardoso Fonseca E., Martin H., Sondag F., Bolle J.N., Cardoso Fonseca E., Martin H., and Sondag F.

Abstract

The study aims at the detection of anomalous soils and stream sediments in the vicinity of a mineralised zone and at the use of selective extractions for regional geological mapping. A kinetic study of selectivity of partial chemical extractions applied to minerals of U has been carried out to establish a systematic procedure which could be recommended for soils and stream sediments of areas known to host U mineralisations in Portugal., The study aims at the detection of anomalous soils and stream sediments in the vicinity of a mineralised zone and at the use of selective extractions for regional geological mapping. A kinetic study of selectivity of partial chemical extractions applied to minerals of U has been carried out to establish a systematic procedure which could be recommended for soils and stream sediments of areas known to host U mineralisations in Portugal.

25. Geographical origin of Amazonian freshwater fishes fingerprinted by ⁸⁷Sr/⁸⁶Sr ratios on fish otoliths and scales.

Author

Pouilly M, Point D, Sondag F, Henry M, and Santos RV

Subjects
Animals, Brazil, Geography, Humans, Animal Migration, Fishes metabolism, Fishes physiology, Otolithic Membrane chemistry, Rivers, Strontium Isotopes analysis
Abstract

Calcified structures such as otoliths and scales grow continuously throughout the lifetime of fishes. The geochemical variations present in these biogenic structures are particularly relevant for studying fish migration and origin. In order to investigate the potential of the (87)Sr/(86)Sr ratio as a precise biogeochemical tag in Amazonian fishes, we compared this ratio between the water and fish otoliths and scales of two commercial fish species, Hoplias malabaricus and Schizodon fasciatus, from three major drainage basins of the Amazon: the Madeira, Solimões, and Tapajós rivers, displaying contrasted (87)Sr/(86)Sr ratios. A comparison of the (87)Sr/(86)Sr ratios between the otoliths and scales of the same individuals revealed similar values and were very close to the Sr isotopic composition of the local river where they were captured. This indicates, first, the absence of Sr isotopic fractionation during biological uptake and incorporation into calcified structures and, second, that scales may represent an interesting nonlethal alternative for (87)Sr/(86)Sr ratio measurements in comparison to otoliths. Considering the wide range of (87)Sr/(86)Sr variations that exist across Amazonian rivers, we used variations of (87)Sr/(86)Sr to discriminate fish origin at the basin level, as well as at the sub-basin level between the river and savannah lakes of the Beni River (Madeira basin).

Published
2014
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