Le système régional d'action éolienne (SRAE) du bassin de l'Aral (Kazakhstan,Ouzbékistan et Turkménistan)The regional Aeolian action system of the Aral Basin     

Monique Mainguet  René Létolle  Frédéric Dumay 《Comptes Rendus Geoscience》2002,334(7):475-480

The endorheic basin of the Aral Sea, a tectonic depression resulting from two Tertiary fault bundles, NNE–SSW and east–west ones, represents the termination of a flow by closure of the Aral Basin opposite Central Asia and Siberia. The conditions of Quaternary climate and sediment deposition, especially aridity increased by coldness, a pedogenesis inhibitor, and absence of palaeosoils favour the activity of the Aralian Regional Aeolian Action System (RAAS), 700 km long. Such a system develops in a lowland topography where wind, in a progressive shift, reconstructs by deflation the sandy material resulting from Pleistocene accumulations, gives rise to thin and vulnerable ergs and explains at once the fertility of Khoresm and the dewatering of the Aral Sea, which is one of the most complex and severe ecological catastrophe in the 20th century. To cite this article: M. Mainguet et al., C. R. Geoscience 334 (2002) 475–480.  相似文献   

Démantèlement des paysages cuirassés anciens en zones forestières tropicales d'Afrique centrale : formation d'accumulations ferrugineuses actuelles en bas de versantOld ferricrete landscape dismantling in Central Africa rain forest zone: formation of the present downslope iron accumulations     

Émile Temgoua  Dieudonné Bitom  Paul Bilong  Yves Lucas  Hans-Rudolf Pfeifer 《Comptes Rendus Geoscience》2002,334(8):537-543

Present downslope iron accumulations were investigated in the rainforest zone in southern Cameroon. Six clay and Fe-hydroxide dominated patterns have been identified and occur on the lower part of hill slopes. They can be subdivided in three different sequences, related to gentle, moderate or steep slopes. They are discontinuous with respect to the dismantling zone of the old ferricrete cap formed at Cretaceous period. They show a gradual development from a soft Fe-crust (carapace) to a vesicular facies that will, with time, cover the whole landscape again. To cite this article: É. Temgoua et al., C. R. Geoscience 334 (2002) 537–543.  相似文献   

Evolution quantitative à long terme des rotifères au cours de l'eutrophisation du Lac Léman     

Gérard Balvay  Monique Laurent 《Aquatic Sciences - Research Across Boundaries》1990,52(2):162-175

Eutrophication in Lake Geneva (= Lake Léman) appears primarily as changes in chemical characteristics and plankton populations, inducing quantitative changes in the rotifer assemblages and species combinations.In the course of eutrophication, an increase of the rotifer abundance was found, together with settlement of new species and increase of eutrophication tolerant species, and despite the decrease or disappearance of eutrophication sensitive species.The new equilibrium in the trophic state of Lake Geneva related with the decreasing inputs of nutrients, induces a new structure and less abundance of the total pelagic rotatorian community.

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Meta-igneous origin of Hercynian peraluminous granites in N.W. French Massif Central: implications for crustal history reconstructions     

Laurent Turpin  Michel Cuney  Marc Friedrich  Jean-Luc Bouchez  Monique Aubertin 《Contributions to Mineralogy and Petrology》1990,104(2):163-172

Seventy samples of Hercynian peraluminous granites (Guéret, Millevaches and Saint Sylvestre massifs) and metamorphic units of the Limousin area were analysed for Rb–Sr and Sm–Nd. The source rocks of the peraluminous granites can be found in the metamorphic rocks of Limousin, among them meta-igneous rocks were largely predominent over meta-sedimentary rocks in the source of the three granites. Millevaches and Guéret granites were generated by the partial melting of rocks comprising meta-volcanics and meta-sediments, whereas the Saint Sylvestre granite was produced exclusively by the melting of late Precambrian granites. This leads to confusing T _DM ^Nd values, the confusion being amplified by the segregation of monazite during the petrogenetic evolution of the peraluminous granites, which leads to dramatic fractionation in Sm/Nd ratios. The data of the present study tend to demonstrate that peraluminous granites do not give a good representation of isotopic mean crustal estimates. Late Precambrian time seems, however, to have been a period of extensive crustal generation in Western Europe.  相似文献   

The influence of trade winds,local air-masses and topographic obstacles on the aeolian movement of sand particles and the origin and distribution of dunes and ergs in the Sahara and Australia     

Monique Mainguet 《Geoforum》1978,9(1):17-28

The Saharan ergs consist of a wide range of aeolian land forms, while in Australia, sand-ridges are the main form. The ergs are situated along major sandflows of continental extent along which sand is transported. These are oriented approximately from NE to SW in the Sahara. In Australia they form an anticlockwise pattern open to the west. The spatial and temporal factors that govern the origin of sand-ridges are reviewed.  相似文献   

Les Rotifères du lac Léman     

Gérard Balvay  Monique Laurent 《Aquatic Sciences - Research Across Boundaries》1981,43(1):126-139

The published literature on the zooplankton of Lake Léman has been reviewed and all specific names were rewritten according to the valid nomenclature. Some dubious species are reinstated in a new systematical position. Four species are new for the Lake Léman.  相似文献   

Catastrophes and earth history. The new uniformitarianism : Edited by W. A. Berggren & John A. Van Couvering. 464 pp. Princeton University Press, Princeton, U.S.A. $19.50     

Spencer G. Lucas  Adrian Hunt 《Cretaceous Research》1985,6(4):387-389

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Remote Sensing and Geophysical Investigations of Glacial Buried Valleys in Northeastern Kansas     

Jane E. Denne  Harold L. Yarger  P. Allen Macfarlane  Ralph W. Knapp  Marios A. Sophocleous  James R. Lucas  Don W. Steeples 《Ground water》1984,22(1):56-65

Aquifers found in glacial buried valleys are a major source of good-quality ground water in northeastern Kansas. The extent and character of many of these deposits are not precisely known, so a detailed study of the buried valleys was undertaken. Test drilling, Landsat imagery, shallow-earth temperature measurements, seismic refraction, surface electrical resistivity, and gravity data were used to evaluate two sites in Nemaha and Jefferson Counties. Tonal patterns on springtime Landsat imagery and winter/summer anomalies in shallow-earth temperatures were quick and inexpensive methods for locating some glacial buried aquifers and suggested areas for more intensive field studies. Reversed seismic refraction and resistivity surveys were generally reliable indicators of the presence or absence of glacial buried valleys, with most depth determinations being within 25% of test-drilling results. The effectiveness of expensive test-hole drilling was greatly increased by integrating remote sensing, shallow-earth temperature, seismic, and resistivity techniques in the two buried valley test areas. A gravity profile allowed precise definition of the extent of one of the channels after the other techniques had been used for general information.  相似文献   

Mesozoic Paleogeography of the West-central United States Rocky Mountain Paleogeography Symposium 2     

S.G. Lucas  N.J. Mateer 《Cretaceous Research》1984,5(4)

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Mesozoic Paleogeography of the West-central United States Rocky Mountain Paleogeography Symposium 2 | Edited by M.W. Reynolds & E.D. Dolly. 391 pp. The Rocky Mountain Section of the Society of Economic Paleontologists and Mineralogists,Denver, U.S.$17.00     

S.G. Lucas  N.J. Mateer 《Cretaceous Research》1984,5(4):381-383

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