Présentation des travaux des chercheurs des facultés universitaires Notre-Dame de la Paix concernant les corrélations pollens-diatomées et les interprétations des paléoclimats liées aux diatomées.
Etude de l'isolement de deux bassins lacustres et de la régression marine dans la région de Kuujjuaq à l'aide de l'analyse des diatomées. Mise en évidence du grand potentiel de l'analyse des diatomées pour la reconstruction précise de courbes de
Sedimentary, palynological and diatom data from a dunefield lake deposit in the interior of Vanderlind Island are presented. The AA. use the pollen-based precipitation indices from Walala with additional paleohydrological inferences obtained from
diatoms to test the northern Australia effective precipitation model.
Succession of diatom phases in Late-Glacial lacustrine deposits at Niechorze, western Pomerania, Poland, permits recognition of two main stages in development of the basin. The early stage/Oldest Dryas, Bolling and the beginning of Older Dryas
/is distinctive in discontinuities in diatom distribution resulting from sedimentary disturbances, and in poorly preserved and species-poor diatom assemblages dominated by Fragilaria pinnata. Diatoms were very aboundant at the late stage /the decline of Older
Dryas, Allerod, and Younger Dryas/ and their ubiquity indicates and increased stability in the pattern of limnic sedimentation. At the late stage of basin development, the diatom assemblage was dominated by Fragilaria construens var. venter and F
Postglacial diatom stratigraphy of Kirchner Marsh, Minnesota
Amérique du Nord ; Diatomée ; Etats-Unis ; Géographie physique ; Holocène ; Kirchner marsh ; Limnologie ; Minnesota ; Paléohydrologie ; Quaternaire zones moyennes
Fossil diatom assemblages from a 12-m core from Kirchner Marsh were compared with modern surface assemblages from 159Minnesota and Labrador lakes using cluster analysis. The deepest levels of the core (spruce pollen zone 13,000 to 10,200yr BP
) resemble modern diatom assemblages from deep oligotrophic lakes of northeastern Minnesota. Diatom assemblages of the pine pollen zone (about 10,200 to 9,500yr BP) have few modern analogs. In the oak zone (9,500yr BP to present) after a brief pulse of diatom
, Geological Society of America Bulletin 77, 1339-1360) show that this shift to shallow-water diatoms occurred when aquatic macrophytes appeared at the site in abundance.
This tentative approach shows that freshwater diatoms in Atlantic cores may be a good tool for reconstructing paleoclimates and for establishing continent-ocean correlations if species analyses are made and if the continental distribution
Late Quaternary paleoceanography of the western Baffin Bay region : evidence from fossil diatoms
Arctique ; Diatomée ; Géographie des régions polaires ; Holocène ; Mer de Baffin ; Paléo-océanographie ; Paléobiogéographie ; Paléoclimatologie ; Quaternaire
Résultats des variations du contenu en diatomées de sept carottes marines prélevées sur la côte orientale de l'île Baffin et reconstitution des conditions paléo-océanographiques de l'Holocène.
Présentation de la séquence litho- et bio-stratigraphique complétée par une liste des espèces, un tableau des principaux assemblages et un diagramme des diatomées.
Etude des diatomées dans les dépôts mensuels de quelques réservoirs finlandais. A côté des formes actuelles, on trouve un pourcentage important de formes d'eaux marines et saumâtres datant des différents épisodes holocènes de la Mer Baltique.
Diatom ; Finland ; Holocene ; Lacustrine sediment ; Lake ; Lake level ; Palaeogeography ; Palynology ; Pollen diagram ; Stratigraphy
Cores of Holocene calcareous sediments (marls) from 2 small lakes (Putaanlampi and Ylimmäinen Kuivajärvi) in Kuusamo, NE Finland, were analysed for pollen, Cladocera, and diatoms, to investigate lake-level changes.
The diatom populations were examined in Cratoneurion associations on a slope travertine deposit in Belgian Lorraine. The floristic list (48 taxa), where the genus Cymbella is dominating (14 taxa), consists mainly of calciphilous and/or aerophilous
elements. Based on multivariate analysis of 21 relevés from the various incrustate microhabitats, three diatom assemblages may be characterized| a first one seems particular to the Cratoneurom community, the other two being related to the main aspects
Biological indicator ; Climate reconstruction ; Diatom ; European part of Russia ; Holocene ; Lake ; Lake hydrology ; Moscow ; Palaeoclimate ; Thermal regime
Analyse des complexes de diatomées de sédiments de l'Holocène supérieur de ce lac de l'oblast de Moscou.
This paper presents a 40,000-yr pollen- and diatom-based paleoenvironmental record from a crater lake, Tritrivakely, in the Madagascar highlands. It aims at understanding the response of a southern tropical land area to changes in solar radiation
C 14 dating ; California ; Continental margin ; Continental slope ; Diatom ; Marine sediment ; Palaeo-environment ; Quaternary ; Stratigraphy ; United States
The earlier estimate for the age of laminated sediment formation, late Pleistocene to Holocene, was based on extrapolation of diatom data in the cores witn conventional 14C and oxygen-isotope chronologies. However,new radiocaebon ages for cores show
Costa Rica ; Diatom ; Glacial lake ; Holocene ; Human impact ; Lacustrine sediment ; Methodology ; Palaeoclimatology
In paleoclimatological reconstruction from lake sediments in Central America, climate and human disturbance signals are difficult to separate. The analysis of diatoms offers paleoclimate records less influenced by human activity. Paper describes
the first diatom record a lake sediment core in Costa Rica. Specific study site is Lago de las Morrenas in Chirripó National Park. A single diatom, Aulacoseira lirata/alpigena overwhelmingly dominated all core samples, but whether this reflects long-term
Diatom ; Drought ; Geochemistry ; Holocene ; Lacustrine sediment ; Lake ; Montana ; Oxygen 18 ; Palaeo-environment ; Quaternary ; United States of America ; Varves ; Water balance
A 2200-yr long, high-resolution record of drought variability in northwest Montana is inferred from diatoms and δO 18 values of bio-induced carbonate preserved in a varved lacustrine core from Foy Lake. A previously developed model of the diatom
response to lake-level fluctuations is used to constrain estimates of paleolake levels derived from the diatom data. Spectral analysis of the δO 18 data indicates that severe droughts occurred with multi-decadal (50 to 70 yr) frequency.