Hostname: page-component-8448b6f56d-c47g7 Total loading time: 0 Render date: 2024-04-25T00:18:57.860Z Has data issue: false hasContentIssue false
  • English
  • Français

Evidence of Atmospheric Paleocirculation over the Gulf of Guinea since the Last Glacial Maximum

Published online by Cambridge University Press:  20 January 2017

Anne-Marie Lezine ,
Jean-Pierre Tastet  and
Marcel Leroux
Get access Rights & Permissions [Opens in a new window]

Abstract

High-resolution pollen and eolian input studies from core KS 84063 in the Gulf of Guinea record the response of the tropical atmospheric circulation to global paleoclimatic events during the last glacial/interglacial transition. Two depositional phases centered around 15,000 and 10,300 yr B.P. are characterized by maximum values of pollen concentration and of eolian activity index (EA1). Pollen spectra record the significant presence of Artemisia and Ephedra of Saharan origin and the scattered occurrence of Podocarpus from Guinean mountain forests; these demonstrate the intensity of the meridional atmospheric circulation over equatorial West Africa during dry periods. The early Holocene humid phase, ca. 8500 yr B.P., is marked by minima in pollen concentrations and EAI. Saharan taxa are absent and, in contrast, Podocarpus reached its highest relative values. This evidence has been interpreted as reflecting a weakening in the continentocean eolian transport and the importance of monsoonal fluxes. Downcore variations in Podocarpus percentages are used to identify the atmospheric circulation patterns over the low latitudes of West Africa during extreme (dry/humid) climatic conditions.

Type
Short paper
Information
Quaternary Research , Volume 41 , Issue 3 , May 1994 , pp. 390 - 395
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aka, K., and Tastet, J. P. (1986). Late Quaternary sedimentation on the Ivorian margin: First results of Transivoire cruise. Bulletin de I’lnstitut de Geologie du Bassin d’Aquitaine 40, 97–153.Google Scholar
Bard, E. Arnold, M. Maurice, P. Du prat, J. Moyes, J., and Duplessy, J. C. (1987). Retreat velocity of the North Atlantic polar front during the last deglaciation determined by 14C accelerator mass spectrometry. Nature 328, 791–794.Google Scholar
Bertrand, J. Baudet, J., and Drochon, A. (1974). Importance des aerosols naturels en Afrique de l’Ouest. Journal des Recherches Atmospheriques 8, 845–860.Google Scholar
Broecker, W. S. Andree, M. Wolfi, W. Oeschger, H. Bonani, G. Kennett, J., and Peteet, D. (1988). The chronology of the last deglaciation: Implications to the cause of the Younger Dryas event. Paleoceanography 3(1), 1–19.Google Scholar
COHMAP (1988). Climatic changes of the last 18,000 years: Observations and model simulations. Science 241, 1043–1052.Google Scholar
De Deckker, P. Correge, T., and Head, J. (1991). Late Pleistocene record of cyclic activity from tropical Australia suggesting the Younger Dryas is not an unusual climatic event. Geology 19, 602–605.2.3.CO;2>CrossRefGoogle Scholar
Duplessy, J. C. Bard, E. Arnold, M. Shakleton, N.J. Duprat, J., and Labeyrie, L. (1991). How fast did the ocean-atmosphere system run during the last deglaciation? Earth and Planetary Science Letters 103, 27–40.Google Scholar
Dupont, L. M., and Agwu, C. O. C. (1991). Environmental control of pollen grain distribution patterns in the Gulf of Guinea and offshore NW-Africa. Geologische Rundschau 80(3), 567–589.Google Scholar
Elenga, H. (1992). “V6g6tation et climat du Congo depuis 24000 ans A. P. Analyse palynologique de sequences s£dimentaires du pays Bat6k6 et du littoral.” Thesis, Univ. Aix-Marseille 3.Google Scholar
Faegri, K., and Iversen, J. (1975). “Textbook of Pollen Analysis,” Blackwell, Oxford.Google Scholar
Gasse, F. T6het, R. Durand, A. Gibert, E., and Fontes, J. C. (1990). The arid-humid transition in the Sahara and the Sahel during the last deglaciation. Nature 346, 141–146.Google Scholar
Hooghiemstra, H. (1988). Changes of major wind belts and vegetation zones in NW Africa 20,000-5000 yr B.P. as deduced from a marine pollen record near Cap Blanc. Review of Palaeobotany and Palynology 55, 101–140.Google Scholar
Hooghiemstra, H. (1989). Variations of the African trade wind regime during the last 140,000 years: Changes in pollen flux evidenced by marine sediment records. In “Paleoclimatology and Paleometeorology: Modem and Past Patterns of Global Atmospheric Transport” (Leinen, M. and Sarnthein, M., Eds.), pp. 733–770. Kluwer, Dordrecht.Google Scholar
Kudrass, H. R. Erlenkeuser, H. Vollbrecht, R., and Weiss, W. (1991). Global nature of the Younger Dryas cooling event inferred from oxygen isotope data from Sulu Sea cores. Nature 349, 406–408.CrossRefGoogle Scholar
Leroux, M. (1983). “Le climat de 1’Afrique tropicale.” Champion, Paris.Google Scholar
Leroux, M. (1988). La variability des precipitations en Afrique occidental: Les composantes adrologiques du probleme. Veille Climatique Satellitaire 22, 26–45.Google Scholar
Leroux, M. (1990). Natural protection and voluntary extension of the tropical African forest cover. In “Greenhouse-Effect, Sea-Level and Drought” (Paepe, R. et al. Eds.), NATO ASI Ser. C, 325, pp. 241–252. Kluwer, Dordrecht.Google Scholar
Leroux, M. (in press). The mobile polar high: A new concept which explains the actual mechanisms of the meridian air-mass and energy exchanges, and the global propagation of palaeoclimatic changes. Global and Planetary Changes. Google Scholar
Lezine, A. M. (1991). West African paleoclimates during the last climatic cycle inferred from an Atlantic deep-sea pollen record. Quaternary Research, 35, 456–463.CrossRefGoogle Scholar
Lezine, A. M. (1993). Chemchane, histoire d’une sebkha. Sechercssc 4, 25–30.Google Scholar
Lezine, A. M., and Casanova, J. (1989). Pollen and hydrological evidence for the interpretation of past climates in tropical West Africa during the Holocene. Quaternary Science Reviews 8, 45–55.CrossRefGoogle Scholar
Lezine, A. M., and Hooghiemstra, H. (1990). Land-sea comparison during the last glacial-interglacial transition: Pollen records from West Tropical Africa. Palaeogeography, Palaeoecology, Palaeoclimatology 79(3/4), 313–331.Google Scholar
Ldzine, A. M., and Edorh, T. (1991). Modern pollen deposition in West African Sudanian environments. Reviews of Palaeobotany and Palynology 67(1-2), 41–58.Google Scholar
Lezine, A. M., and Le Thomas, A. (1993). Reponse du massif forestier guin£o-congolais aux changements du climat depuis 15000 ans: Analyse palynologique d’une carotte du golfe de Guin6e. In “International Symposium in Tropical Phytogeography, Paris,” abstract.Google Scholar
Lezine, A. M., and Vergnaud-Grazzini, D. (1994). Evidence of forest extension in West Africa since 22,000 B.P.; A pollen record from the Eastern Tropical Atlantic. Quaternary Science Reviews 12, 203–210.Google Scholar
Maley, J. (1991). The African rain forest vegetation and palaeoenvironments during Late Quaternary. Climatic Changes 19, 79–98.Google Scholar
Maley, J. Caballe, G., and Sita, P. (1990). Etude d’un peuplement rdsiduel a basse altitude de Podocarpus latifolius sur le flanc congolais du massif du Chaillu. Implications pal6oclimatiques et biogdographiques. Etude de la pluie pollinique actuelle. In “Paysages quatemaires de l’Afrique centrate atlantique” (Schwartz, D. and Lanfranchi, R., Eds.), ORSTOM, Paris.Google Scholar
Mix, A. C. Ruddiman, W. F., and McIntyre, A. (1986). Late Quaternary paleoceanography of the Tropical Atlantic. 1. Spatial variability of annual mean sea-surface temperatures, 0-20,000 years B.P. Paleoceanography 1(1), 43–66.Google Scholar
Mix, A. C., and Ruddiman, W. F. (1985). Structure and timing of the last Deglaciation: oxygen-isotope evidence. Quaternary Science Reviews 4, 59–108.CrossRefGoogle Scholar
Pastouret, L. Chamley, H. Delibrias, J. C., and Thiede, J. (1978). Late Quaternary climatic changes in western Tropical Africa deduced from deep-sea sedimentation off the Niger delta. Oceanologica Acta 1(2), 217–232.Google Scholar
Parkin, D. W., and Shackleton, N. J. (1973). Trade wind and temperature correlations down a deep-sea core off the Saharan coast. Nature 245, 455–457.CrossRefGoogle Scholar
Pokras, E., and Mix, A. C. (1985). Eolian evidence for spatial variability of late Quaternary climates in Tropical Africa. Quaternary Research 24, 137–149.Google Scholar
Ruddiman, W. F., and McIntyre, A. (1981). The North Atlantic Ocean during the last deglaciation. Palaeogeography, Palaeoecology, Paiaeoclimatology 35, 145–214.Google Scholar
Samthein, M. Tetzlaff, G Koopmann, B. Wolter, K., and Pflaumann, U. (1981). Glacial and interglacial wind regimes over the eastern subtropical Atlantic and North West Africa. Nature 293, 193–196.Google Scholar
Samthein, M. Thiede, J. Pflaumann, U. Erlenkeuser, H. Fiitterer, D. Koopmann, B. Lange, H., and Seibold, E. (1982). Atmospheric and oceanic circulation patterns off northwest Africa during the past 25 Millions years. In “Geology of the Northwest African Continental Margin” (Von Rad, U. Hinz, K. Samthein, M., and Seibold, E., Eds.), pp. 545–604. Springer-Verlag, Berlin.Google Scholar
Servant, M. (1983). “Sequences continentales et variations climatiques: Evolution du bassin du Tchad au Cdnozoi’que sup6rieur.” Travaux et Documents, Vol. 159, ORSTOM, Paris.Google Scholar
Talbot, M. R., and Johannessen, T. (1992). A high resolution paleoclimatic record for the last 27,500 years in Tropical West Africa from the carbon and nitrogen isotopic composition of lacustrine organic matter. Earth and Planetary Science Letters 110, 23–37.Google Scholar
Tiedemann, R. Sarnthein, M., and Stein, M. (1989). Climatic changes in the Western Sahara: Aero-marine sediment record of the last 8 million years (sites 657-661). In “Proceedings of the Ocean Drilling Program, Scientific Results” (Ruddiman, W. and Sarnthein, M., Eds.), Vol. 108, pp. 241–261, College Station, TX.Google Scholar
White, F. (1983). “The Vegetation of Africa.” UNESCO, Paris.Google Scholar