Hostname: page-component-5c6d5d7d68-wbk2r Total loading time: 0 Render date: 2024-08-21T04:21:28.788Z Has data issue: false hasContentIssue false
  • English
  • Français

Source Areas and Transport Mechanisms for Freshwater and Brackish-Water Diatoms Deposited in Pelagic Sediments of the Equatorial Atlantic1

Published online by Cambridge University Press:  20 January 2017

Edward M. Pokras
Edward M. Pokras*
Affiliation:
Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York 10964
Get access Rights & Permissions [Opens in a new window]

Abstract

Distributions of freshwater and brackish-water diatoms from dust samples and modern sediments of the equatorial Atlantic demonstrate different transport mechanisms and source areas. Both Melosira spp. and Stephanodiscus spp. are transported via winds from the southern Sahara and Sahel in Northern Hemisphere winter. The core-top distribution of Cyclotella striata delineates the extent of the low-salinity plume formed by runoff from the Zaire River into the extreme eastern Atlantic. The transport mechanism and source areas for Melosira spp. during arid phases have not changed appreciably in the last 130,000 yr. There is no evidence for long-distance transport of freshwater diatoms by the southeast trade winds. This study confirms the validity of paleoclimatic research which inferred eolian transport of Melosira spp. in the winter dust plume from source regions north of the equator, although fluviatile input of Melosira valves into nearshore sediments cannot be ruled out.

Type
Research Article
Information
Quaternary Research , Volume 35 , Issue 1 , January 1991 , pp. 144 - 156
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.)

Footnotes

1

Lamont-Doherty Geological Observatory, Contribution No. 4698.

References

Chuey, J.M. Rea, D.K. Pisias, N.G. Late Pleistocene paleoclimatology of the central equatorial Pacific: A quantitative record of eolian and carbonate deposition Quaternary Research 28 1987 323 339 CrossRefGoogle Scholar
Curry, W.B. Lohmann, G.P. Carbon deposition rates and deep water residence time in the equatorial Atlantic Ocean throughout the last 160,000 years Geophysical Monograph 32 1985 285 301 Google Scholar
Darwin, C. An account of the fine dust which often falls on vessels in the Atlantic Ocean Quarterly Journal of the Geographical Society of London 2 1846 26 30 CrossRefGoogle Scholar
Delany, A.C. Parkin, D.W. Griffin, J.J. Goldberg, E.D. Reimann, B.E.F. Airborne dust collected at Barbados Geochimica et Cosmochimica Acta 31 1967 885 909 CrossRefGoogle Scholar
Feldman, G. Kuring, N. Ng, C. Esaias, W. McClain, C. Elrod, J. Maynard, N. Endres, D. Evans, R. Brown, J. Walsh, S. Carle, M. Podesta, G. Ocean color: Availability of the global data set EOS Transactions, American Geophysical Union 70 1989 634 641 CrossRefGoogle Scholar
Gasse, F. Stabell, B. Fourtanier, E. van Iperen, Y. Freshwater diatom influx in intertropical Africa: Relationships with continental records from Africa Quaternary Research 32 1989 229 242 CrossRefGoogle Scholar
Gorshkov, S.G. Atlantic and Indian Oceans World Ocean Atlas Vol. 2 1978 Pergamon Oxford Google Scholar
Hastenrath, S. Lamb, P.J. Heat Budget Atlas of the Tropical Atlantic and Eastern Pacific Oceans 1977 University of Wisconsin Press Madison Google Scholar
Janecek, T.R. Rea, D.K. Quaternary fluctuations in northern hemisphere trade winds and westerlies Quaternary Research 24 1985 150 163 CrossRefGoogle Scholar
Kolbe, R.W. Fresh-water diatoms from Atlantic deep-sea cores Science 126 1957 1053 1056 CrossRefGoogle Scholar
McTainsh, G.H. A dust monitoring programme for dsertification control in West Africa Environmental Conservation 13 1986 17 25 CrossRefGoogle Scholar
Parmenter, C. Folger, D.W. Eolian biogenic detritus in deep-sea sediments: A possible index of Ice Age aridity Science 185 1974 695 698 CrossRefGoogle ScholarPubMed
Pokras, E.M. Diatom record of late Quaternary climatic change in the eastern equatorial Atlantic and tropical Africa Paleoceanography 2 1987 273 286 CrossRefGoogle Scholar
Pokras, E.M. Mix, A.C. Eolian evidence for spatial variability of late Quaternary climates in tropical Africa Quaternary Research 24 1985 137 149 CrossRefGoogle Scholar
Pokras, E.M. Mix, A.C. Earth's precession cycle and Quaternary climatic change in tropical Africa Nature 326 1987 486 487 CrossRefGoogle Scholar
Pokras, E.M. Molfino, B. Oceanographic control of diatom abundances and species distributions in surface sediments of the tropical and southeast Atlantic Marine Micropaleontology 10 1986 165 188 CrossRefGoogle Scholar
Prell, W.L. Kutzbach, J.E. Monsoon variability over the past 150,000 years Journal of Geophysical Research 92 1987 8411 8425 CrossRefGoogle Scholar
Prospero, J.M. Arid regions as sources of mineral aerosols in the marine environment Pewe, T.L. Desert Dust: Origin, Characteristics, and Effect of Man Vol. 186 1981 Geological Society of America Special Paper 71 86 Google Scholar
Servant, M. Servant-Vildary, S. L'environnement quaternaire du bassin du Tchad Williams, M.A.J. Faure, H. The Sahara and the Nile 1980 Balkema Rotterdam 133 162 Google Scholar
Stabell, B. Variations of diatom flux in the eastern equatorial Atlantic during the last 400,000 years (“meteor” cores 13519 and 13521) Marine Geology 72 1986 305 323 CrossRefGoogle Scholar
Stabell, B. Initial diatom record of ODP Sites 657 and 658: On the history of upwelling and continental aridity Ruddiman, W. et al. Proceedings of the Ocean Drilling Program, Scientific Results Vol. 108 1989 Ocean Drilling Program College Station, TX 149 156 Google Scholar
Street-Perrott, F.A. Harrison, S.P. Temporal variations in lake levels since 30,000 yr B.P.—and index of the global hydrological cycle Hansen, J.E. Takahashi, T. 1984 American Geophysical Union Washington, DC 118 129 Google Scholar
Sverdrup, H.U. Johnson, M.W. Fleming, R.H. The Oceans 1942 Prentice-Hall New York Google Scholar
Tchernia, P. Descriptive Physical Oceanography 1980 Pergamon Oxford Google Scholar
van Iperen, J.M. van Weering, T.C.E. Jansen, J.H.F. van Bennekom, A.J. Diatoms in surface sediments of the Zaire deep-sea fan (S.E. Atlantic Ocean) and their relation to overlying water masses Netherlands Journal of Sea Research 21 1987 203 217 CrossRefGoogle Scholar