Hostname: page-component-848d4c4894-8bljj Total loading time: 0 Render date: 2024-07-01T16:50:43.506Z Has data issue: false hasContentIssue false

Implications of Radiolarian Assemblages for the Late Quaternary Paleoceanography of the Eastern Equatorial Pacific

Published online by Cambridge University Press:  20 January 2017

Cynthia T. Schramm*
Affiliation:
Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island 02882

Abstract

The distribution of radiolarian assemblages identified by Q-mode factor analysis of radiolarian microfossils in surface sediments from low latitudes in the Pacific Ocean reflects their associations with surface water masses. Downcore fluctuations of these radiolarian assemblages at two sites, RC10-65 and V19–29, indicate changes in circulation in the eastern equatorial Pacific during the past 500,000 yr. Surface-water radiolarian assemblages characteristic of zonal flow have dominated siliceous sedimentation in the eastern equatorial Pacific, except during times of intense upwelling which can occur along the coast of Peru and in the Equatorial Undercurrent. Fluctuations in the importance of this upwelling have not been consistent with glacial/interglacial changes in ice volume throughout the late Quaternary. Intensification of upwelling in the equatorial divergence, however, has consistently coincided with increases in ice volume in the past 500,000 yr. The times at which changes in the nature of the relationship between upwelling and ice volume occur (approximately 240,000 and 380,000 yr B.P.) roughly coincide with times of observed changes in other proxy indicators of oceanographic conditions in the Pacific and Indian oceans.

Type
Research Article
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

CLIMAP Project Members, (1976). The surface of the ice-age earth Science (Washington, D.C.) 191, 11311137 CrossRefGoogle Scholar
Dauphin, J.P. (1983). Eolian Quartz Granulometry as a Paleowind Indicator in the Northeast Equatorial Atlantic, North Pacific, and Southeast Equatorial Pacific Unpublished Ph.D. dissertation University of Rhode Island Google Scholar
Heath, G.R. Hollister, C.D. Anderson, D.R. Leinen, M. (1983). Why consider subseabed disposal of high-level nuclear wastes? Park, P.K. Kester, D.R. Duedall, I.W. Ketchum, B.H. Wastes in the Ocean Vol. 3 Wiley & Sons New York Google Scholar
Imbrie, J. Hays, J.D. Martinson, D.G. McIntyre, A. Mix, A.C. Morley, J.J. Pisias, N.G. Prell, W.L. Shackleton, N.J. (1984). The orbital theory of Pleistocene climate support from a revised chronology of the marine delta 18O record Berger, A. Imbrie, J. Hays, J. Kukla, G. Saltzman, B. Milankovitch and Climate Reidel Boston Google Scholar
Imbrie, J. Kipp, N.G. (1971). A new micropa-leontological method of quantitative paleoclimatology: Application to a late Pleistocene Caribbean core Turekian, K.K. The Late Cenozoic Glacial Ages Yale Univ. Press New Haven, Conn 71181 Google Scholar
Klovan, J.E. Imbrie, J. (1971). An algorithm and Fortran IV program for large-scale Q-mode factor analysis and calculation of factor scores Mathematical Geology 3, 1 6177 CrossRefGoogle Scholar
Knauss, J.A. (1966). Further measurements and observations on the Cromwell Current Journal of Marine Research 24, 206239 Google Scholar
Koblentz-Mishke, O.J. Volkovinsky, V.V. Kabanova, J.G. (1970). Plankton primary productivity of the world ocean Wooster, W.S. Scientific Exploration of the South Pacific U.S. Natl. Acad. Sci Washington, D.C 183193 Google Scholar
Molina-Cruz, A. (1977a). Radiolarian assemblages and their relationship to the oceanography of the subtropical southeastern Pacific Marine Micropaleontology 2, 315352 CrossRefGoogle Scholar
Molina-Cruz, A. (1977b). The relation of the southern tradewinds to upwelling processes during the last 75,000 years Quaternary Research 8, 324338 Google Scholar
Moore, T.C. Jr. (1973). Method of randomly distributing microscopic examination Journal of Sedimentology and Petrology 431, 3 904 Google Scholar
Moore, T.C. Jr. (1978). The distribution of radiolarian assemblages in the modern and ice-age Pacific Marine Micropaleontology 3, 229266 Google Scholar
Morley, J.J. Hays, J.D. (1979). Cycladophora davisiana: A stratigraphic tool for Pleistocene north Atlantic and interhemispheric correlation Earth and Planetary Science Letters 444, 383389 CrossRefGoogle Scholar
Nigrini, C. Moore, T.C. Jr. (1979). A Guide to Modern Radiolaria Cushman Foundation for Foraminiferal Research Special Publication 16Google Scholar
Pak, H. Zaneveld, J.R.V. (1973). Optical and hydrographic observations of the Cromwell Current between 92W and the Galapagos Islands Journal of Geophysical Research 78, 27082715 CrossRefGoogle Scholar
Pak, H. Zaneveld, J.R.V. (1974). Equatorial front in the eastern Pacific Ocean Journal of Physical Oceanography 4, 4 570578 2.0.CO;2>CrossRefGoogle Scholar
Peterson, L. (1983). Late Quaternary Deep Water Paleoceanography of the East Equatorial Indian Ocean: Evidence from Benthonic Foraminifera, Carbonate Dissolution, and Stable Isotopes Unpublished Ph.D. dissertation Brown University Google Scholar
Pisias, N.G. Leinen, M. (1984). Milankovitch forcing of the oceanic system: Evidence from the Northwest Pacific Berger, A. Imbrie, J. Hays, J. Kukla, G. Saltzman, B. Milankovitch and Climate Reidel Boston Google Scholar
Pisias, N.G. Martinson, D.G. Moore, T.C. Shackleton, N.J. Prell, W.L. Hays, J. Boden, G. (1984). High resolution stratigraphic correlation of benthic oxygen isotopic records spanning the last 300,000 years Marine Geology 56, 119136 CrossRefGoogle Scholar
Reid, J.L. Jr. (1959). Evidence of a South Equatorial Counter-current in the Pacific Ocean Nature (London) 184, 209210 Google Scholar
Romine, K. (1980). A Study of Radiolarian Assemblage Distributions and Paleoceanography of the Eastern Equatorial Pacific Ocean during the Last 127,000 Years Unpublished Master's thesis University of Rhode Island Google Scholar
Romine, K. (1982). Late Quaternary history of atmospheric and oceanic circulation in the east equatorial Pacific Marine Micropaleontology 7, 2 163187 Google Scholar
Sancetta, C. (1983). Late Pleistocene (Bruhnes) stepwise expansion of the North Pacific Subarctic Gyre. Abstracts with programs Geotogical Society of American 15, 6 677 Google Scholar
Schramm, C.T. (1983). Changes in Atmospheric and Oceanic Circulation in the East Equatorial Pacific during the Late Quaternary Unpublished Master's thesis University of Rhode Island Google Scholar
Shackleton, N.J. Opdyke, N.D. (1973). Oxygen isotope and paleomagnetic stratigraphy of equatorial Pacific core V28–238: Oxygen isotope temperatures and ice volumes on a 100,000 year time and 1,000,000 scale Quaternary Research 3, 3955 CrossRefGoogle Scholar
Shaw, A.B. (1964). Time in Stratigraphy McGraw-Hill New York Google Scholar
White, W.B. (1969). The Equatorial Undercurrent, the South Equatorial Countercurrent, and Their Extensions in the South Pacific Ocean East of the Galapagos Islands during February-March 1967 Texas A&M University Ref. 69-4-TGoogle Scholar
Wooster, W.S. (1961). Yearly changes in the Peru Current Limnology and Oceanography 6, 222226 Google Scholar
Wooster, W.S. (1969). Equatorial front between Peru and Galapagos Deep Sea Research 16, 407419 Google Scholar
Wyrtki, K. (1966). Oceanography of the eastern equatorial Pacific Ocean Oceanography and Marine Biology Annual Review 4, 3368 Google Scholar
Wyrtki, K. (1974). Equatorial currents in the Pacific 1950–1970 and their relations to the trade winds Journal of Physical Oceanography 4, 372 2.0.CO;2>CrossRefGoogle Scholar
Wyrtki, K. (1981). An estimate of upwelling in the Pacific Journal of Physical Oceanography 11, 9 12051214 Google Scholar