Late Quaternary climate change from δ18O records of multiple species of planktonic foraminifera: High‐resolution records from the Anoxic Cariaco Basin, Venezuela

Seasonal trade wind-induced upwelling along the southern margin of the Caribbean Sea occurs in response to the annual migration of the Intertropical Convergence Zone. Laminated, high deposition rate sediments of the Cariaco Basin, a small anoxic basin on the Venezuelan continental shelf, clearly record large changes in the past intensity of this upwelling. Because sediments of the Cariaco Basin are largely unbioturbated, they offer a natural opportunity to study the stable isotopic records of multiple planktonic foraminiferal taxa and to evaluate their sensitivity to both the modern hydrography and temporal changes in upwelling intensity and climate. Oxygen isotope data (δ18O) from four dominant foraminiferal taxa are presented for the time period covering the last 28 kyr. The δ18O data from Globigerina bulloides, after correction for nonequilibrium precipitation, are used as a monitor of sea surface conditions during the winter-spring upwelling season. The δ18O data from white Globigerinoides ruber are used as a measure of annual-average conditions in the near surface, while pink G. ruber data are consistent with use as an index of endmember conditions during the summer-fall nonupwelling season. Data from the deeper dwelling Neogloboquadrina dutertrei yield information on conditions near the base of the local thermocline. During the last glacial, δ18O data from G. ruber and generally reduced interspecific differences indicate cooling of surface waters over the Cariaco Basin by up to 4°C. This longer-term cooling does not appear to be related to changes in upwelling intensity along the coast but may instead reflect more regional cooling of the larger Caribbean. Superimposed on this pattern, between 12.6 and ∼10 ka, is a convergence of δ18O data between G. bulloides and N. dutertrei, implying much stronger upwelling during the last deglaciation. This scenario is consistent with other evidence for high productivity at this time. At ∼14 ka, a sharp δ18O depletion event observed in all taxa seems to have been produced by increased freshwater discharge to the southern Caribbean, suggesting either higher regional rainfall or the influence of glacial melting in the Andes. Minimum δ18O values of pink G. ruber around 6–7 ka record warmer summer sea surface temperatures and/or decreased salinity in the mid-Holocene.

[1]  P. Wiebe,et al.  Vertical Distribution and Isotopic Composition of Living Planktonic Foraminifera in the Western North Atlantic , 1980, Science.

[2]  R. Fairbanks,et al.  Seasonal Oxygen Isotopic Variations in Living Planktonic Foraminifera off Bermuda , 1979, Science.

[3]  J. Overpeck,et al.  A high-resolution late Quaternary upwelling record from the anoxic Cariaco Basin, Venezuela , 1991 .

[4]  L. W. Prell.  Monsoonal climate of the Arabian sea during the Late Quaternary : a response to changing solar radiation , 1984 .

[5]  M. Sarnthein,et al.  Stable-Isotope Composition of Foraminifers: The Surface and Bottom Water Record of Coastal Upwelling , 1983 .

[6]  D. Kroon,et al.  Oxygen and carbon isotopes in planktonic foraminifera as indicators of upwelling intensity and upwelling-induced high productivity in sediments from the northwestern Arabian Sea , 1992, Geological Society, London, Special Publications.

[7]  C. Clapperton.  Glacier readvances in the Andes at 12 500–10 000 YR BP: Implications for mechanism of Late‐glacial climatic change , 1993 .

[8]  A. Mix,et al.  Late Quaternary Paleoceanography of the Tropical Atlantic, 1: Spatial Variability of Annual Mean Sea-Surface Temperatures, 0-20,000 Years B.P. , 1986 .

[9]  F. Street-Perrott.  Lake levels and climate reconstruction , 1985 .

[10]  W. G. Deuser.  Seasonal variations in isotopic composition and deep-water fluxes of the tests of perennially abundant planktonic foraminifera of the Sargasso Sea; results from sediment-trap collections and their paleoceanographic significance , 1987 .

[11]  B. Kromer,et al.  A stable-isotope tree-ring timescale of the Late Glacial/Holocene boundary , 1991, Nature.

[12]  M. Brenner,et al.  Paleolimnology of the Peten Lake District, Guatemala , 1983 .

[13]  Glenn A. Jones,et al.  Reconstruction of Caribbean climate change over the past 10,500 years , 1991, Nature.

[14]  Wallace S. Broecker,et al.  Massive iceberg discharges as triggers for global climate change , 1994, Nature.

[15]  S. Hastenrath.  On Modes of Tropical Circulation and Climate Anomalies , 1978 .

[16]  R. Fairbanks,et al.  Oxygen Isotopic Composition of Multiple Species of Planktonic Foraminifera: Recorders of the Modern Photic Zone Temperature Gradient , 1992 .

[17]  B. Leyden.  Guatemalan forest synthesis after Pleistocene aridity. , 1984, Proceedings of the National Academy of Sciences of the United States of America.

[18]  R. Thunell,et al.  Seasonal changes in the isotopic composition of planktonic foraminifera collected in Panama Basin sediment traps , 1983 .

[19]  M. Bevis,et al.  Amazon cone isotopic stratigraphy: evidence for the source of the tropical freshwater spike , 1988 .

[20]  R. Thunell,et al.  Seasonal Variability in the δ18O and δ13C of Planktonic Foraminifera from an Upwelling Environment: Sediment Trap Results from the San Pedro Basin, Southern California Bight , 1991 .

[21]  B. Geel,et al.  Upper quaternary vegetational and climatic sequence of the fuquene area (Eastern Cordillera, Colombia) , 1973 .

[22]  T. Hammen,et al.  Glacial sequence and environmental history in the Sierra Nevada del Cocuy (Colombia) , 1980 .

[23]  R. Thunell,et al.  Glacio-eustatic sea-level control on Red Sea salinity , 1988, Nature.

[24]  W. G. Deuser,et al.  Seasonally abundant planktonic Foraminifera of the Sargasso Sea: succession, deep water fluxes, isotopic compositions, and paleoceanographic implications , 1989 .

[25]  V. Markgraf.  Palaeoclimates in Central and South America since 18 , 1989 .

[26]  W. Showers,et al.  Evidence for a tropical freshwater spike during the last glacial/interglacial transition in the Venezuela Basin: δ18O and δ13C of calcareous plankton , 1985 .

[27]  H. Oeschger,et al.  14C and Other Parameters During the Younger Dryas Cold Phase , 1980, Radiocarbon.

[28]  C. Clapperton,et al.  Quaternary Glaciations in the northern Andes (Venezuela, Colombia and Ecuador) , 1990 .

[29]  R. Fairbanks,et al.  Reconstructing tropical Atlantic hydrography using planktontic foraminifera and an ocean model , 1990 .

[30]  C. Hemleben,et al.  Seasonal changes in species composition, numbers, mass, size, and isotopic composition of planktonic foraminifera settling into the deep sargasso sea☆ , 1981 .

[31]  R. Thunell,et al.  Atlantic‐Mediterranean water exchange during the Late Neocene , 1987 .

[32]  J. Overpeck,et al.  Rapid climate changes in the tropical Atlantic region during the last deglaciation , 1996, Nature.

[33]  B. Leyden.  Late Quaternary Aridity and Holocene Moisture Fluctuations in the Lake Valencia Basin, Venezuela , 1985 .

[34]  A. Mcintyre,et al.  Seasonal reconstructions of the earth's surface at the last glacial maximum , 1981 .

[35]  J. Duplessy,et al.  Oxygen and carbon isotopic composition and biogeographic distribution of planktonic foraminifera in the Indian Ocean , 1981 .

[36]  J. Kutzbach,et al.  Milankovitch forcing of fluctuations in the level of tropical lakes from 18 to 0 kyr BP , 1985, Nature.

[37]  Richard G. Fairbanks,et al.  Tropical Temperature Variations Since 20,000 Years Ago: Modulating Interhemispheric Climate Change , 1994, Science.

[38]  T. Kinder,et al.  Some aspects of the Caribbean circulation , 1985 .

[39]  Samuel Epstein,et al.  REVISED CARBONATE-WATER ISOTOPIC TEMPERATURE SCALE , 1953 .

[40]  R. Thunell,et al.  Glacial–Holocene salinity changes in the Mediterranean Sea: hydrographic and depositional effects , 1989, Nature.

[41]  Nilva G. Kipp,et al.  New Transfer Function for Estimating Past Sea-Surface Conditions from Sea-Bed Distribution of Planktonic Foraminiferal Assemblages in the North Atlantic , 1976 .

[42]  M. Domingo.  Los foraminíferos planctónicos vivos y sedimentados del margen continental de Venezuela (resumen) , 1971 .

[43]  E. Bard,et al.  Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U–Th ages from Barbados corals , 1990, Nature.

[44]  D. Piperno,et al.  Paleoenvironments and Human Occupation in Late-Glacial Panama , 1990, Quaternary Research.

[45]  A. T. Grove,et al.  Global Maps of Lake-Level Fluctuations since 30,000 yr B.P. , 1979, Quaternary Research.

[46]  F. Muller‐Karger,et al.  Mesoscale processes affecting phytoplankton abundance in the southern Caribbean Sea , 1994 .

[47]  W. Lewis,et al.  Late Quaternary Environmental History of Lake Valencia, Venezuela , 1981, Science.

[48]  H. Curl.  Primary production measurements in the north coastal waters of South America , 1960 .

[49]  Wl Prell,et al.  Faunal and isotopic indices of monsoonal upwelling - western arabian sea , 1981 .

[50]  H. Craig,et al.  Deuterium and oxygen 18 variations in the ocean and marine atmosphere , 1965 .

[51]  W. D. Athearn.  SEDIMENT CORES FROM THE CARIACO TRENCH, VENEZUELA , 1965 .

[52]  D. Rodbell.  The timing of the last deglaciation in Cordillera Oriental, northern Peru, based on glacial geology and lake sedimentology , 1993 .

[53]  E. Vincent,et al.  Sable isotopes in deep-sea carbonates - box core erdc-92, west equatorial pacific , 1978 .

[54]  H. Craig.  The measurment of oxygen isotope paleotemperatures , 1965 .

[55]  R. Fairbanks,et al.  Seasonal stable isotopic variations in living planktonic foraminifera from bermuda plankton tows , 1981 .

[56]  J. Overpeck,et al.  The nature of varved sedimentation in the Cariaco Basin, Venezuela, and its palaeoclimatic significance , 1996, Geological Society, London, Special Publications.

[57]  C. Emiliani.  Depth habitats of some species of pelagic Foraminifera as indicated by oxygen isotope ratios , 1954 .

[58]  R. Thunell,et al.  Planktonic foraminiferal faunal and stable isotopic indices of upwelling: a sediment trap study in the San Pedro Basin, Southern California Bight , 1992, Geological Society, London, Special Publications.

[59]  R. Fairbanks.  A 17,000-year glacio-eustatic sea level record: influence of glacial melting rates on the Younger Dryas event and deep-ocean circulation , 1989, Nature.

[60]  R. Dunbar.  Stable Isotope Record of Upwelling and Climate from Santa Barbara Basin, California , 1983 .

[61]  D. Peteet,et al.  Late-Quaternary climate in the Ridge and Valley of Virginia, U.S.A.: Changes in vegetation and depositional environment. A contribution to the 'North Atlantic seaboard programme' of IGCP-253, 'Termination of the Pleistocene' , 1993 .

[62]  L. Benson.  Timing of the last highstand of Lake Lahontan , 1991 .

[63]  P. Wiebe,et al.  Vertical distribution and isotopic fractionation of living planktonic foraminifera from the Panama Basin , 1982, Nature.

[64]  T. Hammen,et al.  The Pleistocene Changes of Vegetation and Climate in Tropical South America , 1974 .

[65]  B. C. Hansen,et al.  A 50,000-Year Record of Climate Oscillations from Florida and Its Temporal Correlation with the Heinrich Events , 1993, Science.

[66]  J. Overpeck,et al.  Climate change in the circum-North Atlantic region during the last deglaciation , 1989, Nature.

[67]  R. Thunell,et al.  Seasonal succession of planktonic foraminifera in the subpolar North Pacific , 1985 .

[68]  A. Bé,et al.  Seasonal distribution of planktonic foraminifera in the western North Atlantic , 1971 .

[69]  R. Thunell,et al.  Paleoceanographic record of the last glacial/interglacial cycle in the Red Sea and Gulf of Aden , 1988 .