Late Quaternary upwelling variations in the eastern equatorial Atlantic Ocean as inferred from dinoflagellate cysts, planktonic foraminifera, and organic carbon content
C. Holl et S. Kemle-von Mucke, Late Quaternary upwelling variations in the eastern equatorial Atlantic Ocean as inferred from dinoflagellate cysts, planktonic foraminifera, and organic carbon content, QUATERN RES, 54(1), 2000, pp. 58-67
Analysis of multiple proxies shows that eastern equatorial Atlantic upwelli
ng was subdued during isotope stage 5.5, more intense during stages 4, 5.2,
5.4, and 6, and most intense early in stage 2. These findings are based on
proxy measures from a core site about 600 km southwest of Liberia. The pro
xies include total organic carbon content, the ratio of peridinoid and ocea
nic organic-walled dinoflagellate cyst species, accumulation rates of calca
reous dinoflagellates, estimates of sea surface paleotemperatures, the diff
erence in stable oxygen isotope composition between two species of plankton
ic foraminifera that lire at different water depths, and the abundance of t
he planktonic foraminifera Neogloboquadrina dutertrei. Most of these parame
ters consistently vary directly or inversely with one another. Slight discr
epancies between the individual parameters show the usefulness of a multipl
e proxy approach to reconstruct paleoenvironments. Our data confirm that no
rthern summer insolation strongly influences upwelling in the eastern equat
orial Atlantic Ocean. (C) 2000 University of Washington.