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Free keywords:
Stratigraphy; Southern Ocean; Radiolaria; Paleoceanography
DDC:
550 - Earth sciences
Abstract:
We calibrated the Cycladophora davisiana abundances versus oxygen isotope stratigraphy back to 220 ka for the subantarctic Atlantic Ocean. The relative abundances of C. davisiana and 18O measurements of benthic and planktic foraminifera have been determined in two sediment cores. Oxygen isotope stratigraphy has been used to date the C. davisiana records and to assign SPECMAP ages to the C. davisiana events. Comparisons with an existing calibration from the subantarctic Indian Ocean show, that the C. davisiana events ''b2, c1, c2, d, e1, e2, e3, f, h, i1 and i2' occur synchronous within the errors of the oxygen isotope stratigraphy in the Indian and the Atlantic sectors of the Southern Ocean. Larger deviations occur only for events ''b1' and ''g'. Furthermore, the long-term fluctuations in C. davisiana abundances have been studied in a sediment core covering the last 700 kyr. Based on biostratigraphic extinction levels, ages for early Brunhes C. davisiana events have been estimated. Major C. davisiana abundance maxima occur approximately every 100 ka in conjunction with glacial/interglacial cycles over the entire record.
