Implications of upper Quaternary stable isotope records of marine ostracodes and benthic foraminifera for paleoecological and paleoceanographical investigations

• Main Authors: Didie, Claudia, Bauch, Henning A.
• Other Authors: Holmes, J. A., Chivas, A. R.
• Format: Book Part
• Language: English
• Published: AGU (American Geophysical Union) 2002
• Subjects: Iceland Plateau; Iceland; Nordic Seas
• Online Access: https://oceanrep.geomar.de/id/eprint/5577/; https://oceanrep.geomar.de/id/eprint/5577/1/Didie_Bauch.pdf

A sediment core, covering marine isotope stage (MIS) 7 to I, and several urface sediment samples, all from the Iceland Plateau, were investigated for deep- ea ostracode carbon and oxygen isotopes. In contrast to the benthic foraminiferal species Cibicidoides wuellerstorfi and Oridorsalis umbonatus, which both di play well-known negative off ets from the oxygen isotope value of the equilibrium calcite, the investigated ostracode genera Krithe and Henryhowella reveal positive offsets. We calculated an offset of about+ 1.4 %o for Krithe and about +0.4 %o for Henryhowella with respect to the equilibrium calcite. Downcore isotope analyses revealed differences between the oxygen i otope records of the infaunai-Iiving foraminiferal species 0 . umbonatus and the epifaunal-living species C. wuellerstorfi during periods of increa ed deposition of IRD (iceberg rafted debris). These differences between infaunal and epifaunal oxygen isotope signals have been recognized before within the area of the Nordic Seas and were likely caused by environmental conditions during late MIS 6 and MIS 2, affecting mainly the epifaunal-living taxa. The oxygen isotope record of Henryhowella reveal the same trend as the record of C. wuellerstorfi, whereas the oxygen i otope records of Krithe and 0 . wnbonatus are parallel to each other. This sugge ts an epifaunal habitat for Henryhowella and an infaunal habitat for Krithe, which is in agreement with the faunal abundance data as well as with other ostracode studie . The carbon isotope records of Henryhowella and 0. umbonatus display a globally ob erved trend of low o''C values during the glacial and high value during the interglacial periods, whereas the one record of Kritlze shows no such climate-related trend, probably due to strong vital effects.