36. OXYGEN AND CARBON ISOTOPE RECORD THROUGH THE OLIGOCENE, DSDP SITE 366, EQUATORIAL ATLANTIC

• Main Author: Anne Boersma
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Planktonic foraminifera
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.564.3078; http://www.deepseadrilling.org/41/volume/dsdp41_36.pdf

Detailed 18O and I3C records were constructed through the Oligo-cene section at Site 366 (DSDP Leg 41) in the eastern equatorial Atlantic. Samples were analyzed at intervals of more than one per million years using both benthic and planktonic foraminifera, and no significant hiatuses were encountered. A survey of the depth habitats of planktonic ' foraminifera has shown that the chiloguembelinids, pseudohastigerinids, cassi-gerinellids, and in the latest Oligocene, Globigerinoides lived in the warmest waters. Below these surface forms the unkeeled globo-rotaliids, large globigerinids, small globigerinids occurred; Catapsydrax lived at the coolest temperatures. The surface temperature at Site 366 ranges from 15 ° to 16 ° in the early Oligocene to 12°C in the late Oligocene. A significant temperature increase characterizes the termination of the Oligocene. Intermediate depth temperatures are taken from the planktonic genus Catapsydrax whose temperature record closely parallels that of the benthonic foraminifera, suggesting that the deep water masses are controlled by high latitude processes independent of tropical surface conditions. The 13C variations demonstrate that the deep waters in the equatorial Atlantic were depleted in oxygen by about 2 ml/1 compared with the South Atlantic Site 357.