Late eocene-early oligocene carbonate sedimentation in the deep sea


Journal Article

Calcium carbonate accumulation rate patterns for the late Eocene-early Oligocene interval in 12 DSDP sites show inter- and intra-basin variations. Significant increases in calcium carbonate accumulation at the Eocene/Oligocene boundary are seen at Sites 77B, 292, 289 (Pacific Ocean), and Sites 214 and 219 (Indian Ocean), whereas a decrease is observed at Site 516F (South Atlantic). In contrast, no major changes are seen at Sites 73 and 277 (Pacific Ocean) or at Sites 363, 366 and 360 (Atlantic Ocean). Intra-oceanic variation in the accumulation records from the Pacific is observed as well. In comparison to Sites 292, 289 and 77B, Sites 73 and 277 show no change at the boundary. Instead increases are observed in Site 277 during the late Eocene and in Site 73 at the early/late Oligocene boundary. In general, the observed changes in carbonate accumulation rates follow the patterns established for fluctuations in the position of the CCD across the Eocene/Oligocene boundary. The Pacific CCD undergoes the greatest drop at the boundary and the greatest increase in accumulation rates occurs in this ocean as well. The Indian Ocean is characterized by an intermediate change in both the depth of the CCD and carbonate accumulation rates at the Eocene/Oligocene boundary, while the South Atlantic records only a small change in accumulation rates and an intermediate change in the depth of the CCD. The inter-ocean differences in both accumulation rate patterns and changes in the position of the CCD argue against a global causal event, such as a change in sea level, to account for the observed sedimentation changes. Instead, this variability may best be explained by changes in surface water productivity and bottom water circulation patterns. The intra-ocean variability in the Pacific can be explained by these variables as well. © 1986, Elsevier Science & Technology

Full Text

Duke Authors

Cited Authors

  • Thunell, RC; Corliss, BH

Published Date

  • January 1, 1986

Published In

Volume / Issue

  • 9 / C

Start / End Page

  • 363 - 380

International Standard Serial Number (ISSN)

  • 0920-5446

Digital Object Identifier (DOI)

  • 10.1016/S0920-5446(08)70140-7

Citation Source

  • Scopus