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Geophysical Monograph Series



  • Paleoclimatology—Quaternary
  • Climatic changes

Index Terms

  • 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology
  • 1040 Geochemistry: Isotopic composition/chemistry
  • 4803 Oceanography: Biological and Chemical: Bacteria
  • 3030 Marine Geology and Geophysics: Micropaleontology



The mid-Brunhes transition in ODP sites 1089 and 1090 (subantarctic South Atlantic)

D. A. Hodell, S. L. Kanfoush, K. A. Venz, C. D. Charles, and F. J. Sierro

We studied cores from ODP sites 1089 and 1090 in the subantarctic South Atlantic to reconstruct paleoceanographic changes during the mid-Brunhes in the context of climate evolution of the Pleistocene. The “mid-Brunhes event” is marked by an abrupt shift toward lower δl8O values during interglacial stages beginning with MIS 11, consistent with Jansen et al. [1986] who first proposed a mid-Brunhes transition to more humid, interglacial conditions in the southern hemisphere. In addition, we identified the “mid-Brunhes dissolution cycle” as part of a long-period oscillation that is expressed in dissolution indices and planktic δ13C, which reach maximum values during interglacial stages 13 and 11. Taking advantage of the high sedimentation rates at site 1089 (15 cm/kyr), we enumerate the sequence of events that occurred during Termination V and MIS 11 and speculate about their cause(s). A comparison between site 1089 and the Vostok ice core suggests that peak conditions of stage 11 are accurately captured in the ice core record, and that temperatures in the high-latitude southern hemisphere and global pCO2 levels during stage 11 were similar to the Holocene. Furthermore, a remarkable correlation between Vostok pCO2 and % foraminiferal fragmentation at site 1089 suggests a strong coupling of the marine carbonate system and atmospheric pCO2 during the mid-Brunhes. Although stage 11 and the Holocene share some similarities (e.g., orbital configuration, pCO2, etc.), caution is advised in using stage 11 as an analog for the Holocene because the maximum in dissolution and δ13C during the mid-Brunhes indicate that the marine carbonate-carbon cycle was fundamentally different than today.

Citation: Hodell, D. A., S. L. Kanfoush, K. A. Venz, C. D. Charles, and F. J. Sierro (2003), The mid-Brunhes transition in ODP sites 1089 and 1090 (subantarctic South Atlantic), in Earth's Climate and Orbital Eccentricity: The Marine Isotope Stage 11 Question, Geophys. Monogr. Ser., vol. 137, edited by A. W. Droxler, R. Z. Poore, and L. H. Burckle, pp. 113–129, AGU, Washington, D. C., doi:10.1029/137GM09.

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