Benthic Foraminifer Stable Isotope Record from Site 849 (0-5 Ma): Local and Global Climate Changes

Benthic foraminifer and 13 C data from Site 849, on the west flank of the East Pacific Rise (0 11 'N, 1103 l'W; 3851 m), give relatively continuous records of deep Pacific Ocean stable isotope variations between 0 and 5 Ma. The mean sample spacing is 4 k.y. Most analyses are from Cibicides wuellerstorfi> but isotopic offsets relative to Uvigerina peregrina appear roughly constant. Because of its location west of the East Pacific Rise, Site 849 yields a suitable record of mean Pacific Ocean ' 3 C, which approximates a global oceanic signal. The ~lOO-k.y.-period climate cycle, which is prevalent in 18 does not dominate the long-term 13 C record. For 13 C, variations in the -400-and 41-k.y. periods are more important. Phase lags of 13 C relative to ice volume in the 41-and 23-k.y. bands are consistent with 13 C as a measure of organic biomass. A model-calculated exponential response time of 1-2 k.y. is appropriate for carbon stored in soils and shallow sediments responding to glacial-interglacial climate change. Oceanic 13 C leads ice volume slightly in the 100-k.y. band, and this suggests another process such as changes in continental weathering to modulate mean river 13 C at long periods. The 13 C record from Site 849 diverges from that of Site 677 in the Panama Basin mostly because of decay of 13