We present Pleistocene oxygen and carbon isotope records from two planktonic foraminifer species (Globigerinoides sacculifer and Neogloboquadrina dutertrei) from Ocean Drilling Program Site 847 (0° 16'N, 95° 19'W; 3334 m water depth). An average sample resolution of 4500 yr was obtained by sampling at an interval of 15 cm through a continuous 35-m section from 0 to 1.15 Ma. Our δ 18 O-based chronology is similar to that derived independently by astronomically tuning the gamma-ray attenuation porosity evaluator (GRAPE) record (Shackleton et al., this volume), though offsets as large as ±30 k.y. occur on occasion.The surface waters at eastern equatorial Pacific Site 847, 380 km west of the Galapagos, are characterized by strong and constant upwelling, elevated nutrient concentrations, and high productivity. The isotopic composition of G. sacculifer (300-355 µm) reflects conditions in the thin-surface mixed layer, and the composition of N. dutertrei (355-425 µm) records are used to infer vertical contrasts in upper ocean water temperature and nutrient concentration, though δ C may also be influenced by other factors, such as CO 2 gas exchange. Variations in the isotopic differences are often synchronous with glacial/interglacial climate change. Glacial periods are characterized by smaller vertical contrasts in both temperature and nutrient concentration, and by notably greater accumulation rates of N. dutertrei and CaCO 3 . We attribute these responses to greater upwelling at the equatorial divergence. Superimposed on the glacial/interglacial Δδ !8 O d _ s pattern is a long-term trend possibly associated with the advection of Peru Current waters. The temporal fluctuations in the isotopic contrasts are strikingly similar to those observed at Site 851 (Ravelo and Shackleton, this volume), suggesting that the inferred changes in thermal and chemical profiles occurred over a broad region in the equatorial Pacific.
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