DEPTH PROFILES OF DELTA-C-13 IN BOTTOM WATER AND CORE TOP C-WUELLERSTORFI ON THE ONTONG JAVA PLATEAU AND EMPEROR SEAMOUNTS

We have measured the carbon isotopic composition of dissolved inorgani c carbon in bottom waters of the Ontong Java Plateau (western equatori al Pacific) and on the northern Emperor Seamounts (northwest Pacific). Each of these locations is several hundred miles from the nearest Geo chemical Ocean Sections Study (GEOSECS) stations, and the observed del taC-13 values at each site differ substantially from regionally averag ed GEOSECS deltaC-13 profileS. We discuss the possible causes of these differences, including horizontal variability, near-bottom effects, a nd problems with the Pacific GEOSECS deltaC-13 data. We also measured the isotopic composition (C and O) of core top C. wuellerstorfi from a depth transect of cores at each location. The deltaO-18 data are used to verify that our samples are Holocene. Comparison of foraminiferal and bottom water deltaC-13 values shows that this species faithfully r ecords bottom water deltaC-13 at both sites and demonstrates that ther e is no depth-related artifact in the dissolved inorganic carbon-C. wu ellerstorfi deltaC-13 relationship at these sites.