To better understand the deglacial upwelling pattern in the east Pacific, we have made radiocarbon (14C) measurements on benthic foraminifera and macrofauna from a 3.5 m long interval in ODP Core 893A from Santa Barbara Basin, California, representing early deglaciation. This work serves to investigate the source of apparent disagreement between radiocarbon data sets from Leibnitz Laboratory, Kiel University (Kiel) and Carbon Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory (LLNL). These data sets are based on measurements of mixed benthic and mixed planktonic foraminifera. Interlaboratory 14C results are similar for the planktonic foraminiferal analyses; however, Kiel measurements on mixed benthic foraminifera are much older than mixed benthic measurements from equivalent depths measured at LLNL. Our new results show distinct 14C differences between taxa, with Pyrgo sp. giving ages consistently older than Kiel measurements on mixed benthic taxa, while ages for Nonionellina sp., Buliminella sp., Uvigerina sp., and benthic macrofauna were much younger, even younger than the LLNL mixed benthic data. The new data supports benthic-planktonic age offsets of no more than 300 years, indicating that bottom waters within the basin remained significantly younger during early deglaciation than some previous results have suggested and are thus consistent with sedimentary and faunal evidence for well-oxygenated conditions.

DEPTH, sediment/rock [m] is given in mbsf. This dataset shows data from Hendy et al., (2002) and Sarnthein et al., (2007), plus new 14C data from this study. Lawrence Livermore National Laboratory 14C results originally published in Ingram and Kennett [1995] were recalculated in Hendy et al. (2002) to properly correct for the presence of 14C-dead carbon as well as modern carbon in 14C small-sample processing backgrounds. All data have been placed on the Hendy et al. (2002) depth scale for ODP 893A: void-corrected depths within each ODP core section were calculated based on Merrill and Beck (1995), and these are keyed to the sectiontop depths of Behl (1995). We have followed Hendy et al. (2002) in correcting the Behl (1995) depths for 1.5 m and 0.75 m of missing core at the 1H-2H and 2H-3H section boundaries, respectively, and in our use of 27.7 m for the top of 4H1 rather than the adjusted Behl (1995) depth of 25.8 + 2.25 m (see the 4H1 depths shown in Hendy et al. (2002, Table 3)).

Supplement to: Magana, Alexandra L; Southon, John R; Kennett, James P; Roark, E Brendan; Sarnthein, Michael; Stott, Lowell D (2010): Resolving the cause of large differences between deglacial benthic foraminifera radiocarbon measurements in Santa Barbara Basin. Paleoceanography, 115(4), PA4102