Statistical analysis of bulk nitrogen isotopes from IODP Site 323-U1342

Here, we present the results of a statistical analysis published in Knudson et al., (2021, Science Advances), which investigates nitrogen isotopes from Integrated Ocean Drilling Program Expedition 323 Site U1342 in the Bering Sea, from 0-1.2 Ma. We analyzed the Site U1342 15Nbulk record from Knudson and Ravelo (2015, Geophysical Research Letters, https://doi.org/10.1002/2015GL066317). In Knudson et al. (2021), the bulk d15N record was detrended and Z-scores were calculated to determine statistically significant peaks. Z-scores were significantly higher during laminated intervals compared to non-laminated intervals (0.779 versus -0.112, P ≤0.0001). These data, in combination with high-resolution paleo-productivity indicators at the same site, provide evidence for enhanced nitrate utilization during laminated intervals compared with non-laminated intervals.