Plot of (a) P versus Na and (b) P versus Sr for drill core MBS-047 1-m raw data. The trend lines are the stratigraphic trends as shown in Fig. 1. Plots of (c) P versus Na and (d) P versus Sr using the 3-m composite values. The two bottom plots (e) and (f) compare the data for MBS-047 and MBS-170 (from the North Margin region) with the dashed line showing the stratigraphic trends for the latter.