Fig. 2: Diagrams showing correlations between 206Pb/204Pb and trace and major elemental ratios for petit-spot basalts from the NW Pacific plate.
From: Melting of recycled ancient crust responsible for the Gutenberg discontinuity
a the comparison of measured 206Pb/204Pb with the Ce/Pb ratio for the basalts from Site A, B, and C. The 2SD of the 206Pb/204Pb are from 0.002 to 0.02, which are all smaller than the scale of the symbols. The relative uncertainty (2SD) of the Ce/Pb ratio is 7%, which is calculated as \(\sqrt {\sigma _{Ce}^2 + \sigma _{Pb}^2} \) (σCe and σPb are the relative uncertainty for Ce and Pb measurement, both of which is around 5%). The corresponding value of lower continental crust (LCC), global subducting sediments (GLOSS), the low δ26Mg marine sediments in the subducting oceanic slab, the normal-MORB (N-MORB), the depleted MORB mantle (DMM), and the carbonatite melt are shown for comparisons (data are from20,58,59,60,61). b the comparison of measured 206Pb/204Pb with Ti/Eu ratio. The relative uncertainty (2SD) of the Ti/Eu ratio is 7%. The white hexagon and the dark real arrow shows the composition of the carbonatite, and the data are from ref. 60. c the comparison of measured 206Pb/204Pb with Zr/Hf ratio. The relative uncertainty (2SD) of the Zr/Hf ratio is 7%. The dashed curve shows the simulated mixing between the DMM and the carbonatite melt (data for these two endmembers are from ref. 59,60, and the numbers are the percentage by weight of the carbonatite melt. d the comparison of measured 206Pb/204Pb with Nb/Ta ratio. The relative uncertainty (2SD) of the Nb/Ta ratio is 7%.The dashed curve shows the simulated mixing between the DMM and the carbonatite melt (data for these two endmembers are from ref. 59,60, and the numbers are the percentage by weight of the carbonatite melt. e the comparison of 206Pb/204Pb with primitive mantle normalized Sm/Yb ratio. The relative uncertainty (2SD) of the Sm/Yb ratio is 7%. The primitive mantle composition is from ref. 62. f the comparison of measured 206Pb/204Pb with K2O/TiO2 ratio. The relative uncertainty (2SD) of the K2O/TiO2 ratio is 7%.
