Destructive margin magmatism and the contributions from the mantle wedge and subducted crust

Abstract

Destructive plate margin magmas may be considered in two groups on the basis of their REE ratios. Many island arc suites have low Ce/Yb, and remarkably restricted isotope ratios of 87Sr/86Sr = 0.7033 (±0.0002), 143Nd/144Nd = 0.51302 (±0.December 20014), 206Pb/204Pb = 18.76 (±0.13), 207Pb/204Pb = 15.57 (±0.02) and 208Pb/204Pb = 38.4 (±0.18). However, they also have Rb/Sr (0.027 ± 0.025), Th/U (2.18 ±0.5) and Ce/Yb (8.4 ±2.7) ratios that are significantly less than accepted estimates for the bulk continental crust. The high Ce/Yb suites have higher incompatible element contents, more restricted HREE and much more variable isotope ratios, and these have been attributed to both contributions fro..