Fig. 2: Secular variations in global arc basalts since the late Neoproterozoic.
From: The sub-arc mantle has remained oxidized since the Neoproterozoic oxygenation event
a Variations of the mean V/Sc ratio in global primitive arc basalts in 100-Myr bins (see “Data Availability”). Stars indicate the average V/Sc ratios of modern primitive arc basalts (~7.50, red) and MORBs (~7.10, gray), compiled from the GEOROC and PetDB databases, respectively. The histogram shows the number of primitive arc basalts known to have erupted through time (n ≈ 840). The kernel density estimate (KDE) is a nonparametric estimation of the probability density function of the basalt sampling dataset102. The relatively large uncertainties on V/Sc at ~0.65 Ga is due to the scarcity of basalts erupted during 0.7–0.6 Ga. b, c Estimated mean melting P and T of primary arc basalts through time, respectively, assuming a water content of 4 wt%57,58. Error bars in a–c indicate 2 s.e.m. uncertainties. Horizontal lines and shaded bands in a–c illustrate average values since ~0.8 Ga and 95% confidence intervals, respectively. Cen. Cenozoic.
