Fig. 3: δ26Mg vs. MgO and TiO2 for petit-spot basalt samples.
From: Melting of recycled ancient crust responsible for the Gutenberg discontinuity
a The comparison of δ26Mg with bulk rock Mg#. The gray box with a dashed line shows the Mg isotopic composition of the global MORB and OIBs (ref. 21), referred to as the Normal Mantle value here. The Mg isotope composition of the Pitcairn Island EM1 basalts and the continental intraplate EM1 basalts from northeastern China (Wudalianchi, WDLC) are shown for comparison (ref. 39,41). All error bars represent 2 standard deviations. Symbols for petit-spot basalts are the same as in Fig. 2. #1392R10 marks the sample from Site C, which is out of the trend between δ26Mg and TiO2. b The comparison of δ26Mg with the TiO2 content of the bulk rocks. All the symbols are the same to a and Fig. 2. R is the correlation coefficient of the linear regression for all the petit-spot basalt samples except #1392R10, which clearly stands outside the trend.
