Magnesium and zinc isotopic anomaly of Cenozoic lavas in central Myanmar: Origins and implications for deep carbon recycling

Mantle Oxidation Induced by Recycled Carbonate: Insights From Mg‐Zn‐Fe‐Cu Isotopic Systematics of Intraplate Basalts

“…On the other hand, olivine crystallization during early differentiation, if any, produces higher δ 56 Fe values and negligible Cu isotope fractionation in the melts (e.g., Kilauea lki trend in Figures 5a and 5b; Savage et al, 2015;Teng et al, 2008). However, our samples with higher δ 56 Fe and lower δ 65 Cu values have lower SiO 2 contents (Figures 5a and 5b) and are less differentiated (MgO > 5 wt%; Lee et al, 2016;M.-L. Li et al, 2021), which is inconsistent with isotope fractionation induced by differentiation (J. Liu, Rudnick, et al, 2023).…”

“…Seismic tomography indicates that the subducted west-Pacific and Neo-Tethyan oceanic slabs are currently stagnant in the MTZ underlying the two areas, respectively (Figure 1b; J.-L. Huang & Zhao, 2006;Lei & Zhao, 2016). Thus, these Cenozoic basalts are widely proposed to be related to the stagnated slabs in the MTZ based on the spatial association as well as geochemical features of the basalts (e.g., M.-L. Li et al, 2021;S.-G. Li et al, 2017;Liu, Qu, et al, 2022). The lithology of these basalts is mainly alkaline with minor subalkaline formed by various degrees of mantle partial melting (Figure 2; Yu et al, 2018).…”

“…Overall, phenocryst abundance and size decrease gradually with weaker alkalinity. For basalt samples from central Myanmar, the petrology, chemistry, and Sr-Nd-Mg-Zn isotopes have been previously described (Lee et al, 2016;M.-L. Li et al, 2021). Myanmar alkaline basalts are generally unaltered and display obvious phenocrysts such as clinopyroxene and plagioclase with groundmass containing Fe-Ti oxides and olivine.…”

“…The widespread Cenozoic intraplate basalts in both northeast China and central Myanmar are proposed to have originated from the MTZ associated with the stagnated slabs (Lee et al, 2016;S.-G. Li et al, 2017), and decarbonization and dehydration of the stagnated slabs have been confirmed by multiple means (e.g., Kuritani et al, 2011;J.-F. Yang & Faccenda, 2020). The enrichment of the mantle sources of these basalts has been mediated by various subducted materials (e.g., marine carbonates, terrigenous sediments) released from subducted plates (M.-L. Li et al, 2021;S.-G. Li et al, 2017;Liu, Qu, et al, 2022). Thus, these basalts are ideal samples to explore the possible linkage between deep mantle oxidation and recycled crustal components on a large scale.…”

Zinc Isotopes of the Mariana and Ryukyu Arc‐Related Lavas Reveal Recycling of Forearc Serpentinites Into the Subarc Mantle

“…Wang, Liu, Wang, et al, 2018) and AOC (up to 0.55‰; Huang et al, 2016) have much heavier Zn isotopic compositions relative to the terrestrial mantle (0.18 ± 0.06‰; Doucet et al, 2020;Sossi et al, 2018; (Figure 1). Correspondingly, the heavy Zn isotopic compositions of basaltic magmas from eastern China (Jin et al, 2020;Liu et al, 2016;, southeastern Tibet (Liu et al, 2020), the Myanmar arc (M. L. Li et al, 2021), ocean islands (Beunon et al, 2020), and Emeishan Large Igneous Province (Yang & Liu, 2019) are associated with recycled sedimentary carbonates or AOC into the mantle. Comparatively, siliciclastic sediments are isotopically similar to or lighter than the terrestrial mantle (Figure 1) (Bentahila et al, 2008;Inglis et al, 2017;Little et al, 2016;Pons et al, 2011), and thus, magmas derived from a mantle source metasomatized by recycled siliciclastic sediments have light Zn isotope compositions (Beunon et al, 2020;Jin et al, 2020;Liu et al, 2020).…”