Large correlated zinc isotope variability in the eastern Pacific mantle as a result of low-degree melt metasomatism
Description
This dataset includes major, trace element data, Sr-Nd-Pb isotope data and Zn-Fe isotope data of near-EPR 5-15°N seamount lavas, as well as major element abundances corrected for the effect of fractional crystallization to Mg# = ~72, modeling result of the Zn isotope variation during mantle melting, and estimation result of the age of the enriched source component. Recently, Zn isotope systematics has been widely used as a novel tracer for subducted carbonate sediments in mantle-derived magmas. However, the effect of magmatism in Zn isotope variations in mantle-derived magmas has been overlooked. This study reports the largest δ66Zn variation range (0.19-0.52‰) known in oceanic basalts in lavas from seamounts near the East Pacific Rise (EPR) between 5° and 15°N. The variably high δ66Zn values have a clear magmatic origin because: (1) high-δ66Zn lavas have low CaO and CaO/Al2O3, clearly arguing against an origin from recycled carbonates, and (2) high-δ66Zn lavas have higher abundances of progressively more incompatible elements with more enriched radiogenic Sr-Nd-Pb isotope compositions, which requires low-degree melting from a compositionally enriched mantle component of ancient low-degree melt metasomatic origin. We conclude that the high-δ66Zn signature in terrestrial basalts is not evidence for recycled carbonates as widely advocated but evidence for the effects of low-degree mantle melting as a way of Earth’s chemical differentiation over its histories.
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National Natural Science Foundation of China
42376051
National Natural Science Foundation of China
42006049
National Natural Science Foundation of China
91958215
National Natural Science Foundation of China
ZR2020MD029
Shandong Basic Research Office
WSR2023018
Higher Education Discipline Innovation Project
B18048