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Magnesium Isotopic Evidence for Ancient Subducted Oceanic Crust in LOMU‐Like Potassium‐Rich Volcanic Rocks
Author(s) -
Sun Yang,
Teng FangZhen,
Ying JiFeng,
Su BenXun,
Hu Yan,
Fan QiCheng,
Zhou XinHua
Publication year - 2017
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1002/2017jb014560
Subject(s) - geology , geochemistry , oceanic crust , adakite , crust , subduction , mantle (geology) , eclogite , volcanic rock , isotope , volcano , tectonics , paleontology , physics , quantum mechanics
To evaluate the role of subducted oceanic crust in the genesis of potassium‐rich magmas, we report high‐precision Mg isotopic data for a set of Cenozoic volcanic rocks from Northeast China. These rocks overall are lighter in Mg isotopic composition than the normal mantle and display considerable Mg isotopic variations, with δ 26 Mg ranging from −0.61 to −0.23. The covariation of δ 26 Mg with TiO 2 in these rocks suggests that their light Mg isotopic compositions were derived from recycled oceanic crust in the form of carbonated eclogite in the source region. The strong correlations between δ 26 Mg and (Gd/Yb) N ratio as well as Sr‐Pb isotopes further indicate a multicomponent and multistage origin of these rocks. Magnesium isotopes may thus be used as a novel tracer of recycled oceanic crust in the source region of mantle‐derived magmas.