Molybdenum isotopic constraints on the origin of EM1-type continental intraplate basalts. (15th January 2022)

• Record Type: Journal Article
• Authors: Ma, Liang; Xu, Yi-Gang; Li, Jie; Chen, Li-Hui; Liu, Jian-Qiang; Li, Hong-Yan; Huang, Xiao-Long; Ma, Qiang; Hong, Lu-Bing; Wang, Yu
• Is Part Of: Geochimica et cosmochimica acta. Volume 317(2022)
• Page Start: 255
• Page End: 268
• Publication Date: 2022-01-15
• Subjects: Molybdenum stable isotopes -- Enriched mantle 1 -- Continental intraplate basalts -- Light -- Molybdenum reservoir -- Deep mantle; Geochemistry -- Periodicals; Meteorites -- Periodicals; Géochimie -- Périodiques; Météorites -- Périodiques; Geochemie; Astrochemie; Electronic journals; 551.905
• DOI: 10.1016/j.gca.2021.11.013
• Languages: English
• ISSNs: 0016-7037

Abstract

Abstract: The origin of enriched mantle 1 (EM1) component in the mantle has long been debated. EM1 source of basalts has been variously attributed to recycled sub-continental lithosphere, recycled lower continental crust, or recycled oceanic crust plus pelagic sediments. Molybdenum stable isotope systematics has the potential to resolve this debate, because of the significant isotopic differences between mantle and crustal reservoirs. Here we present molybdenum isotope data for EM1-type continental intraplate basalts from Nuominhe (NMH), Northeast China. The NMH basalts display significant variations in both δ 98/95 Mo ( 98 Mo/ 95 Mo ratio relative to NIST SRM 3134, −0.49 to −0.15‰) and Mo/Ce (0.009–0.037), and strong correlations between δ 98/95 Mo, Mo/Ce and Hf isotope and trace elements. EM1 end-member of the NMH basalts shows the lightest δ 98/95 Mo and lowest Mo/Ce values. The involvement of continental crust and sub-continental lithospheric mantle cannot account for the light Mo isotopic compositions of the basalts. By contrast, the recycled oceanic crust with pelagic sediments, characterized by low δ 98/95 Mo and Mo/Ce values, is the satisfactory candidate for the EM1 component in the NMH basalts. Our results also suggest a residual slab reservoir with light δ 98/95 Mo values (<−0.5‰) in the mantle beneath Northeast China, representing the complementary reservoir to heavy Mo isotope continental crust. Identification of this reservoir makes the Mo isotope system a powerful tracer of crust-mantle interactions.