Triple oxygen isotope constraints on the origin of ocean island basalts
- 1International Center for Isotope Effects Research, Nanjing University, Nanjing 210023, P. R. China (xiaobincao@nju.edu.cn)
- 2School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, P. R. China
- 3Department of Geology and Geophysics, Louisiana State University, Baton Rouge, LA 70803, USA
Understanding the origin of ocean island basalts (OIB) has important bearings on Earth’s deep mantle. Although it is widely accepted that subducted oceanic crust, as a consequence of plate tectonics, contributes material to OIB’s formation, its exact fraction in OIB’s mantle source remains ambiguous largely due to uncertainties associated with existing geochemical proxies. We have shown, through theoretical calculation and examining published data, that unlike many known proxies, triple oxygen isotope compositions (i.e. Δ17O) in olivine samples are not affected by crystallization and partial melting. This unique feature allows olivine Δ17O values to identify and quantify the fractions of subducted ocean sediments and hydrothermally altered oceanic crusts in OIB’s mantle source. In this work, new Δ17O measurements for OIB will be presented, and the implications will be discussed.
How to cite: Cao, X., Bao, H., and Peng, Y.: Triple oxygen isotope constraints on the origin of ocean island basalts , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17738, https://doi.org/10.5194/egusphere-egu2020-17738, 2020