Fig. 4: Schematic diagram illustrating the generation of N-MORB-like gabbros with light oxygen isotope compositions from Cona area of the Comei LIP in the context of plate tectonics and mantle plume.

a Schematic cross-section of the mantle showing major mantle structures and locations of potential chemical reservoirs with variable oxygen isotopic, radiogenic isotopic, trace elemental compositions. These include a heterogeneous large low shear velocity province (LLSVP) (indicated by different shades of dark red, including mantle plumes), ultra-low velocity zones (ULVZs, red) and subducted oceanic lithosphere transporting recycled surface materials with variable oxygen isotope composition (e.g., gabbros, blue) into the mantle (Revised after ref. ⁶). Upper mantle peridotite, N-MORB, and OIB whole-rock δ¹⁸O values are from refs. ^41,42,120, respectively; arc lavas whole-rock δ¹⁸O values are from refs. ^78,108. Whole-rock δ¹⁸O values for Cona gabbros area were calculated from zircon using ref. ¹²¹. Abbreviations: EM-I, enriched mantle I; EM-II enriched mantle II, HIMU high μ (U/Pb). Mantle plume compositions reflect contributions from multiple mantle reservoirs, including recycled crustal material. b Penrose model of oceanic crust based on Oman ophiolite, showing estimated alteration temperature and bulk rocks δ¹⁸O data (modified from ref. ⁸²). Whole-rock δ¹⁸O ranges for the N-MORB-like Cona gabbros are included for comparison.