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Highly siderophile element abundances and 182W/184W and 187Os/188Os were determined for a suite of Mauna Kea lavas from the Hawaiian Scientific Drilling Project phase 2 drill core. The new analyses, combined with previous measurements, compose the largest database for μ182W (the parts-per-million deviation of 182W/184W from a terrestrial standard) for a single volcano (n = 16). Although most lavas analyzed are characterized by negative μ182W values, lavas with values similar to the modern bulk silicate Earth are found throughout the entire stratigraphic column. This suggests that components with normal μ182W are collocated with components that host μ182W deficits in the plume. Negative μ182W values are associated with elevated 3He/4He, as well as elevated Ti and Nb. These correlations may link μ182W anomalies to ancient deep mantle crystal-liquid fractionation processes. Consistent with previously measured 3He/4He (R/RA) in the drill core, the magnitude of negative μ182W values was greatest when Mauna Kea was close to the plume axis then generally decreased over the ~400 kyr captured by the stratigraphic section. The component with anomalous μ182W was either concentrated near the plume axis, or was more effectively sampled by melting near the plume axis where the temperature excess was greatest, suggesting it was less fusible than the dominant plume components. The process leading to the generation of a mantle component with a negative μ182W anomaly could either be related to some form of core-mantle isotopic equilibration, or early-Earth fractionation within the silicate Earth. At present each possibility remains viable. 

Abstract Mantle plumes contain heterogenous chemical components and sample variable depths of the mantle, enabling glimpses into the compositional structure of Earth's interior. In this study, we evaluated ocean island basalts (OIB) from nine plume locations to provide a global and systematic assessment of the relationship betweenfO₂and He‐Sr‐Nd‐Pb‐W‐Os isotopic compositions. Ocean island basalts from the Pacific (Austral Islands, Hawaii, Mangaia, Samoa, Pitcairn), Atlantic (Azores, Canary Islands, St. Helena), and Indian Oceans (La Réunion) reveal thatfO₂in OIB is heterogeneous both within and among hotspots. Taken together with previous studies, global OIB have elevated and heterogenousfO₂(average = +0.5 ∆FMQ; 2SD = 1.5) relative to prior estimates of global mid‐ocean ridge basalts (MORB; average = −0.1 ∆FMQ; 2SD = 0.6), though many individual OIB overlap MORB. Specific mantle components, such as HIMU and enriched mantle 2 (EM2), defined by radiogenic Pb and Sr isotopic compositions compared to other OIB, respectively, have distinctly highfO₂based on statistical analysis. ElevatedfO₂in OIB samples of these components is associated with higher whole‐rock CaO/Al₂O₃and olivine CaO content, which may be linked to recycled carbonated oceanic crust. EM1‐type and geochemically depleted OIB are generally not as oxidized, possibly due to limited oxidizing potential of the recycled material in the enriched mantle 1 (EM1) component (e.g., sediment) or lack of recycled materials in geochemically depleted OIB. Despite systematic offset of thefO₂among EM1‐, EM2‐, and HIMU‐type OIB, geochemical indices of lithospheric recycling, such as Sr‐Nd‐Pb‐Os isotopic systems, generally do not correlate withfO₂. 

Rare high- 3 He/ 4 He signatures in ocean island basalts (OIB) erupted at volcanic hotspots derive from deep-seated domains preserved in Earth’s interior. Only high- 3 He/ 4 He OIB exhibit anomalous 182 W—an isotopic signature inherited during the earliest history of Earth—supporting an ancient origin of high 3 He/ 4 He. However, it is not understood why some OIB host anomalous 182 W while others do not. We provide geochemical data for the highest- 3 He/ 4 He lavas from Iceland (up to 42.9 times atmospheric) with anomalous 182 W and examine how Sr-Nd-Hf-Pb isotopic variations—useful for tracing subducted, recycled crust—relate to high 3 He/ 4 He and anomalous 182 W. These data, together with data on global OIB, show that the highest- 3 He/ 4 He and the largest-magnitude 182 W anomalies are found only in geochemically depleted mantle domains—with high 143 Nd/ 144 Nd and low 206 Pb/ 204 Pb—lacking strong signatures of recycled materials. In contrast, OIB with the strongest signatures associated with recycled materials have low 3 He/ 4 He and lack anomalous 182 W. These observations provide important clues regarding the survival of the ancient He and W signatures in Earth’s mantle. We show that high- 3 He/ 4 He mantle domains with anomalous 182 W have low W and 4 He concentrations compared to recycled materials and are therefore highly susceptible to being overprinted with low 3 He/ 4 He and normal (not anomalous) 182 W characteristic of subducted crust. Thus, high 3 He/ 4 He and anomalous 182 W are preserved exclusively in mantle domains least modified by recycled crust. This model places the long-term preservation of ancient high 3 He/ 4 He and anomalous 182 W in the geodynamic context of crustal subduction and recycling and informs on survival of other early-formed heterogeneities in Earth’s interior.