Dataset for: A huge mantle reservoir for subducted carbon beneath Central-East Asia

This dataset originates from the article “A huge mantle reservoir for subducted carbon beneath Central‑East Asia.” Mg‑Zn‑Sr‑Nd‑Hf‑Pb isotopic and major‑trace element data from Russian Cenozoic basalts reveal mantle metasomatism by slab‑derived melts/fluids, providing key evidence for deep carbon recycling and slab–mantle/crust–mantle interactions in Central‑East Asia. Detailed geochemical analyses were conducted on well‑correlated late Cenozoic volcanic systems in southeastern Siberia—Oka, Vitim, Udokan, and Tok. The samples exhibit SiO₂ (41.2–52.0 wt.%), total alkali (Na₂O+K₂O, 3.8–7.9 wt.%), Al₂O₃ (11.2–16.0 wt.%), MgO (6.6–12.0 wt.%), and TiO₂ (1.6–3.2 wt.%) contents similar to low‑silica basaltic melts in East Asia. They are enriched in light rare earth and large‑ion lithophile elements, depleted in heavy rare earths, with (La/Yb)ₙ = 8.78–31.0, resembling ocean‑island basalts. Radiogenic isotopes vary as (⁸⁷Sr/⁸⁶Sr)i = 0.703577–0.705135 and εNd(t) = +4.93 to –2.24, indicating the mantle source with multiple components. Magnesium isotopes show δ²⁶Mg values of –0.25±0.03‰ to –0.43±0.03‰, lower than peridotitic mantle and mid‑ocean ridge basalts (MORBs). Zinc isotopes show δ⁶⁶Zn values of +0.30±0.010‰ to +0.44±0.02‰, higher than normal mantle and MORBs. This coupled light‑Mg–heavy‑Zn signature points to the presence of carbonate in the melts (carbonate minerals can have δ²⁶Mg as low as –5.57‰ and δ⁶⁶Zn up to +1.67‰). Subducted slabs can deliver substantial carbon carriers (marine sediments, altered oceanic crust) into the deep mantle; melting of these slabs at depth generates low‑silica, carbonate‑bearing melts, offering a novel perspective on the origin of Russian Cenozoic basalts.