Using D/V Meng Xiang to drill intact magmatic crust in the Pacific to reveal the petrological nature of the oceanic Moho

• No intact magmatic ocean crust forms at slow- and ultraslow-spreading ridges • Ocean crust formed at slow- and ultraslow-spreading ridges comprise basaltic rocks and serpentinized mantle peridotite. • Moho at the base of the crust formed is predicted to be serpentinization front of mantle peridotite. • Drilling to penetrate full thickness of ocean crust formed at slow- and ultraslow-spreading ridges not recommended. • Drilling to penetrate intact ocean crust formed at the fast-spreading East Pacific Rise will prove feasible. I have recently published “Do we really need to drill through the intact ocean crust?” in this journal (Geoscience Frontiors, 2025, Volume 16, 101954), which is a theme talk at the “ International Workshop on Fulfilling the Quest of Drilling Through the Ocean Crust Using D/V Meng Xiang (‘梦想号’)” held in Guangzhou (November 24 ‒ 27, 2024), and is an objective account of petrological properties of the oceanic Moho. The global geoscience community universally acknowledges that Moho is a seismic discontinuity representing the boundary between the crust ( V P ≤ 7 km/s) and mantle ( V P ≥ 8.0 km/s). However, the longstanding assumption of purely magmatic origin for the ocean crust has misled the subject field. Evidence shows that the ocean crust formed at many slow-spreading ridge localities maintains a globally constant seismic thickness of ∼ 6 ± 1 km yet paradoxically comprises predominantly serpentinited mantle peridotite. This observation rationalizes the 60-year-old Hess-type Ocean crust hypothesis, while also underscoring the imperative for direct verification through intact ocean crust drilling − the core objective of the abandoned Project Mohole (1957‒1966). The workshop participants unanimously concurred that D/V Meng Xiang is currently the only operational platform capable of achieving intact ocean crust penetration. However, selection of optimal drilling sites needs further multidisciplinary discussion for successful Moho penetration, allowing addressing the core question on the petrological nature of the oceanic Moho . Here, I suggest the following with justifications for consideration: (1) It is not possible and thus has no significance to drill into the Moho on seafloors formed at slow- and ultraslow-spreading ridges; (2) it is feasible to succeed with well-prepared efforts in drilling through intact magmatic crust at ideal sites of seafloors produced at the fast-spreading East Pacific Rise; (3) if the Pacific Moho is discovered to be serpentinization front, this will bring about a paradigm shift.