Earth and Planetary Science

Abiotic Oxygen Oases in Neoarchean Oceanic Large Igneous Provinces: A Hypothesis of Basalt Thermo‑Acidolysis Triggered by Mantle Plume Redox Reactor

Alexandre de Oliveira Chaves

Federal University of Minas Gerais (UFMG)

DOI: https://doi.org/10.36956/eps.v5i2.3253

Received: 14 April 2026; Published: 7 August 2026

Abstract

This paper suggested a conceptual, thermodynamically motivated hypothesis in which Neoarchean oceanic Large Igneous Provinces (LIPs) above oversized mantle plumes functioned as enormous abiotic oxygen reactors. In this framework, high heat flow and magmatic volatile fluxes (HCl, SO₂) drive pervasive thermo-acidolysis of oceanic lithosphere and oversized basaltic plateaus (oceanic LIPs), leading to slight water thermolysis, sulfur disproportionation, and local increases in oxygen fugacity toward the hematite-magnetite buffer (HM) within hydrothermal conduits. As an open system, progressive Fe exhaustion and advanced argillic alteration produce pyrophyllite-hematite-quartz linings that passivate conduit walls, while differential diffusion, degassing and rapid advection favour the kinetic survival of abiotic O₂ in an otherwise anoxic ocean, providing oxidative oases that preceded and possibly conditioned the emergence of biological oxygen production. The hypothesis yields testable predictions for thermodynamic-kinetic models and for the interpretation of hematite- and pyrophyllite-bearing alteration zones in Neoarchean greenstone belts. It is also suggested here that the precipitation of banded iron formations (BIFs), dolomitic carbonates and anhydrite was a spontaneous consequence of the basalt thermo-acidolysis. This process would have served as a precursor for the Paleoproterozoic Great Oxidation Event (GOE), contributing to generating the oxygen necessary to change the climate (Huronian Glaciation), the atmospheric chemistry (end of sulfur mass-independent fractionation, MIF-S), and the signature of life (Lomagundi-Jatuli δ13C positive excursion).

Keywords: Neoarchean, LIP, Basaltic Oceanic Plateau, Volatiles, GOE, Abiotic Oxygen

References