A Hybrid Iron/Green-Rust-Urea Model for Prebiotic Chemistry: A Synthesis of Testable Pathways for Planetary Astrobiology

We propose a quantitative, testable framework for abiogenesis that links submarine alkaline vents, which supply H₂, ΔpH, and Fe/Fe–S catalysis, to subaerial hot-spring fields that provide wet–dry concentration and UV-driven photoredox chemistry. To bridge dilution between environments, we specify mobile “holding pens” (green-rust/iron flocs, silica mats, pumice rafts, and sea-surface microlayer/foam) that concentrate, shuttle, and release prebiotic cargo into shoreline pools. We present an energy ledger that couples geologic gradients and Fe(III)–citrate photoredox to activation currencies (thioesters, condensed P), enabling short-oligomer copying under citrate-buffered Mg²⁺ and protocell membranes compatible with wet–dry cycles. The model makes falsifiable predictions across geology, chemistry, and missions: laminated silica–iron–phosphorus–organic microfacies in Archean analogs; specific rover-detectable co-occurrences on Mars; and plume-analyte patterns on ocean worlds. We provide transport budgets achieving ≥10³ concentration gain per day, ΔG signposts for keystone steps, autonomous-reactor pass/fail metrics, and an early evolution error-threshold box that motivates short, selectable motifs. The framework paints the big picture while codifying zoomable, lab- and mission-ready tests that can confirm or falsify each link.