A Hypothesis for Subsurface Silicon-Based Life Based on Crustal Chemical Disequilibrium and Detection in Deep Primary Magma

Following the astrobiological criterion that identifies carbon-based life through atmospheric chemical disequilibrium, this paper puts forward an analogous hypothesis for subsurface silicon-based life. It posits that the Earth’s crust serves as the "atmosphere-like medium" for silicon-based life, and the coexistence of reduced silicon compounds and oxidized minerals in the crust acts as a signature of silicon-based biological activity. Silicon-based biomacromolecules are hypothesized to take Si–O long chains as their backbone, which can perform information storage and catalytic functions, corresponding to the carbon chain backbone, DNA, and proteins of carbon-based life. The paper clarifies that most ordinary volcanic magmas, as products of crustal remelting, tend to destroy silicon-based structures via recrystallization, while mantle-derived primary magmas (e.g., kimberlite) that ascend rapidly are most likely to preserve intact silicon-based macromolecules. To verify this falsifiable hypothesis, two experimental methods are designed: in-situ high-temperature spectroscopy and ultrafast quenching cryo-electron microscopy. This hypothesis unifies the chemical judgment criteria for carbon-based and silicon-based life, provides a testable theoretical framework for subsurface life forms, and explores two plausible origins of silicon-based life—independent abiogenesis in the early deep mantle and evolutionary transition from hyperthermophilic carbon-based life. It is a logically self-consistent, structurally symmetrical scientific hypothesis with significant scientific value and breakthrough potential.