Geometric Energy Transfer in General Relativity without Field Equation Modification

We propose a conservative mechanism within General Relativity in which energy associated with matter can be irreversibly transferred to non-localizable geometric degrees of freedom of spacetime, without modifying Einstein’s field equations. The mechanism relies on intrinsic geometric energy modes that do not correspond to propagating fields and therefore evade localization. Energy transfer proceeds discretely and applies exclusively to massive matter fields, leading to an accumulated geometric contribution that alters the effective gravitational response on large scales. We show that this framework naturally reproduces phenomenology commonly attributed to dark matter and dark energy, including galactic rotation curves, cluster-scale mass discrepancies, and late-time cosmic acceleration, without introducing new particles or modifying gravity. The model predicts a finite saturation of geometric energy and a dynamically inert final cosmological state. Observable consequences and falsifiability conditions are discussed.