We propose a purely geometric dark matter candidate: Local Spacetime Fragments (LSFs)—stable topological solitons formed during preheating in scalar–Gauss–Bonnet gravity. The action includes a coupling f(\phi)\mathcal{G}, where \mathcal{G} is the Gauss–Bonnet invariant. During preheating, parametric resonance amplifies \mathcal{G} above a critical threshold \mathcal{G}_c \sim M_{\rm Pl}^4, triggering a tachyonic instability that fragments spacetime into LSFs carrying a conserved topological charge \pi_3(S^3). The auxiliary field \phi decays after fragmentation, leaving LSFs as purely gravitational objects. The LSF mass function follows a log-normal distribution with mean m_0 \approx 10^3 M_{\rm Pl} and width \sigma \approx 0.5, yielding the observed dark matter abundance and a naturally peaked mass spectrum consistent with cold dark matter phenomenology. The model provides a unified geometric origin for dark matter, linking it directly to the quantum-gravitational structure of spacetime without invoking new fundamental particles. AI Usage Note: All theoretical ideas, mathematical derivations and conclusions are independently created by the author. Generative AI was only used for linguistic polishing of sentences. The author takes full responsibility for all content.