Decoupling Surface Geochemistry from Basin Genesis at the Luna Structure, Gujarat: A Testable Framework for Resolving the Impact-Slag Debate

The Luna structure in the Banni Plains of Kutch, Gujarat, India, is a debated circular geomorphological feature approximately 1.5-1.8 km in diameter. Recent interpretations have divided between a hypervelocity impact origin and an archaeometallurgical slag hypothesis based on dense, glassy, iron-rich surface nodules. The 2026 study by Asokan et al. used mineralogy, highly siderophile element abundances, and Re-Os isotope systematics to reinterpret the sampled nodules as terrestrial pyrometallurgical slags rather than meteoritic impactites. This paper accepts that the sampled surface materials may be convincingly explained as slag, but argues that surface-material provenance and basin genesis are not logically equivalent. It further emphasizes a mechanical constraint: non-impact models such as sinkhole collapse, evaporite withdrawal, liquefaction, or tectonic sagging may explain a depression, but a continuous elevated rim requires a specific rim-forming mechanism that must be mapped and tested. Hypervelocity impact mechanics are also emphasized as a distinct velocity-dominated shock-energy regime: because kinetic energy scales with the square of velocity, even modest projectiles can generate outward excavation flow and rim uplift that are not directly equivalent to sinkhole collapse, liquefaction, or tectonic sagging. The paper proposes a decoupled testing framework separating (1) the origin of the surface nodules, (2) the formation mechanism of the basin and rim, and (3) the post-formational sedimentary, saline, hydrological, and anthropogenic overprint. It also discusses Libyan Desert Glass and Tutankhamun's pectoral scarab as a comparative example showing that impact-derived materials can enter high-status ancient cultural contexts, without using that comparison as proof for Luna. The impact hypothesis remains unproven, but surface slag alone does not decisively falsify it. Deep continuous coring, geophysical profiling, rim stratigraphy, petrography, and shock-metamorphic analysis are identified as the critical tests needed to resolve the debate.