Solving Planetary Cold Cases: Geochemical Fingerprints of Impact-Driven Extinctions from the Ordovician to the Holocene

Throughout Earth's 500-million-year Phanerozoic history, multiple mass extinction events display clear evidence of catastrophic environmental change—yet without obvious triggering mechanisms. This forensic analysis examines seven major extinction and environmental crisis events spanning 445 million years, applying the Antipodal Bullet Theory framework to identify impact signatures where craters are absent or unrecognized. We demonstrate three distinct mechanisms by which cosmic impacts trigger catastrophic volcanism: (1) Full Antipodal Bullet penetration for large metal-rich impactors (>12 km), resulting in antipodal Large Igneous Provinces; (2) Partial Penetration with Seismic Triggering for medium-sized impactors (5-10 km), triggering pre-loaded volcanic systems globally; and (3) Direct Volcanic Impact for smaller impactors (0.05-5 km) that strike directly into active volcanic systems, destroying their own evidence. Events analyzed include: Late Ordovician (445 Ma), Late Devonian (375-359 Ma), Capitanian (262 Ma), Toarcian (183 Ma), PETM (55.5 Ma), Toba (74 ka), and Younger Dryas (12.8 ka). Each displays characteristic geochemical "fingerprints"—iridium anomalies, platinum group element enrichment, osmium isotope shifts, carbon isotope excursions—even when impact craters are missing due to oceanic impacts, subduction, and erosion over geological time. Statistical analysis reveals impact-LIP-extinction correlations occur with probability p < 0.0001 for random coincidence, strongly supporting causation. The framework makes falsifiable predictions testable with current technology, including systematic PGE analysis of extinction boundaries and LIP bases, osmium isotope high-precision studies, and geophysical surveys of predicted antipodal regions. This work establishes that geological time has systematically destroyed impact evidence through plate tectonics, making the absence of craters the expected outcome rather than evidence against the impact hypothesis. Understanding these mechanisms has critical implications for planetary defense, climate science, astrobiology, and long-term human survival. As an independent researcher, I welcome collaboration with members of the scientific community who find value in this work.Researchers registered as arXiv endorsers in Geophysics (physics.geo-ph), Astrophysics (astro-ph.EP), or related fields who are willing to support submission of this paper to arXiv are invited to contactthe author at [email protected]. https://orcid.org/0009-0006-1089-9023