Earth's Bad Decades: A Sedimentary Record of the Chicxulub Aftermath from the New Jersey Coastal Plain and Offshore

Kenneth G. Miller, Peter J. Sugarman, Selen Esmeray-Senlet, Alexander Hudak, Yoshinori Miyazaki, William John Schmelz , James V. Browning, Timothy Shamus, Lauren Neitzke Adamo, Richard K. Olsson

The New Jersey Coastal Plain (NJCP) preserves records of the Chicxulub impact approximately 2,500 km from the crater, providing a unique archive of ejecta fallout, sediment reworking, ecological disruption, and recovery following the end-Cretaceous mass extinction. Preservation of impact deposits varies with depositional setting. Offshore sections beneath the NJ continental shelf and slope contain major unconformities, likely formed by slope failure and sediment remobilization triggered by the Chicxulub impact and its aftermath. In the NJCP, the most downdip (seaward) site, Bass River ( ~100 m paleodepth), records an undisturbed spherule layer of rapid fallout of impact ejecta deposited within hours of the event. More updip sites, including Ancora (~70 m paleodepth), contain reworked spherules and deposits consistent with tsunami-related sediment transport. At Campo Pit and the adjacent Buck Pit corehole (~20-30 m paleodepth), a 30-60 cm thick event deposit composed of lower red and upper green clay contains reworked impact spherules, a prominent iridium (Ir) anomaly near the base of the green clay, and several thin white kaolinite laminae near the top of the succession. Grain-size distributions, softsediment deformation structures, and reworked spherule-bearing clasts suggest multiple episodes of sediment erosion, transport, and redeposition rather than a single depositional event. The Ir horizon was deposited settling of fine impact-derived particles that followed impact by a decade or more whereas the overlying white laminae may reflect repeated sediment-remobilization events, perhaps associated with impact-triggered aftershocks. At the Inversand core adjacent to Edelman Fossil Park (~30-40 m paleodepth), the Main Fossiliferous Layer (MFL) occurs approximately 50 cm above a bioturbated K/Pg boundary and lacks a significant Ir anomaly, suggesting a complex history of accumulation and reworking. Collectively, these sections may preserve evidence of a decades-long period of post-impact environmental disruption and recovery that we term Earth's "Bad Decades."