The Zhamanshin Impact Event: Potential Implications for Environmental Responses and Biological Linkages on Earth and Beyond

TL;DR

This study re-evaluates the Zhamanshin impact event, suggesting it was twice as large as previously thought, with significant implications for understanding its environmental and biological effects during the Middle Pleistocene.

Contribution

It provides a revised estimate of the impact crater size and energy, highlighting potential global environmental impacts during the Middle Pleistocene transition.

Findings

Zhamanshin crater likely 26.5 km in diameter, doubling previous estimates.

Impact energy exceeds 240,000 Megatons, with a 7-10 times increase in environmental effects.

Impacts of this magnitude could have influenced climate transitions and biological responses around 0.9 Ma.

Abstract

At least one large-body (diameter > 1.1 km) hypervelocity cratering event occurred during ~ 0.8-0.90 Ma (Zhamanshin, Kazakhstan) in the Middle Pleistocene Transition period. Analysis designed to reduce uncertainty in the dimensions of the Zhamanshin structure employing high resolution topography demonstrated that it likely generated a ~ 26.5 km diameter multi-ring crater. This is at least two times larger than the current best estimates. Using a range of accepted impactor sizes, velocities, compositions, and angles of impact, such impacts typically yield kinetic energies of impact over 240,000 Megatons (TNT). Explosive energetic events of this magnitude (e.g., Yellowstone Caldera) at other times (K-Pg) have created global environmental effects. The factor of two discrepancy in the dimensions of Zhamanshin increases the kinetic energy yield by factors of 7-10, with significantly larger environmental consequences. This justifies examination of rapid climate transitions linked to biological consequences, including those related to environmental perturbations, at ~0.9 Ma.