The Hopewell airburst event, 1699-1567 years ago (252-383 CE)

Meteorites, silicious vesicular melt glass, Fe and Si-rich magnetic spherules, positive Ir and Pt 25 anomalies, and burned charcoal-rich Hopewell habitation surfaces demonstrate that a cosmic airburst event occurred over the Ohio River valley during the late Holocene. A comet-shaped earthwork was constructed near the airburst epicenter. Twenty-nine radiocarbon ages demonstrate that the event occurred between 252 and 383 CE, a time when 69 near-Earth comets were documented. While Hopewell people survived the catastrophic event, it likely contributed to their cultural decline. The Hopewell comet airburst expands our understanding of the frequency and impact of cataclysmic cosmic events on complex human societies.

Hydrogen Isotopic Variations in the Shergottites

Hydrogen isotopes in the shergottite Martian meteorites are among the most varied in Mars laboratory samples. By collating results of previous studies on major hydroxyl, deuterium, and H2O bearing phases, we provide a compendium of recent measurements in order to elucidate crustal-rock versus mantle-rock processes on Mars. We summarize recent works on volatile and δD measurements in a range of shergottite phases: from melt inclusions, apatite, merrillite, maskelynite, impact melt glass, groundmass glass, and nominal anhydrous minerals. We interpret these observations using an evidence-based approach, considering two particular scenarios: (1) water-rock crustal interactions versus (2) magmatic-based processes. We consider the implications of these measurements and the scope they have for future studies, paying particular attention to future works on H, S, and Cl isotopes in situ, shedding light on the nature of volatiles in the hydrosphere and lithosphere of Mars.

A synchrotron X-ray spectroscopy study of titanium co-ordination in explosive melt glass derived from the trinity nuclear test

This work presents the first determination of Ti speciation and co-ordination in trinitite via the use of X-ray absorption spectroscopy.