DETERMINING THE ORIGIN OF ANTHROPOGENIC INCLUSIONS IN TRINITITE GLASS USING ISOTOPIC COMPOSITIONS

The White Sands Missile Range, near Alamogordo (NM) witnessed the world’s first detonation of an atomic bomb, the Trinity Test, on the morning of July 16, 1945. The bomb was an implosion device with an enriched plutonium core (99.1% ²³⁹Pu). The extreme energy and heat generated temperatures >8000° C, which melted and fused the arkosic sand at ground zero. The resulting blast melt is referred to as “Trinitite”, which contains a variety of inclusions, including those originating from the device, infrastructure present at ground zero (e.g., steel tower used to suspend the bomb), and unmelted remnants of precursor minerals present within the desert sand (e.g., quartz, feldspar, ilmenite). The anthropogenic inclusions generally present themselves on the surface of Trinitite as opaque marks sometimes surrounded by a halo shaped discoloration in the glass. They can also be identified in petrographic thin section by their unique shapes, colors, and characteristics observed during reflective light-microscopy. The objective of this research is to determine the ultimate origin of the anthropogenic inclusions within the Trinitite glass.

Bulk Trinitite samples were examined visually for anthropogenic inclusions present at the surface. Once located, inclusions were removed from the surface and subsequently analyzed for their major element compositions using Micro-X-Ray Fluorescence (µ-XRF) and scanning electron microscopy (SEM) using Electron Dispersive X-Ray Spectroscopy (EDS). The inclusions are then dissolved and subsequently analyzed quantitatively for their trace element compositions using solution mode-inductively coupled plasma mass spectrometry (ICP-MS). The inclusions found in petrographic thin sections were also investigated by µ-XRF and SEM-EDS methods. Inclusions within thin sections will be analyzed by laser ablation (LA)-ICP-MS for determining their trace element concentrations. This will permit for a direct comparison of trace element abundances obtained by both analytical methods. The capacity to decipher bomb-related components within nuclear explosion debris greatly aids in source attribution, which ultimately results in promoting national security.