Oxygen isotope composition of trinitite postdetonation materials

Area of Science:

• Geochemistry
• Nuclear Forensics
• Isotope Geology

Background:

• Trinitite is melt glass formed during the 1945 Trinity nuclear test.
• The geological setting involved arkosic sand fused with radioactive debris.
• Nuclear test site materials offer insights into explosion effects on the environment.

Purpose of the Study:

• Analyze oxygen isotope ratios (δ(18)O) in Trinity site materials.
• Investigate the impact of the nuclear explosion on oxygen isotope systematics.
• Determine the origin of oxygen isotope signatures in trinitite.

Main Methods:

• Examined precursor minerals (quartz, feldspar, calcite) and trinitite samples.
• Utilized scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) for elemental analysis.
• Measured oxygen isotope values (δ(18)O) and correlated them with major element composition.

Main Results:

• Bulk trinitite samples showed a wide range of δ(18)O values (11.2-15.5‰).
• Oxygen isotope values did not correlate with (152)Eu activity, indicating no perturbation by neutron flux.
• δ(18)O values correlated with major element abundances from precursor minerals.

Conclusions:

• The oxygen isotope ratios in trinitite are primarily inherited from the pre-existing mineralogy of the arkosic sand.
• The nuclear explosion did not significantly alter the (18)O/(16)O isotope systematics of the affected materials.
• Trinitite serves as a valuable archive for understanding pre-explosion geological conditions and isotopic signatures.