Surface and subsurface damage caused by bullet impacts into sandstone

The shift of armed conflicts to more urbanised environments has increased risk to cultural her-itage sites. Small arms impacts are ubiquitous in these circumstances, yet the effects and mecha-nisms of damage caused are not well known. A sandstone target was shot under controlled con-ditions to investigate surface and subsurface damage. A 3D model of the damaged block, created by structure from motion photogrammetry, shows that internal fracturing was at least as exten-sive as the visible surface fractures. Back scatter electron imaging of the damaged surface shows a shift from intragranular fracturing and grain size reduction at <5 mm from the impact point, to primarily circumgranular fracturing and grain ‘plucking’ at 20 mm from the impact point. In-ternal fracture intensity decreased with distance from the centre of the crater. Volumes around the impact point are therefore at greater risk of subsequent weathering deterioration, but signif-icant damage extends to the periphery of the target, rendering whole blocks vulnerable. The surface crater, despite being one of the most conspicuous aspects of conflict damage, has many times less area than internal and surface fractures.

Supplemental Material: Metamorphism of the Sierra de Maz and implications for the tectonic evolution of the MARA terrane

<div>Analytical methods, garnet compositional maps, a comparison of thermobarometry methods, monazite back-scatter electron images, mineral chemistry, and garnet and monazite isotopic data.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>

Supplemental Material: Metamorphism of the Sierra de Maz and implications for the tectonic evolution of the MARA terrane

<div>Analytical methods, garnet compositional maps, a comparison of thermobarometry methods, monazite back-scatter electron images, mineral chemistry, and garnet and monazite isotopic data.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>

Supplemental Material: Metamorphism of the Sierra de Maz and implications for the tectonic evolution of the MARA terrane

<div>Analytical methods, garnet compositional maps, a comparison of thermobarometry methods, monazite back-scatter electron images, mineral chemistry, and garnet and monazite isotopic data.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>