Petrology and mineralogy of volcanic glass in meteorite Northwest Africa 11801: Implications for their petrogenesis

Abstract

AbstractThe study of lunar magma evolution holds significant importance within the scientific community due to its relevance in understanding the Moon's thermal and geological history. However, the intricate task of unraveling the history of early volcanic activity on the Moon is hindered by the high flux of impactors, which have substantially changed the morphology of pristine volcanic constructs. In this study, we focus on a unique volcanic glass found in the lunar meteorite Northwest Africa 11801. This kind of volcanic glass is bead‐like in shape and compositionally similar to the Apollo‐14 and Apollo‐17 very low‐Ti glass. Our research approach involves conducting a comprehensive analysis of the petrology and mineralogy of the volcanic glass, coupled with multiple thermodynamic modeling techniques. Through the investigation, we aim to shed light on the petrological characteristics and evolutionary history of the glass. The results indicate that the primitive magma of the glass was created at 1398–1436°C and 8.3–11.9 kbar (166–238 km) from an olivine+orthopyroxene mantle source region. Then, the magma ascended toward the surface along a non‐adiabatic path with an ascent rate of ~40 m s−1 or 0.2 MPa s−1. During the magma ascent, only olivine crystallized and the onset of magma eruption occurred at ~1320–1343°C. Finally, the glass cooled rapidly on the lunar surface with a cooling rate ranging between 20 and 200 K min−1. Considerable evidence from petrology, mineralogy, cooling rate, and the eruption rate of the glass beads strongly supports the occurrence of ancient explosive volcanism on the Moon.