Shock Deformation and Transformation Effects in Unbrecciated Lunar Mare Basalt Northwest Africa 032

Abstract

Lunar meteorites are an important source of information about the Earth’s moon. In this study, the mineralogy and texture of lunar meteorite Northwest Africa 032, an unbrecciated lunar basalt, is characterized. Shock veins and shock melt pockets are the main foci, which gives a better understanding of the impact history of this lunar meteorite. Four types of instruments were used: the petrographic microscope, scanning electron microscope, electron microprobe, and Raman spectrometer. The microprobe quantified the abundance of elements contained in the shock veins and shock melt pockets: Si, Ti, Al, Cr, Fe, Mn, Mg, Ca, Na, K, P and S. SEM provide detailed high-resolution images where we are interested in. Raman spectroscopy shows the structure of minerals that crystallized from shock melt, as well as the state of igneous plagioclase, which is sensitive to shock pressure. The studied shock effects tell us that NWA 032
may have experience shock pressure >23 GPa. This shock was likely the same impact event that ejected the meteorite from the Moon. The shock pressure raised the shock veins and shock melt to temperatures over 1200 °C. As a result, the partial melting took place. NWA 032 is currently the youngest dated (2.93 Ga) lunar igneous rock. The history of the lunar sample NWA 032 holds evidence that a significant number of impact events occurred in the past on the moon's surface.

Discipline: Physical Science

Faculty Mentor: Dr. Erin Walton