WEBINAR - Shawn Wright

TIR spectroscopy of shocked Deccan basalt: Implications for Mars and Martian meteorites

Shawn Wright
Institute of Meteoritics
Department of Earth and Planetary Sciences
University of New Mexico
Hundreds of thousands of impact craters dominate the surfaces of the Moon, Mercury, and Mars. There exists much geomorphic and spectral evidence for basalt on those surfaces, so basaltic target rocks are most likely common. However, little work has been done on the thermal infrared (TIR) spectroscopy of shocked basalt metamorphosed by meteorite impact. This will have a direct application to the large amount of TIR data currently being returned from Mars orbiters and Rovers. The relationship between these TIR data collected remotely and laboratory data of samples is of much interest given that our only samples of Mars are shocked basalts. Results of research involving field work and samples from Lonar Crater, India, the only known terrestrial impact site emplaced in basalt, are described. The Deccan “Traps” flood basalts have been labeled as an excellent compositional and spectral analog for plagioclase-rich basalt on Mars identified from various orbiter and Rover instruments. Petrography provides details on the approximate range of shock pressure each class of shocked basalt has been subjected to, and field work has yielded an “ejecta stratigraphy” that displays where each class of shocked basalt is located. A comparison of the TIR spectroscopy of the unshocked Deccan basalt to its shocked equivalent aids in quantifying the changes due to shock. An application of this research has provided constraints on possible source craters/regions of certain shergottite meteorites, the shocked basalts from Mars.