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291-7 The Power of Pyroxenes: Spectroscopic Clues to Planetary Thermal Evolution
Session: Mineralogy in the Solar System
Presenting Author:
Rachel Klima
Author:
Klima, Rachel L.1
(1) Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA,
Abstract:
Pyroxene is one of the most abundant and spectrally distinctive minerals in the solar system. The chemical compositions of coexisting pyroxenes, measured in the laboratory, have been used for decades to characterize the phase equilibria of igneous systems, and for geothermometry. Detailed analyses of Mg-Fe2+ ordering between crystallographic sites in a pyroxene provide further constraints on the cooling rates and history of pyroxene-bearing rocks. Transition metal-bearing pyroxenes exhibit characteristic spectral features at visible, near and shortwave infrared wavelengths, which vary based on chemical composition as well as site ordering. In the thermal infrared, pyroxenes, like other silicates, exhibit distinguishing vibrational features, which also vary in position and shape based on the cation composition. The distinctive spectral properties, coupled with the variety of cations that can be hosted within a pyroxene structure, make pyroxenes particularly powerful for remotely characterizing the geochemical properties and thermal history of asteroids and planets. This work reviews some of the discoveries that harnessing the power of pyroxene spectroscopy has enabled on the Moon, Mercury, and asteroids, and looks forward to upcoming missions that will provide new clues to the solar system evolution.