Experimentally shock-loaded anhydrite: Unit-cell dimensions, microstrain and domain size from X-ray powder diffraction
Roman Skála, Friedrich P. Hörz, Falko Langenhorst, 2005. "Experimentally shock-loaded anhydrite: Unit-cell dimensions, microstrain and domain size from X-ray powder diffraction", Large Meteorite Impacts III, Thomas Kenkmann, Friedrich Hörz, Alex Deutsch
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The Cretaceous-Tertiary boundary is characterized by mass extinctions triggered by a large body impact into predominantly limestone-, dolomite-, and anhydrite-bearing sediments of the Yucatan peninsula, Mexico. Decomposition of these volatile-rich minerals and associated deterioration of the atmosphere and hydrosphere rank among the most prominent kill mechanisms during this global catastrophe. As a consequence, we conducted optical and scanning electron microscopy and X-ray diffraction studies of anhydrite (CaSO4) that was experimentally shock-loaded to pressures from 4 to 64 GPa to determine the shock damage and potential loss of volatiles as a function of shock stress. We did not find any decomposition products in any of the recovered samples. It appears that anhydrite is stable over a wide pressure range (up to 64 GPa). Peak widths of the X-ray diffraction powder patterns increase with peak shock pressure up to ∼50 GPa, yet the peaks become narrower again above this pressure, implying some recrystallization.