[Hornemann] Shock effects in sulfates: nature - experiments - modeling

German Title: Shock effects in sulfates: nature - experiments - modeling

Abbreviation: 25

Current Status: completed

Main Applicant:Dr. Ulrich Hornemann

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Conveyor Duration:
Year: 1998


The release of CO2 and SOx by the Chicxulub impact event likely changed the composition and radiative balance of the atmosphere and consequently affected the climate at the K/T boundary. Our observations show that meting and devolatilization of carbonates and anhydrite is indeed documented in the ICDP wells YAX-1, which was successfully drilled into the Chicxulub impact crater. Recent theoretical assessments of the Chicxulub event stress that the greenhouse effect due to the CO2 input was probably minor compared to the prolonged cooling by sulfur-bearing aerosols. The amplitude of this "impacr winter" is mostly determined by the so far unconstrained SOx amount. In 2004, we will therefore (i) perform final shock experiments on anhydrite with a newily developed high-explosive setup, enabling to reach pressures in the 1 Mbar range, (ii) extend our mineralogical investigations to the recently sampled Chicxulub drill cores (YAX-1, Y-6, C-1) with a special emphasis on sulfate clasts in impact melt breccias and (iii) model the so far unknown phase diagram of anhydrite. These investigations are aimed (i) to provede a basic understanding of the shock behavior of andydrite, (ii) to determine and model the p,T field relevant for devolatilization and (iii) to constrain the amount of SOx released by the Chicxulub impact.