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Experimental Investigation of Carbonate Inclusions in Meteor Crater Impactites

Session: 37th Annual Undergraduate Research Exhibition Sponsored by Sigma Gamma Epsilon (Posters)

Presenting Author:

Lior Segal

Authors:

Segal, Lior H ¹, Macris, Catherine A ², Marrs, Ian J³, Gullikson, Amber L⁴, Salvatore, Mark R⁵

(1) Department of Earth and Environmental Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA, (2) Department of Earth and Environmental Sciences, Indiana University Indianapolis, Indianapolis, Indiana, USA, (3) Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona, USA, (4) USGS, Astrogeology Science Center, Flagstaff, Arizona, USA, (5) Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, Arizona, USA,

Abstract:

Some impact melts from Meteor Crater in Arizona contain carbonate inclusions, whose origins remain debated. One hypothesis is that these inclusions formed during the impact via partial melting and recrystallization of carbonate-bearing target material. An alternative explanation suggests a later, secondary origin. To better understand carbonate melt behavior during impact events, we conducted 1-atm experiments simulating short-lived, high-temperature conditions relevant to ejecta droplets, spatter, and near-surface melt veneers.

Starting materials were based on impact melt estimates from Hörz et al. (2002), which comprise mixtures of target rocks from the Coconino, Moenkopi, and Kaibab Formations, with added Fe₂O₃ to simulate meteoritic input. We used two grain size fractions (45–63 μm and 125–150 μm) to test whether coarser clasts might influence carbonate melting rather than complete volatilization. Experiments were heated to 1600–2000°C for 15–120 seconds in a flow of Ar gas using an Aerodynamic Laser Levitation Furnace (ALLF), then rapidly quenched.

Quenched products were typically holohyaline, some containing relict quartz and iron oxide grains. No carbonate phases were preserved in any experiments. These results suggest that under 1 atm, carbonate is unlikely to survive melting and quenching under the tested conditions. However, these findings should be interpreted within the limitations of our experimental design, which does not reproduce the full pressure-temperature-time (P-T-t) history of natural impact events. Instead, the experiments target a specific portion of that space: short-lived, high-temperature, low-pressure regimes that may occur in splash droplets or surface-adjacent melt films. The preservation of carbonate-silicate immiscibility textures at craters such as Ries and Haughton suggests that carbonate melts may form and quench under conditions not reproduced in these trials.

Our experiments provide a first-order constraint on carbonate stability under these limited conditions. Future work will explore lower temperatures, shorter heating durations, and slower quenching paths, as well as the use of CO₂-bearing levitation gas to increase the surrounding CO₂ partial pressure. This may promote carbonate melt retention and better approximate conditions in carbonate-rich impact environments.

Hörz et al., 2002, Meteorit. Planet. Sci., 37, 501–531.