Evaluating the influence of meteorite impact events on global potassium feldspar availability to the atmosphere since 600 Ma.

Published on 2018-10-03T19:50:43Z (GMT) by
Potassium feldspar present in global mineral aerosol (<5%) plays a disproportionate role in modulating the microphysics of mixed-phase cloud. Via exceptional ice nucleation properties, it is capable of changing cloud properties and behaviour. Here we identify times of substantial and abrupt change in the global availability of potassium feldspar since 600 Ma. Normally, weathering and vegetation cover contribute to low availability, with clay dominating mineral aerosol. Periods of maximum availability are reasoned to follow the emplacement and remobilisation of ejecta blankets from major meteorite impact events, before returning to background on the order of hundreds-thousands of years. We review the 44 largest confirmed craters and evaluate the potassium feldspar content of their target rocks, which range from <i>c</i>. 0 to >30%. By combining crater size and tectonic reconstructions, we are able to provide a quantitative and self-consistent assessment of changes to global potassium feldspar availability. Considerable differences in potassium feldspar availability following meteorite impact events are revealed. Different impact events generated dust containing different amounts of potassium feldspar. Differing levels of influence upon climate is hypothesized, and should now be tested by looking at stratigraphic records of these events to reveal the sensitivity of climate to different dust mineralogy.

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Coldwell, B.C.; Pankhurst, M.J. (2018): Evaluating the influence of meteorite impact events on global potassium feldspar availability to the atmosphere since 600 Ma.. Geological Society of London. Collection.