Melt spherules in an impact setting are usually made from the impactor material, so I'm curious if they would form in fulgurites. The PT values necessary for their formation are well reached by most lightnings, so theoretically it might be possible...
Dear Houssam,
Impact spherules are either composed of impactor material, of melted target rocks or depict a mixture of both, projectile and target rocks.
Spherules produced by lightning in the context of fulgurites were already reported in a very early study by:
Alexis A. Julien (1901) A Study of the Structure of Fulgurites. The Journal of Geology
Vol. 9, No. 8 (Nov. - Dec., 1901), pp. 673-693.
And in more recent studies by, e.g.,:
Matthew Pasek & Kristin Block (2009) Lightning-induced reduction of phosphorus oxidation state: Nature Geoscience 2, 553 - 556.
Michael L. Joseph (2012) A Geochemical Analysis of Fulgurites: from the inner glass to the outer crust. Thesis at the University of South Florida.
All the best
Elmar
Dear Elmar,
thank you for your clear answer. It is much appreciated!
I will check these papers out.
Have a nice day!
Houssam
Dear Volker,
the Ries crater is just a mid-sized crater (~25 km in diameter), the biggest craters on Earth have diameters of ~100-250 km. And more important, Moldavites are no spherules but tektites. The formation processes of tektites, impact spherules, and fulgurites are completely different, your statements are at least misleading...
Best wishes
Elmar
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