Libyan desert glass
Libyan desert glass or Great Sand Sea glass is an impactite, made mostly of lechatelierite,[1] found in areas in the eastern Sahara, in the deserts of eastern Libya and western Egypt. Fragments of desert glass can be found over areas of tens of square kilometers. Like obsidian, it was knapped and used to make tools during the Pleistocene.[2]
Geologic origin
The origin of desert glass is uncertain. Meteoritic origins have long been considered possible, and recent research links the glass to impact features, such as zircon breakdown, vaporized quartz and meteoritic metals, and to an impact crater.[3][4][5][6][7][8][9]Template:Overcite Some geologists[10] associate the glass with radiative melting from meteoric large aerial bursts, making it analogous to trinitite created from sand exposed to the thermal radiation of a nuclear explosion. Libyan Desert glass has been dated as having formed about 29 million years ago.[11]
Analysis of samples with the electron backscatter diffraction (EBSD) technique revealed zircon crystal structures that form only when reidite melts at very high temperatures and is then converted to zircon.[11] Reidite has been found only at meteorite impact sites, where it was formed at the very high pressures of impact. Airbursts never yield this type of mineral transformation.[12]
See also
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References
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- ↑ Kramers, J.D et al (2013): Unique chemistry of a diamond-bearing pebble from the Libyan Desert Glass strewnfield, SW Egypt: Evidence for a shocked comet fragment. Earth and Planetary Science Letters 382, 21-31 Script error: No such module "CS1 identifiers".
- ↑ B. Kleinmann (1968): The breakdown of zircon observed in the Libyan desert glass as evidence of its impact origin. Earth and Planetary Science Letters 5, 497-501. Script error: No such module "CS1 identifiers".
- ↑ Weeks, R. (1984): Libyan Desert glass: A review. Journal of Non-Crystalline Solids, 67, 593-619. Script error: No such module "CS1 identifiers".
- ↑ Seebaugh, W. R. & Strauss, A. M. (1984): Libyan Desert Glass: Remnants of an Impact Melt Sheet. LUNAR AND PLANETARY SCIENCE XV, 744-745. [Abstract.] Bibcode:1984LPI....15..744SScript error: No such module "check bibcode".
- ↑ Barbara Kleinmann, Peter Horn and Falko Langenhorst (2001): Evidence for shock metamorphism in sandstones from the Libyan Desert Glass strewn field. Meteoritics & Planetary Science 36, 1277-1282 Script error: No such module "CS1 identifiers".
- ↑ Giovanni Pratesi, Cecilia Viti, Curzio Cipriani and Marcello Mellini (2002): Silicate-silicate liquid immiscibility and graphite ribbons in Libyan desert glass. Geochimica et Cosmochimica Acta 66, 903-911.Script error: No such module "CS1 identifiers".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b Script error: No such module "Citation/CS1".
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Literature
- V. de Michele (ed.): Proceedings of the Silica '96 Meeting on Libyan Desert Glass and related desert events, Bologna, 1997 Contents
- P.A. Clayton / L.J. Spencer: Silica Glass from the Libyan Desert, Vortrag vom 09.11.1933 online
External links
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