Microtektites discovered in Caribbean shed light on origin of tektites — Science News. August 11, 1972
Though their origin remains a mystery to scientists, huge strewn fields of tektites have been found in widely separated areas of the world…. Microtektites have now been found in the Caribbean, and the characteristics of these newly found specimens may ultimately shed some light on the question of tektite origin….
Some believe the tektites came from the Moon. They feel that tektites were formed when an asteroid hit the moon, splashing droplets of molten rocks so high that they escaped the moon’s gravity and fell to Earth. The mass spectrographic study of lunar samples reveals that the elements found in the lunar crust differ from those found in tektites. The tektites resemble the elements found in Earth’s continental crust. [Planetary scientist Billy P. Glass]The parent material can be used to create a variety of products. [newfound] microtektites can be determined … the discovery of the origin of the glassy objects might quickly follow suit.
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Glass surmised that these geologic curiosities have earthly origins, based on his and his colleagues’ analyses of the North American strewn field — a blanket of glassy particles that covers much the southeastern United States and Caribbean and dates to about 35 million years ago. Researchers took 20 more years to find the source.
In 1994, tektites in southern Virginia and fault lines concentric to them revealed an impact crater 85 kilometers wide under the Chesapeake Bay. Science News reported that “a structure this size would rank as The largest crater on the United States” and would be among the largest on Earth (SN: 8/20/94). What’s more, when the space rock slammed into our planet, the collision created The intense seismic waves bent microfossilsScientists reported that they had found themselves in odd shapes nearly a decade after (SN: 6/11/03).
Taken together with evidence from Earth’s three other major strewn fields, the findings helped confirm that tektites form when a bolide slams into our planet with enough force to blast liquified chunks of Earth’s crust into the atmosphere. The chunks of Earth’s crust that are thrown into the atmosphere by a bolide then become hardened into ravioli, barbell and raindrop shaped particles.
Researchers have so far linked three of four major strewn areas with impact craters. The North American strewn fields are linked to the Chesapeake Crater in Virginia. The central European strewn fields are associated with the Ries Crater in Germany. And the Ivory Coast’s strewn fields originate from the Bosumtwi Crater in Ghana. The holdout is the Australasian strewn field, which is the largest known and covers about 10 percent of Earth’s surface.
Recently, scientists got a break on the case. The source of the tektites, other geological evidence and computer simulations are likely to be based on analyses of tektites from Thailand. About 800,000 years back, a 2-kilometer-wide asteroid struck Laos.Scientists reported in 2020 that debris was flung across Asia, Australia, and Antarctica. Proceedings of National Academy of Sciences.
The team believes that the crater – which could be 13 kilometers by 17 kilometers – was eventually buried beneath volcanic material. Verifying this hypothesis will require drilling through lava fields to see if the rocks underneath show melting and shattering — both hallmarks of an impact.
The curiosities that are found in an impact crater can be full of poetry and wonder to a collector. To a planetary scientist, these small pieces of evidence may yet open big windows into Earth’s geologic past.
