* Astronomy

Scientists excited about potential site of meteorite
May 22, 2005

The crash millions of years ago of what could have been a 900-foot-wide meteorite in St. Clair Count, US, could provide lessons for today if a small meteorite evading current detection methods hits Earth.


weaubleau
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"It's not a question if it will happen again, it's a question of when It happens again." - Christian Koeberl University of Vienna researcher.

Koeberl is part of a group of researchers who have studied meteorite impacts from South America and Africa to near the Arctic Ocean described their research at a meeting at the Southwest Missouri State University.
He talked about a multinational research effort at the Bosumtwi Impact Crater in Ghana, said he's looking forward to possibly working with Southwest Missouri State University geology professor Kevin Evans and other university researchers on what's now called the Weaubleau-Osceola Structure.

Koeberl doesn't predict when meteors might become meteorites and strike the Earth; he described what happens when they hit to members of the Society for Sedimentary Geology. They were attending a research conference at SMS and later on moved from their lecture room to climbing around shattered rocks in an area along Missouri 13 between Osceola and Weaubleau.
If a meteorite created the structure, it hit some 300 million years ago when mid-Missouri was part of an ancient Jurassic Age sea. The strike obliterated plant-like crinoids.
A similar event today would be cataclysmic.

"Today, if something like this would happen, you'd have a kill zone of 50 to 100 kilometres." - Christian Koeberl

"The evidence looks fairly compelling to me." Jean Self-Trail of Virginia, U.S. Geological Survey scientist.

The Missouri site is one of several some scientists say run in a line from Kansas to Indiana. Whether impact can be added to the Weaubleau-Osceola Structure or not depends on more intensive research.

But Evans is confident a theory will become accepted fact.

"It's pretty well accepted, actually. We still have a lot more work to do. The impact community is pretty well behind us."

But discussing how - or whether - meteorites created the growing
Number of craters found around the world can be intense.
Austrian scientist Koeberl wants more evidence before declaring the
Weaubleau-Osceola site about 60 miles north of Springfield a meteorite impact site.

"At this point, there really is no confirming evidence".


Osceola Fold

Twisted layers of rocks and an impact-related stone called breccia are present, but Koeberl wants to see direct evidence a meteorite hit by detecting bits that survived an impact so violent it could have caused the inland sea to recede for a time.
That's why Evans said he and others are working on a grant application to better fund research and have an acknowledged expert in his field like Koeberl participate.
People like Evans are fascinated by the idea that a giant rock fell on the Earth, but he said researching meteorite impacts can affect non-scientists, too.

The most obvious way is providing information on what might happen when a meteor flying through space becomes a meteorite when it strikes Earth.

And there actually are benefits from such cataclysmic events.
Major oil and mineral deposits have been found near impact sites.
The meteorites themselves didn't create oil, zinc, or gold, but they do create the conditions needed for those minerals to be deposited.
The Weaubleau crater is part of a suspected crater chain.

"Eight circular depressions (3-17 km wide) distributed along a 700 km line across Kansas, Missouri, and Illinois may comprise part of a crater chain Two of the eight structures (Decaturville and Crooked Creek in Missouri) are known from field studies to be impact craters ~300 Million years old."



The eight locations are: Hicks, IL; Avon, MO; Furnace Creek, MO; Crooked Creek, MO; Hazel Green, MO; Decaturville, MO; Weaubleau, MO; Rose, KS.
Crooked Creek is the clearest and most obvious impact crater—its central rebound peak is indicated, which suggests that it may have had more rings than it does now, 6 kilometres being a smallish crater to have produced a central peak.


crooked creek DEM

The 19 kilometre Weaubleau structure is virtually hidden from ground view, but it shows up in radar from orbit very nicely.


Crooked creek


Weaubleau-Osceola Structure: Carbonate Duck Soup (PDF 2.6 MB)