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"The Arizona Shattering Impact"
Calendar: PAS Public Event Calendar
Event Posted By: Don Boyd  
*The times shown may change, depending on DST settings
Mike Marron's talk July 9th 7:00 PM will be on "The Arizona Shattering Impact" a large 11.6 million year old crater complex in the center of our state. Exploring Arizona, collecting impact mineralizations, and studying maps have given new details about the event that Mike discovered just two years ago that rearranged much of Arizona's geology. While erosion has damaged and slightly obscured the vast impact structure much of the crater walls still rise thousands of feet so this is not a worn out, nearly invisible ancient crater. To explore just the crater complex in a day and follow the path of the iron through the landscape would require a plane or helicopter. Greater than vehicle sized fragments of the impact tore through Cave Creek rock leaving miniature versions of how the large crater was carved. Even though the asteroids were about the same size, the Arizona impact crater complex is slightly bigger than the circular Manson impact because our impact had such a low impact angle that it made a giant oval crater. Penetrating about a mile deep the impact blasted away Arizona's previous geology into a thick breccia ejecta blanket that now covers southern Arizona and northern Mexico while leaving exposed in central and northern Arizona the path the asteroid carved into the rock. Most of Arizona's canyons are the crustal extension cracks from the almost horizontal impact which is now called basin and range geology. For the right people Mike will give local tours and teach how to recognize impact material in the other parts of the state by comparisons to his collection of meteorites, shattercones, and other impactites from craters around the world. This Arizona impact is not officially recognized but it has everything you want in a large crater, abundances of shattercones, breccias, impact melt suevites, shocked quartz, towering crater walls, and lots of iron in the right places. Details on viewing this lecture will be posted on the Calendar listing for July 9th prior to the lecture, probably the day before.
Here's the link to the July 9th Calendar entry.
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