by Staff Writers
San Francisco CA (SPX) Apr 13, 2017
Researchers have found signs of fault displacement at well-known rock outcrops in Colorado that mark the end-Cretaceous asteroid impact that may have hurried the extinction of the dinosaurs. They will present their results in a poster at the 2017 Seismological Society of America's (SSA) Annual Meeting.
Norm Sleep of Stanford University and colleagues suggest that the impact, which occurred near the Yucatan Peninsula of Mexico, could have generated massive seismic waves that triggered earthquakes as far away as Colorado, in the center of a tectonic plate where no previous fault had existed.
Sleep and his colleagues found evidence for the fault in two areas in Colorado's Trinidad Lakes State Park, where a layer of iridium generated by the asteroid impact clearly marks the boundary between Cretaceous and Tertiary-age rocks, at the time of the dinosaurs' extinction about 65 million years ago.
At the Long's Canyon and Madrid Canyon roadcuts, "there is a fault that slipped about a meter at the time of the impact," Sleep said. "It offset the material below the impact layer but not above, but it's not something that would be obvious to the casual observer."
The researchers suggest that the Colorado earthquake may have been as large as magnitude 6. Very strong seismic waves from the impact - much larger than would be generated by a regular earthquake, Sleep said - would be necessary to trigger an earthquake in this location, in the middle of a tectonic plate with no previous faults.
The end-Cretaceous asteroid strike, however, could have generated ground velocities of a meter or two per second, Sleep said. "The ground would be moving up and down and sideways like a ship in a strong storm."
At the time of the earthquake, the area in Colorado was a swampy, delta-like environment, crossed by large braided streams that ran from the young Rocky Mountains. Sleep and his colleagues saw signs that the earthquake had diverted a small stream in the area.
This summer, the researchers will be checking in New Mexico near the Raton Basin for further signs of intraplate quakes that may have been triggered by the asteroid strike.
Zurich (UPI) Mar 7, 2017
New analysis of Earth's myriad craters turned up no evidence of an impact pattern. Earth is bombarded at random, the research shows. Some astronomers suggest the sun possesses a companion star, which makes its closest approach to the solar system every 26 million years, triggering a barrage of asteroids. But the sibling star, named Nemesis, has never been found, and the latest analysis ... read more
Seismological Society of America
Asteroid and Comet Mission News, Science and Technology
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|