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Imaging and Modelling Impact Generated Deformation at the Chicxulub Crater
Principal Investigators: Sean Gulick and Gail Christeson

Award is for a multichannel seismic survey across the offshore portions of the Chicxulub impact crater. The multichannel seismic survey will be added on to a funded British tomographic survey that will be conducted in the summer of 2003 aboard the R/V Maurice Ewing. The multichannel seismic survey will map features that cannot be constrained by the tomographic study, including the geometry of the peak ring, and the possible thrust boundary beneath the peak ring. The modeling effort, together with the multichannel seismic profiles will determine the approach direction of the impactor and constrain the angle of impact to with 10 degrees. The multichannel seismic profiles together with the tomographic data will complete the required site survey over two proposed IODP sites.

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(298) Baptistina
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impact_5

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The Yucatan Peninsula
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This image of the Yucatan Peninsula was acquired by the Terra satellite on April 11, 2007.
The Yucatan Peninsula, part of Mexico, separates the Caribbean Sea from the Gulf of Mexico.

yackge4 yacke3
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Credit: Jeff Schmaltz/MODIS team/NASA

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Chicxulub impact site
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Title: Impact and extinction in remarkably complete Cretaceous-Tertiary boundary sections from Demerara Rise, tropical western North Atlantic
Authors: Kenneth G. MacLeod, , Donna L. Whitney, , Brian T. Huber, , Christian Koeberl,

Ocean Drilling Program (ODP) Leg 207, on the Demerara Rise in the western tropical North Atlantic, recovered multiple Cretaceous-Palaeogene boundary sections containing an ejecta layer. Sedimentological, geochemical, and palaeontological changes across the boundary closely match patterns expected for a mass extinction caused by a single impact. A normally graded, ~2-cm-thick bed of spherules that is interpreted as a primary air-fall deposit of impact ejecta occurs between sediments of the highest Cretaceous Plummerita hantkeninoides foraminiferal zone and the lowest Palaeogene P0 foraminiferal zone. There are no other spherule layers in the section. In addition to extinction of Cretaceous taxa, foraminiferal abundance drops from abundant to rare across the boundary. Ir concentrations reach a maximum of ~1.5 ppb at the top of the spherule bed, and the Ir anomaly is associated with enrichment in other siderophile elements. We attribute the unusually well-preserved and relatively simple stratigraphy to the fact that Demerara Rise was close enough (~4500 km) to the Chicxulub impact site to receive ~2 cm of ejecta, yet was far enough away (and perhaps sheltered by the curve of northern South America) to have been relatively unaffected by impact-induced waves.

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About 65 million years ago, a massive disruption led to worldwide extinction of dinosaurs. The impact of a giant asteroid created massive tsunamis and spewed forth a global cloud of carbon gases that altered Earth’s atmosphere and blocked the light for weeks, possibly years. In recent years, that impact event has been linked to a 112-mile-wide crater, dubbed Chicxulub, on the coast of Mexico’s Yucatan Peninsula.
Since its discovery in the 1980s, the Chicxulub crater has left its own impact on sky-watchers and sci-fi fans worldwide, and impact events have been depicted in Hollywood films such as “Armageddon” and “Deep Impact,” as well as countless artistic renditions.
Despite the spotlight on the theories surrounding the impact, Michael Whalen, associate professor of geology at University of Alaska Fairbanks, has managed to stay “out of the limelight, yet into the limestone” with his work sampling the core of the crater. Due to the efforts of Buck Sharpton, UAF vice chancellor for research, Whalen became part of an international effort to correlate seismic data with information obtained from a drill hole that reaches more than 1.2 miles deep, through the impact layer and beyond.
Interestingly enough, unlike other more noticeable craters, the Chicxulub crater spent 55 million years in virtual obscurity, due to the fast infilling that masked its presence. Speedy recovery, which by geologists’ standards amounts to about 10 million years, preserved the crater by mantling it with sediment, attracting geologists like Whalen, who studies the effects of extinction events on carbonate layers, also known as limestone, and the organisms that make up those layers.
On Jan. 20, Whalen will be travelling with a team to the Chicxulub site for a week to obtain more core samples in order to get a better understanding of how the crater filled in and how the earth itself recovered from the massive impact. He’s also part of an ongoing collaboration that is trying to secure funding to drill two more holes in the crater, one offshore and one through the peak ring.

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The dinosaurs, along with the majority of all other animal species on Earth, went extinct approximately 65 million years ago. Some scientists have said that the impact of a large meteorite in the Yucatan Peninsula, in what is today Mexico, caused the mass extinction, while others argue that there must have been additional meteorite impacts or other stresses around the same time. A new study provides compelling evidence that "one and only one impact" caused the mass extinction, according to a University of Missouri-Columbia researcher.

"The samples we found strongly support the single impact hypothesis. Our samples come from very complete, expanded sections without deposits related to large, direct effects of the impact - for example, landslides - that can shuffle the record, so we can resolve the sequence of events well. What we see is a unique layer composed of impact-related material precisely at the level of the disappearance of many species of marine plankton that were contemporaries of the youngest dinosaurs. We do not find any sedimentological or geochemical evidence for additional impacts above or below this level, as proposed in multiple impact scenarios" - Ken MacLeod, associate professor of geological sciences at MU and lead investigator of the study.

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There's growing evidence that the dinosaurs and most their contemporaries were not wiped out by the famed Chicxulub meteor impact, according to a palaeontologist who says multiple meteor impacts, massive volcanism in India, and climate changes culminated in the end of the Cretaceous Period.
The Chicxulub impact may, in fact, have been the lesser and earlier of a series of meteors and volcanic eruptions that pounded life on Earth for more than 500,000 years

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Growing evidence shows that the dinosaurs and their contemporaries were not wiped out by the famed Chicxulub meteor impact alone, according to a palaeontologist who says multiple meteor impacts, massive volcanism in India and climate changes culminated in the end of the Cretaceous Period.

The Chicxulub impact may have been the lesser and earlier of a series of meteor impacts and volcanic eruptions that pounded life on Earth for more than 500,000 years, say Princeton University palaeontologist Gerta Keller and her collaborators Thierry Adatte from the University of Neuchatel, Switzerland, and Zsolt Berner and Doris Stueben from Karlsruhe University in Germany.
A final, much larger and still unidentified impact 65.5 million years ago appears to have been the last straw, said Keller, exterminating two-thirds of all species in one of the largest mass extinction events in the history of life. It's that impact - not Chicxulub - that left the famous extraterrestrial iridium layer found in rocks worldwide that marks the impact that finally ended the Age of Reptiles, Keller believes.

"The Chicxulub impact alone could not have caused the mass extinction, because this impact predates the mass extinction" - Gerta Keller.

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Cretaceous
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China has begun to drill the first well as part of scientific research on climate change that occurred during the Cretaceous period, in Daqing city of Heilongjiang province in northeast China.

Professor Wang Chengshan from China's University of Geosciences, the lead scientist in the project, said that the research will be aimed at probing climate change during a period from 65 million to 140 million years ago.
Meanwhile, he said the drilling would also help to probe the oil reserve for the sustainable development of the Daqing oil field.

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Cuban researchers say there are signs in the centre of Cuba of the Chicxulub meteor.
Fossilised remains of oysters and sea urchins have been identified at a late-Cretaceous dig site in the central Cuban province of Sancti Spiritus.

`The fossils "shared with the dinosaurs the colossal catastrophe" and represent part of an "animal guide to the late Cretaceous" period` - Abel Hernandez, ecologist and one of a team of researchers working at the site.

The Chicxulub impact released a force of five billion atomic bombs, and let loose huge clouds of sulphuric acid and particulate matter that blocked the sun's rays and caused mass extinction of animal and plant species, opening the way to a new geologic era.

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