Chicxulub Crater, Yucatán Peninsula, Mexico – Artist’s Impression Image: University of Colorado
Posted on 03/28/2013 9:02:58 AM PDT by Ernest_at_the_Beach
From the AGU:
Global fires after the asteroid impact probably caused the K-Pg extinction
Chicxulub Crater, Yucatán Peninsula, Mexico – Artist’s Impression Image: University of Colorado
About 66 million years ago a mountain-sized asteroid hit what is now the Yucatan in Mexico at exactly the time of the Cretaceous-Paleogene (K-Pg) mass extinction. Evidence for the asteroid impact comes from sediments in the K-Pg boundary layer, but the details of the event, including what precisely caused the mass extinction, are still being debated.
Some scientists have hypothesized that since the ejecta from the impact would have heated up dramatically as it reentered the Earth’s atmosphere, the resulting infrared radiation from the upper atmosphere would have ignited fires around the globe and killed everything except those animals and plants that were sheltered underground or underwater.
Other scientists have challenged the global fire hypothesis on the basis of several lines of evidence, including absence of charcoal-which would be a sign of widespread fires-in the K-Pg boundary sediments. They also suggested that the soot observed in the debris layer actually originated from the impact site itself, not from widespread fires caused by reentering ejecta.
Robertson et al. show that the apparent lack of charcoal in the K-Pg boundary layer resulted from changes in sedimentation rates: When the charcoal data are corrected for the known changes in sedimentation rates, they exhibit an excess of charcoal, not a deficiency. They also show that the mass of soot that could have been released from the impact site itself is far too small to account for the observed soot in the K-Pg layer. In addition, they argue that since the physical models show that the radiant energy reaching the ground from the reentering ejecta would be sufficient to ignite tinder, it would thereby spark widespread fires. The authors also review other evidence for and against the firestorm hypothesis and conclude that all of the data can be explained in ways that are consistent with widespread fires.
Source:
Journal of Geophysical Research-Planets, doi:10.1002/jgrg.20018, 2013
http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20018/abstract
Title:
K/Pg extinction: Reevaluation of the heat/fire hypothesis
Authors:
Douglas S. Robertson: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA; William M. Lewis: Department of Ecology and Evolutionary Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, Colorado, USA; Peter M. Sheehan: Department of Geology, Milwaukee Public Museum, Milwaukee, Wisconsin, USA; Owen B. Toon: Department of Atmospheric and Oceanic Sciences and Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, Colorado, USA.
It seems as if it was changed by these people:
http://en.wikipedia.org/wiki/International_Commission_on_Stratigraphy
Oh, that Before Christian Era thingy? (8^P)
Thanks.
Gigantic Jenga Busters make such a mess.. not to worry, no one is left to clean up afterwards
Anytime. I owe you some links anyway. :)
“Cretaceous–Paleogene (K–Pg) boundary (formerly known as the K–T boundary) is a geological signature, usually a thin band, dated to 66.0 Ma (million years) ago.[1] K is the traditional abbreviation for the Cretaceous period, and Pg is the abbreviation for the Paleogene period. The boundary marks the end of the Cretaceous period, which is the last period of the Mesozoic era, and marks the beginning of the Paleogene period of the Cenozoic era. The boundary is associated with the Cretaceous–Paleogene extinction event, a mass extinction, which is considered to be the demise of the non-avian dinosaurs.[2] The boundary layer was once known as the K–T boundary, but Tertiary has been deprecated as a formal time or rock unit by the International Commission on Stratigraph”
http://en.wikipedia.org/wiki/K%E2%80%93T_boundary
Of course!
An absolutely necessary International Commission. What would we do without them?
Roughly the same as setting off 100,000,000,000,000,000,000 tons of TNT. Count dem zeroes, that's 100 million megatons.
Add to all that energy dumped instantaneously into the atmosphere and near space the intrinsic heat of the now exposed yellow-hot mantle.
As an added bonus, it was an edge of a shallow sea strike. Where does the ocean go? Well, after the big splash, it tries to refill the crater.
Imagine that, pouring an ocean of cold water into a 10,000 square mile 2400°F furnace. That's a recipe for steam-cleaning half a planet!
Do you think that all that water rushing into the crater would be crystal clear, or do you think it might be full of silt and sand scoured from the sea floor? Would the grit passively settle to the crater floor or be blasted into the are with a 100 mile wide jet of live steam?
How high would world humidity be after the month of so of an entire ocean finally won the battle for the crater floor?
The atmosphere would be utterly saturated with water vapor, thick clouds and dust. Torrential rains where it's warm enough, sleet, hail, and snow everywhere else. And with that unbroken cloud cover reflecting the sun's heat back into space, the warm areas are pretty small.
Then things get worse. The Yucatan was covered by about a mile and a half of limestone, nature's carbon dioxide storage medium. the heat and pressure of the impact broke the bonds holding the carbon in the calcium carbonate, besides a supervolcano of live steam, the blast released a vast cloud of that most evil of chemicals, CO2!
I'll get to the bad part shortly.
Limestone also contains vast quantities of sulfur (ever drink well water in Florida?) That sulfur gets vaporized and oxidized and hydrated into sulfuric acid.
Now the bad part.
All the air within 300 or so miles of the impact was heated and shocked and zapped by ultraviolet and electrical discharges so hard that most of the oxygen and nitrogen were ionized, generating vast quantities of oxides of nitrogen, which combined with all that water vapor to form nitric acid.
All that rain and snow? Full of carbonic acid, sulfuric acid and nitric acid.
All in all, it was a pretty bad day to be a dinosaur...
On the bright side, after a couple years of dirty rain and snow, the cloud cover clears. Now all we have is an atmosphere with a huge residual eeeeevil CO2 concentration.
Things get warm and dank. The land has a fresh new layer of mineral rich ejecta, and more minerals have been freed up by all the acids unlocking them from solid rock. The atmosphere is full of that essential plant nutrient, CO2.
It would have been a virtual garden of Eden for anything that managed to survive.
so basically a stone only 7 miles long destoys and entire planet.
yeh right.
so basically a bullet only .22 inches wide kills an entire human.
yeh right.
It’s like the K-Pg13 but with less profanity.
Hmmm....OK....adding to my dictionary...LOL!
That is a huge impact....certainly gonna change things.
Forgot to check the spelling....Mice=> Nice...
Mice works. They survived.
I did leave out the part about the fires. Flaming debris would arrive in distant locations well before the new weather pattern shows up.
Essentially it’s like a billion red hot intercontinental ballistic missiles screaming in around the globe, with the water bomber fleet slouching in later for clean-up.
The planet is fine.
The life living on the thin crust of the planet, which life can only survive in a very narrow temperature and climate band? Almost all dead.
Not hard to believe, at all.
In fact, from this Christian’s perspective, an asteroid impact is predicted in Revelations called “wormwood” which is a “star” that falls from the sky and causes basically all the same crap the scientist have talked about kiling the dinos.
Such an impact would ring the planet like a bell.
Any fault line with enough tension built up would be shaken loose into an earthquake, "mountain and island were moved out of their places".
Earthquakes and shocks would disturb aquifers, cracking rock and exposing the waters to fresh supplies of salts and soluble minerals, "making a third of the waters bitter", perhaps?
Once the eject starts reentering the earth's atmosphere what would that look like? Like "the stars of heaven fell unto the earth"!
What survived Chixulub? The very creatures the lived or nested underground, that "hid themselves in the dens and in the rocks of the mountains".
What would the mushroom cloud/ejecta blanket look like as it swept high over an observer? Like a scroll rolling over the heavens, maybe?
See my description at post #29. Does my description of the volcano of steam sound even a little bit like:
And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit.Yeah. A disaster of quite literally Biblical proportions.
Mammals survived—a Good Thing—huh?
Cretaceous - Paleogene (Paleogene corresponds to Paleocene + Eocene, the 1st two epochs of the Tertiary.
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