Note: this topic is from 05/19/2014. Adding to the list, not pinging.
Posted on 05/19/2014 4:31:05 PM PDT by SunkenCiv
Here, for the first time (to our knowledge), we are able to demonstrate unambiguously that the impact at the Cretaceous–Paleogene boundary (K–Pg, ∼66 Mya) was followed by a so-called “impact winter.” This impact winter was the result of the injection of large amounts of dust and aerosols into the stratosphere and significantly reduced incoming solar radiation for decades. Therefore, this phase will have been a key contributory element in the extinctions of many biological clades, including the dinosaurs. The K–Pg boundary impact presents a unique event in Earth history because it caused global change at an unparalleled rate. This detailed portrayal of the environmental consequences of the K–Pg impact and aftermath aids in our understanding of truly rapid climate change.
Abstract: The mass extinction at the Cretaceous–Paleogene boundary, ∼66 Ma, is thought to be caused by the impact of an asteroid at Chicxulub, present-day Mexico. Although the precise mechanisms that led to this mass extinction remain enigmatic, most postulated scenarios involve a short-lived global cooling, a so-called “impact winter” phase. Here we document a major decline in sea surface temperature during the first months to decades following the impact event, using TEX86 paleothermometry of sediments from the Brazos River section, Texas. We interpret this cold spell to reflect, to our knowledge, the first direct evidence for the effects of the formation of dust and aerosols by the impact and their injection in the stratosphere, blocking incoming solar radiation. This impact winter was likely a major driver of mass extinction because of the resulting global decimation of marine and continental photosynthesis.
J.V., J.S.S.D. and H.B. designed research; J.V., J.S., and H.B. performed research; S.S. contributed new reagents/analytic tools; J.V. and J.S. analyzed data; and J.V., A.S., J.S., S.S., J.W.H.W., J.S.S.D., and H.B. wrote the paper.
(Excerpt) Read more at pnas.org ...
That book’s an excellent, fun read, I wonder if it is used in K-12, because it really ought to be.
It has been said that new ideas don’t take hold because of their merit, but because their opponents die off. :’)
There are two obvious impact remnants framing the northern and southern extents of South America.
The climate change activists must be offering incantations for my early demise.
TOTALLY agree!
If you torture the data enough it will eventually confess. To anything!
Incantations are far too long and complex. They need one or two syllable words, and profane ones are favored. :’)
You ought to take another look. The one million year long basaltic flow was punctuated by Rhyolitic explosive super volcano like eruptions. The traps as now preserved would have covered in a thick lava flow an area like modern Europe. Originally, the indications are that it covered an area four times that size. It makes the Deccan Traps look small. We are mining copper and nickel in huge ore deposits dating back to intrusions under the mat of basalt and dacite. Then, you have to consider the coal deposits that were set on fire. The indications I am aware of suggesting an asteroid are of one which may have triggered this initially. The delta O18 measurements of the time show ocean temperatures of 40C.
An asteroid by itself brings on a so called nuclear winter. The rhyolitic volcanos would have put up a lot of ash which would cool things only in the very short run (a couple of years to a decade) but if rain wasn’t able to scrub the atmosphere, a lot of nasty gas would be left in the air.
The P-T impact was probably on the ocean somewhere, as the oceanic carbon shifted from C13 toward C12, which is something that volcanic eruptions won’t do; either the C12 was in the impactor, or the impact released methane ices on the ocean floor.
These large asteroid impacts blanket the Earth with cloud cover in a couple of hours, and this takes years to clear. The hydrologic cycle slows to a crawl as solar energy can’t reach the surface. Within days large fauna start to die, and vegetation eaters begin to starve. Predator species eventually run out of food; they may even lose their marbles from the constant darkness.
Ocean temperatures of 40C may have released some of the “frozen” methane very late in the progression initiated by the traps. In fact, that is what a number of geologists believe happened. Time will tell.
The traps were just volcanoes, nothing more.
Just a plume volcano pushing deep basaltic magma from deep below the crust on such amounts as to cover an area exponentially larger than Europe with a kilometer thick lava flow and accompanied by very explosive rhyolitic eruptions. It put out one and a half billion tons of SO2 yearly (not to mention CO2). It was estimated to be a crack in the earth, at times, one thousand miles in length. But yeah, just a volcano.
The extinction of the dinosaurs was due to overhunting by Christians.
There, more accurate now.
NTBCW a Windy City strip-joint frequented by *most* male Democrat pols from the local "organization" ....
And then there is Chatterjee’s work on the Shiva “crater”, a structure off the coast of Mumbai about 4 times the area of the Yucatan crater and of the same relative age. Of course like all big ideas his is controversial. See this link,
http://gleeaikin.blogspot.com/2014/01/pres-obama-save-middle-class-sen-mccain.html
and Google Shiva Crater for other links.
Sorry about the wrong link. My Control C wasn’t working right and didn’t hold the Shiva URL. Here is the correct one and some others:
http://en.wikipedia.org/wiki/Shiva_crater
http://news.discovery.com/animals/shiva-impact-crater-dinosaurs.htm
And many images of craters there and elsewhere:
https://www.google.com/search?q=shiva+crater&tbm=isch&tbo=u&source=univ&sa=X&ei=i4N9U-yBNuLgsATo6YDgDQ&sqi=2&ved=0CDIQsAQ&biw=1024&bih=653
Thanks. Really interesting.
>> This folks is how most scientific papers appear. Dreadfully boring, bounded by the limitations of the study...
And to be critically analyzed and weighed against other studies, preferably without references to hockey sticks and rambunctious polar bears.
Note: this topic is from 05/19/2014. Adding to the list, not pinging.
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