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Thread: Asteroid impact plunged dinosaurs into catastrophic 'winter'

  1. #1
    marcus300's Avatar
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    Asteroid impact plunged dinosaurs into catastrophic 'winter'

    The impact hit with the energy equivalent to 10 billion Hiroshima bombs

    Scientists say they now have a much clearer picture of the climate catastrophe that followed the asteroid impact on Earth 66 million years ago.

    The event is blamed for the demise of three-quarters of plant and animal species, including the dinosaurs.

    The researchers' investigations suggest the impact threw more than 300 billion tonnes of sulphur into the atmosphere.

    This would have dropped temperatures globally below freezing for several years.

    Ocean temperatures could have been affected for centuries. The abrupt change explains why so many species struggled to survive.

    "We always thought there was this global winter but with these new, tighter constraints, we can be much more sure about what happened," Prof Joanna Morgan, from Imperial College London, told BBC News.
    The UK geophysicist was the co-lead investigator on the 2016 project to drill into what remains of the impactor's crater under the Gulf of Mexico.

    She and colleagues spent several weeks retrieving the rock samples that would allow them to reconstruct precisely how the Earth reacted to being punched by a high-velocity space object.

    Their study suggests the asteroid approached the surface from the north-east, striking what was then a shallow sea at an oblique angle of 60 degrees.

    Roughly 12km wide and moving at about 18km/s, the stony impactor instantly excavated and vaporised thousands of billions of tonnes of rock.

    This material included a lot of sulphur-containing minerals such as gypsum and anhydrite, but also carbonates which yielded carbon dioxide.

    The team's calculations estimate the quantities ejected upwards at high speed into the upper atmosphere included 325 gigatonnes of sulphur (give or take 130Gt) and perhaps 425Gt of carbon dioxide (plus or minus 160Gt).

    The CO2 would eventually have a longer-term warming effect, but the release of so much sulphur, combined with soot and dust, would have had an immediate and very severe cooling effect.

    An independent group earlier this year used a global climate model to simulate what would happen if 100Gt of sulphur and 1,400Gt of carbon dioxide were ejected as a result of the impact.

    This research, led by Julia Brugger from the University of Potsdam, Germany, found global annual mean surface air temperatures would decrease by at least 26C, with three to 16 years spent at subzero conditions.

    "Julia's inputs in the earlier study were conservative on the sulphur. But we now have improved numbers," explained Prof Morgan.

    "We now know, for example, the direction and angle of impact, so we know which rocks were hit. And that allows us to calibrate the generation of gases much better. If Julia got that level of cooling on 100Gt of sulphur, it must have been much more severe given what we understand now."

    The generation of what has become known as the Chicxulub Crater was an astonishing event.

    The initial hole punched in the Earth would have been about 30km deep and 80-100km across. Unstable, and under the pull of gravity, the sides of this depression would then have collapsed inwards.

    At the same time, the centre of the bowl likely rebounded, briefly lifting rock higher than the Himalayas, before also falling down to cover the inward-rushing sides of the initial hole. And although this violent reconfiguration of the Earth's crust took just minutes to complete, its consequences led to the fifth great mass extinction on our planet.



    Asteroid impact plunged dinosaurs into catastrophic 'winter' - BBC News
    Last edited by marcus300; 11-01-2017 at 09:51 AM.
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    Ok where did it hit?

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    Quote Originally Posted by songdog View Post
    Ok where did it hit?
    Gulf of Mexico

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    They can’t even make accurate models of the climate with real time data. I have a hard time believing they would be able to do it with some samples of mud 200 feet under water.

    To me though, it’s pretty amazing anything could survive an impact like that on the planet. Supposedly there is an even bigger impact under the ice in Antarctica.

    Earth's Biggest Asteroid Impact Ever -Did It Occur in Antarctica? NASA Gravity Maps Point to "Yes" - The Daily Galaxy --Great Discoveries Channel
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    Quote Originally Posted by MuscleScience View Post
    They can’t even make accurate models of the climate with real time data. I have a hard time believing they would be able to do it with some samples of mud 200 feet under water.

    To me though, it’s pretty amazing anything could survive an impact like that on the planet. Supposedly there is an even bigger impact under the ice in Antarctica.

    Earth's Biggest Asteroid Impact Ever -Did It Occur in Antarctica? NASA Gravity Maps Point to "Yes" - The Daily Galaxy --Great Discoveries Channel
    The dirt can tell you more than you'd think

    I agree, pretty astonishing that life could survive but as they say life finds a way

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    Quote Originally Posted by Sh0tsf1red View Post
    The dirt can tell you more than you'd think

    I agree, pretty astonishing that life could survive but as they say life finds a way
    I agree about the dirt, use to take core samples on salt flats to see how microbial communities in harsh environments change over time. But you can only infur so much from the data.

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    Marcus300, got something to add?

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    The research team and scientists who work on projects like this have a far more understanding than us I just find it so amazing to read the research and data what slowly gets released. There's been a few impacts but this one in particular was 66 millions years ago. The data was released in the journal Geophysical Research Letters along with many other interesting facts if your into stuff like this. The crater is buried partly offshore and partly onshore, under Mexico's Yucatan Peninsula


    Some more information what you may find interesting on this subject

    Scientists have drilled into the 200km-wide Chicxulub crater now buried under the Gulf of Mexico.

    They say its rocks show evidence of having been home to a large "hydrothermal system", where hot fluids flowed through cracks and fissures.

    Similar systems, generated by impacts on the early Earth, could have helped kickstart the first lifeforms.

    The hydrothermal system at Chicxulub may have been active for two million years or more, the scientists say.

    Dr David Kring, from the Lunar and Planetary Institute in Houston, is one of the researchers who discovered and reported the crater's location.

    "The impact generated a very large subsurface hydrothermal system," he told BBC News.

    "That's exciting because we are using Chicxulub as a proxy for other, large impact events very early in Earth's history when we think these kinds of systems might have been crucibles for pre-biotic chemistry and the habitats for the evolution of the earliest life on our planet."

    About 829m of Chicxulub core material was drilled between May and June 2016. Since then, team-members have been hard at work examining rocks from the crater which was punched in the crust by a 15km-wide space object some 66 million years ago.

    The drilling project targeted an area called the peak ring, which contains the rocks that moved the greatest distance in the impact.

    At a briefing here at the Lunar and Planetary Science Conference (LPSC) in Texas, Prof Sonia Tikoo, who studies palaeomagnetism, said the cores had given scientists a lower bound for how long this hydrothermal system lasted.

    The direction of Earth's magnetic field flips every few hundred thousand years. When the Chicxulub extinction event occurred it had the reverse polarity to today.

    "One thing that was very intriguing was that there were several samples in the breccia melt sequence that had what's now the normal polarity - the same direction as what we have today," the Rutgers University, New Jersey, scientist said.

    "Three hundred thousand years [after the impact] the Earth's magnetic field crosses over and assumes the 'normal' polarity - it has the opposite direction [to that which existed at the time of the impact]. These rocks must have acquired their magnetisation during one of these normal polarity times that came later. Since the first of these happened 300,000 years later - that provides a lower bound constraint for the hydrothermal system, telling us how long hot fluids were going through the crater."

    The whole system may at first have been too hot for even the most heat-tolerant microorganisms. However, as time went on, the peak ring would have cooled down, allowing tiny lifeforms to exploit the chemicals dissolved in the hot fluids for fuel.

    ◾A 15km-wide object dug a hole in the crust 100km across and 30km deep
    ◾This bowl then collapsed, leaving a crater 200km across and a few km deep
    ◾Its central zone rebounded and relaxed, producing an inner "peak ring"
    ◾Today, much of the crater is offshore, buried under 600m of sediments
    ◾On land, it is covered by limestone deposits, but its outline is visible
    ◾It is evident in an arc of famous sinkholes referred to as cenotes
    Mexico's famous sinkholes (cenotes) have formed in weakened limestone overlying the crater


    With regard to the hydrothermal system, we've been able to deduce the mineralogy that the hot water fluids produced," said Dr Kring.

    "We're starting to track, in time, the thermal evolution: how hot the waters got and we've been able to watch how they cool down.

    "Eventually, they get cool enough to support thermophilic and hyperthermophilic organisms - the same type of biota that live at volcanic hot springs. These would have lived within the fractures and the veins of this subsurface impact crater.

    "We don't know how diverse this population will be. Is it two species that persists for millions of years? Or will we see an explosion of life so that we suddenly see 15 or 30 or 50 species?"

    The asteroid impact killed off 75% of species on Earth, including the dinosaurs.

    Debris thrown into the atmosphere probably saw the skies darken and the global climate cool. It may also have triggered raging wildfires. But why this environmental cataclysm killed off some groups such as the dinosaurs, while allowing birds and mammals, for example, to survive remains unclear.

    "The differential survival of animals on the planet - we don't know why birds survived and why turtles and some types of reptiles survived," pondered Dr Kring. "But based on this borehole, we are going to get some limits on important parameters like energy, like trajectory - and all of that is data that will carry us towards those answers."

    The project to drill into Chicxulub Crater was conducted by the European Consortium for Ocean Research Drilling (ECORD) as part of the International Ocean Discovery Program (IODP). The expedition was also supported by the International Continental Scientific Drilling Program (ICDP).
    Last edited by marcus300; 11-02-2017 at 02:24 AM.

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    I love this kinda stuff.
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    Me too, Great read! To me, the most interesting part is about the organisms living in the cooled-off hot water trapped in those fissures. Kind of like a seed bank to support new life on earth. I wonder if we can find a way to make it extinct too?
    I heard somewhere that much of the water in our atmosphere came from meteorites.
    Last edited by Quester; 11-02-2017 at 11:13 AM.
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    WOW! So if we manage to go extinct, there's a chance some other intelligent life form discovers our fossils and left over crap, before Earth turns into a star...

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    Quote Originally Posted by MuscleScience View Post
    I love this kinda stuff.
    Quote Originally Posted by Quester View Post
    Me too, Great read! To me, the most interesting part is about the organisms living in the cooled-off hot water trapped in those fissures. Kind of like a seed bank to support new life on earth. I wonder if we can find a way to make it extinct too?
    I heard somewhere that much of the water in our atmosphere came from meteorites.
    I've got some more stuff on this I'll post tomorrow.
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    Quote Originally Posted by marcus300 View Post

    Debris thrown into the atmosphere probably saw the skies darken and the global climate cool.
    Ah, here in England we just say "it's spitting" when it gets like that.

    Seriously, tho - the cenotes in the Yucatan are amazing. If you haven't been, you should go and see. I am heading back there on the 2nd of December to spend nearly the whole month in the sun and cenotes.

    The magnetic field at the bottom of the crater is stronger, and there's some research going on about how good the sea life that has grown in that stronger magnetic field is for humans to eat, full of zinc, and DHA.
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    Quote Originally Posted by thisAngelBites View Post
    Ah, here in England we just say "it's spitting" when it gets like that.

    Seriously, tho - the cenotes in the Yucatan are amazing. If you haven't been, you should go and see. I am heading back there on the 2nd of December to spend nearly the whole month in the sun and cenotes.

    The magnetic field at the bottom of the crater is stronger, and there's some research going on about how good the sea life that has grown in that stronger magnetic field is for humans to eat, full of zinc, and DHA.
    All the dramatic differences in habitat structure and mineral exposure allows for an amazingly diverse number of creatures to find their preferred niche. All in relatively close proximity to other unique sea floor structures.
    “If you can't explain it to a second grader, you probably don't understand it yourself.” Albert Einstein

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