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Mon Jun 19, 2017, 06:02 PM

Volcanic eruptions triggered dawn of the dinosaurs

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Following the discovery of volcanic rocks of the same age as the extinction, volcanic carbon dioxide (CO2) emissions had previously been suggested as an important contributor to this extinction event. Previous studies have also shown that this volcanism might have occurred in pulses, but the global extent and potential impact of these volcanic episodes has remained unknown. These volcanic rocks covered a huge area, across four continents, representing the Central Atlantic Magmatic Province (CAMP).

Researchers from the Oxford University Department of Earth Science worked in collaboration with the Universities of Exeter and Southampton to trace the global impact of major volcanic gas emissions and their link to the end of the Triassic period. The findings link volcanism to the previously observed repeated large emissions of carbon dioxide that had a profound impact on the global climate, causing the mass extinction at the end of the Triassic Period, as well as slowing the recovery of animal life afterwards.

By investigating the mercury content of sedimentary rocks deposited during the extinction, the study findings revealed clear links in the timing of CAMP volcanism and the end-Triassic extinction. Volcanoes give off mercury gas emissions, which spread globally through the atmosphere, before being deposited in sediments. Any sediments left during a large volcanic event would therefore be expected to have unusually high mercury content.

The team sourced six sediment deposits were sourced from the UK, Austria, Argentina, Greenland, Canada and Morocco, and their mercury levels analysed. Five of the six records showed a large increase in mercury content beginning at the end-Triassic extinction horizon, with other peaks observed between the extinction horizon and the Triassic-Jurassic boundary, which occurred approximately 200 thousand years later.


Read more at: https://phys.org/news/2017-06-volcanic-eruptions-triggered-dawn-dinosaurs.html#jCp

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Response to muriel_volestrangler (Original post)

Mon Jun 19, 2017, 06:10 PM

1. And also ushered in their demise

Via the Deccan Traps in India, two massive eruptions that began about 70 million years ago. Likely the asteroid just provided the coup de grace, which is why the stratum just below it isn't choked with dinosaur bones from a sudden event.

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Response to Warpy (Reply #1)

Mon Jun 19, 2017, 06:20 PM

2. I have wondered from time to time about the timing of that and if the Deccan Traps

and the impact crater in the Gulf of Mexico might have been related say due to a large comet or asteroid that broke up and whose pieces stayed in or around the earths orbit to eventually impact on the planet?

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Response to cstanleytech (Reply #2)

Mon Jun 19, 2017, 06:37 PM

3. The Deccan Traps predated the asteroid by about 4 million years

and continued to erupt for another 6 million years. While it's conceivable that the second plume might have been triggered by the shock wave traveling through the planet, the asteroid didn't start the entire thing, the timeline is wrong.

The iridium layer is thin enough to indicate a single event, however, yes, there could have been much smaller impacts all over the planet after it partially broke up in the atmosphere, the bulk landing off Chicxulub. Smaller craters dating from the same time have been found in several places.

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Response to Warpy (Reply #3)

Mon Jun 19, 2017, 07:00 PM

4. Yes I am aware of the gap in time but that doesnt mean it couldnt have all been from the same object

with pieces of it slowly impacting over time.

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Response to muriel_volestrangler (Original post)

Mon Jun 19, 2017, 08:09 PM

5. i thought noah forgot to get the triassic animals.



actually very interesting reading.

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Response to muriel_volestrangler (Original post)

Tue Jun 20, 2017, 04:54 PM

6. Maybe most of the major volcanic eruptions in earth's history may have been triggered by impacts

When I first heard about Chicxulub I ran to a globe to see if India was on the other side of the earth. I then and looked for a map of where Mexico and India were 65 million years ago. I had a like minded friend who independently did the same thing. Comet Shoemaker-Levy 9 brought home the idea that one might expect more than one impact associated with a mass extinction and eons could elapse between the between the impacts of the various pieces.

Geologists have found huge volcanic eruptions around the time of at least a few mass extinctions. My friend and I have always been skeptical about how "huge" volcanic eruptions compare to titanic impacts that can eject rocks into earth escape orbits or even melt the entire earth and potentially create the moon. The problem with old mass extinction craters is they have either been destroyed by continental drift or are buried on the seabed or under ice. The Wilkes Land crater(s) are under the ice in Antarctica. https://en.wikipedia.org/wiki/Wilkes_Land_crater

Here is a very interesting compilation of confirmed and unconfirmed impact craters:
https://en.wikipedia.org/wiki/List_of_unconfirmed_impact_craters_on_Earth

I think the Permian extinction was associated with one of the largest known volcanic eruptions (Siberian Traps). However there are a number of really large potential crater that could fall in that time span.

Over time as more research confirms more impact craters and their age ranges, I suspect volcanic eruptions will become items on the lists of major side effects from the impacts.


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