Deccan traps volcanic output and the Chicxulub impact

In summary, the article discusses the competing theories of bolide impact and flood volcanism as potential causes of the terminal-Cretaceous mass extinctions. The study suggests that these two mechanisms may be genetically related and cannot be considered in isolation. The Deccan Traps magmatic system underwent a state shift after the Chicxulub impact, resulting in a significant increase in lava flow. This prolonged ecological impact may have lasted for several hundred thousand years. The hypothesis that seismic waves from the impact caused the surge in Deccan Traps activity is still being debated. Multiple causes and time frames make it difficult to determine the exact cause of mass extinctions, as seen in the example of the extinction of mammoths on Wrangel Island.
  • #1
jim mcnamara
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http://www.sciencemag.org/content/350/6256/76

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State shift in Deccan volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact

Paul R. Renne
Courtney J. Sprain1
Mark A. Richards
Stephen Self
Loÿc Vanderkluysen
Kanchan Pande
Bolide impact and flood volcanism compete as leading candidates for the cause of terminal-Cretaceous mass extinctions. High-precision 40Ar/39Ar data indicate that these two mechanisms may be genetically related, and neither can be considered in isolation. The existing Deccan Traps magmatic system underwent a state shift approximately coincident with the Chicxulub impact and the terminal-Cretaceous mass extinctions, after which ~70% of the Traps' total volume was extruded in more massive and more episodic eruptions. Initiation of this new regime occurred within ~50,000 years of the impact, which is consistent with transient effects of impact-induced seismic energy. Postextinction recovery of marine ecosystems was probably suppressed until after the accelerated volcanism waned.

The concept is that the impact increased the lava flow markedly. So the ecological impact of the impact was extended over a longer period of time by the vast lava outflows for several hundred thousand years.
 
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  • #2
Chicxulub and the Alvarez's have been "targets" for thirty years. The approximately antipodal location of the Deccan Traps has been especially appealing/attractive as an alternative/coincident driver for the K-T extinction. Such speculations regarding flood basalts (Siberian:Permian::Deccan:K-T) disregard MOR, mid-ocean ridge, annual basalt formation rates, ~ 10 km3/a.
https://en.wikipedia.org/wiki/Deccan_Traps
 
  • #3
At one point there was a hypothesis that, because of plate tectonics, at the time of the impact the Deccan traps site was approximately antipodal to the Chicxulub impact. In this hypothesis seismic waves from the impact were focused at the Deccan trap site and were the cause of the outpouring of lava. Does anyone know if this is still a valid hypothesis?
 
  • #4
phyzguy said:
In this hypothesis seismic waves from the impact were focused at the Deccan trap site and were the cause of the outpouring of lava. Does anyone know if this is still a valid hypothesis?

That appears to be the premise in the paper linked to in the OP.
Its what I was also taught in my geology classes at univ.D
 
  • #6
"Error bars for the impact event, 2013."

I think what Bystander may be trying to convey, succinctly, I'm expanding:

The duration or even the fact of a mass extinction gets muddled up after 60 million years. And. It generally gets fuzzier the further back you go in time. How long did it take for the dinosaurs to beome extinct? We can see (from our viewpoint) very clearly that at some point there were lots of fossils from certain clades of animals and plants. More recent fossils: none. So, voila, extinction. No question there. But did it happen in a week? 15000 years? That is the 'error bar' in Bystander's comments. IMO. He can certainly correct my impression.

If we can narrow down the time frame, can we tie that period of time to some causative agent(s)? That is what this paper is talking about. In this case the Deccan traps were active (do not forget the timing fuzz problem) and at some point close in time near the Chicxalub impact, the activity surged apparently by orders of magnitude. Cause and effect?

Cute micro-mammoth from Wrangel Island:
http://factday.com/2012/04/27/the-last-mammoths-died-on-wrangel-island-around-2000-2500-bce/
See:
http://www.nature.com/nature/journal/v362/n6418/abs/362337a0.html

Mammoths are extinct. Mammoths used to be in North America. So when did that happen? Supposed to be during the Pleistocene Megafauna extinction event. Robin Gibbons at Stanford: From: http://web.stanford.edu/group/journal/cgi-bin/wordpress/wp-content/uploads/2012/09/Gibbons_NatSci_2004.pdf

During the Pleistocene, the world saw a dramatic number of extinctions of very large terrestrial
species. The losses of these megafauna have been attributed to either of two different hypotheses.

One hypothesis states that global climate changes occurring during the Pleistocene caused
environmental pressures that forced the extinction of several megafaunal species. The second
hypothesis proposes that the global spread of
Homo sapiens and hunter-gatherer subsistence
practices were responsible for these deaths. Examining these two theories reveals that neither
climate changes nor human overkill were likely to be individually responsible for the Pleistocene
extinctions. Instead, a synthetic model that includes both hypotheses appears to be the most
plausible explanation for the Pleistocene losses.

This is another guise of the exact same problem set being discussed here. Multiple causes and time frames. Did humans cause the extinction? Climate? or both?

Mammoths lived on Wrangel island until about 2000BC. In other words our discrete approach to extinction as an assumption: 'Wham, you're dead',
may not be the way extinctions work.

As a side note - it is very interesting that extinct beasties - we associate mammoths as 'long ago animals' - persisted well into the time of written history. Extensive writing existed in Egypt at this time. As did writing in several other places throughout the Middle East, Asia Minor, India, and China. They did not seem to be interested in dwarf mammoths in the Artic, however. Nobody wrote about them. AFAIK. But they were extant during historical times.
 
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  • #7
The link referenced is to a copy of the article behind a paywall. There is a .pdf available here.
http://www.media.inaf.it/wp-content/uploads/2015/10/renne151002.pdf

A while back when I was a Geology student, the Jurassic dolerite in Tasmania, (15000 km3, ~175Ma), was reported to have been injected into the older Permian–Triassic sediments in a geologically instantaneous 24 hour period. That could be explained by an impact event. Whether the impact was then thought to be direct or antipodean to the Tasmania of that time, I am unaware.

The injection of the dolerite has also been described as taking place over a period of 20 Ma, correlated with the separation of Tasmania from Antarctica as part of the Gondwanaland breakup. The Jurassic dolerite is also found in Antarctica. But that does not help identify the reason for the unusual rise of a dense magma.

It appears that the details and interpretation reported may be selected to confirm the personal preferences.
Scientists are People too.
 
  • #8
The position of hotspots appear to be mutually antipodal.
http://www.mantleplumes.org/WebDocuments/Antip_hot.pdf
"One aspect of the hotspot distribution that has received little attention is its antipodal character. Of 45 dprimaryT hotspots found in most hotspot compilations 22 (49%) form antipodal pairs within observed hotspot drift limits (<= 20 mm/yr). In addition, the available ages, or possible age ranges, for both hotspots of an antipodal pair tend to be similar (<= 10 Myr difference) or overlap."
 
  • #9
"...the ecological impact of the impact..." Awkward. "the ecological effect of the impact..." Better.
 

1. What are the Deccan Traps?

The Deccan Traps are a large volcanic province located in western India. It is made up of multiple layers of lava flows that together cover an area of over 200,000 square kilometers.

2. How did the Deccan Traps form?

The Deccan Traps formed as a result of intense volcanic activity that lasted for millions of years, starting around 66 million years ago. This activity was caused by the movement of the Indian tectonic plate over a hotspot in the Earth's mantle.

3. What is the connection between the Deccan Traps and the Chicxulub impact?

The Deccan Traps and the Chicxulub impact are two of the main theories proposed for the cause of the Cretaceous-Paleogene (K-Pg) mass extinction event that occurred around 66 million years ago. Some scientists believe that the Deccan Traps may have contributed to the extinction by releasing large amounts of greenhouse gases and causing drastic climate change, while others argue that the Chicxulub impact was the main cause.

4. Which event had a greater impact on the environment, the Deccan Traps or the Chicxulub impact?

This is a highly debated topic and there is no clear answer. Some studies suggest that the Deccan Traps may have had a longer and more gradual impact on the environment, while the Chicxulub impact had a more sudden and catastrophic effect. Other studies suggest that both events played significant roles in the mass extinction event.

5. Are there any ongoing studies or research on the Deccan Traps and the Chicxulub impact?

Yes, there is still ongoing research and debate on the role of the Deccan Traps and the Chicxulub impact in the K-Pg mass extinction event. Scientists continue to study these events and gather new evidence to better understand their impact on the Earth's environment and biodiversity.

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