CHAPTER 4.8
Cause & Effect Involving Cosmic Impacts and Antipodal Volcanism

   
Cause & Effect Involving Cosmic Impacts and Antipodal Volcanism


Shown below is my response to an innovative look at antipodal volcanism, as published in Science Magazine on 2October2015. Although this look at antipodal impact effects is far less ambitious than my proposal, it does have the courage to move in this direction, even though mainstream geology doesn't want to consider the possibility of cause and effect in this regard.

Examining Cause and Effect 66 MYA In the Chicxulub Impact & Deccan Traps


The article entitled "State shift in Deccan Volcanism at the Cretaceous-Paleogene boundary, possibly induced by impact," by Paul R. Renne et. al., was published in the 2October2015 issue of Science.

This article presents evidence that the Chicxulub impact caused a new, different, and much more vigorous kind of volcanism at the Deccan traps in India 66 MYA. This article also presents the possibility that the Chicxulub impact may have been the trigger for the massive volcanism at the Deccan traps.

Previous to this article, the geological community has been reluctant to seriously consider the possibility of cause and effect regarding the Chicxulub impact and the Deccan traps volcanism. The reason for this reluctance has been due to the mantle plume mechanism, as understood today. The current theory posits that a mantle plume rises through the mantle at a rate of about one inch per year. This means that a mantle plume rising from the mantle/core boundary would take approximately 100,000 years to reach the underside of the Earth's crust. Therefore, it would be impossible for an impact to create a full, synchronous mantle plume eruption.

However, Renne et. al. have found evidence of a definite change in volcanism at the Deccan traps that dates to the same time period as the Chicxulub impact. While this contemporaneous change in eruption could be viewed as merely a coincidence, it is also possible that this new volcanism could be the result of impact energy setting off a mantle plume that was nearly ready to burst forth anyway.

And what a bursting it was. The Deccan traps produced by far the largest amount of volcanic material emitted in the last 100 million years. In fact, the scale of this eruption was one of the largest in the known history of the Earth.

So, on the one hand, Renne et. al. are saying that we may now be able to eliminate the uncomfortable coincidence of the biggest (by far) impact of the last 100 million years happening at the same time as the biggest effusion of lava (by far). We can now consider these synchronous events to be the likely result of cause and effect, rather than the result of pure coincidence.

However, in another sense, we have merely traded one coincidence for another. We now have the coincidence of a super massive mantle plume being ready to burst forth at just the right time to coincide with the super massive Chicxulub impact. How convenient.

Furthermore, there is no evidence of other examples of extraordinary volcanism at the same time. The Hawaiian hotspot system was operating at that time and it didn't go crazy. Neither did any of the other volcanic systems.

Why do we have the Deccan trap system going completely ballistic and the other volcanic systems staying relatively quiet? This is almost as bad a coincidence as the previous lack of cause and effect coincidence.

I would like to suggest an alternative that will solve this coincidence of the Deccan traps as being the only volcanic system to go ballistic at the time of the Chicxulub impact. This solution involves a reexamination of the location of India 66 MYA.

India was a continent on the move 66 MYA. Famously, it was moving at a rate of 15-18 cm per year, (double or triple the usual tectonic plate rate) as it raced towards its impact with Eurasia. But the question is: "Where was it moving from?"

The usual theory has India sitting off the coast of Africa 66 MYA (while its Pangaean partners, Australia and Antarctica, had been moving east and a bit south for almost 200 million years). Then, just before 66 MYA, India races to the north and east. This movement allows India to pass over the Reunion Island hotspot 66 MYA for a big jolt of lava eruption.

Mark Richards, one of the authors of the 2October2015 Science article, indicates why India's location was not at the antipode of the Chicxulub impact in a University of California - Berkeley release by Robert Sanders in April of 2015. Sanders writes, "He (Mark Richards) stresses that his proposal differs from an earlier hypothesis that the energy of the impact was focused around the Earth to a spot directly opposite, or antipodal, to the impact, triggering the eruption at the Deccan traps. The 'antipodal focusing' theory died, when the impact crater, called Chicxulub, was found off the Yucatan coast of Mexico, which is about 5,000 kilometers from the antipode of the Deccan traps."

So, what's wrong with the usual theory? Lots.

First, there is no doming of the layers of rock around the site of the volcanism, as noted in the extensive research of Dr. Hetu Sheth and explained in his articles at www.mantleplumes.org. In all other cases of hotspot volcanism in the world (except for the hugely massive outpourings of the Siberian traps 252 MYA), there is doming around the site of the volcanism, as the hotspot melts its way to the surface over the course of five to twenty million years, depending upon the thickness of the Earth's crust at that location.

Second, with a a plume eruption, there is a hotspot trail. The seamounts leading up to the Hawaiian Islands are a classic example of this characteristic. In the case of the Deccan traps, there was a huge underlayment of basalt underneath the western side of the fast moving Indian peninsula. This huge underlayment dated from 66 MYA at the Deccan traps down to 60 MYA at the tip of the peninsula … and then it stopped! There is no trail of seamounts leading to the Reunion Island hotspot.

What kind of hotspot acts like this? It's not the kind of hotspot that we find anywhere else on the planet.

Third, as noted before, there are no other volcano systems going ballistic at this time. Why not?

Fourth, again as noted by Dr. Hetu Sheth, the lava of the Deccan traps was extruded at 30° south latitude. The usual theory has to invoke "polar wander" to explain this, since the Reunion Island hotspot is located at 21° south latitude.

All of these problems can be resolved by reexamining the purported position of India 66 MYA. If we assume that India (which was located slightly farther to the north than Australia and Antarctica in the Pangaean arrangement 252 MYA) moved with Australia and Antarctica to the west and south, then India would have actually ended up at the antipode of the Chicxulub impact 66 MYA.

In other words, the antipodal focusing theory may have been abandoned prematurely.

If we look at India as laying on its side on top of Australia 66 MYA, the Deccan traps site could have easily been located at 30° south. Furthermore, the path of India from that location to its present site today would have brought it along the edge of the Southeast Asian peninsula. India would have created the Sunda trench and pushed up much of the land of Java, Sumatra, Thailand and Malaysia as the coriolis effect forced it to take a curved arc to the north and east. After crashing into Asia and building up a huge plateau in Asia on its easterly side (see Gregory D. Hoke et.al.'s article entitled "Stable isotopes reveal high southeast Tibetan Plateau margin since the Paleogene" in Earth and Science Letters, April, 2014 about the massive nature of this easterly plateau 40 MYA), the Indian continent would have slid to the north and east to the area of least resistance, opening up the Bay of Bengal and building up the Himalayan plateau to the north and west. Note that the coast of Burma fits right into the coast of eastern India, especially after allowing for the huge amount of sediment from the Ganges river that filled in some of the gap, creating most of low-lying Bangladesh.

More importantly, this scenario allows us to account for a huge, raging hotspot that left a very visible hotspot trail after the Indian continent had finished passing over it 60 MYA. This huge hotspot is not just a line of seamounts. Rather, it is the entire Indonesian Island chain, including the western sides of Java and Sumatra. And where is this giant hotspot? It is located just to the north and west of Lake Toba in Sumatra, where it last erupted 74,000 years ago in the biggest volcanic explosion of the last 19 million years. Yes, this is a serious hotspot … bigger than Yellowstone. And yes, the Indonesian Island chain is the most volcanically active area in the world.

Please note that the line of volcanic activity in Indonesia starts at East Timor in the southeast and gradually moves to Mount Sinabung in the northeast (just beyond Lake Toba), and then it just STOPS! The Sunda trench (the supposed subductive mechanism) keeps going to the north and then bends to the east. But the serious volcanism just plain stops several miles beyond Lake Toba.

If the Sunda trench (the second deepest trench in the world) were the controlling mechanism for this supposed subductive volcanism, then we would expect to see at least a reasonable amount of serious volcanism after the Lake Toba area … but we don't see any. The reason for this lack of volcanism is the fact that the hotspot hasn't affected that area yet.

So far, we have seen how an antipodal location of India would solve the creation of lava at 30° south and how it would answer the question about a hotspot trail. Furthermore, we have seen some of the evidence left behind by this alternative journey of India.

The other problems associated with the usual theory are the lack of doming at the site of volcanism and the fact that no other volcanic systems were behaving like the Deccan traps 66 MYA. The antipodal focusing theory deals with these problems, as well.

The Earth is nearly spherical in shape. If the Deccan traps were located at the antipode of the Chicxulub impact 66 MYA, then the huge radiating earthquake forces would have travelled around the world and focused at this antipode. This concentration of earthquake waves at this one spot would have shattered any cohesion of the rocks at this location. This giant earthquake, estimated to be as much as 12.4 on the Richter scale, would have created an incredibly weak crustal area at the antipode.

Therefore, if an incipient mantle plume were located at or near enough to the antipode that its plume head would extend to the antipode, then it would have an easy avenue with little resistance through the Earth's crust. This is an advantage that no other incipient mantle plume on Earth would have. This would mean that the plume would not have to spend 5 to 20 years doming and melting its way through the crust. Therefore, there would be no doming needed, since the extremely weak crust at the antipode would offer little resistance.

Thus, the questions of doming and contemporaneous eruption of an incipient mantle plume would be answered by an antipodal location of India.

At this point, we have found that an antipodal location of India addresses all of the concerns relating to cause and effect for the Chicxulub impact and the Deccan traps eruptions … except one.

This unanswered concern would be the unlikely coincidence that the largest incipient mantle plume of the last 100 million years would just happen to be lurking right at the antipode of the largest cosmic impact of the last 100 million years. While this type of coincidence is possible, it isn't necessarily likely.

Is there some other way to explain this kind of correlated event that doesn't rely upon unlikely coincidence?

Well, yes, there is. There is the possibility that the extreme shaking (s waves) created by a very large cosmic impact could cause the mantle to become much more permeable. In this way, some of the vast energy of the impact (p waves) could be transmitted around the core to the opposite side of the planet.

Due to the likelihood of an off-center impact, it is probable that the center of the energy antipode (p waves) might not be exactly at the same spot as the physical antipode, but it should be relatively close. If the plume head is too far away (either because the plume head is too small or because of a very off-center impact) from the physical antipode, then this new mantle plume will have to go through the 5 to 20 million year process of melting and doming in order to reach the surface.

However, all of this talk of a much more permeable mantle allowing for the nearly instantaneous creation of a mantle plume at the energy antipode of a large impact is quite speculative. After all, wouldn't we then expect other not-quite-so-large cosmic impacts to show contemporaneous volcanism at or near their physical antipodes, as well?

Well, guess what? They do!

In the past 100 million years, the Earth has seen four large impacts from cosmic objects that produced craters of more than 55km in diameter. Although the Earth is an active planet that erases much of the evidence of events over time, we can still reconstruct the locations of the Popagai, Chesapeake Bay and Kara impacts, along with the attendant contemporaneous (allowing for doming) antipodal volcanism and the subsequent hotspot trails.

If we go back 50 million years more, we find that the two additional examples which occurred during that time provide similar, but harder-to-pin-down-exactly results.

This means that, if we include a position for India that is antipodal to the Chicxulub impact, we are batting six for six in the category of contemporaneous antipodal volcanism among the larger-than-55-km-in-diameter impact examples occurring in the last 150 million years.

Naturally, a reader would want to see more detailed information about these claims before accepting them. On the one hand, this level of detail is beyond the scope of this already very long letter. On the other hand, the detail for these claims is freely available at www.solvingthemassextinctions.com.

So, do I agree with the paper by Renne et. al.? Absolutely. Not only does this paper provide us with important new information about the nature of the change in the Deccan traps eruptions, but it also allows us to consider new paths to an entirely different understanding of what may have really occurred there.






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