CHAPTER 3.2
FLOOD BASALT ERUPTIONS & MASS EXTINCTIONS

   
CHAPTER 3.2
FLOOD BASALT ERUPTIONS & MASS EXTINCTIONS


An article in "Elements" in Dec. 2005 entitled "the Link between Large Igneous Province Eruptions and Mass Extinctions" by Paul Wignall asserts the following:

"In the past 300 million years, there has been a near-perfect association between extinction events and the eruption of large igneous provinces, but proving the nature of the causal links is far from resolved." 77

He further states:

"The associated environmental changes often include global warming and the development of widespread oxygen-poor conditions in the oceans."

However, he also notes that younger volcanic provinces have not led to high extinction rates. In other words, there is not a mechanism to explain why it happens and why it doesn't happen. 77

An article by Steve Self and Michael Rampino published by The Geological Society, July, 2010, lists a comparison of major flood basalt flows and major extinctions. 76

They suggest that there is likely to be a causal link between the creation of large igneous provinces and mass extinctions. However, they note that finding the mechanism is quite difficult. They say:

"Every now and again in geology, as in any other science, evidence is obtained and presented that cannot easily be explained in terms of familiar processes or accepted ideas. Such a case was continental drift, proposed by Wegener in 1912, which languished as a theory for about 45 years because there was no logical explanation of HOW continents could move." 76 pg3


They go on to note:

"The time relationship between flood basalt province formation and mass extinctions of organisms is another scientific 'hard nut to crack.'" 76 pg 3

When it comes to a causal link between flood basalt events and mass extinctions, Rampino and Self suggest that it may have to do with the gasses released. But they note that basaltic eruptions are not particularly explosive, even though they are "often very rich in dissolved sulphur, and sulphuric acid aerosols formed from sulphur volatiles (largely SO2) are injected into the stratosphere by convective plumes rising above volcanic vents and fissures." 76 pg 4

They also remind us that some scientists suggest "that a coincidence of both a large impact and a flood basalt eruption might be necessary in causing severe mass extinctions." 76 pg 4

Clearly, this information tells us that scientists are looking at Large Igneous Provinces (LIPs) and mass extinctions. Some are also expressing the need for a coincidental large impact.

Until now, no one has presented a mechanism whereby large impacts cause LIPs (and possible continental uplift) at the antipode, with directional motion. If the LIP is part of an uplifted continent and if the LIP is at the edge of the continent, then subduction can occur at the edge of the LIP. Furthermore, much of this subduction will include water-infused crust that will go into the lower reaches of the LIP. As the water turns to steam during subduction, the nature of the eruption will change from gentle to violent. These violent and persistent eruptions will provide plenty of explosive sulfuric gases and ash.

In any case that I have investigated where a continent was uplifted, there was at least a minor mass extinction, with the exception of South America. However; with South America,

1. We had a major Oceanic Anoxic Event (OAE).

2. We had an antipodal hotspot that was interior to the continent's edge, thus greatly reducing the opportunity for subduction of water-laden crust.

3. We had a LIP that was moving in a straight line with the continent in front of it, thereby not creating a situation where water-laden crust could be subducted under it as the continent turned. Therefore, there was little opportunity for explosive eruption.

The CAMP eruption was huge and likely led to many situations where water-laden crust was subducted into the path of basaltic eruptions. And, again, the ultimate cause of the CAMP was the secondary effects of a very big impact.

Therefore, I would argue that we now do have the mechanisms needed to understand the causal relationships between LIPs and mass extinctions. Furthermore, I would argue that the causal relationships necessarily involve very large impacts, as well.

Self and Rampino include two charts showing correlative examples of LIPs and mass extinctions. They suggest that more work be done in researching this. 76 I would suggest that a chart of large impacts be added to this correlative research. 77, 77, 76, 76 pg3, 76 pg 3, 76 pg 4, 76 pg 4


CLUES FOR THE FIRST MAJOR EXTINCTION

In this book I have refrained from trying to figure out anything older than the Permian extinction, caused by a large cosmic impact around 252 MYA. The continuous tectonic movement of the plates makes it very difficult to understand the influence of impacts that occurred at dates earlier than that.

However, LIPs have an advantage here. If they can be dated, they can be lined up with extinctions, even if the underlying impact cannot be figured out. With impacts that are very old, the evidence may be eroded, subducted or changed in form (i.e. it may get folded into a newer mountain range, etc.).

Published in the journal Geology in 2014, Dr. Fred Jourdan was able to show that the massive eruptions in the Kalkarindji volcanic province in Australia ocurred 510 MYA, at the same time as the first Cambrian mass extinction, which wiped out 50% of existing species at that time. Another piece of the puzzle comes into focus
.