FINDING INDIA'S TRAILING HOTSPOT
If, as I assert, the Deccan traps erupted at the
antipode of the Chicxulub impact, then there should be a really big hotspot
that would leave a really big trail after the Indian continent moved on to
collide with Asia.
So, where is it? It's easy to see the Hawaiian
hotspot and its trail of seamounts. Where is the hotspot that created the
Deccan traps? Where is the trail of seamounts? The answer is found in the
Indonesian Island chain. More properly, it is the Indonesian Island chain.
The hotspot was so powerful that it continued to create significant
islands (or, in the case of the huge islands of Java and Sumatra, the western
side of those islands) as it moved in the direction dictated by its original
VOLCANISM AT THE SUNDA TRENCH
The Sunda (or Java) Trench, the second deepest trench in the world, extends
from the east at East Timor in Indonesia all the way up to the border of
Bangladesh and Burma. Along the eastern edge of the trench are the Nicobar and
Andaman islands, as well as Sumatra, Java and the other islands of the
Indonesian island chain.
Java and Sumatra have many active volcanoes,
some of which are among the biggest in the world.
The Standard Theory
explains the extreme volcanism in Java and Sumatra as being the result of
subduction of the Australian-Indian plate underneath the neighboring plate.
However, the extreme volcanism stops at the northern end of Sumatra.
The Sunda trench continues for hundreds of miles to the north, but, suddenly,
there are no more big volcanoes as a result of subduction.
Why is this?
Here we have a series of very strong volcanoes that lead northwest until they
culminate at Lake Toba, the biggest super-volcano in the world. And then the
volcano chain just stops. The Sunda trench goes on, but the volcano chain
stops. Why? The Standard Theory has no answer at all.
Impact Theory has a clear explanation: The follow-on antipodal hotspot from the
Chixculub impact 65 MYA started at East Timor and ran up through (and created)
The Indonesian chain, up through Java and up to the north end of Sumatra. The
hotspot is currently below the northern end of Sumatra at the Lake Toba
The reason that there isn't any additional extreme
volcanism along the Sunda trench beyond northern Sumatra is because the hotspot
hasn't gotten there yet. As noted in "The Toba Complex" by Craig A. Chesner,
this volcanic activity continues to migrate to the west.
Furthermore, if we could zoom ten million years into the
future, we would find that the hotspot's continued motion would carry it north
and west and into and through the Sunda trench!
The hotspot's turn to
the west after it crossed the equator can already be seen on the map. The
hotspot is actually moving in a straight line relative to the mantle, but the
speed of the surface layer is decreasing (at the equator, the surface layer
moves at 1,000 miles per hour, but near the poles it is near zero), causing the
hotspot to appear to move to the northwest, relative to the surface.
The Sunda trench is unrelated to the hotspot. The Sunda trench was
created by the Indian continent pulling the surface apart, as it made its tight
turn going north.
The Sunda trench is often called a double trench,
because there are two distinct ridges along the trench for much of its length.
It may well be that the eastern edge of the continental blob did its own
pulling apart as it passed by before the tail came by later.
EVIDENCE FOR THE INDONESIAN ISLANDS' CREATION BY A
Now it is time to address the question as to why I
believe that the Indonesian Islands were created by a mantle plume that now
resides somewhere just to the northwest of Lake Toba in Sumatra.
geologists point out, the entire Indonesian Island chain would seem to be
merely the product of two converging tectonic plates. Furthermore, geologists
would ask why Lake Toba should be treated as anything more than just a
supervolcano at a convergent plate boundary, as opposed to it being a
supervolcano that is fed by a mantle plume.
CONVERGENT OR TRANSFORM PLATE
Let's look at the plate boundary at the edge of
the Indonesian Islands. Is it a convergent boundary or a transform boundary? I
have attached two different maps of the area around Lake Toba (from Wikipedia).
One map shows the convergent boundary of the
Australian plate as it is subducted under the Eurasian plate. It also shows a
transform fault called the Sumatran fault that actually runs through the
western side of the island of Sumatra. The second map shows a close-up of Lake
Toba with the Sumatran fault shown clearly to the west of Lake Toba.
So, what does this mean? It means that we have a large transform fault
sandwiched between a convergent boundary and its line of active volcanoes.
Isn't that strange? How does such a thing come about?
interpretation of the situation is that the boundary between the Australian
plate and the Eurasian plate was originally a transform boundary. The Sumatran
fault would have been a secondary mirroring transform fault.
as the antipodal hotspot from the Chicxulub impact began moving along a similar
path towards India's collision with Asia (but much more slowly), it cut through
the lithosphere like a plasma torch 125 , creating a natural avenue
for lithosphere and mantle material (especially to the west of it) to fall
into. This process gradually led to a weakness along the boundary, allowing a
subduction process to begin.
In other words, the boundary began as a
transform boundary and gradually became mostly a convergent boundary.
It is especially noteworthy that the Indonesian Islands are the most
intensely volcanic area on the face of the Earth 124 ... and, yet,
the volcanism dies down at the northwest end of the island of Sumatra. Why
doesn't it continue? The Sunda trench continues. All the maps still show a
convergent boundary continuing ... but the volcanism dies off.
Because the hotspot hasn't moved beyond the end of Sumatra yet.
SIZE OF ERUPTION
to look at the issue of whether or not an active mantle plume underlies the
Lake Toba area is to look at the size of the Lake Toba eruption ... the amount
of material ejected from the volcano. Is this amount more typical of a plume
fed eruption or is it more in line with an ordinary convergent boundary
Some of the other volcanoes of the Indonesian Island chain
have produced prodigious amounts of pyroclastic material. Krakatau in 1883 was
legendary. Mount Tambora in 1815 created the year without a summer and
contributed to Mary Shelley's icy setting for the novel "Frankenstein."
These Indonesian Island volcanic events are some of the most notorious
convergent boundary volcanic events in recorded history.
And, yet, they
pale in comparison to the Lake Toba eruption 73,000 years ago. Mount Tambora
had an ejected volume of less than 5% of the Lake Toba eruption. Krakatau was
smaller by two orders of magnitude ("Supervolcanoes and Their Explosive
Supereruptions" by Calvin F. Miller and David A. Wark). 123
The Lake Toba eruption was the largest supervolcano event in the past
18 million years. Bigger than the largest Yellowstone eruption. Larger than any
Taupo eruption in New Zealand (Wikipedia).
Was there a convergent
boundary aspect to the Lake Toba eruption? Undoubtedly. But there must have
According to Miller and Wark (cited earlier):
"What sets them (supervolcanoes) apart, however
is simply the enormous amount of eruptible magma that accumulates in shallow
chambers, which are in turn only a minor component of even larger magma
reservoirs. As suggested by all the papers in this issue, deeper-level, hotter,
less silicic basaltic and andesitic magmas, though rarely evident in the
products of the eruptions themselves, provide the thermal energy that drives
the supervolcano system and contribute at least some of their mass to the
silicic erupting magmas." 123pg12
the Mount Tambora and Krakatau eruptions were big, but they didn't have the
reservoir of heat and material supplied by a large hotspot underneath them. I
believe that Lake Toba did, and it made all the difference.
In order to
create the largest volcanic eruption of the last 18 million years, it takes
more than just the ordinary elements of convergent boundary subduction. It
takes the help of a hotspot, too.
These are some of the major reasons
that I believe that the Indonesian Island chain is more than just a set of
convergent boundary volcanoes. There are other reasons, which relate to the
timing of the creation of different parts of the islands and the composition of
the material of the larger islands and other factors as presented in Chapter
2.2 of this book, but these are the main reasons relating to volcanism.