Impact Induced Volcanism in Deep-Time: A Colloquy

The Tusk is going slightly off-topic to cover the fascinating discussion of Citizen Castastrophists Hermann Burchard and Han Kloostermann concerning their belief that volcanic hot-spots are caused by impacts in deep time (deep time being the off-topic part).

I’m in Austin, Texas all week at the national swamp swappers conference, which makes me a busy bee.  So please excuse the formatting (which is always nightmare) until I can get settled down to shape the blog up and perhaps provide some figures and links.  Same goes for Rod Chilton’s great blog below, as well as the latest revelations from above that are sneaking into the traditionally ignorant MSSM (MainStream Science Media).

From [email protected] Fri Apr 30 00:48:59 2010
Date: Fri, 30 Apr 2010 00:48:50 -0500 (CDT)
From: Hermann Burchard
To: Johan Bert Kloosterman
Subject: Catastrophist Manifesto

Han,
after reading your Catastrophist Manifesto (& comments)
and some of the web sites about your life (kayaking in
Brazil for nine days past mostly rhyolite!), I thought
that maybe I could persuade George Howard to have TUSK
embrace a wider scope in the sense of temporal extent
and older impacts and including what you seem to call
the North American school, which rejects for the most
any major comet or asteroid impact influences, unless
I mistake your intentions, which seem to refer to the
“punctuated equilibrium” crypto-uniformitarian view:
Punctuated by what?  Mass extinctions again and again
attributed not to ET comets and assorted space rocks
but to “Deccan flood basalt volcanism”, “Sibirian
traps flood basalt volcanism”, and “CAMP flood
basalt volcanism,”  the last just this week timed
to the end-Triassic extinction, mirabile dictu.

Well, punctuated by those ornery comet impacts,
of course, giving rise to impact volcanism that
produces the flood basalts, including Kerguelen,
etc etc, and Yellowstone, too.   The mechanism
has been well explained for Yellowstone, not
in an impact scenario, unfortunately, by Steve
Sparks, who was on BBC Horizon with this,
years ago, and has written numerous papers
on explosive volcanism, which is the main point.

The volcanism results when the impact cavity
enters the mantle, most likely to occur for
thin crust like oceanic or Western US, which
is why several resurgent calderas from impacts
(I contend) are found in the Western parts of
this country, including Yellowstone, Long Valley,
Valles (near Los Alamos) or LIPs on ocean
bottoms.

As an example by expert geologists (which I am
not as a mere applied math guy),  I attach a PDF
by Chatterjee (Lubbock, Texas) et al, including
Richard Donofrio, from whose company web page
I downloaded the PDF, which includes a beautiful
graphic of the 400 km Shiva crater off of Mumbai
which happened within minutes i.m.h.o. of
Chicxulub by fragments of the same comet.

I had sent this PDF to George for posting on the
TUSK but he hasn’t done so for the obvious reason
I suppose of exceeding his brief.

Best regards,

Hermann G W Burchard

PS. Sorry about Mr V and paranormal for
which I never had the least bit of interest..
– hgwb.

From [email protected] Fri Apr 30 14:47:51 2010
Date: Fri, 30 Apr 2010 21:47:49 +0200
From: Johan Bert Kloosterman <[email protected]>
To: Hermann Burchard <[email protected]>
Subject: Re: Catastrophist Manifesto

Herman, I’d also like to see data on older impacts included –
but who decides is Howard.

I don’t like the word “punctuated” because it was introduced
by Gould c.s., crypto-uniformitarians in my view. It sounds
as if somebody who had a car-crash, total loss, speaks of
having had a puncture. They just were afraid to use
catastrophe, as the geologists of the early 20th century
were, and spoke of diastrophism. There were some cautious
catastrophists then, Joseph Prestwich, Termier, Obruchev, and
also in Germany I think (von Seidlitz?). Prestwich, an early
friend of Lyell, converted to diluvialism (NOT biblical!)
around 1890.
Velikovsky was more of a scholar than of a scientist. He
collected some 25 Earth-reversal myths (1950),  and thought
that the Earth in prehistoric times had decelerated, then
accelerated in the opposite direction, not giving a damn
about the energy problem
But the (Velikovskian) physicist Peter Warlow WAS preoccupied
with the energy problem, and came (1980) with the tippetop
model. Slabinski’s debunking of it was uncritically accepted,
generally, and especially by Leroy who has his trauma of
having been a Velikovskian. Warlow thought, Velikovsky-wise,
of the fly-by of a planet-sized body, as a cause for the
reversal.
But physicist Stig Flomark (U of Stockholm) calculated that
internal energy could be sufficient, thus getting rid of the
Deus ex Machina.
I have continued the search in worldwide myths, and found
more than 60 of them (including those published by
Velikovsky).

It is the perfect mechanism of geomagnetic reversals, the
mantle turning over around the nucleus which keeps its
position to the ecliptica. ( the planet-within-a-planet model
is academic consensus, since the 1990s).

Conclusion: I might be rather more “alternative” than you
are.

Gr.,

Han.

J.B. Kloosterman

From [email protected] Fri Apr 30 17:56:15 2010
Date: Fri, 30 Apr 2010 17:56:03 -0500 (CDT)
From: Hermann Burchard <[email protected]>
To: Johan Bert Kloosterman <[email protected]>
Subject: Re: Catastrophist Manifesto

Han,
thanks for that endorsement (partial) which I am
forwarding to George and Leroy.

But you say nothing about impacts causing LIPs??

Continue to have trouble with tippetop dynamics,
and believe impacts cause pole reversal.  E.g.,
the Australasian tektite strewnfield is timed
reliably to the Brunhes-Matuyama reversal.

When you kayaked in Brazil, the rhyolite you
met was from the Central Atlantic Magmatic
Province (CAMP)?  This is considered the
largest LIP.  It has parts on four
continents bordering the newly formed
Atlantic Ocean. A comteary impact at the
Azores likely was the cause, splitting
open the new ocean at the Newark Palisades
along the Hudson River and causing the
Azores hotspot. A recent paper timing this
to the end-Triassic mass extinction by
Whiteside (Brown U), Olsen (LDEO) et al
in PNAS is attached (PDF), but these
authors do not mention ET impacts either.

Very glad to have your reply.

Best,
Hermann

From [email protected] Fri Apr 30 18:50:42 2010
Date: Sat, 1 May 2010 01:50:40 +0200
From: Johan Bert Kloosterman <[email protected]>
To: Hermann Burchard <[email protected]>
Subject: Re: Catastrophist Manifesto

Hermann, protest!
I have no trouble with tippetop mechanics.
I don’t believe impacts cause pole reversals.
I know about the Australasian strewnfield correlation with
the Br-Mat. reversal.

1) Tippetop mechanics don’t exist. Some mathematicians have
worked out a few formulae, 50y ago, and have surmised that
the resistance of the table or floor is essential for the
reversal to occur. As far as I know purely theoretical,
nobody has tried to vary the variables, such as size,
density, angular velocity, and the amount of mass lacking at
the top of the top. And the roughness of the table-top.
Perhaps I am wrong here, if not it seems an example
of blindly giving prevalence to theory over empiry.

2) The term pole reversal should be avoided, because most
people think then of axial shift.
With an 180-degree axial shift , N becomes S, whereas W and
E continue W and E.
But with a tippetop reversal N becomes S, and E becomes W.
The Sun will rise in the W, as in the famous Herodotus quote
(Book II, 142). (1 out of 60+ stories).
Perhaps some impacts cause reversals. But for all those
geomagnetic events and reversals I trust in Flodmark.

3) The Australasian strewnfield is famous for the absence of
a crater. I wonder whether the tektites could have formed by
the aura of a post-perihelium comet when it all of a sudden
meets the resistance of a planet, whereas the cometary
body itself is only nearly-hitting, and flies by.

Han.


J.B. Kloosterman

– – – – – – –
– – – – – – –
File #2:
IMPACT VOLCANISM SUMMARY
– – – – – – –

From [email protected] Sat May  1 23:03:48 2010
Date: Sat, 1 May 2010 23:03:39 -0500 (CDT)
From: Hermann Burchard <[email protected]>
To: George Howard <[email protected]>
Subject: Re: Catastrophist Manifesto

George, thank you very much for that msg,
your “great stuff” response makes this day
look bright under a cloudy sky, on a bad
day with oil gushing from a broken rig in
the Gulf.

Here is a brief version of what I had in mind
sending:

IMPACT VOLCANISM, SUMMARY
= = = = = = = = = = = = =

Comet and asteroid impacts when striking at
oceanic or thin continental crust (Western
US) are capable of excavating deep initial
cavities, 1/10 as deep as diameter, that may
penetrate into the mantle beneath the crust.
The result of the inital impact explosion
and excavation relieves pressure sufficiently
so that magma erupts in flood basalts, and
volatiles dissolved in the  mantle can be set
free coming out of solution which leads
to series of further explosions, resulting
in a “resurgent caldera,” tied to a “hotspot,”
or magma chamber in the upper mantle.

The controversial, older theory is that these
hotspots sit atop “mantle plumes” that rise
from the core-mantle boundary (Morgan, 1971).

Attempts to prove this using seismic tomography
have largely failed due to the homogeneity
of the mantle with only slight variations
in seismic velocity (perhaps the mantle
is “transparent” to seismic waves) and also
the inherent mathematical difficulties of
inversion of the Radon and related transforms.

Seismic tomography has recently been used to
prove the Yellowstone hotspot is shallow
(Christiansen-Evans-Foulger).

For the impact volcanism theory, which at
present is considered heterodox by official
geology, see the Shiva paper abstract by
Chatterjee, Donofrio, et al (PDF attached
once more).  Steve Sparks, Bristol U, has
worked on explosive volcanism, but not in
an impact context (although he has
consulted with BBC Horizon on the
Yellowstone hotspot and its resurgent
eruptions).

There are a number of stereotypical surficial
features that accompany this process that
begins with a space rock penetrating to
the mantle, with quite a few examples on our
planet existing for observation.

Feature #1.  The initial impact crater, often
obscured by the flood basalts or later orogenies,
plate tectonics, or erosion, yet perhaps still
showing up in gravity and/ or magnetic anomalies.

Feature #2. A Large Igneous Provinces (LIP), of magmatic
lavas covering a large area of the planet.

Feature #3. Magma chamber in mantle or hotspot.

Feature #4. The track of hotspot, as the crust
slides over it and the resurgent caldera erupts
again and again.

Feature #5. Splitting open of oceanic tectonic
plates, and generation of new oceanic ridges or
spreading centers.   The continued spreading
may simply be a consequence of isostacy*,
the response to gravity of the plates and
depressurization of the mantle under the
opening between plates once the split is
created in the initial impact event and
subsequent magma flood along the entire
ridge.

– – –
*) I believe there is some recent work
in this direction contradicting the Morgan
plume model; gravity cited on Wikipedia as a
cause for the Marianas Deep, where the
oldest, heaviest part of the Pacific plate
is subducted.
Forthcoming book by G Foulger, Durham U:
Plates vs Plumes:  A Geological Controversy,
by Gillian R. Foulger,
ISBN: 978-1-4051-6148-0, Paperback, 472 pages,
September 2010, Wiley-Blackwell, £32.50 /
€37.40 / $65.00
(Gillian may be using gravity/ isostacy approach,
judging from the title, not sure, she ignores
impacts, see her webpage mantleplumes.org which
is anti-plume while keeping an open mind.)
– – –

EXAMPLES:  These should all be considered
heterodox (non-orthodox) to standard
geology.

a)  Impact at Azores at end of Triassic:
(a.1) Crater not apparent, could be in Azores,
buried under eruptives.
(a.2) Central Atlantic Magmatic Province (CAMP)
the largest LIP on Earth.  See the map in the
paper by Whiteside, Olsen, et al. attached.
(a.3) Azores hotspot.
(a.4) Track absent or obscure due to lack of
plate motion over the spot.
(a.5) Split open the newly created Atlantic
Ocean, created Atlantic Mid Ocean Ridge and
spreading center.   Hudson River Palisades
familiar witnesses of break-up events.

b)  Impact at Mumbai/ Seychelles at end of
Cretaceous:
(b.1) Crater in part near Mumbai. See
Shiva paper by Chatterjee attached.
Part of the crater is the Seychelles.
(b.2) LIP is the Deccan plateau
(b.3) Reunion Island, Mascarene Islands
(b.4) Maldive, Laccadive Island chains
(b.5) Split open Indian Ocean, created
Carlsberg Ridge, a part of the Central
Indian Ridge spreading center driving
India into soft underbelly of Asia.

c)  Siberian Impact at end of Permian.
Suspect two fragments of comet breaking
up just before impact in tidal forces
of “impact focussing.”  Other frags
possible impactors at additional sites
(Emeishan, SW China, claimed to be
older).
(c.1)  W Siberian Basin, S Kara Sea,
Ural Mountain is partial crater wall,
had been peneplain in Permian, exhumed
at 250 M yrs BP.  Eclogite band along
entire mountain chain witness to burial
to at least 10 km depth prior to
exhumation and reheating. U Stanford
PhD thesis Mary Leech on Uralian events
and geology (no impacts mentioned).
(c.2) LIP is Siberian traps with Putorana
Plateau the initial heavy outpouring,
plus of course W Siberian Basin, S Kara
Sea underlain by largest basaltic
volumes on Earth.
(c.3) Hotspot Mt Kilauea, Hawaii.
(c.4) Track: See my earlier blog on
Cosmic Tusk. Tarduno claims he proved
(2003) the kink in the Hawaiian sea mount
chain resulted from move of the magma
chamber in the  mantle, the hospot having
been at more Northerly latitudes prior
to 85 M yrs BP, the age of the Detroit Sea
Mount, the last one clearly visible before
the cusp in the Aleut-Kuril trenches.  His
method is to prove increasing orientation
toward the vertical of magnetic field lines
frozen in rocks as we move toward older
sea mounts.
(c.5) Split open the ancestral Pacific
Ocean, in fact creating the extant basin
which covers half the planet, the hotspot
still centrally located, never mind
Tarduno, with a large segment of crust
obliterated, sea surface level lowered
by ejecting H2O along ballistic trajectories
into space, with “great loss of life”  —
sounds catastrophic to me.

d)  Impact at Modoc Plateau, NE
California, early Miocene.
(d.1) Crater/  caldera in NE  California in
Modoc plateau, central peak “Chalk Mountain,”
located at coordinates 40.994,-121.809 on
Google terrain map (not satellite; terrain
recently placed in new menu portion), near
Burney, CA.  Some remnants of concentric
multi-ring uplift craters are still barely
visible.  Should consider later Cascadian
and Cordilleran orogenies and Mt Shasta
volcanism obscure early Miocene impact
structure  may have been 100 miles across.
This was an oceanic impact near the
cratonal margin at the time 17 Ma, the rebound
erupted in diatomaceous earth, hence “Chalk
Mountain”. Caldera was found in work for
Colorado School of Mines MS thesis by
Tom Bowens, who now works for a mining
company involved with the Magadan gold mines,
—  last heard of as VP Exploration,
Fortress Minerals in Vancouver, B.C.,
and traveling to Siberia a lot.
(d.2) LIP is Columbia River flood basalts
(d.3) Yellowstone caldera in NW Wyoming
(d.4) Hotspot track traced to the Nevada/
California state line by Nash-Perkins of U
of Utah.  See their map (was attached to
earlier email).  They counted 143 (!)
caldera eruptions over the 17 M yr life
time of the hotspot.
(d.5) May have created spreading ridge
along NW American coast?  More importantly,
has continued to “split” the continent
along Nevada Basin-and-Range terrain,
which amounts to accordeon folds of very
thin crust, spread out by the passage of
Yellowstone hotspot along its track, the
extent of thinning going far beyond
Nevada, including basaltic traps in
Idaho, etc.

More example: Kerguelen, other S Ocean
sites . .

  • Just as an aside, I am sure you are both aware of the view that earthquakes may be triggered by close passes of bolides and also those that strike th planet as well.

  • E.P. Grondine

    Han –

    I think you need to go back and check your translations.

    There is no evidence of the surface effects that a gravity induced crustal shift such as you propose have occurred in historical times, if ever.

    There are also no crustal shifts associated with impacts that I am aware of yet in historical times.
    No craters of sufficient size either.

    My opinion has been that Velikovsky’s bad physics set back impact studies, and will continue to, until disposed of.

    Rod, I don’t think that there is a body of sufficient mass which has passed close enough to set off earthquakes.

    The redistribution of planetary mass by spin is another question, one that is beyond me now.

  • Hermann Burchard

    E.P.,
    this is about a longer time frame, not historical, as George remarks at the start of this tentative blog. Plate motion is measured in the range of at most a few inches per year so in 5 K yrs of “historical times” you get a couple hundred meters.. W.r.to “no evidence of the surface effects that a gravity induced crustal shift.. occurred,” if you refer to plate tectonics, the idea is that plates slide “downhill” away from spreading centers or mid-ocean ridges. See Wikipedia articles for Mariana Trench and Subduction: Older, denser plate subducted under younger plate. Does that answer you?
    Rod, interesting idea about close passage but remote impact more likely (ocean, Sahara). Perhaps 1755 Lisbon quake antipodal to Australian impact shortly before James Cook arrived, but Abbott, Bryant, et al have different time frame..

  • Han Kloosterman

    This is private correpondence, which was posted on the Tusk by Burchard without my permission. I resent that, it amounts to disregarding ethical standards of conduct.

    I have asked George Howard to delete it.

    Han Kloosterman.

  • Hermann Burchard

    Han,
    you have my gratitude for your emails copied above. None of these were “private,” if you will recall, as all had cc to George and Leroy [redacted out above by myself]. Included in my reply to you (vide supra) is this notice:

    “Han, thanks for that endorsement (partial) which I am forwarding to George and Leroy.”

    George and Leroy being included as readers from the beginning, of course I meant for George Howard to consider posting, as the entire correspondence resulted from my reading your excellent and interesting Tusk blog, “Catastrophist Manifesto”, with which I fully agree, but felt that the actual extent to which cosmic bodies impacting on Earth has shaped the planet, anathema to uniformitarians, shoud be explained, sort of as an addendum to the “Manifesto.”

    I am happy with the outcome, this blog that George has kindly posted.

    Also, later [Tue, 4 May 2010 02:01:30 -0500 (CDT)] I wrote: “Han, it seems that George Howard, our host on Cosmic Tusk finds our email exchange that we had recently to be of sufficient general interest, and plans to post all or part on Tusk. This email to you from me is to make sure that you are agreeable to this. Just in case you wish to review some of your remarks, I am attaching a full set of our four (4) previous email exchanges and also a brief proposed SUMMARY ON IMPACT VOLCANISM.”

    Here is your reply [Tue, 4 May 2010 13:56:27 +0200], w/o ANY objections from you to posting: “Hermann, I have done some editing in our correspondence but I don’t know how to fix the changes, so perhaps you don’t receive them. […] Cheers, Han.”

    Above ellipsis stands for a little joke you made about our two first names being commonly misspelled (Hans for Han and Herman with one “n”).

    Please consider to send edits of your emails to George, I believe he would not mind posting. In case you choose to do so, I will request George to delete these presents.

    Very sorry my lack of proper care has led to your discomfort and unhappiness with my actions.

    Yours affectionately,
    “Herman”

  • Han Kloosterman

    George, the cc’s were NOT sent by me.

    I repeat my request, to urgently remove my e-mails.

    Why don’t you just do it, when I ask you? I’m really getting irritated.

    Han.

  • Thank-you Han and also to Hermann. I do agree Han that it is not very likely that anything but a very large bolide is likely to be capable of contributing to erathquakes and volcanic activity. However, an object of say ten kilometres and larger just perhaps may have sufficient mass to initiate tectonic activity. Certainly, I have a number of references including those of Dr. Mike Baillie (Exodus to Arthur p. 81 and p. 181),suggest impacts are likely associated earthquakes that subsequently trigger volcanic eruptions. Dr. John S. Lewis (Rain of Iron and Ice p.34, as well as Dr. David Morrison and Chapman both indicate that comets for their part are associated with enormous amounts of energy upon impact. It is interesting that many of the climate downturns back through the Holocene as well as the Younger Dryas cold stadial (intervals when it now seems were times of cosmic impacts also had increased or at least very significant volcanic eruptions and earthquakes. The Younger Dryas too, though the Greenland Ice cores signature of volcanic eruptions is largely masked by other gases, was also a time of many volcanic eruptions.

  • Hermann Burchard

    Han,
    you saw my cc’s and read that I was sending everything to George & Leroy and you seemed “agreeable to” posting msgs, MAKING NO NOISES until AFTER I suggested to you (unwisely) to edit your email.

    No objections from me against George taking out your emails. It will look like a funny blog, best if it ia just tossed.

    *Can I make a plea to keep the IMPACT VOLCANISM SUMMARY*

    “Herman”

  • E.P. Grondine

    Hi Rod, Hermann, Han –

    As we can clearly see at the KT boundary, large impacts do indeed trigger both anti-podal volcanic flows and nearby ones. Chatterjee’s new Deccan sequence and Shiva clearly demonstrate this.

    Hermann, I think it is now time to look at the areas which were anti-podal to your hotspots when they occurred.

    Rod, whether any recent earthquake or volcanic activity was triggered by recent smaller impacts is pretty much unexamined, to my knowledge.

    Hermann, the hytpothetical gravity I refered to was from nearby passes of asteroids or comets. While I understand plate tectonics, I will say that one of the thing that baffles me is what caused the breakup of Pangea and powered the subsequent drifts and rifting.

  • Hi E.P. Yes I think you are correct, it likely takes a fairly large object (say like the impact event as discussed by Dr. Marie Agnes Courty some 4200 BP), and also the alledged impact event round the time of Santorini to trigger tectonic activity.

  • Hermann Burchard

    E.P., Rod,
    according to Chatterjee et al, the Shiva bolide “impact was so intense that it led to several geodynamic anomalies: it fragmented, sheared, and deformed the lithospheric mantle across the western Indian margin and contributed to major plate reorganization in the Indian Ocean. This resulted in a 500-km displacement of the Carlsberg Ridge and initiated rifting between India and the Seychelles. At the same time, the spreading center of the Laxmi Ridge jumped 500 km westerly close to the Carlsberg Ridge.” Reading the entire abstract, it appears to support the idea that impacts can cause continents to break up. Cbatterjee et al mention a vertical rebound “upward for more than 50 km during the transient cavity stage as revealed by the mantle upwarping”, which exceeds most continental thicknesses. The Pangea break-up would have begun with an Azores bolide impact, splitting N Africa from N America. – The Santorini volcano is a resurgent caldera that has erupted repeatedly prior to 1650 BC (if that is now the best estimate). The hotspot track may be apparent in geomorphic features in the Agean Sea and the Greek peninsulas all seeming to indicate a SE to NW displacement. Perhaps Lake Ohrid is the impact crater??

  • E.P. Grondine

    Regarding KT impact volcanism:

    http://www.thelocal.de/sci-tech/20100510-27097.html

    What is pathetic is the funding for impact research, whether very ancient or recent.

    Right now, we don’t know what hit when. Hermann, you’ll please have to excuse my inability to work on ancient impacts; what little abilities I have left since my stroke I have to focus on the more immediately pressing problem of the recent impact rate.

  • E.P. Grondine

    PS – An earthquake along the fault preceded the eruption of Thera. The release of toxic lake water near the sources of the Nile River most likely accounts for the memories of the “plagues” as preserved in the Old Testament.

    This earthquake was NOT impact caused, particularly by the gravitational or impact effects of Comet Encke.

    If it had of been, it would have been remembered.

  • Hi E.P Sorry I don’t agree, as I do believe Thera like so many other volcanic eruptions was triggered by an impact. See Mike Baillie’s very find book “Exodus to Arthur” for his presentation of impact related signatures from not only the Med. region but as far away as China at this time. The signs in the Med. were perhaps mostly volcanic and earthquake in nature, but not entirely.

  • E.P. Grondine

    Hi Rod –

    Its been a long time since I read “From Exodus to Arthyr” but cometary dust loading does not necessarily mean an impact took place. (BTW, it appears that the dust loading in itself is sufficient to cause climate collapse. And one catastrohe does not exclude another from happening at the same time.

    I did not find any in the period immediately before 1628 BCE. That does not mean one didn’t happen, its just that I could not find any records of it.

    There was an impact, but ca 1585 BCE. viz:
    1998-2002
    On the Joshua impact event
    http://abob.libs.uga.edu/bobk/ccc/cc032098.html
    http://abob.libs.uga.edu/bobk/ccc/cc032598.html
    http://abob.libs.uga.edu/bobk/ccc/cc033098.html
    http://abob.libs.uga.edu/bobk/ccc/cc012102.html
    http://abob.libs.uga.edu/bobk/ccc/cc021202.html

    Impacts roughly 40-50 years after the dust loading occurred at least twice, Bazas being the second example.

  • Hermann Burchard

    Hi Rod, E.P.,
    about Santorini/ Thera’s prehistoric eruptions, here is an excerpt from a Geological Society, London, Memoir with some details, edited:

    Geological Society, London, Memoirs; 1999; v. 19; p. 13-59;
    DOI: 10.1144/GSL.MEM.1999.019.01.03
    © 1999 Geological Society of London
    Chapter 3 Development of the Santorini volcanic field in space and time

    Excerpt: Santorini is one of the largest Quaternary volcanic centres of the Aegean Region. The caldera cliffs preserve well-exposed sequences of lavas and pyroclastic deposits, which record the long development of the volcano in space and time. These include the products of 12 major explosive eruptions and the dissected remains of several ancient lava shields, stratovolcanoes, and lava-dome complexes. The former existence of multiple eruptive centres scattered over the present-day islands shows that Santorini is best considered as a volcanic field, which probably also continues under the sea (Heiken & McCoy 1984). Santorini is best known for the Minoan eruption of the late Bronze Age (Bond & Sparks 1976; Heiken & McCoy 1984; Sparks & Wilson 1990), but some of the previous explosive eruptions may have been as large (Druitt et al. 1989). The occurrence of repeated explosive eruptions has triggered formation of at least four large calderas, such that the present-day caldera is a composite structure (Druitt & Francaviglia 1992). Santorini is potentially one of the most dangerous volcanoes in Europe, having had numerous eruptions in historic times, some of them with significant explosive components (Fytikas et al. 1990a). The evolution of Santorini has been the focus of several detailed studies (Fouqué 1879; Reck 1936; Pichler & Kussmaul 1980; Heiken & McCoy 1984; Huijsmans 1985; Druitt et al. 1989; Druitt & Francaviglia 1992) as summarized in Chapter 1. Pichler & Kussmaul (1980) published a geological map of the islands that has been the basis of volcanological studies for the last eruptions.

  • Hermann Burchard

    Here is a list of authors for the above quoted LGS memoir:

    T. H. Druitt, Laboratoire Magmas et Volcans (UMR6524 et CNRS), Université Blaise Pascal, 5, Rue Kessler, 63038 Clermont Ferrand, France

    L. Edwards, Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK

    R. M. Mellors, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK

    D. M. Pyle, Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK

    R. S. J. Sparks, Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK

    M. Lanphere, Branch of Isotope Geology, MS 937, US Geological Survey, 345, Middlefield Road, Menlo Park,
    California 94025, USA

    M. Davies, Laboratoire Magmas et Volcans (UMR6524 et CNRS), Université Blaise Pascal, 5, Rue Kessler, 63038 Clermont Ferrand, France

    B. Barreirio, NIGL, British Geological Survey, Keyworth, Nottingham NG12 5GG, UK

  • Hi E.P. and Hermann: Thank-you for the volcanic eruption references. I am putting together a summary on my views in this regard. I will post very soon.

  • Hi again E.P. and Hermann: I finally got around to sythesizing my thoughts regarding the role volcanic eruptions may have had in the catastrophic events, at least through the Holocene and extending back at least to the Younger Dryas approximately 13,000 BP. I have for my little summary examined three climate downturns within the mid to late Holocene. The three intervals are: 1) approximately 4200 to 4300 BP, 2) about 3600 BP and finally 3)almost 1500 BP. That these three climate downturns were all characterized by suddenly colder, drier conditions that were apparent around the world attest to their main forcing mechanism, and that it would seem are cosmic encounters. That volcanic eruptions on their own are capable of the large repercussionas seen at these three times is highly unlikely. This is because the aftermath of volcanic eruptions, even the very large ones, are rarely for more that a year or two at most. The earliest of the cold intervals, dated at 4345 BP was upwards of two hundred years in length, with the other two admittedly of much shorter duration, (decades to several decades). All are nonetheless too long and severe to be initiated by volcanic eruptions on their own. I say on their own because volcanic eruptions most certainly contributed to the climate deterioration, at least for the 1628 BC inteval. In that case, it was of course Thera (Sanorini) that added dust to the atmosphere. That the dust was far more extensive in duration and in geographic extent than can be attributed to volcanic eruptions (perhaps other than megavolcanoes) is attested to by a number of interesting features. They range from astronomical observations of usually visible heavenly bodies being obscured from view for many months at a time. Also, other intriguing references to what appear to have been significnat comets, not that far from earth Observations by peoples in China, Europe and the Mediterranean are some the regions where interesting features in the sky were to be noted. There are some other features too, such as unusual compacted layers, as discovered by Dr. Marie Agnes Courty, dated at about 4300 BP. As well, a possible comet impact crater, likely originating from the same time was discovered not for away from Syria (where Dr. Courty discoverd her interesting layer); this in southern Iraq. Now, it is very plausilbe that volcanic eruptions and earthquakes both are triggered by most certainly large meteorite impacts. Somewhat more speculative are the possible affects of changing continental glacial mass (associated with the sudden locking up of more ice in higher latitude regions), and also the close by passage of comets not actually striking the earth, but leaving their signature, both in the form of cosmic showers and repercussions in the form of large gravitational forces, that then may well initiate tectonic activity.

  • E.P. Grondine

    Hi Rod –

    I think you are missing Hermann’s point: these wounds were both very ancient and very massive.

    Those researching impacts have been trying for quite some time to sort out solar variability, volcanic dust loads, impact dust loads,(and more recently possible AGW effects).

    The problem has been lack of research funding for geological work on recent impacts.

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  • Hermann Burchard

    From an ancient 1988 article in GRL.

    Australasian tektite impact crater off center Vietnam coast at 13°47′N,110°37′E:
    Schnetzler, C. C., L. S. Walter, and J. G. Marsh (1988), Source of the Australasian Tektite Strewn Field: A possible off‐shore impact site, Geophys. Res. Lett., 15(4), 357-360.

    http://europa.agu.org.argo.library.okstate.edu/?uri=/journals/gl/GL015i004p00357.xml&view=article

    I used to think the impact was at the Spratly Islands further East. Maybe a multiple impact, like we have heard so often?

  • Hermann Burchard

    URL for the Australasian tektite crater, please amend:

    http://europa.agu.org/?uri=/journals/gl/GL015i004p00357.xml&view=article

  • E.P. Grondine

    Thanks, Hermann –

    The crater source for these tektites has been a mystery for quite a while.

    Of course, oil pools in impact fractures. Given the crater’s location, one wonders what has been going on earlier privately, and what the future geopolitical reaction to the public news will be.