Holocene Start Impact Event Controversy Continues
In “Holocene Start Impact Event Controversy Continues” at
http://www.mail-archive.com/meteorite-list@meteoritecentral.com/msg110580.html
E.P. Grondine wrote,
“What Boslough did not mention or is not being reported
is several recent possible major astroblemes, such as (sic)
Ilturalde Crater and the Lloydminster Structure. Nor that
the layer of impactites has been independently confirmed
by others.”
First, if you would read Boslough et al. (2012) you will
find that the so-called “layer of impactites” and their
allegedly being “independently confirmed by others” is
discussed in detail their paper. Your complaint about
“layer of impactites” not being discussed is completely
groundless and wrong.
Second, although the Ilturralde Structure has the
appearance of a real impact structure, the best estimate
of it age seems to be 10,000 to 30,000 BP according to
Campbell et al. (1988, 1998). The older range of the
structure is based upon radiocarbon dates from "fossil
tree trunks" in permeable fluvial sediments in a tropical
climate. Given my experience with radiocarbon dates
from similar samples and matrix, their dates in the 30,000
BP range could very well be much older, even "dead"
samples contaminated by modern carbon in the
groundwater. In fact, Campbell et al. (1985) reports
dates of greater than 40,500 years BP for these deposits.
Thus, the maximum age of the sediment in which the
Ilturralde Structure, and the structure itself, is
developed could be considerably older than 30,000 BP,
even back to the last interglacial or more.
Thus from what little I can find, it is unknown exactly
how old this proposed crater might be. There is a lack
of any solid evidence for claiming that this feature
is contemporaneous with and part of a hypothesized
Younger Dryas impact event. Until such evidence is
published, it is premature to criticize anyone for not
discussing this hypothetical structure in association
with a hypothetical Younger Dryas event. If you want
the Ilturralde Structure discussed in a paper about the
Younger Dryas, you need to provide and formally publish
definitive evidence that it is an impact structure and
it is contemporaneous with the start of the Younger Dryas.
Even if the Ilturralde Structure is an impact “crater”
and dates to the Younger Dryas, any impact that forms an
8-km in diameter impact crater in soft sediments within
the Lower Amazon jungle of Bolivia very likely will not have
any significant effect in North America. Being soft-sediment,
the original transient crater, unlike Meteor Crater, which
is in rock, has completely collapsed. Thus, the diameter of
the original transient crater was significant smaller (by
kilometers ) in diameter than the current structure that
has only 3 meters of relief. Also, there are numerous
pollen sites and other documented and published
paleoenvironmental records lying between this circular
structure and North America that show a complete lack of
any environmental effects from any impact during the
Younger Dryas. It is highly implausible that an impact
associated with a structure of this size in soft sediment
is going to create the havoc that is argued to have occurred
in North America at the start of the Younger Dryas.
Boslough et al. (2012) did not need to mention the
Iturralde Structure because 1. it is not yet determined
to be an impact structure, 2. it is unknown if it is
contemporaneous with the start of the Younger Dryas,
3. it is unproven that this feature has any association with
a hypothetical Younger Dryas impact event and 4. it is
much too small to have been an impact that would have
had any effect on North America.
Some web pages are: "Iturralde Crater"
http://en.wikipedia.org/wiki/Iturralde_Crater
And "Araona Crater (Iturralde Structure)"
http://svs.gsfc.nasa.gov/vis/a000000/a000900/a000925/index.html
Third, petroleum and other geologists have studied in
great detail the geology of the Lloydminster Heavy Oil Area,
which apparently what you have repeatedly referred to
as your so-called "Lloydminster Structure," in east-central
Alberta and west-central Saskatchewan. If a person looks
though what has been published about it, including
structural maps, a person finds a complete absence of
any geological evidence that it either is an impact
structure or its development is associated with the start
of the Younger Dryas in any fashion. There is even a
complete lack of either any ring faulting or any other
circular structure(s) that can be used to define or
postulate the existence of an extraterrestrial impact in
within the Lloydminster Heavy Oil Area. According
interpretations made from the an abundance of available
geophysical logs, cores, and cuttings from oil and gas
wells and innumerable seismic lines, the geological
structures are clearly the result of irregular collapse of
Cretaceous and overlying strata because of the subsurface
dissolution of thick Middle Devonian Prairie Evaporite
rock salt that underlie these strata rest. If this is the so-
called "Lloydminster Structure," then enough has been
published about its origin to completely discredited this
alleged "structure" as a possible impact crater. There
is no need, in this case, to discuss an imaginary "crater"
that has never been formally proposed judging from
what I have so far found. For more details, consult
Gregor (1997), Kohlruss et al. (2010), and Orr et al. (1977)
It is nonsensical for Boslough et al. (2012) to have to
discuss every lake, “paleolagoon,” ring igneous intrusion,
other geologic structure, or other feature that someone,
often on the basis of a quite vivid imagination, speculates
to be an Younger Dryas impact crater without offering a
single shred of hard evidence. The circular and even
noncircular lakes, structures, and other features that
people interpret to be impact craters are seemingly
endless and uncountable. In fact, Boslough et al. (2012)
did take the time and space to discuss the geologically
illiterate claim that the Great Lakes are in part impact
craters.
Fourth, I will disregard the details of ill-tempered and
imaginary Vogon Poetry about another impact researcher
personal motivations. As with various Young Earth
creationists, some people obviously need to understand
that stating such fiction for mudslinging, and character
assassination involving other people's motivation and
character because they disagree with you is definitely
not a productive technique to win friends and positively
influenced people. They also need to understand that
fictional ad hominem attacks about personal motivations
are not an acceptable part of scientific discourse.
[Besides Boslough et al. (2012) has 16 coauthors. Are
you implying that they all have some sort personal
axes to grind? :-) :-) ]
Finally you, stated:
“"Denial" is a strange psychological mechanism, and
undoubtedly we will hear stories about how an
"asteroid impact did not kill the dinosaurs" for many
years to come.”
From what I have found, complaints about people, who
disagrees with a specific point of view, being in “denial”
is the standard silly, scientifically illiterate, and just
plain stupid psychobabble that I hear from Young Earth
creationists; supporters of Rand Flem-Ath’s / Charles
Hapgood’s ideas about Earth Crustal displacement; Ed
Conrad’s Carboniferous human bones; and supporters
of many other fringe pseudoscientific claims. This
whining about people being in “denial” at its most basic
level, an ad hominem attack on any person, who
disagrees with a specific pet idea or theory. I consider
it an ad hominem attack because it insinuates that their
disagreement is based, not on the facts, but on some
mental impairment. Again, such complaints about other
people being in "denial" neither wins friends and
positively influences people nor has anything to do
with scientific discourse.
Judging from what you argue about the Ilturralde
Structure and your imaginary "Lloydminster Structure,"
I suspect that if the age of the Chicxulub impact
structure was unknown that either you or someone else
would be arguing that it was also an Younger Dryas
impact structure as well. :-) :-) :-)
References Cited:
Boslough, M., K. Nicoll, V. Holliday, T. L. Daulton, D.
Meltzer, N. Pinter, A. C. Scott, T. Surovell, P. Claeys, J. Gill,
F. Paquay, J. Marlon, P. Bartlein, C. Whitlock, D. Grayson,
and A. J. T. Jull, 2012, Arguments and Evidence Against a
Younger Dryas Impact Event. , in Climates, Landscapes,
and Civilizations, Geophysical. Monograph Series, vol. 198,
edited by L. Giosan et al. 13–26, AGU, Washington,
D. C., doi:10.1029/2012GM001209.
http://www.agu.org/books/gm/v198/2012GM001209/2012GM001209.shtml
Campbell, K. E., Jr., C. D. Frailey, and L. J. Arrelano, 1985,
The geology of the Rio Beni: further evidence for Holocene
flooding in Amazônia. Contributions in Science. vol. 364,
pp. 1-18.
Campbell, K. E., Jr., R. A. F. Grieve, Z. Pacheco, and J. B.
Garvin, 1988, A Possible Impact Structure in Amazonian
Bolivia. Abstracts of the Lunar and Planetary Science
Conference, vol. 19, p. 163-164.
Campbell, K. E., Jr., R. A. F. Grieve, Z. Pacheco, and J. B.
Gavin, 1989, A newly discovered probable impact
structure in Amazonian Bolivia. National Geographic
Research. vol. 5, no. 4, pp. 495-499.
Gregor, V. A., 1997, Mannville Linear in the Lloydminster
Heavy Oil Area and Their Relationship to Fractures and
Fluid Flow in the Western Canada Sedimentary Basin.
In S. G. Pemberton and D. P. James, ed., pp. 428-474.
Petroleum Geology of the Mannville Group. Memoir no. 18,
Canadian Society of Petroleum Geology, Calgary, Alberta,
Canada.
Kohlruss, D. A. Marsh, G. Jensen, P. Pedersen, and G.
Chi, 2010, Lower Cretaceous Mannville Group
Sandstones in the Clearwater River Valley, Northwestern
Saskatchewan: Preliminary Observations, Bitumen
Sampling, and Mapping. In Summary of Investigations
2010, Volume 1, Miscellaneous Report 2010-4.1,
Paper A-1. Saskatchewan Geological Survey, Regina,
Saskatchewan, Canada.
Orr, R. D., J. R. Johnston, and E. M. Manko, 1977, Lower
Cretaceous Geology And Heavy Oil Potential Of The
Lloydminster Area. Journal of Canadian Petroleum
Technology. vol. 17, no. 1, pp. 1187-1221.
Best wishes,
Paul H.
