[meteorite-list] Bad Science on ancient meteorite impactor? - Part 2

[Paul]

In "Bad Science on ancient meteorite impactor?", 

Sterling K. Webb wrote:

“See, I started out sceptical, and now I'm not so sure...

This collector considers "köfelsite" as an impactite:
http://www.somerikko.net/collection/index.html
"Age between 8000 and 16000 years is from glass.
Theory has been recently presented that köfels has been
formed during a giant landslide about 9000 years ago.
That landslide was so huge that rock melted because
friction. So there is still a possibility that Köfels is not
an impact structure. However, there is lots of big 
landslides in Alps but no other similar cases is found 
yet. Also PDF's in quartz has been reported in samples 
from Köfels, and PDF's are produced only by impacts."
http://www.somerikko.net/old/geo/imp/refer.htm

There has been iridium analysis, but it's inconclusive.”

The origin of the pumice, called either “hyalomylonites” or 
“frictionites” associated with the Köfels has been studied in 
great detail by:

Erismann, T. H., 1977, Der bimsstein von Köfels impaktit oder 
friktionit?. Material und Technik. vol. 5, pp. 190–196.

and Erismann, T. H., H. Heuberger, and E. Preuss, 1977,  Der 
Bimsstein von Köfels (Tirol), ein Bergsturz-“Friktionit. Mineralogy
and Petrology. vol. 24, no. 1-2, pp. 67-119.

The abstract to Erismann et al. (1977) stated:

“For more than a century the genesis of the fused rocks 
found in the landslide masses of Köfels (Ötztal, Tyrol) 
has remained enigmatic. The initially promoted hypothesis 
of a volcanic origin could not be backed by sufficient 
evidence. So in the last decade the possibility of a meteorite 
impact has been accepted by a large number of scientists. 
It is, however, by no means in accordance with all facts 
observed. In 1971, Preuss presented the idea of the melting 
heat being generated by the friction between sliding and 
stationary rock surfaces. As this working hypothesis 
proved to be in good accordance with petrographic and 
geomorphological evidence it was studied in detail by the
authors in cooperation with the Swiss Federal Laboratory 
for Testing Materials (EMPA). The corresponding research 
project (ldquoBig Sliderdquo) was based on a careful 
analysis of the effects of the energy generated by the 
landslide. By setting up plausible models for movement, 
heat generation, and heat transfer and by solving the 
resulting differential equations it became evident that —
as far as the landslide masses did not glide on a very 
thick layer of stone powder (dynamically a rather 
unprobable supposition)-large amounts of fused rock 
(ldquofrictioniterdquo, for definition see chapter 2.2) must 
have been produced. The enormous size of the particular 
landslide was recognized as a determining factor in this 
connection. The theoretical results thus obtained could 
be backed experimentally by producting artificial pumice 
under conditions approaching those of the Köfels landslide.”

Erismann et al. (1977) fairly well demonstrates that the estimated 
kinetic energy of the rock mass displaced by the landslide would 
have generated the heat necessary to melt the rock and form the 
“pumice”, which they called “frictionite”. The frictionite occurs 
in dikes several decimeters to meter thick at the top of the landslide 
deposit.

The Köfels landslide, about 2 to 3 cubic kilometers in mass, is the 
**largest** landslide in Europe. It is not surprising that it has some 
unique aspects to it being the only one of its size in the region.

Another study, which examined glass found in the Köfels landslide is:

Masch, L., H.. R. Wenk, and E. Preuss, 1985. Electron microscopy 
study of hyalomylonites-evidence for frictional melting in landslides. 
Tectonophysics. vol. 115, pp. 131–160.

They studied glass, which they called “hyalomylonite”, which occurs
in the Köfels landslide deposits. It differs from frictionite in that it 
occurs as veins 1 mm to 3 cm thick and lacks porosity. from their 
analysis, they concluded that the hyalomylonite was created by 
kinetic heating of the rock during the landslide.

Similar hyalomylonite / frictionite deposits has also been found in 
megalandslides in the Himalayas of Nepal and Peru as discussed by:

Heuberger, H., L. Masch, E. Preuss, and A. Schrocker, 1984, 
Quaternary Landslides and Rock Fusion in Central Nepal and in the 
Tyrolean Alps. Mountain Research and Developments. vol. 4, no. 4, 
pp. 345-362.

Weidinger, J. T., J.-M. Schramm, and R. Surenian, 1996, On preparatory 
causal factors, initiating the prehistoric Tsergo Ri landslide (Langthang 
Himal, Nepal). Tectonophysics. vol. 260, no. 1-3, pp. 95-107.

and

Legros, F., J.-M. Cantagrel, and B. Devouard, 2000, Pseudotachylyte 
(Frictionite) at the Base of the Arequipa Volcanic Landslide Deposit 
(Peru): Implications for Emplacement Mechanisms. The Journal of 
Geology. vol. 108, no. 5, pp. 601–611.

Hermanns et al. (2006) presents significant problem for the impact 
hypothesis in that he found that there is evidence of multiple landslides. 
It was the largest and youngest of these landslides that created the 
frictionite when it slid over the older deposits. To explain multiple 
periods of landsliding, a person would have to argue that two different 
impacts occurred at virtually same spot at different times separated by 
a significant period of time.

Hermanns et al. (2006) also noted of the younger deposits, which 
contain the frictionite:

“Pieces of wood recovered from a reconnaissance gallery 
in the Tauferberg gave a conventional 14C age of 8710+/-150 
years BP (Heuberger, 1966), and an AMS 14C age of 8705+/-
55 years BP (Ivy-Ochs et al., 1998),”

References Cited:

Hermanns, R.., L.. Blikra, M. Naumann, B. Nilsen, K. Panthi, D. 
Stromeyer, O. Longva, 2006, Examples of multiple rock-slope collapses
from Köfels (Ötz valley, Austria) and western Norway. Engineering 
Geology. vol. 83, no. 1-3, pp. 94-108.

-- Alledged PDFs  --

Impacts and meteorites
http://www.somerikko.net/old/geo/imp/refer.htm

The above web page, states

“Also PDF's in quartz has been reported in samples 
from Köfels, and PDF's are produced only by impacts.”

The alleged PDFs found in the deposits of the Köfels landslide were
examined by Dr. Christian Koeberl according to:

Deutsch, A., C. Koeberl, J.D. Blum, B.M. French, B.P. Glass,
R. Grieve, P. Horn, E.K. Jessberger, G. Kurat, W.U. Reimold,
J. Smit, D. stoffler, and S.R. Taylor, 1994, The impact-flood
connection: Does it exist? Terra Nova. vol. 6, pp. 644-650.

This paper reports that Dr. Koeberl found them **not** to be PDFs.
Rather, he identified them to be nonPDF  llamellar deformation 
features typical of tectonic, not impact, processes. 

How these llamellar features formed is discussed by:

Leroux, H., and J.-C. Doukhan, 1993, Dynamic deformation of quartz 
in the landslide of Koefels, Austria. European Journal of Mineralogy. 
vol. 5,  no. 5, pp. 893-902.

-- Additional Note --

Sorenson et al. (2003) concluded:

“Analysis of the Köfels sturzstrom seems to indicate
that most aspects can be explained without recourse to
exotic emplacement scenarios. The bulk of the material
resembles the debris from an energetic but conventional
landslide.”

Reference Cited

Sorensen, S.-A., and Berthold Bauer, 2003, On the dynamics of
the Köfels sturzstrom. Geomorphology, vol. 54, no. 1-2, pp. 11-19.

Yours,

Paul H.







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