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Enigmatic Meteorite Impact Signature: Field Evidence and Ground Penetrating Radar (GPR) Measurements Suggest Megascopic Impact Spallation Features

Abstract

Spallation is a well-known process in technical fracture mechanics that describes the particularly destructive effect of dynamic tensile stresses as a result of reflected dynamic compressive stresses. In meteorite impacts, it is primarily reflected shock waves (rarefaction waves) that leave their mark in dimensions from mega to micro. We describe the investigation of quite unusual and so far geologically not understood layer deformations with geophysical ground penetrating radar (GPR) measurements and consider impact shock spallation as causal force.
Enigmatic Meteorite Impact Signature: Field Evidence and Ground Penetrating Radar (GPR) Measurements
Suggest Megascopic Impact Spallation Features.
AGU FALL MEETING 2019
EP53F-2239 Earth and
Planetary Surface Processes
Kord Ernstson1 & Jens Poßekel2
1Faculty of Philosophy, University of Würzburg, Germany
2Geophysik Poßekel Mülheim, Germany
GPR equipment: Transient Technologies VIY3-300, 300 MHz antenna
GPR terrains (this poster)
Mandlberg abandoned quarry; Bach surficially melted granite layer
The beginning: the Ries crater (Germany) impact event
At the eastern Ries crater rim (large
Malmian limestone quarry in
Wemding; formerly: Schneider;
photo 2001. The abrupt horizontal
and vertical change from well-
bedded largely untouched
limestone layers to strongly folded
and heavily fractured rocks is
remarkable and incompatible with
any normal tectonic concept.
Mandlberg abandoned limestone
quarry in the Ries crater companian
impact strewn field some 100 km to
the east.(Rutte 1971[4] 2003[5],
E rn st s o n e t a l . 2 0 1 9 [ 6 ] ) : a
practically detailed copy of the
outcrop from the Ries crater (photo
2019). While the outcrop in the Ries
cr at e r no l on ge r e xi st s , t he
Mandlberg was ideally accessible
for the GPR in this still freshly
exposed situation.
Discussion of the spallation effects in the Mandlberg abandoned
limestone quarry
-- The layering of the Malmian limestones: no textbook tectonics - no other geologically
convincing explanation.
-- An identical structure at the rim of the Ries impact crater: similar mechanism of
deformation; source: a big meteorite impact.
-- Mandlberg and Ries crater: both phenomena originated in the same event - the Mandlberg
as part of the much larger Ries impact event postulated by Rutte (1971, 2003).
-- Fully rejected by German impact researchers and official Bavarian geology.
-- Recent investigations (Ernstson et al. 2019): Rutte's ideas are more or less convincing and
are giving new impetus to Ries impact research.
-- The Mandlberg quarry: a prominent geologic outcrop in the impact model of the much
larger Ries impact event.
-- The GPR measurements in the Mandlberg quarry: important megascopic spallation
"tectonics" are giving further convincing proof.
-- Posthumous justice to this great Bavarian geologist. The early spontaneous rejection by the
German Ries impact research group and the regional official geology was simply short-
sighted.
Discussion of the spallation effects in the superficially affected granitic
melt rock
-- The 500 m x 50 m extended melt layer: no human or known geological background.
-- Source: a meteorite impact airburst that did not create a crater but transformed the
granite surface into a sheet-like molten rock with abundant glass.
-- Shock effects in solely surviving quartz grains of the molten granite prove an impact event.
-- The GPR measurements: prominent tensile bowl-shaped reflectors at shallow depth in
the homogeneous granite.
-- Interpretation: tensile horizons are thin, low-density, porous, air-filled layers from spallation
reaction to the incoming airburst shock front.
-- Further observations: complex GPR reflections speak for a very complex airburst impact
event, the process of which is still largely unexplained.
-- Airburst shock waves, their reflections and refractions with a Mach stem formation and the
superposition of several neighboring and simultaneous, also smaller airbursts, must be
considered.
Conclusions
General
-- Impact research: rarefaction waves are considered more effective with regard to
destruction and deformation in the geological subsurface (lower tensile strength of rocks).
-- Tangible examples of impact structures are published less regularly or almost not at all.
-- Probable reason: geologists are not trained to impact physics and overlook such terrain
conspicuities or give it little thought.
-- Geophysics can tell more about the process of spallation during dynamic deformation in the
geological underground.
-- GPR measurements: their high structural and lithofacial resolution, precisely features such
spallation effects as an important and meaningful addition to terrain observations.
Mandlberg quarry
-- The details of the spallation process and the deformations are still not understood, but
amazing similarities with experimentally generated spallation structures are very remarkable.
-- The extensive spallations found with GPR exclude a reference to "normal" geological
processes.
-- Objections against Rutte's hypothesis and rejection of official geological positions
expressed in the past and up to the present day against a significantly larger impact event,
which had an effect far beyond the pure formation of the Ries crater, is no longer tolerable.
Shocked granitic melt sheet
-- The extensive melting and vitrification (temperatures >1,200 °C): another explanation than
that of an airburst with a shock front directed towards the earth's surface is not conceivable.
-- Meteorite airbursts are increasingly registered (most prominent the Tunguska impact event
of 1908)-
-- The Bavarian airburst probably documents an event at low altitude above the earth's
surface due to its shock effects, the high temperatures and the distinct geophysical (GPR)
signature.
-- It could be the first such documented impact event on Earth without the formation of a
crater.
Impact spallation "tectonics" and ground penetrating radar
(GPR)
References
[1] Ernstson, K.( 2014) http://www.impact-structures.com/impact-educational/meteorite-impact-spallation-from-
mega-to-micro-scale/; [2] Melosh, H.J. (1989) Impact Cratering: A Geologic Process. Oxford University Press,
New York, NY. 245 pp.; [3] http://www.impact-structures.com/impact-spain/the-azuara-impact-
structure/peculiar-structural-features-in-the-azuara-impact-structure/; [4] Rutte, E. (1971) Geoforum, 7, 84-
92, ] [5] Rutte, E. (2003) Land der neuen Steine, 110 p., Regensburg (Univ.Verlag); [6] Ernstson et al. (2019)
50th LPSC, 1370.pdf; [7] Ernstson et al. (2010) J. Siberian Federal University, Engineering & Technology, 1
(2010 3) 72-103; Rappenglück, M. et al. (2017) Zeitschrift für Anomalistik, vol. 17 (2017), p. 235-260.
ResearchGate has not been able to resolve any citations for this publication.
Article
The mechanisms involved in the formation of impact craters are examined theoretically, reviewing the results of recent investigations. Topics addressed include crater morphology, stress waves in solids, the contact and compression stage, the excavation stage, and ejecta deposits. Consideration is given to the scaling of crater dimensions, the crater modification stage, multiring basins, cratered landscapes, atmospheric interactions, and the implications of impact cratering for planetary evolution. Extensive diagrams, graphs, tables, and images of typical craters are provided.
  • E Rutte
Rutte, E. (1971) Geoforum, 7, 84-
Land der neuen Steine
  • E Rutte
Rutte, E. (2003) Land der neuen Steine, 110 p., Regensburg (Univ.Verlag);
  • Ernstson
LPSC, 1370.pdf; [7] Ernstson et al. (2010) J. Siberian Federal University, Engineering & Technology, 1 (2010 3) 72-103;
  • M Rappenglück
Rappenglück, M. et al. (2017) Zeitschrift für Anomalistik, vol. 17 (2017), p. 235-260.