PARADIGM SHIFT IN IMPACT RESEARCH: THE HOLOCENE CHIEMGAU METEORITE IMPACT CRATER STREWN FIELD AND THE DIGITAL TERRAIN MODEL

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PARADIGM SHIFT IN IMPACT RESEARCH: THE HOLOCENE CHIEMGAU METEORITE IMPACT
CRATER STREWN FIELD AND THE DIGITAL TERRAIN MODEL K. Ernstson1 and J. Poßekel2 1Univ. of
Würzburg, 97074 Würzburg, Germany (kernstson@ernstson.de), 2Geophysik Poßekel Mülheim, Germany
(jens.possekel@cityweb.de).
Introduction: For about 20 years, the enormous,
elliptically shaped crater strewn field of roughly 60 km
x 30 km in size in south-eastern Germany has been
scientifically investigated using methods of geology,
geophysics, mineralogy-petrography, geochemistry,
geomorphology and archeology/history after its
discovery, and is now considered an established
Holocene impact event due to the clear and extensive
impact evidence generally recognized in impact
research [1-4]. More than 150 rimmed craters with
diameters ranging from a few meters to a current
maximum of 1,300 meters have been documented in the
Bronze Age/Iron Age (900-600 B.C.) dated strewn
field. Impact research in the strewn field was given a
very special boost by the now free online access to the
Digital Terrain Model. The DTM (DGM 1 in Germany)
is available and can be downloaded for free for the
complete impact strewn field as a compilation of
roughly 1,500 tiles of 1 km x 1 km size each and has
been used in this study in highest resolution with a 1 m
grid and a vertical resolution of 10 cm (DGM 1), which
by interpolation may even be reduced. In many respects,
the unsurpassable advantage of the LIDAR DTM is its
virtually unrestricted operation free of any vegetation,
including dense forests and otherwise inaccessible
swamp areas with data acquisition of the bare ground.
Without doubt, the enormous progress of Chiemgau
impact research results from these previously
unimaginable possibilities.
Fig. 1. Location map of the elliptically shaped
Chiemgau impact crater strewn field in the Alpine
forelands. - Map of the investigated strewn field of
about 1,500 DTM tiles of 1 km x 1 km size, each of
which for free can be downloaded online as (x,y,z) files
with 1 Mill. data sets.
DTM data processing. The downloaded (x,y,z) data
have in most cases undergone a low-pass moving
average filtering to subtract a terrain trend field. The
resulting maps computed and presented here comprise
topographic maps with high-resolution counter intervals
of mostly 5-10 cm, 3D surface maps of arbitrary
orientation, and shadowed relief maps of arbitrary view
and lighting (e.g., Fig. 2). Topographic profiles with
terrain height resolution down to centimeters may be
extracted for arbitrary orientations.
Morphology of the smaller craters: The
Schatzgrube #001 crater exhibits the basic
characteristics and elements of most strewn field craters
exemplarily (Fig. 2).
Fig. 2. Data processing of the Schatzgrube #004 crater.
In particular the gradient curves in the lower part prove
the incredibly strong circularity even in details (arrows).
The almost exactly centimeter-precise circular shape
of the cauldron with ring wall and surrounding
depression is striking and excludes geological and
anthropogenic formations. By no means all craters show
a largely circular structure, as Figs. 4, 5 document with
a few examples. A discussion of these Chiemgau craters
with comparable structures on the Moon and Mars can
be found in parallel articles [5, 6].
Fig. 3. Examples of non-circular and multiple-impact
craters. DGM 1 contour maps.
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Fig. 4. Examples of more complex crater structures
with terraced and wavy crater rims considerably
enlarging the impact-affected ground.
The larger craters: The great new possibilities of
the DTM have opened up completely new aspects of
impact research in the crater strewn field.
Abb. 5. A compilation of selected larger craters in the
Chiemgau impact strewn field. Note the large, almost
perfectly circular flat and rimmed impact depressions,
which rule out the previous interpretation as ice age
relics (e.g. dead-ice holes).
This can easily be explained by the fact that large
areas in the strewn ellipse are covered with forest and
large areas are occupied by lake landscapes in swampy
areas. The majority of the enormous increase in the
number of craters in recent years can also be attributed
to detection with the DTM in these areas. A selection of
the newly discovered craters with diameters between
roughly 5 m and 250 m is shown in Fig. 5. The almost
strict circularity is already clear to the naked eye in the
DTB images in Fig. 5. This applies in particular to the
crater rims, as the example of the Schernsee crater in the
diametrical profile clearly shows in Fig. 5 below.
Discussion and conclusions: The official listing of
established, officially recognized impact structures in
databases (e.g. Canadian Earth Impact Database)
currently counts around 200 mentions, which are also
reflected in various listing publications [7-9]. These lists
are not universally accepted in impact research (e.g.
[10] and are regarded as misleading because they ignore
impacts that have been established for decades, but also
new results of impact research. The existing lists in the
databases and articles are based on the criteria of the
standard literature and forget that new findings and
ideas on impact events also affect very important points,
which in particular concern the previously formulated
statistics on terrestrial impact frequency, the resulting
threat of underestimated collision probabilities and the
defensive measures that have been increasingly
discussed recently. The reasons for a rethink in this
respect are increasing findings on previously neglected
impact events caused by comets and asteroids with huge
near-Earth airburst impacts with extreme pressure and
heat effects, which leave their traces relatively close to
the surface but could pose far greater threats to
humanity. In this respect, the statistics in the databases
and the future impacts still to be expected and derived
from them are pure rubbish. In particular, it must be
taken into account that such impacts have very little,
albeit extreme, effect on the surface in the
approximately 30% of the world's forested areas and
also in areas that are otherwise hardly explorable. This
applies not only to these impact-unexplored areas, but
in particular, of course, to all those areas and times in
which erosion has rapidly removed such impact traces
geologically.
It is in this sense that the explanations given here
should be seen, which could or, to put it better, should
put the previously considered impact scenario on a
completely new basis, suggesting the paradigm shift
mentioned in the title. There should be no doubt that
with the new possibilities of the DTM, the
aforementioned forest and otherwise unexplored areas
worldwide can be scanned for unknown and, above all,
shallow airburst craters by the thousands. We should
bear in mind that the number of craters to be assumed in
the Chiemgau impact strewn field alone, with the help
of the extremely high-resolution DTM, will already
reach the number of about 200 that the Canadian
database of established and accepted impacts currently
shows.
References: [1] Ernstson, K. et al. (2010) J. Siberian
Federal Univ., Engin. & Techn., 1,72-103. [2]
Rappenglück, M.A. et al. (2017) Z. Anomalistik, 17,
235-260. [3] Ernstson, K. et al. (2023) Earth Sciences,
12, 26-40. [4] Rappenglück, B. et al, 2023 Mediter.
Archaeol. Archaeom., 23, 209-234. [5] M.A. Rappen-
glück et al.(2021) 12th PCC Mtg. Abstract # 2021. [6]
Ernstson, K. et al. (2024) This LPSC meeting. [7]
Schmieder, M. and Kring, D.A. (2020) Astrobiology,
20, 91-14. [8] Kenkmann, T. (2021) Meteor. & Planet.
Sci., 56, 1024-1070. [9] Osinski, G.R. et al. (2022) Earth
Sc. Rev., 232, 104112. [ 10] Claudin, F.M. and
Ernstson, K. (2023) Met. Soc. Mtg. 2023, Abstract
#6058.
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