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An eight kilogram chunk and more: evidence for a new class of iron silicide meteorites from the Chiemgau impact strewn field (SE Germany)

Authors:
Frank Bauer at Andor Technology
Frank Bauer
M. Hiltl
M. Hiltl
M. Hiltl
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Michael A. Rappenglück at vhs Gilching and Observatory Gilching
Michael A. Rappenglück
  • vhs Gilching and Observatory Gilching
Kord Ernstson at University of Wuerzburg
Kord Ernstson
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Abstract

The finds of iron silicides composed, among others, of xifengite, gupeiite, hapkeite with inclusions of titanium carbide, khamrabaevite and moissanite, and CAIs, together with about 30 elements including uranium and REE, which have been regarded as extraterrestrial for about 15 years in the crater strewn field of the Chiemgau impact, have been enriched by an 8 kg find with analogous composition.
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359
X. Минералогия астроблем и метеоритов
использовалось оборудование ЦКП «Геонаука»,
финансируемого из средств темы НИР #
AAAA-A17-117121270036-7.
Литература
1. Shumilova T. G., Isaenko S. I., Makeev B. A.,
Zubov A. A., Shanina S. N., Tropnikov Ye. M., Askhabov
A. M. Ultrahighpressure liquation of an impact melt //
Doklady Earth Sciences. 2018. 480(1): 595—598.
2. Shumilova T. G., Zubov A. A., Isaenko S. I., Karateev
I. A. & Vasiliev A. L. Mysterious longliving ultrahigh
pressure or secondary impact crisis // Sci Rep 10. 2591
(2020).
3. Shumilova T. G., Lutoev V. P., Isaenko S. I.,
Kovalchuk N. S., Makeev B. A., Lysiuk A. Yu., Zubov A. A.,
Ernstson K. Spectroscopic features of ultrahighpres
sure impact glasses of the Kara astrobleme // Scientific
Reports. V. 8. № 6923 (2018). doi:10.1038/s41598018
25037z.
An eight kilogram chunk and more: evidence for a new class of iron silicide
meteorites from the Chiemgau impact strewn field (SE Germany)
F. Bauer1, M. Hiltl2, M. A. Rappenglück3, K. Ernstson4
1 Oxford Instruments GmbH NanoScience, Wiesbaden, Germany; frank.bauer @oxinst.com
2 Carl Zeiss Microscopy GmbH, D73447 Oberkochen, Germany; mhiltl@online.de
3 Institute for Interdisciplinary Studies, D82205 Gilching, Germany; mr@infis.org
4 University of Würzburg, D97074 Würzburg, Germany; kernstson@ernstson.de
Introduction
The find of a big 8 kg weighting iron silicide
chunk (Fig. 1) found about 30 years ago in the
Chiemgau meteorite impact strewn field (Fig. 1)
[1—3 and references therein] has strongly sup
ported the earlier formulated hypothesis [1—3
and references therein] of an extraterrestrial or
igin for the abundant occurrences of iron silicides
(Fig. 2) in connection with the craters in the ellip
tically formed strewn field sized about 60 × 30 km
[1]. Up to now some thousands of iron silicide parti
cles have been sampled, mostly by metal detectors,
roughly amounting to a mass of a few kilograms
(apart from the 8 kg chunk). Here we report on new
analyses, which establish an obviously common for
mation and origin.
Fig. 1. Location map for the Chiemgau impact crater strewn field. Middle, right: Iron silicide finds addressed analytically
in this paper
Fig. 2. Various aspects (apart from Fig. 1) of the iron silicide finds from the Chiemgau impact strewn field
Modern Problems of Theoretical, Experimental,
and Applied Mineralogy (Yushkin Readings — 2020) - Proceedings of Russian
conference with international participation - Syktyvkar, Komi Republic, Russia
7—10 December 2020
Text
360
Юшкинские чтения — 2020
Methods and results
Optical microscopy, SEM, TEM and EBSD analy
ses, Raman spectroscopy.
Elements: Apart from the main constituents Fe,
Si more than 30 other chemical elements have been
evidenced so far like uranium, the REE cerium, yt
trium und ytterbium, or gallium. No decay products
of uranium like thorium or lead have been mea
sured.
Iron silicide minerals of the matrix: gupei
ite, xifengite, hapkeite, naquite and linzhite; hap
keite Fe2Si in its cubic polymorph and in its trigo
nal polymorph (the most stable iron silicide up to
255 GPa).
Identified minerals: Carbides — silicon carbide
moissanite SiC (cubic and hexagonal polymorphs),
titanium carbide TiC, khamrabaevite (Ti,V,Fe)C,
probably zirconium carbide ZrC (Fig. 4) — Graphite
C, zircon ZrSiO4; Carbon and TiC/(Ti,V,Fe)C in a ma
trix of cubic hapkeite and cubic gupeiite; SiC and
TiC/(Ti,V,Fe)C as superpure crystals in the iron sili
cide matrix (Fig. 2). — Calciumaluminum inclusion
(CAI) minerals CaAl2O4, calcium monoaluminate,
krotite, and Ca2Al2O5, dicalcium dialuminate.
Shock metamorphism and micro-impacts: pla
nar deformation features (PDF) in moissanite; open,
tensile spallation fractures in titanium carbide crys
tals; cosmic particle impacts (Fig. 3).
Conclusion
Enigmatic internal structures and exotic com
position for all sizes of iron silicide samples from
Fig. 3. Internal structure of iron silicides from the Chiemgau strewn field under the SEM
Fig. 4. SEMEDS micrographs and analyses; samples from Fig. 1, right. Quite comparable analyses have been made in the
8 kg iron silicide chunk (Fig. 1) [3] and in earlier analyses of various finds
the Chiemgau impact crater strewn field establish a
common formation process and a common source.
Artificial production, geogenic formation (and
e.g. fulgurite formation) can be excluded, which is
basically also supported by the find situations in the
field [1, 2]. The iron silicides are of extraterrestri
al origin.
The iron silicides in their entity belong to the
Chiemgau meteorite impact strewn field.
They should constitute a new class of meteor
ites. For reasons of definiteness we suggest to name
the trigonal Fe2Si polymorph hapkeite — 2T possi
bly rating a new mineral name [2].
References
1. Rappenglück, M. A., Rappenglück, B. & Ernstson.
K. Kosmische Kollision in der Frühgeschichte. Der
ChiemgauImpakt: Die Erforschung eines bayerischen
MeteoritenkraterStreufelds // Zeitschrift für Anomalistik.
2017. V. 17. P. 235—260 (English translation in [2]).
2. Rappenglück, M. A., Rappenglück, B. & Ernstson.
K. Cosmic collision in prehistory. — The Chiemgau
Impact: research in a Bavarian meteorite crater strewn
field // Zeitschrift für Anomalistik. 2017. V 17. P. 235—
260. http://www.impaktstrukturen.de/wpcontent/up
loads/2018/11/Anomalistentranslation.pdf.
3. Bauer, F., Hiltl, M., Rappenglück, M. A., Ernstson,
K. Trigonal and cubic Fe2Si polymorphs (hapkeite) in
the eight kilograms find of natural iron silicide from
Grabenstätt (Chiemgau, Southeast Germany)// 50th
Lunar and Planetary Science Conference. The Woodlands,
LPI. 2019, abstract 1520.pdf.
... In our commentary on the Kenkmann et al. article, we discuss not only these methodologically serious shortcomings of the paper, which culminate in the fact that such a large primary impact event with a comparably large crater strewn field has been established long ago and for 15 years. This Holocene event of the Chiemgau impact in SE Germany can, according to the extensively published literature (Schüssler et al. 2005;Rappenglück et al. 2009;Ernstson et al. 2010Ernstson et al. , 2012Liritzis et al. 2010;Hiltl et al. 2011;Isaenko et al. 2012;Shumilova et al. 2012;Rappenglück et al. 2013;Bauer et al. 2013;Neumair and Ernstson 2013;Rappenglück et al. 2014;Ernstson et al. 2014;Ernstson 2012Ernstson , 2016Ernstson and Poßekel 2017;Rappenglück et al. 2017;Shumilova et al. 2018;Poßekel and Ernstson 2019;Bauer et al. 2019;Bauer et al. 2020;Ernstson et al. 2020a;B. Rappenglück et al. 2020;Poßekel and Ernstson 2020;Ernstson et al. 2020b;Rappenglück et al. 2021), be described as probably the most important terrestrial impact crater strewn field at present, leaving the Wyoming strewn field now described far behind in scientific importance. ...
Secondary cratering on Earth: The Wyoming impact crater field. More than three question marks. – Comment on the Kenkmann et al. article (GSA Bulletin)
Article
Full-text available
  • Apr 2022
Secondary craters in impacts on moon, planets and their moons are a well known phenomenon, which has been investigated many times. In the article commented by us here, the authors report on a crater strewn field in the American state of Wyoming, which is interpreted as a field of secondary craters of a so far unknown larger primary impact structure and as a first on Earth. We compare the Wyoming crater strewn field with the Chiemgau impact crater strewn field in SE Germany and find that both have nearly identical characteristics of virtually all relevant features, in terms of geometries and petrography. We conclude that the alleged Wyoming secondary crater field is a fiction and the craters attributable to a primary impact. The alleged evidence is very poor to easily refuted. A primary crater does not exist to this day. The negative free-air gravity anomaly referred to, but not even shown, is invalid for this purpose. The Bouguer gravity map shows no indication of a possible large impact structure. Also unsuitable is the use of asymmetries with elongations of assumed secondary craters with a very questionable corridor intersection for the ejecta. Of 31 craters surveyed as proven, 15 are circular (eccentricity 1) and more than half (19) have an eccentricity ≤1.2. Circular and elongated craters are intermixed. The evaluated crater axes may just as well originate in a multiple primary impact. Elongated craters may also result from doublets of overlapping craters that are no longer fresh, as described by the authors themselves. In their paper, the authors do not show a Digital Terrain Model with contour lines for any of the surveyed craters, but only aerial photos blurred by vegetation. A verification of the crater measurements with the deduced eccentricities and strike directions is impossible. Not a single topographic profile over even a single crater in the strewn field is shown, either from DTM data or from an optical leveling, which could have been accomplished in an instant given the relatively small craters. Grave is the misconception that such a large crater field of 90 km length with three separate clusters is not possible according to 20 years old model calculations. A primary impact with multiple projectiles could perhaps be conceivable under rare circumstances, which are described by the authors as not relevant. The alleged impossibility of such a large primary strewn field with referring to the known small impact fields of Morasko, Odessa, Wabar, Henbury, Sikhote Alin, Kaalijärv, and Macha is contradicted by the three larger impact strewn fields of Campo del Cielo, Bajada del Diablo (very likely), and Chiemgau, which are best described in the literature but are not mentioned by Kenkmann et al. with a single word. The comparison of the Wyoming strewn field with the Chiemgau impact crater strewn field of about the same size here in the commentary article proves the scientifically clearly much greater significance of the Chiemgau impact, which must be considered as currently the largest and most significant Holocene impact despite the rejection and ignoring in some parts of the so-called impact community.
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Kollision in der Frühgeschichte
  • K Kosmische
K. Kosmische Kollision in der Frühgeschichte. Der ChiemgauImpakt: Die Erforschung eines bayerischen MeteoritenkraterStreufelds // Zeitschrift für Anomalistik.