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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)

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  • vhs Gilching and Observatory Gilching
359
X. Минералогия астроблем и метеоритов
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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
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
MeteoritenkraterStreufelds // 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.
Article
Full-text available
We use Schmieder and Kring's article to show how science still works within the so-called "impact community" and how scienti c data are manipulated and "rubber-stamped" by reviewers (here, e.g., C. Koeberl and G. Osinski). We accuse the authors of continuing to list the Azuara and Rubielos de la Cérida impact structures and one of the world's most prominent ejecta occurrences of the Pelarda Fm. in Spain 1 2 as non-existent in the compilation. The same applies to the spectacular Chiemgau impact in Germany, which has been proven by all impact criteria for several years. For the authors' dating list, we propose that the multiple impact of Azuara is included together with the crater chain of the Rubielos de la Cérida impact basin as a dated candidate for the third, so far undated impact markers in the Massignano outcrop in Italy.
Kollision in der Frühgeschichte
  • K Kosmische
K. Kosmische Kollision in der Frühgeschichte. Der ChiemgauImpakt: Die Erforschung eines bayerischen MeteoritenkraterStreufelds // Zeitschrift für Anomalistik.