TY - JOUR
T1 - The old, unique C1 chondrite Flensburg – Insight into the first processes of aqueous alteration, brecciation, and the diversity of water-bearing parent bodies and lithologies
AU - Bischoff, Addi
AU - Alexander, Conel M.O.D.
AU - Barrat, Jean Alix
AU - Burkhardt, Christoph
AU - Busemann, Henner
AU - Degering, Detlev
AU - Di Rocco, Tommaso
AU - Fischer, Meike
AU - Fockenberg, Thomas
AU - Foustoukos, Dionysis I.
AU - Gattacceca, Jérôme
AU - Godinho, Jose R.A.
AU - Harries, Dennis
AU - Heinlein, Dieter
AU - Hellmann, Jan L.
AU - Hertkorn, Norbert
AU - Holm, Anja
AU - Jull, A. J.Timothy
AU - Kerraouch, Imene
AU - King, Ashley J.
AU - Kleine, Thorsten
AU - Koll, Dominik
AU - Lachner, Johannes
AU - Ludwig, Thomas
AU - Merchel, Silke
AU - Mertens, Cornelia A.K.
AU - Morino, Précillia
AU - Neumann, Wladimir
AU - Pack, Andreas
AU - Patzek, Markus
AU - Pavetich, Stefan
AU - Reitze, Maximilian P.
AU - Rüfenacht, Miriam
AU - Rugel, Georg
AU - Schmidt, Charlotte
AU - Schmitt-Kopplin, Philippe
AU - Schönbächler, Maria
AU - Trieloff, Mario
AU - Wallner, Anton
AU - Wimmer, Karl
AU - Wölfer, Elias
N1 - Funding Information:
One day after the fireball event, on Friday the 13 th of September, a small meteorite was found by accident by Mr. Erik Due-Hansen on the lawn of his front garden in the southwestern part of Flensburg, Schleswig-Holstein, Germany (Fig. S2; coordinates: 54°45.6873′ N, 9°22.7353′ E = 54.761455° N, 9.378922° E) and on September 15 th he reported the meteorite find to the IMO website. More details on the fireball event and on the post-recovery procedures are given in the “Supplementary Material” (SM). The finding of a fresh meteorite is supported by short-lived cosmogenic radionuclide detection by gamma-spectrometry.
Funding Information:
We thank U. Heitmann (M?nster) for sample preparation, and Jasper Berndt (M?nster), Beate Schmitte (M?nster), Sabrina Beutner (Dresden), and Sarah Lentfort (M?nster) for their analytical assistance and support. We greatly acknowledge the constructive suggestions of Jemma Davidson and two further reviewers as well as the help and support of the Associate Editor Pierre Beck. The help of Martin Whitehouse and Robbin Visser with providing standards for the analyses and data of carbonates is greatly acknowledged. We also thank Gerd Baumgarten and Felix Bettonvil for calibrations of video records of the daylight fireball with night time images. The mindfulness of Erik Due-Hansen and his kind cooperation with the scientists is highly appreciated. We acknowledge the contributions of Ji?? Borovi?ka and Pavel Spurn?, Ond?ejov Observatory (Czech Republic), who determined the atmospheric path. This work is partly funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) ? Project-ID 263649064 ? TRR 170 (A.B. C.B. T.K.); this is TRR170 Publication No. 119. M.S. and C.M. thank the Swiss National Science Foundation (SNF) for support. The work of H.B. and M.S. has been in parts carried out within the framework of the NCCR PlanetS supported by SNF. D.H. thanks F. Langenhorst for support and access to the FIB-SEM and TEM facilities at FSU-IGW, which are funded by the DFG via grant LA830/14-1. D.F. (CIW) acknowledges the support of the NASA awards 80NSSC19K0559 and 80NSSC20K0344. Parts of this research were carried out at the Ion Beam Centre (IBC) at the Helmholtz-Zentrum Dresden?Rossendorf e.V. a member of the Helmholtz Association. We would like to thank other members of the AMS teams for their assistance with AMS measurements, and A. Renno (HZDR), I. Leya (U Bern) and J. Oberst (DLR) for great organizational skills and/or discussion. A.W. S.P. and D.K. would like to acknowledge support from the Australian Research Council through Project DP180100495. AJTJ thanks the University of Arizona AMS Laboratory staff and also partial support from the European Union and the State of Hungary, co-financed by the European Regional Development Fund in the project GINOP-2.3.2.-15-2016-00009 ?ICER?. MT and WN acknowledge support by the Klaus Tschira Foundation.
Publisher Copyright:
© 2020 The Authors
PY - 2021/1/15
Y1 - 2021/1/15
N2 - On September 12, 2019 at 12:49:48 (UT) a bolide was observed by hundreds of eye-witnesses from the Netherlands, Germany, Belgium, Denmark and the UK. One day later a small meteorite stone was found by accident in Flensburg. The presence of short-lived cosmogenic radionuclides with half-lives as short as 16 days proves the recent exposure of the found object to cosmic rays in space linking it clearly to the bolide event. An exceptionally short exposure time of ∼5000 years was determined. The 24.5 g stone has a fresh black fusion crust, a low density of <2 g/cm3, and a magnetic susceptibility of logχ = 4.35 (χ in 10−9 m3/kg). The rock consists of relict chondrules and clusters of sulfide and magnetite grains set in a fine-grained matrix. The most abundant phases are phyllosilicates. Carbonates (∼3.9 vol.%) occur as calcites, dolomites, and a Na-rich phase. The relict chondrules (often surrounded by sulfide laths) are free of anhydrous silicates and contain abundant serpentine. Lithic clasts are also surrounded by similar sulfide laths partly intergrown with carbonates. 53Mn-53Cr ages of carbonates in Flensburg indicate that brecciation and contemporaneous formation of the pyrrhotite-carbonate intergrowths by hydrothermal activities occurred no later than 4564.6 ± 1.0 Ma (using the angrite D'Orbigny as the Mn-Cr age anchor). This corresponds to 2.6 ± 1.0 or 3.4 ± 1.0 Ma after formation of CAIs, depending on the exact absolute age of CAIs. This is the oldest dated evidence for brecciation and carbonate formation, which likely occurred during parent body growth and incipient heating due to decay of 26Al. In the three oxygen isotope diagram, Flensburg plots at the 16O-rich end of the CM chondrite field and in the transition field to CV-CK-CR chondrites. The mass-dependent Te isotopic composition of Flensburg is slightly different from mean CM chondrites and is most similar to those of the ungrouped C2 chondrite Tagish Lake. On the other hand, 50Ti and 54Cr isotope anomalies indicate that Flensburg is similar to CM chondrites, as do the ∼10 wt.% H2O of the bulk material. Yet, the bulk Zn, Cu, and Pb concentrations are about 30% lower than those of mean CM chondrites. The He, Ne, and Ar isotopes of Flensburg show no solar wind contribution; its trapped noble gas signature is similar to that of CMs with a slightly lower concentration of 20Netr. Based on the bulk H, C, and N elemental abundances and isotopic compositions, Flensburg is unique among chondrites, because it has the lightest bulk H and N isotopic compositions of any type 1 or 2 chondrite investigated so far. Moreover, the number of soluble organic compounds in Flensburg is even lower than that of the brecciated CI chondrite Orgueil. The extraordinary significance of Flensburg is evident from the observation that it represents the oldest chondrite sample in which the contemporaneous episodes of aqueous alteration and brecciation have been preserved. The characterization of a large variety of carbonaceous chondrites with different alteration histories is important for interpreting returned samples from the OSIRIS-REx and Hayabusa 2 missions.
AB - On September 12, 2019 at 12:49:48 (UT) a bolide was observed by hundreds of eye-witnesses from the Netherlands, Germany, Belgium, Denmark and the UK. One day later a small meteorite stone was found by accident in Flensburg. The presence of short-lived cosmogenic radionuclides with half-lives as short as 16 days proves the recent exposure of the found object to cosmic rays in space linking it clearly to the bolide event. An exceptionally short exposure time of ∼5000 years was determined. The 24.5 g stone has a fresh black fusion crust, a low density of <2 g/cm3, and a magnetic susceptibility of logχ = 4.35 (χ in 10−9 m3/kg). The rock consists of relict chondrules and clusters of sulfide and magnetite grains set in a fine-grained matrix. The most abundant phases are phyllosilicates. Carbonates (∼3.9 vol.%) occur as calcites, dolomites, and a Na-rich phase. The relict chondrules (often surrounded by sulfide laths) are free of anhydrous silicates and contain abundant serpentine. Lithic clasts are also surrounded by similar sulfide laths partly intergrown with carbonates. 53Mn-53Cr ages of carbonates in Flensburg indicate that brecciation and contemporaneous formation of the pyrrhotite-carbonate intergrowths by hydrothermal activities occurred no later than 4564.6 ± 1.0 Ma (using the angrite D'Orbigny as the Mn-Cr age anchor). This corresponds to 2.6 ± 1.0 or 3.4 ± 1.0 Ma after formation of CAIs, depending on the exact absolute age of CAIs. This is the oldest dated evidence for brecciation and carbonate formation, which likely occurred during parent body growth and incipient heating due to decay of 26Al. In the three oxygen isotope diagram, Flensburg plots at the 16O-rich end of the CM chondrite field and in the transition field to CV-CK-CR chondrites. The mass-dependent Te isotopic composition of Flensburg is slightly different from mean CM chondrites and is most similar to those of the ungrouped C2 chondrite Tagish Lake. On the other hand, 50Ti and 54Cr isotope anomalies indicate that Flensburg is similar to CM chondrites, as do the ∼10 wt.% H2O of the bulk material. Yet, the bulk Zn, Cu, and Pb concentrations are about 30% lower than those of mean CM chondrites. The He, Ne, and Ar isotopes of Flensburg show no solar wind contribution; its trapped noble gas signature is similar to that of CMs with a slightly lower concentration of 20Netr. Based on the bulk H, C, and N elemental abundances and isotopic compositions, Flensburg is unique among chondrites, because it has the lightest bulk H and N isotopic compositions of any type 1 or 2 chondrite investigated so far. Moreover, the number of soluble organic compounds in Flensburg is even lower than that of the brecciated CI chondrite Orgueil. The extraordinary significance of Flensburg is evident from the observation that it represents the oldest chondrite sample in which the contemporaneous episodes of aqueous alteration and brecciation have been preserved. The characterization of a large variety of carbonaceous chondrites with different alteration histories is important for interpreting returned samples from the OSIRIS-REx and Hayabusa 2 missions.
KW - Aqueous alteration
KW - C1 chondrite
KW - Carbonaceous chondrite
KW - Carbonates
KW - Early solar system
KW - Oldest carbonates in solar system
KW - Ungrouped C chondrite
KW - Unique chondrite
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U2 - 10.1016/j.gca.2020.10.014
DO - 10.1016/j.gca.2020.10.014
M3 - Article
AN - SCOPUS:85095991404
VL - 293
SP - 142
EP - 186
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
ER -