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Re-investigation of projectile types from terrestrial impact craters - Hiawatha (Greenland), Popigai (Siberia), Clearwater East, Brent, Wanapitei (Canada), Gardnos (Norway), Nördli...

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„Re-interpretation“ of projectile types from terrestrial impact craters Hiawatha (Greenland), Popigai (Siberia), Clearwater East (Canada), Gardnos (Norway), Ries crater (Germany)…

Gerhard Schmidt

Institute of Earth Sciences Heidelberg University

Rhine

People searching for meteorites in the Rhine valley ?

Preliminary version Figure from Palme H. (2018) Cosmochemistry along the Rhine, Geochemical Perspectives EPSC-DPS Joint Meeting 2019 Motivation

On 20 July 2018, the Japanese spacecraft Hayabusa-2 acquired an image of the octahedral asteroid Ryugu, which measures around 1 kilometer in diameter, and has a gravity field 80,000 times weaker than Earth’s. Numerous large boulders on the asteroid’s surface as well as large craters are recognisable. It is assumed that Ryugu is a C-type asteroid – a carbon- rich representative of the oldest bodies of the Solar System.

Castelvecchi (2018) Japanese mission reaches unexplored asteroid Ryugu, Nature 558, 495-496 https://www.nature.com/articles/d41586-018-05544-9

Highly heterogeneous asteroid Ryugu

What sample mass would be required for representative chemical and isotopic analyses ?

Optical Navigation Camera – Telescopic (ONC-T) image of Ryugu, June 26, 2018.

Image credits: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST, Kobe University, Auburn University

EPSC-DPS Joint Meeting 2019 Asteroid Itokawa

• Itokawa was classified as an S-type asteroid from terrestrial remote sensing. Nakamura et al. (2011) reported petrologic data and confirmed that Itokawa is an ordinary chondrite (LL4 to LL6).

• A single grain (~3 micrograms) returned by the Hayabusa spacecraft is mainly composed of olivine with minor amounts of high-Ca pyroxene, plagioclase, Ca-phosphate, and troilite (Ebihara et al. 2015). Olivine, low-Ca pyroxene, low-Ca clinopyroxene, diopside, chromite, troilite, kamacite, taenite, plagioclase, K feldspar, and mesostasis have been identified in dust particles from the surface (Nakamura et al. 2011).

• Ebihara et al. (2011) reported the analysed Itokawa sample Figure from ISAS/JAXA in Britt, Macke and Consolmagno (2010) has similar chemical characteristics (Fe/Sc and Ni/Co ratios) The Density, Porosity, and Structure of Very Small Bodies. Vol. 5, EPSC2010-863, European Planetary Science Congress 2010 to chondrites, confirming that this grain is extraterrestrial in origin and has primitive chemical compositions. Estimated Ir/Ni and Ir/Co ratios for metal in the Itokawa samples are about five times lower than CI carbonaceous chondrite values (Ebihara et al. 2011).

Gamma-ray spectrum for the irradiated sample (49-1) with 40 days for cooling interval. The inset in (B) was expanded for the energy region of 310 to 330 keV from same spectra. Figure from Ebihara et al. (2011) Supporting Online Material, Science 333.

EPSC-DPS Joint Meeting 2019

Chemical analysis of Itokawa samples (Ebihara et al. 2011)

No. 49-1 No. 49-2

Ni (pg) 6650 ± 160 5330 ± 150 Cr (pg) 61 ± 3 76 ± 2 Co (pg) 290 ± 10 230 ± 10 Ir (fg) 31 ± 7 37 ± 12

Ni (µg/g) 4000 ± 10 3200 ± 10 Cr (µg/g) 37 ± 2 45 ± 1 Co (µg/g) 176 ± 3 140 ± 3 Ir (ng/g) 19 ± 4 22 ± 7 Ni/Co 23 ± 1 23 ± 1 Ni/Ir ~215000 ~144000

Counting error (1σ). In calculating the elemental abundances Ebihara et al. (2011) assume that the grain is composed of olivine with plagioclase and metal.

Ebihara et al. (2011) Neutron Activation Analysis of a Particle Returned from Asteroid Itokawa, Science 333, 1119-1120. “Ni/Co ratios for the Itokawa samples clearly indicate that they preserve the primitive elemental abundances of the early solar system.” Ebihara et al. (2011)

Ni/Co ratios of iron meteorites overlap with Ni/Co ratios of chondrites and mantle rocks. (e.g. Schmidt, El Goresy & Pernicka 2017; Schmidt, El Goresy & Palme 2018)

EPSC-DPS Joint Meeting 2019 Cr/Co vs Cr/Ni from asteroid Itokawa, meteorites (acapulcoites, chondrites, irons) and crystalline rocks from the Nördlinger Ries crater

Line represent Ni/Co ratios for primitive elemental abundances of the early solar system and differentiated achondrites.

Sources of data: asteroid Itokawa from M. Ebihara, S. Sekimoto, N. Shirai, Y. Hamajima, M. Yamamoto, K. Kumagai, Y. Oura, T. R. Ireland, F. Kitajima, K. Nagao, T. Nakamura, H. Naraoka, T. Noguchi, R. Okazaki, A. Tsuchiyama, M. Uesugi, H. Yurimoto, M. E. Zolensky, M. Abe, A. Fujimura, T. Mukai & Y. Yada (2011) Science 333 Acapulco data: Palme H., Schultz L., Spettel B., Weber H. W., Wänke H., Michel-Levy M. C. & Lorin J. C. (1981) The Acapulco meteorite: chemistry, mineralogy and irradiation effects. Geochim. Cosmochim. Acta 45, 727–752. Zipfel J. & Palme H. (1994) The chemical composition of Acapulco and Acapulcoites. LPSC XXV, 1563-1564. Dhaliwal J.K., Day J.M.D., Corder C.A., Tait K.T., Marti K., Assayag N., Cartigny P., Rumble III D., Taylor L.A. (2017) Geochimica et Cosmochimica Acta 216, 115-140. Corrigendum Table 3, received from the authors (January 26, 2019) Iron meteorite data are those reported in Folco L., Glass B.P., D’Orazio M. & Rochette P. (2018), Geochimica et Cosmochimica Acta 222, 550- 568. Chondrite data are from the database of Tagle & Berlin (2008) Meteoritics & Planetary Science 43, 541–559. Crystalline basement rock data from Matthes S., Richter P. & Stettner G. (1977) Geologica Bavaria 75 Ni vs Co of Itokawa samples and Ries samples

“Ni/Co ratios for the Itokawa samples clearly indicate that they preserve the primitive elemental abundances of the early solar system.” Ebihara et al. (2011)

Itokawa asteroid samples blue line (Ni/Co ratio; 23 ± 1) Earth mantle (Ni/Co ratio ~ 20)

Figure modified from El Goresy & Schmidt (201?) Geological Magazine, Cambridge University Press, submitted 10 Nov 2017, accepted 06 July 2018

Ni/Co ratios of Itokawa asteroid samples overlap with iron meteorites (e.g. Scott 1972, field between black lines), chondrites and primitive mantle rocks (similar Ni/Co than chondrites)

Ni/Co ratios as fingerprints are not at all conclusive for identification of impactor traces

Scott E.R.D. 1972 Chemical fractionation in iron meteorites and its interpretation. Geochimica et Cosmochimica Acta 36, 1205-1236.

EPSC-DPS Joint Meeting 2019 No detectable meteoritic contaminations of Iridium in the bore-hole Nördlingen 1973 (Ries crater) Morgan et al. 1979, Schmidt 1991, Schmidt and Pernicka 1994, Ackerman et al. 2017

bore-hole FBN73 Nördlingen • Nördlinger Ries → impact crater (Shoemaker & Chao 1961) • ~14.8 Ma • 24 - 26 km diameter crater • excavated from carbonate-bearing sedimentary sequences and underlying crystalline silicate basement materials

EPSC-DPS Joint Meeting 2019 Iridium in target rocks and fall-back material of the Nördlinger Ries impact crater

Figure from Schmidt and Pernicka (1991) 54th Annual Meeting of the Meteoritical Society, Monterey, California

Sample preparation

„Core segments from the Graded Unit (diameter 10 cm) were gently broken to obtain a sample of about 100 g each. Each segment was wrapped in polyethylene, crushed between the jaws of a vice, and then ground in an agate mill untill it passed through a 50 µm polyethylene sieve. Drill core samples containing suevite were treated identically, with the exception that, after crushing, larger rock fragments were removed by hand. The reason for this procedure was that for a coarse grained breccia, such as suevite, a drill core sample cannot be representative in the true sense. Drill core samples of the crystalline basement were generally larger (on the order of 2 kg). Of those, about 300 g chips were broken off and homogenized as described above. In all cases an aliquot of 10 g from each homogenized sample was used for analysis.“ Schmidt G., Pernicka E. The determination of platinum group elements (PGE) in target rocks and fall-back material of the Nördlinger Ries impact crater (Germany). Geochim. Cosmochim. Acta 58 (1994) 5083-5090. doi.org/10.1016/0016-7037(94)90233-X

EPSC-DPS Joint Meeting 2019 Gold in target rocks and fall-back material of the Nördlinger Ries impact crater

Figure from Schmidt G. (1991) PhD thesis, Heidelberg University

Commas in axis label represent points.

Aliquots of 10 g from each homogenized sample were used for Au analysis. Data from Schmidt G. & Pernicka E. The determination of platinum group elements (PGE) in target rocks and fall-back material of the Nördlinger Ries impact crater (Germany). Geochim. Cosmochim. Acta 58 (1994) 5083-5090. doi.org/10.1016/0016-7037(94)90233-X

“Several previous studies have estimated the average gold concentration in the crust. A major summary was compiled by Crocket (1991) and updated by Rudnick and Gao (2003). These studies estimated the average crustal abundance of gold to be 1.3 ppb, a figure that is very similar to the mantle value derived here...and it seems likely that the concentration of gold in the two reservoirs is approximately the same on average, indicating efficient recycling of gold between the crust and the mantle.” J. Edward Saunders, Norman J. Pearson, Suzanne Y. O’Reilly, William L. Griffin (2018) Gold in the mantle: A global assessment of abundance and redistribution processes. Lithos 322 (2018) 376–391. https://doi.org/10.1016/j.lithos.2018.10.022

EPSC-DPS Joint Meeting 2019 Ni vs Ir in asteroid Itokawa, moldavites, suevite and Ries sediments

Sources of data:

black lines, Ni/Ir ratios of asteroid Itokawa samples 49-1 and 49-2 from Ebihara et al. (2011) Neutron Activation Analysis of a Particle Returned from Asteroid Itokawa, Science 333, 1119-1120;

black diamond, composite sample of five South Bohemian moldavites (13.2 % Dolni, 17.4% Netolice, 20% Radomilice, 24.4% Lhenice, 25% Hrbov) from Palme H., Janssens M. J., Hertogen J., Takahashi H., Anders E. & Hertogen J. (1978) Meteoritic material at five large impact craters, Geochim. Cosmochim. Acta 42, 313–323;

other symbols from Ackerman L., Magna T., Žák K., Skála R., Jonášová S., Mizera J & Řanda Z. (2017) The behavior of osmium and other siderophile elements during impacts: Insights from the Ries impact structure and central European tektites. Geochim. Cosmochim. Acta 210, 59-70. Only 0.4 to 2 g sample powder were used for Ir analysis by these authors.

EPSC-DPS Joint Meeting 2019 Acapulcoites and lodranites

• Acapulcoites and lodranites are primitive achondrites that originate from a common parent body with a radius of ≈ 260 km. The burial depths derived are 7-13 km (Neumann et al. 2018).

• Neumann et al. (2018) reported the resulting structure has an iron core, a silicate mantle, a partially differentiated layer, and an undifferentiated outer shell.

Neumann W., Henke S., Breuer D., Gail H.-P., Schwarz W.H., Trieloff M., Hopp J. & Spohn T. (2018) Modeling the evolution of the parent body of acapulcoites and lodranites: A case study for partially differentiated asteroids, Icarus 311, 146-169.

• FeNi grains from acapulcoite meteorites (MET 01195 and GRA 95209) have similar Ru/Rh and Rh/Ir element ratios (see Dhaliwal et al. 2017) than Clearwater melt samples (Schmidt 1997) Meteoritics and Planetary Science 32, 761 -767.

Acapulco data:

Palme H., Schultz L., Spettel B., Weber H. W., Wänke H., Michel-Levy M. C. & Lorin J. C. (1981) The Acapulco meteorite: chemistry, mineralogy and irradiation effects. Geochim. Cosmochim. Acta 45, 727–752.

Zipfel J. & Palme H. (1994) The chemical composition of Acapulco and Acapulcoites. LPSC XXV, 1563-1564.

Dhaliwal J.K., Day J.M.D., Corder C.A., Tait K.T., Marti K., Assayag N., Cartigny P., Rumble III D., Taylor L.A. (2017) Geochimica et Cosmochimica Acta 216, 115-140. Corrigendum Table 3, received from the authors (January 26, 2019)

EPSC-DPS Joint Meeting 2019 Cr/Co vs Cr/Ni from asteroid Itokawa, meteorites and sediment from the impact crater beneath Hiawatha Glacier in northwest Greenland

Line represent Ni/Co ratio for primitive elemental abundances of the early solar system

Red cross: glaciofluvial sediment sample of the Greenland impact crater Kurt H. Kjær, Nicolaj K. Larsen, Tobias Binder, Anders A. Bjørk, Olaf Eisen, Mark A. Fahnestock, Svend Funder, Adam A. Garde, Henning Haack, Veit Helm, Michael Houmark-Nielsen, Kristian K. Kjeldsen, Shfaqat A. Khan, Horst Machguth, Iain McDonald, Mathieu Morlighem, Jérémie Mouginot, John D. Paden, Tod E. Waight, Christian Weikusat, Eske Willerslev, Joseph A. MacGregor (2018) A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances 4, 1-11.

EPSC-DPS Joint Meeting 2019 The projectile of the impact crater beneath Hiawatha Glacier in northwest Greenland

“Glaciofluvial sediment from the largest river draining the crater contains shocked quartz and other impact related grains. Geochemical analysis of this sediment indicates that the impactor was a fractionated iron asteroid,

which must have been more than a kilometer wide to produce the identified crater.”

Kurt H. Kjær, Nicolaj K. Larsen, Tobias Binder, Anders A. Bjørk, Olaf Eisen, Mark A. Fahnestock, Svend Funder, Adam A. Garde, Henning Haack, Veit Helm, Michael Houmark-Nielsen, Kristian K. Kjeldsen, Shfaqat A. Khan, Horst Machguth, Iain McDonald, Mathieu Morlighem, Jérémie Mouginot, John D. Paden, Tod E. Waight, Christian Weikusat, Eske Willerslev, Joseph A. MacGregor (2018) A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances 4, 1-11.

Cr/Ni and Cr/Co element ratios from the glaciofluvial sediment plot close to the Earth mantle, chondrites and acapulcoites (see figure)

If Co, Ni and Cr data are corrected for upper crustal contents (e.g. Park et al. 2012; Chen et al. 2016) the sediment would plot close to chondrites and acapulcoites. However, even the uncorrected Co content of the sediment sample is in the range for the upper crust (~17 µg/g). The Ni and Cr contents of the impactor would result in ~ 200 µg/g and 54 µg/g, respectively.

Cr/Co and Cr/Ni element ratios as fingerprints are not at all conclusive for the classification of the Greenland impactor

EPSC-DPS Joint Meeting 2019

Chemical analysis of sediment sample from northwest Greenland and element concentrations of the upper Earth crust

HW21 2016 upper crust HW21/upper cust Kjær et al. (2018) (e.g. Chen et al. 2016; ratio Park et al. 2012; Palme & O’Neill 2003)

Ni (µg/g) 245 ± 206 47 ± 11 5 Cr in HW21 is only ~60% enhanced. Cr (µg/g) 146 ± 26 92 ± 17 1.6 The Co content of the sediment Co (µg/g) 12.3 ± 2.3 17 ± 1 0.7 sample HW21 2016 is lower than the Os (pg/g) 80 59 ± 16 1.4 upper crustal content and not elevated as stated by the authors. Ir (pg/g) 650 36 ± 8 18 Os in HW21 is not enhanced Ru (pg/g) 1690 79 ± 26 21 compared with the Earth crust.

Rh (pg/g) 3380 ~20 170 Cr, Co, Os and Au cannot used as Pd (ng/g) 18.83 ~1 19 fingerprints of the Greenland projectile. Pt (ng/g) 11 ~1 11 Au (ng/g) 2.99 1.5 ± 0.4 2

“In contrast, every tested subsample of the same sample that contained shocked quartz (HW21-2016) also contains elevated concentrations of Ni, Co, Cr, PGE, and Au, indicative of a relatively rare iron meteorite.” “Third, the PGE anomalies suggest that these metals derive from a highly fractionated iron asteroid.” Kjær et al. (2018) Kurt H. Kjær, Nicolaj K. Larsen, Tobias Binder, Anders A. Bjørk, Olaf Eisen, Mark A. Fahnestock, Svend Funder, Adam A. Garde, Henning Haack, Veit Helm, Michael Houmark-Nielsen, Kristian K. Kjeldsen, Shfaqat A. Khan, Horst Machguth, Iain McDonald, Mathieu Morlighem, Jérémie Mouginot, John D. Paden, Tod E. Waight, Christian Weikusat, Eske Willerslev, Joseph A. MacGregor (2018) A large impact crater beneath Hiawatha Glacier in northwest Greenland. Science Advances 4, 1-11. Supplementary materials, data file S2.

EPSC-DPS Joint Meeting 2019 Chemical fractionation of PGE in iron meteorites

• IIIAB iron meteorites → wide range of Ni/Ir ratios

• Ir, Os, Pt, Rh, Ru enriched in early Ni-poor solid → negatively correlated with Ni

• Pd, Au, Sb, As, P, Co, Mo concentrate in later solid → positive correlations with Ni

 siderophile element fractionations by fractional crystallisation of a liquid iron core in parent meteorite bodies

Scott E.R.D. (1972) Chemical fractionation in iron meteorites and its interpretation. Geochimica et Cosmochimica Acta 36, 1205-1236.

EPSC-DPS Joint Meeting 2019 Element ratios of characteristic elements from various groups of chondritic (undifferentiated) meteorites

Pt/Rh Pd/Rh Ru/Rh Ir/Rh Ru/Ir Pt/Ir Pt/Os Os/Rh

Non carbonaceous chondrites H 6,78 3,59 4,93 3,26 1,52 2,08 1,94 3,50 L 6,19 3,69 4,49 3,01 1,49 2,06 1,91 3,23 LL 6,15 4,35 4,54 2,92 1,55 2,10 1,94 3,17 EH 6,19 4,86 4,85 3,00 1,62 2,06 1,83 3,39 EL 6,16 4,01 4,49 3,06 1,53 2,01 1,81 3,40 mean 6,29 4,10 4,66 3,05 1,54 2,06 1,89 3,34 1σ 0,27 0,52 0,22 0,13 0,05 0,03 0,06 0,14

Carbonaceous chondrites CI 7,01 4,24 5,23 3,55 1,47 1,97 1,87 3,75 CM 6,99 4,08 5,72 3,81 1,50 1,84 1,65 4,25 CV 6,90 3,38 5,50 3,63 1,52 1,90 1,79 3,86 CK 7,32 3,52 5,26 3,62 1,45 2,02 1,89 3,87 mean 7,06 3,81 5,43 3,65 1,49 1,93 1,80 3,93 1σ 0,18 0,42 0,23 0,11 0,03 0,08 0,11 0,22

Commas in Table represent points.

Elemental ratios calculated from the database of Tagle and Berlin (2008) for different groups of chondrites.

EPSC-DPS Joint Meeting 2019 PGE element ratios from sediment of the northwest Greenland impact crater and the proposed iron meteorite Duchesne (type IVA)

“Modeling indicates that the best fit for the siderophile element data is a mixture between local crust and 0.01 to 0.05% of a component similar in composition to the strongly fractionated Duchesne (type IVA) iron meteorite.” Kjær et al. (2018)

If true, the Greenland crater would be the first crater on Earth with a very low iron meteorite component identified in a sediment sample.

bolide types Sääksjärvi → iron meteorite Schmidt, Palme, K.-L. Kratz (1997) Geochimica et Cosmochimica Acta ~ 0.4% of a nominal magmatic iron meteorite component

Northwest Greenland → Iron ? + Kjær et al. (2018) Sci. Adv. (4) 14 November 2018

Duchesne (IVA) iron meteorite Petaev & Jacobsen (2004) Meteoritics & Planetary Commas in axis labels represent points. Science 39, 1685-1697. Comparing the elemental ratios in the sediment sample of the northwest Greenland impact crater and the proposed Duchesne iron meteorite with those calculated from the database of Tagle and Berlin (2008) for different types of chondrites. Error values of 5% of the ratios are indicated for chondrites. Greenland data from Kjær et al. (2018) Sci. Adv. (4) Supplementary materials, data file S2, 14 November 2018. Duchesne iron meteorite data from Petaev & Jacobsen (2004) Meteoritics & Planetary Science 39, 1685-1697. Sääksjärvi melt data from Schmidt, Palme, K.-L. Kratz (1997) Geochimica Cosmochimica Acta 61. Clearwater East data from Schmidt (1997) Meteoritics and Planetary Science 32. Mantle data (Rh) from Schmidt (2004) and Becker et al. (2006).

EPSC-DPS Joint Meeting 2019 Rh/Ir vs Ru/Rh element ratios from sediment of the Greenland impact crater, the proposed iron meteorite Duchesne (type IVA) and the upper crust

Ru/Rh vs. Rh/Ir shows that a mixture of upper crust and 0.01 to 0.05 % Duchesne iron meteorite would not lead to the element ratios determined in the Greenland sediment samples.

Dayton (IIICD) would be a better candidate for a mixture with crustal rocks based on Ir, Ru and Rh.

However, Pt/Ir and Pd/Ir would not support a mixture between Dayton and upper crust either (see next figures).

Comparing the elemental ratios in the sediment sample of the northwest Greenland impact crater and the proposed Duchesne iron meteorite with those calculated from the database of Tagle and Berlin (2008) for different types of chondrites. Error values of 5% of the ratios are indicated for chondrites. Greenland data from Kjær et al. (2018) Sci. Adv. (4), Supplementary materials, data file S2, 14 November 2018. Duchesne iron meteorite data from Petaev & Jacobsen (2004) Meteoritics & Planetary Science 39, 1685-1697.

EPSC-DPS Joint Meeting 2019 “Modeling indicates that the best fit for the siderophile element data is a mixture between local crust and 0.01 to 0.05% of a component similar in composition to the strongly fractionated Duchesne (type IVA) iron meteorite.” Kjær et al. (2018)

Commas in Table represent points.

The sediment HW21 would contain 0.08 to 0.38% of a component similar in composition of Duchesne iron meteorite and not 0.01 to 0.05% as reported by Kjær et al. (2018) (see table).

EPSC-DPS Joint Meeting 2019 Ru/Rh vs Pt/Ir element ratios from sediment of the Greenland impact crater, the proposed iron meteorite Duchesne (type IVA) and the upper crust

Ru/Rh vs. Pt/Ir shows that a mixture of upper crust and 0.01 to 0.05 % Duchesne iron meteorite would not lead to the element ratios determined in the Greenland sediment samples.

EPSC-DPS Joint Meeting 2019 Rh/Ir vs Pd/Ir element ratios from sediment of the Greenland impact crater, the proposed iron meteorite Duchesne (type IVA) and the upper crust

A mixture of upper crust and 0.01 to 0.05 % Duchesne iron meteorite would not lead to the element ratios determined in the Greenland sediment samples.

• usually the identification of meteoric material is carried out on melt rocks (impact melts) and not on glaciofluvial sediments

EPSC-DPS Joint Meeting 2019 Clearwater East impact structure (Canada)

Ordovician East Clearwater, ~ 26 km diameter, ~460 – 470 Ma (Schmieder et al. 2015)

• impact of small asteroid from the breakup of the 100 – 150 km diameter L-chondrite parent body in the asteroid belt (Schmitz et al. 2003, 2018) PGE ratios and Cr isotopes → ordinary chondrite McDonald 2002; Schmidt 1997; Shukolyukov and Lugmair 2000 → bolide typ L chondrite (~ 7% of a nominal CI component) Permian West Clearwater impact (⩾36 km) 286.2 ± 2.2 Ma (Schmieder et al. 2015)

Commas in axis labels represent points.

Comparing the elemental ratios in the impactites of the Clearwater East structure with those calculated from the database of Tagle and Berlin (2008) for chondrite groups. Error values of 5% of the ratios are indicated for chondrites. Figure modified after McDonald (2002) Meteoritics and Planetary Science 37. Clearwater East data from Schmidt (1997) Meteoritics and Planetary Science 32. 10 g aliquot of sample powder used for PGE analysis of Clearwater melts.

EPSC-DPS Joint Meeting 2019 Ru/Rh vs Ir/Rh mass ratios from Clearwater East melt samples and acapulcoite meteorites

Ru/Rh vs Ir/Rh → ordinary chondrite McDonald 2002; Schmidt 1997; Shukolyukov and Lugmair 2000

Ru/Rh and Ir/Rh element ratios in FeNi grains from acapulcoite meteorites match those from Clearwater East melt samples

Commas in axis labels represent points.

Comparing the elemental ratios in the impactites of the Clearwater East structure with those calculated from the database of Tagle and Berlin (2008) for different types of chondrites. Error values of 5% of the ratios are indicated for chondrites. Acapulcoite and Lodranite data from Dhaliwal et al. (2017) Early metal-silicate differentiation during planetesimal formation revealed by acapulcoite and lodranite meteorites. Geochimica et Cosmochimica Acta 216, 115-140. Indicated mantle ratios of Ir/Rh = 2.94 ± 0.47 (n=65) and Ru/Rh = 6.0 ± 0.7 (n=61) from Fischer-Gödde, Becker & Wombacher (2011) Chemical Geology 280.

Ru, Ir and Rh data for Clearwater East melt samples from Schmidt (1997) Meteoritics and Planetary Science 32. 10 g aliquot of sample powder used for PGE analysis of Clearwater melts. Ratios for mantle rocks (n=13) from Schmidt (2004); Ir/Rh = 2.41 ± 0.49; Ru/Rh = 4.84 ± 0.98 (not indicated).

EPSC-DPS Joint Meeting 2019 Case studies for the identification of iron projectiles (Sääksjärvi) and chondrites (Clearwater East) from terrestrial impact craters

Commas in axis labels represent points.

bolide types

Sääksjärvi → iron meteorite Schmidt, Palme, K.-L. Kratz (1997) ~ 0.4% of a nominal magmatic iron meteorite component Geochimica et Cosmochimica Acta

Clearwater East → chondrite Schmidt (1997) ~ 4 to 7% of a nominal CI meteorite component Meteoritics and Planetary Science

Comparing the elemental ratios in the impactites of the Sääksjärvi and Clearwater East structures with those calculated from the database of Tagle and Berlin (2008) for chondrite groups. Error values of 5% of the ratios are indicated for chondrites. Sääksjärvi melt data from Schmidt, Palme, K.-L. Kratz (1997) Geochimica Cosmochimica Acta 61. Clearwater East data from Schmidt (1997) Meteoritics and Planetary Science 32. Mantle data from Becker, Horan, Walker, Gao, Lorand & Rudnick (2006) Geochimica et Cosmochimica Acta 70 and Fischer-Gödde, Becker & Wombacher (2011) Chemical Geology 280. 10 g aliquot of sample powder used for PGE analysis of melt samples.

EPSC-DPS Joint Meeting 2019 Late Eocene Popigai impact crater, Siberia

one of the largest craters on Earth, ~100 km diameter (Grieve 2001, Masaitis, Petrov & Naumov 2018)

“The minimum amount required to obtain reproducible results was 10 g. With a lesser quantity, the values obtained by repetitive analyses are not reproducible. Using 10 g or more in identical analytical conditions, the results of several analyses of the same sample differed by less than 10%.” Tagle & Claeys (2005)

Popigai bolide typ → ordinary chondrite L chondrite (Tagle and Claeys 2005) Commas in axis labels represent points. → L or EL chondrite (this work)

Comparing the elemental ratios in the impactites of the Popigai and Gardnos structures with those calculated from the database of Tagle and Berlin (2008) for different types of chondrites. Error values of 5% of the ratios are indicated for chondrites. Popigai melt data from Tagle and Claeys (2005) Geochimica Cosmochimica Acta 69. Gardnos data from Goderis et al. (2009) Chemical Geology 258.

EPSC-DPS Joint Meeting 2019 Ir, Pd, Ru, Rh and Pt in impactites from Gardnos impact structure, Norway

Earth mantle

Pt/Ir = 2.21 ± 0.21 Ru/Rh = 5.8 ± 0.6 Ru/Ir = 2.03 ± 0.12 Pt/Rh = 6.33 ± 0,32 Rh = 1.2 ± 0.27 ng/g Pt = 7.7 ± 1.3 ng/g Schmidt 2004, Meteoritics & Planetary Science Becker et al. 2006, GCA Goderis et al. 2009 Ru vs Ir; slope of 1.78 ± 0.05 (N=15, Gardnos impactite samples, R = 0.99 as stated in there Table 5).

The average Ru/Ir ratio is 1.57 ± 0.10 for six samples (subtracting 0.38 ng/g Ru and 20 pg/g Ir as indigeneous contents) in agreement with a slope of 1.568

Slopes for six samples with highest Ir and Ru contents in the range of 0.622 to 1.926 ng/g and 1.242 to 3.494 ng/g, respectively, are

Pt/Ir = 2.32, Ru/Rh = 4.15 Pt/Rh = 6.08 Figures redrawn with PGE data from Goderis (2009) GCA 258, Table 4 Six impactite samples with highest Ir contents in the range of 0.622 to 1.926 ng/g Ru/Ir, Ru/Rh and Amount of powder produced for each sample was around 80 g Pt/Rh of six samples overlap with chondrites

“Ru and Rh enrichments suggesting a nonchondritic impactor” ??? Comparing the elemental ratios in the impactites of the Gardnos structure with those Goderis, Kalleson, Tagle, Dypvik, Schmitt, Erzinger, Claeys (2009) calculated from the database of Tagle and Berlin (2008) for different types of chondrites. A non-magmatic iron projectile for the Gardnos impact event. Chemical Geology 258

Commas in axis labels represent points.

EPSC-DPS Joint Meeting 2019 PGE ratios in impactites from Gardnos impact structure

Earth mantle

Pt/Ir = 2.21 ± 0.21 Ru/Rh = 5.8 ± 0.6 Ru/Ir = 2.03 ± 0.12 Pt/Rh = 6.33 ± 0,32 Rh = 1.2 ± 0.27 ng/g Pt = 7.7 ± 1.3 ng/g Schmidt 2004, Meteoritics & Planetary Science Becker et al. 2006, GCA

Goderis et al. 2009 Ru vs Ir; slope of 1.78 ± 0.05 (N=15, Gardnos impactite samples, R = 0.99 as stated in there Table 5).

The average Ru/Ir ratio is 1.57 ± 0.10 for six samples (subtracting 0.38 ng/g Ru and 20 pg/g Ir as indigeneous contents) in agreement with a slope of 1.568

Slopes for six samples with highest Ir and Ru contents in the range of 0.622 to 1.926 ng/g and 1.242 to 3.494 ng/g, respectively, are

Pt/Ir = 2.32, Comparing the PGE ratios in the impactites of the Gardnos structure (Goderis et al. 2009, GCA 258, Ru/Rh = 4.15 Table 4) with those calculated from the database of Tagle and Berlin (2008) for different types of Pt/Rh = 6.08 chondrites. PGE data from the Earth mantle are from Schmidt (2004) and Becker et al. (2006). An

average of six impactite samples with highest Ir contents in the range of 0.622 to 1.926 ng/g (N=6) is indicated by the blue bar. An average of all Gardnos samples (N=12) is indicated by the blue bar with Ru/Ir, Ru/Rh and black border. Amount of powder produced for each Gardnos sample was around 80 g. Pt/Rh of six samples Gardnos bolide typ overlap with chondrites → iron (Rh enrichment ! ) Commas in axis labels represent points. Ru/Ir in some irons and “Ru and Rh enrichments suggesting a nonchondritic impactor” ? chondrites are similar, see next figures

Goderis, Kalleson, Tagle, Dypvik, Schmitt, Erzinger, Claeys (2009) A non-magmatic iron projectile for the Gardnos impact event. Chemical Geology 258

EPSC-DPS Joint Meeting 2019 Ru/Rh vs Ir/Rh from impact craters, tektites, iron meteorites, chondrite groups, Cretaceous-Paleogene boundary and Nördlinger Ries

Nördlinger Ries

(Goderis et al. 2013)

Figure modified from Schmidt (2019)

Suevite samples from the Enkingen core (Ries crater) with elevated Ir, Ru and Rh contents (Reimold et al. 2013) could suggest a small extraterrestrial contribution. However, Ru/Rh and Ir/Rh would indicate non-chondritic ratios of the most immobile platinum group elements.

Reimold, McDonald, Schmitt, Hansen, Jacob & Koeberl (2013) Geochemical studies of the SUBO 18 (Enkingen) drill core and other impact breccias from the Ries crater, Germany. Meteoritics & Planetary Science 48, 1531 - 1571. Schmidt (2019) Neutrons for Cosmochemistry - Identification of Impacting Asteroids.16th Rußbach School on Nuclear Astrophysics – March 13, 2019, Austria EPSC-DPS Joint Meeting 2019 Ru/Rh vs Ir/Rh from impact craters, tektites, iron meteorites, chondrite groups, Cretaceous-Paleogene boundary and Nördlinger Ries

Nördlinger Ries

(Goderis et al. 2013)

Figure modified from Schmidt (2019) Suevite samples from the Enkingen core (Ries crater) with elevated Ir, Ru and Rh contents (Reimold et al. 2013) could suggest a small extraterrestrial contribution. However, Ru/Rh and Ir/Rh would indicate non-chondritic ratios of the most immobile platinum group elements.

Reimold, McDonald, Schmitt, Hansen, Jacob & Koeberl (2013) Geochemical studies of the SUBO 18 (Enkingen) drill core and other impact breccias from the Ries crater, Germany. Meteoritics & Planetary Science 48, 1531 - 1571. Schmidt (2019) Neutrons for Cosmochemistry - Identification of Impacting Asteroids.16th Rußbach School on Nuclear Astrophysics – March 13, 2019, Austria EPSC-DPS Joint Meeting 2019 Ru/Rh vs Ir/Rh from impact craters, iron meteorites, chondrite groups, Cretaceous-Paleogene boundary and Nördlinger Ries

(Goderis et al. 2013)

Nördlinger Ries

Figure modified from Schmidt (2019)

Six Gardnos samples with enriched platinum group elements would indicate non-chondritic ratios of the most immobile platinum group elements, if samples have been corrected for estimated target contents of 0.03 ng/g Ir, 0.5 ng/g Ru and 0.05 ng/g Rh).

Schmidt (2019) Neutrons for Cosmochemistry - Identification of Impacting Asteroids.16th Rußbach School on Nuclear Astrophysics – March 13, 2019, Austria

EPSC-DPS Joint Meeting 2019 Summary

• The refractory highly siderophile elements Rh, Ir, Ru, and Os are abundant in most meteorites but depleted in crustal rocks, the most immobile platinum group elements and therefore the most reliable elements for projectile identification of impact craters

• 10 g homogenized sample powder is the minimum amount required to obtain reproducible results (nugget effect ! e.g., Tagle & Claeys 2005, others and own studies)

• Ni/Co and Ir/Ni element ratios as fingerprints are not at all conclusive for the classification of asteroids and/or meteorites, incidentally, Co-, Ni- and Cr contents of bulk Acapulcoite meteorite samples differ significantly in studies from different authors

• Ir/Rh, Ru/Rh and Os/Ir ratios are suitable for distinguishing different types of meteorite projectiles

• Nördlinger Ries bolide typ Enkingen core suevite samples indicate non-chondritic Ru/Rh and Ir/Rh ratios

• Popigai bolide typ L chondrite (Tagle and Claeys 2005) EL chondrite cannot excluded (this work)

• Clearwater East ordinary chondrite (Schmidt 1997, McDonald 2002, Shukolyukov and Lugmair 2000) FeNi grains from acapulcoite meteorites (MET 01195 and GRA 95209) have identical Ru/Rh and Ir/Rh element ratios (see Dhaliwal et al. 2017) like Clearwater melt samples

• Gardnos Ir/Rh ratios are low compared to chondrites, non-magmatic iron projectile is favoured by Goderis, Kalleson, Tagle, Dypvik, Schmitt, Erzinger, Claeys (2009) Chemical Geology 258

• Greenland „fractionated iron asteroid” is proposed as impactor based on elevated concentrations of Ni, Co, Cr, PGE, and Au in glaciofluvial sediment samples (Kjær et al. 2018) Cr, Co, Os and Au not suitable as fingerprints of the Greenland projectile, these elements are not elevated significantly compared to upper crustal rocks. Incidentally, the Co content in the sediment sample is lower than the upper crustal content - usually the identification of meteoric material is carried out on melt rocks (impact melts), not on glaciofluvial sediments Thank you for your attention

October 21, 2018. I found this bottle in the former riverbed of the Rhine, but no meteorite.

EPSC-DPSView publicationJoint stats Meeting 2019