Experimental constraints on the ordinary chondrite shock darkening caused by asteroid collisions

Kohout, T.; Petrova, E. V.; Yakovlev, G. A.; Grokhovsky, V. I.; Penttilä, Antti; Maturilli, Alessandro; Moreau, Juulia-Gabrielle; Berzin, S. V.; Wasiljeff, Joonas; Даниленко, И. А.; Zamyatin, D. A.; Muftakhetdinova, R. F.; Heikkilä, Mikko

doi:10.1051/0004-6361/202037593

Cited by 16 publications

(18 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As observed by Kohout et al (2020) in a shock experiment with the Chelyabinsk meteorite (porosity 6%), shock-darkening happens at two different pressure ranges of the shock scale at shock stage C-S7 (>70 GPa, whole rock melting, as in Stöffler et al 2018; >90/150 GPa, based on shock models in Figure 1(e) of Kohout et al 2020) or between shock stages CS-5 and 6 (40-60 GPa, metal and iron sulfide melt veins; Kohout et al 2014;Moreau et al 2017Moreau et al , 2018Moreau et al , 2019aMoreau 2019;Moreau & Schwinger 2021). The upper limit of the 40-60 GPa pressure interval is given by the onset of silicate melting and immiscibility of troilite and silicate melts, preventing infusion of troilite melt into residual grains.…”

Section: Introductionsupporting

confidence: 56%

“…The C/X-complex asteroid spectrum, with its weak absorptions and high albedo variation, is often linked to carbonaceous chondrites (low albedo) or metal-rich material (high albedo). However, some so-called shockdarkened ordinary chondrites with associated melting and redistribution of metal and sulfides (Heymann 1967;Stöffler et al 1991Stöffler et al , 2018Keil et al 1992;Britt & Pieters 1994;Kohout et al 2014Kohout et al , 2020 are characterized by optical change toward a dark and featureless spectrum being a remarkably good fit to spectra of the C/Xcomplex asteroids. Thus, if an asteroid fragment of S-complex asteroids is shock-darkened, its spectra may be indistinguishable from those of C/X-complex asteroids.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insight into the Distribution of High-pressure Shock Metamorphism in Rubble-pile Asteroids

et al. 2022

Self Cite

View full text Add to dashboard Cite

Shock metamorphism in ordinary chondrites allows for reconstructing impact events between asteroids in the main asteroid belt. Shock-darkening of ordinary chondrites occurs at the onset of complete shock melting of the rock (>70 GPa) or injection of sulfide and metal melt into the cracks within solid silicates (∼50 GPa). Darkening of ordinary chondrites masks diagnostic silicate features observed in the reflectance spectrum of S-complex asteroids so they appear similar to C/X-complex asteroids. In this work, we investigate the shock pressure and associated metamorphism pattern in rubble-pile asteroids at impact velocities of 4–10 km s−1. We use the iSALE shock physics code and implement two-dimensional models with simplified properties in order to quantify the influence of the following parameters on shock-darkening efficiency: impact velocity, porosity within the asteroid, impactor size, and ejection efficiency. We observe that, in rubble-pile asteroids, the velocity and size of the impactor are the constraining parameters in recording high-grade shock metamorphism. Yet, the recorded fraction of higher shock stages remains low (<0.2). Varying the porosity of the boulders from 10% to 30% does not significantly affect the distribution of pressure and fraction of shock-darkened material. The pressure distribution in rubble-pile asteroids is very similar to that of monolithic asteroids with the same porosity. Thus, producing significant volumes of high-degree shocked ordinary chondrites requires strong collision events (impact velocities above 8 km s−1 and/or large sizes of impactors). A large amount of asteroid material escapes during an impact event (up to 90%); however, only a small portion of the escaping material is shock-darkened (6%).

show abstract

Section: Introductionsupporting

confidence: 56%

Section: Introductionmentioning

confidence: 99%

Insight into the Distribution of High-pressure Shock Metamorphism in Rubble-pile Asteroids

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…Shock impact darkening can suppress the absorption bands and reduce the overall reflectance, which can lead to misclassification of objects (Kohout et al, 2020(Kohout et al, , 2014 as it tends to "move" objects even between complexes. Overall, phase reddening corrections play an important role in constraining the space reddening as they mostly affect spectral slope (Reddy et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Predicting Asteroid Types: Importance of Individual and Combined Features

Klimczak

Kotłowski

Oszkiewicz

et al. 2021

Front. Astron. Space Sci.

View full text Add to dashboard Cite

Asteroid taxonomies provide a link to surface composition and mineralogy of those objects, although that connection is not fully unique. Currently, one of the most commonly used asteroid taxonomies is that of Bus-DeMeo. The spectral range covering 0.45–2.45 μm is used to assign a taxonomic class in that scheme. Such observations are only available for a few hundreds of asteroids (out of over one million). On the other hand, a growing amount of space and ground-based surveys delivers multi-filter photometry, which is often used in predicting asteroid types. Those surveys are typically dedicated to studying other astronomical objects, and thus not optimized for asteroid taxonomic classifications. The goal of this study was to quantify the importance and performance of different asteroid spectral features, parameterizations, and methods in predicting the asteroid types. Furthermore, we aimed to identify the key spectral features that can be used to optimize future surveys toward asteroid characterization. Those broad surveys typically are restricted to a few bands; therefore, selecting those that best link them to asteroid taxonomy is crucial in light of maximizing the science output for solar system studies. First, we verified that with the increased number of asteroid spectra, the Bus–DeMeo procedure to create taxonomy still produces the same overall scheme. Second, we confirmed that machine learning methods such as naive Bayes, support vector machine (SVM), gradient boosting, and multilayer networks can reproduce that taxonomic classification at a high rate of over 81% balanced accuracy for types and 93% for complexes. We found that multilayer perceptron with three layers of 32 neurons and stochastic gradient descent solver, batch size of 32, and adaptive learning performed the best in the classification task. Furthermore, the top five features (spectral slope and reflectance at 1.05, 0.9, 0.65, and 1.1 μm) are enough to obtain a balanced accuracy of 93% for the prediction of complexes and six features (spectral slope and reflectance at 1.4, 1.05, 0.9, 0.95, and 0.65 μm) to obtain 81% balanced accuracy for taxonomic types. Thus, to optimize future surveys toward asteroid classification, we recommend using filters that cover those features.

show abstract

“…Recent studies had a particular focus on shock metamorphism in ordinary chondrites (OCs) (Stöffler et al., 2018), where troilite plays a vital role as a marker of impact events (Kohout et al., 2014, 2020; Moreau et al., 2017, 2018, 2019; Moreau & Schwinger, 2021). The average troilite modal abundance in OCs is 5.5–5.9 wt% (McSween et al., 1991) or ~5 vol% (Hutchison, 2007).…”

Section: Introductionmentioning

confidence: 99%

Bulk synthesis of stoichiometric/meteoritic troilite (FeS) by high‐temperature pyrite decomposition and pyrrhotite melting

Moreau

Jõeleht

Aruväli

et al. 2022

Meteorit & Planetary Scien

Self Cite

View full text Add to dashboard Cite

Stoichiometric troilite (FeS) is a common phase in differentiated and undifferentiated meteorites. It is the endmember of the iron sulfide system. Troilite is important for investigating shock metamorphism in meteorites and studying spectral properties and space weathering of planetary bodies. Thus, obtaining coarse‐grained meteoritic troilite in quantities is beneficial for these fields. The previous synthesis of troilite was achieved by pyrite or pyrrhotite heating treatments or chemical syntheses. However, most of these works lacked a visual characterization of the step by step process and the final product, the production of large quantities, and they were not readily advertised to planetary scientists or the meteoritical research community. Here, we illustrate a two‐step heat treatment of pyrite to synthesize troilite. Pyrite powder was decomposed to pyrrhotite at 1023–1073 K for 4–6 h in Ar; the run product was then retrieved and reheated for 1 h at 1498–1598 K in N2 (gas). The minerals were analyzed with a scanning electron microscope, X‐ray diffraction (XRD) at room temperature, and in situ high‐temperature XRD. The primary observation of synthesis from pyrrhotite to troilite is the shift of a major diffraction peak from ~43.2°2θ to ~43.8°2θ. Troilite spectra matched an XRD analysis of natural meteoritic troilite. Slight contamination of Fe was observed during cooling to troilite, and alumina crucibles locally reacted with troilite. The habitus and size of troilite crystals allowed us to store it as large grains rather than powder; 27 g of pyrite yielded 17 g of stochiometric troilite.

show abstract

Experimental constraints on the ordinary chondrite shock darkening caused by asteroid collisions

Cited by 16 publications

References 53 publications

Insight into the Distribution of High-pressure Shock Metamorphism in Rubble-pile Asteroids

Insight into the Distribution of High-pressure Shock Metamorphism in Rubble-pile Asteroids

Predicting Asteroid Types: Importance of Individual and Combined Features

Bulk synthesis of stoichiometric/meteoritic troilite (FeS) by high‐temperature pyrite decomposition and pyrrhotite melting

Contact Info

Product

Resources

About