Shock compression of fluorapatite to 120 GPa

1M. J. Rucks,2J. M. Winey,2Y. Toyoda,2,3Y. M. Gupta,1T. S. Duffy
Journal of Geophysical Research (Planets) (in Press) Link to Article []
1Department of Geosciences, Princeton University, Princeton, New Jersey, 08544 USA
2Institute for Shock Physics, Washington State University, Pullman, Washington, 99164-2816 USA
3Department of Physics, Washington State University, Pullman, Washington, 99164-2816 USA
Published by arrangement with Hohn Wiley & Sons

Apatite is a phosphate mineral relevant to shock metamorphism in planetary materials. Here, we report on the response of natural fluorapatite from Durango, Mexico under shock wave loading between 14.5 and 119.5 GPa. Wave profile measurements were obtained in plate-impact experiments conducted on [0001]-oriented fluorapatite single crystals. To 30 GPa peak stresses, we observed a two-wave structure indicating an elastic-inelastic response with elastic wave amplitudes of 10.5 – 13.1 GPa. Between 39.1 – 62.1 GPa, a complex wave structure was observed involving the propagation of three waves. At and above 73.7 GPa, only a single shock wave was observed. The data above 73.7 GPa provided the following linear shock velocity – particle velocity relationship: Us = 6.5(2) + 0.78(6) up, (mm/μs). Above 80 GPa, the densities in the shocked state exceed both the extrapolated 300-K density of fluorapatite and the predicted 300-K density for a mixture of the high-pressure assemblage, tuite and CaF2. This result indicates that fluorapatite undergoes a transition to a denser structure under shock loading at these conditions. The shock response of fluorapatite is observed to be similar to enstatite but stiffer than quartz and albite at the stresses examined in this work.

Experimental weathering of rocks and minerals at Venus conditions in the Glenn Extreme Environments Rig (GEER)

1,2Alison R. Santos,1Martha S. Gilmore,1James P. Greenwood,3 Leah M. Nakley,3,4Kyle Phillips,3Tibor Kremic,1Xavier Lopez
Journal of Geophysical Research (Planets) (in Press) Link to Article []
1Department of Earth and Environmental Sciences, Wesleyan University, 265 Church St., Middletown, CT, 06459 United States
2Previously at: NASA Postdoctoral Program Fellow, NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH 44135
3NASA Glenn Research Center, 21000 Brookpark Rd., Cleveland, OH, 44135 United States
4Previously at: HX5 Sierra, LLC, 21000 Brookpark Rd., Cleveland, OH 44135.
Published by arrangement with John Wiley & Sons

We report two experiments using 13 mineral and rock samples exposed to a complex synthetic Venus atmosphere composed of nine gases for durations of 30 and 11 days conducted using the NASA Glenn Extreme Environment Rig (GEER). Examination of our run products using a scanning electron microscope equipped with an energy dispersive spectrometer reveals secondary minerals predominantly formed from reactions of Fe and Ca in the solid samples with sulfur in the atmospheric gas, results largely predicted in the literature, and indicating that such reactions between rocks and the atmosphere at the Venus surface may occur rapidly. Samples that displayed larger degrees of reaction include calcite (forming Ca-sulfate), Fe-Ti oxide (forming an Fe,S phase), biotite (forming an Fe,S phase), chalcopyrite (forming a new Cu,Fe-sulfide and a Ag,Cl phase), and Mid-Ocean Ridge Basalt glass (forming a Ca- and S-bearing phase, Fe- and S-bearing phase, and an Fe-oxide); pyrite was observed to be stable in our 30-day experiment. These reactions indicate that the fS2 of the experiments was above or at the high end of what is thermodynamically predicted for the Venus surface. Apatite, feldspars, actinolite, and quartz did not change in this time frame. The presence of multiple S species in GEER may explain dissimilarities in the style of reactions seen in previous experiments with simpler gas mixtures.

Detection of copper by the ChemCam instrument along Curiosity’s traverse in Gale crater, Mars: Elevated abundances in Glen Torridon

1Walter Goetz et al. (>10)
Journal of Geophysical Research (Planets) (in Press) Link to Article []
1Max-Planck-Institut für Sonnensystemforschung (MPS), D-37077 Göttingen, Germany
Published by arrangement with John Wiley & Sons

Laser-Induced Breakdown Spectroscopy, as utilized by the ChemCam instrument onboard the Curiosity rover, detected enhanced abundances of the element copper. Since landing in Gale crater (August 6, 2012) 10 enhancements in copper abundance were observed during 3007 Martian days (sols) of rover operations and 24 km of driving (as of January 20, 2021). The most prominent ones were found in the Kimberley area on the crater floor (Aeolis Palus) and in Glen Torridon on the lower flanks of Aeolis Mons (Mt. Sharp). Enhancements in copper record the former existence of modestly acidic and oxidizing fluids, which were more oxidizing in Kimberley than in Glen Torridon. Of the two main types of bedrock in the lowest part of Glen Torridon, Mg-rich ‘coherent’ and K-rich ‘rubbly’ (named based on their outcrop expression), copper was only detected in coherent, not in rubbly bedrock. The difference between these two types of bedrock may be due to difference in provenance. Alternatively, based on a recently developed lacustrine-groundwater mixing model, we suggest that rubbly bedrock was altered by modestly acidic, shallow-subsurface lake water that leached out both copper and manganese, while coherent bedrock was affected by dominantly alkaline fluids which would be consistent with its mineralogical composition (including siderite) as returned by the CheMin instrument onboard the rover. Higher up in Glen Torridon, ChemCam data indicated significant gradients in copper concentration in coherent bedrock on a local scale of only few meters, which suggests a different alteration style and possibly different types of diagenetic fluids.

Strontium isotope evidence for the repeated formation of refractory inclusions in the Allende meteorite

1Yuki Masuda,1Tetsuya Yokoyama
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro, Tokyo 152-8551, Japan
Copyright Elsevier

Calcium-aluminum-rich inclusions (CAIs) in chondrite meteorites are the oldest rocks in the Solar System and were formed by condensation from nebular gas. Recent mass spectrometric measurements have revealed that CAIs possess nucleosynthetic isotopic compositions different from those of terrestrial materials for various elements, indicating a heterogeneous distribution of nuclides from various stellar sources in the early Solar System. CAIs are classified into coarse-grained (CGs) and fine-grained (FGs) inclusions. The former have experienced secondary melting through thermal events after their formation, while the latter evidently avoided the remelting. Thus, FGs are considered to be direct condensates from a high-temperature gas, making them ideal for investigation of the origin and formation process of CAIs. In this study, the elemental abundances and Sr isotopic compositions in eight FGs from a carbonaceous chondrite Allende were analyzed by utilizing a micromilling technique. These FG samples were found to have rare-earth element (REE) patterns reflecting various degrees of elemental fractionation and variable µ84Sr values ranging from 61 to 844 ppm. It cannot be ruled out that matrix contamination during micromilling or secondary alteration on the Allende parent body has affected the elemental abundances and µ84Sr values observed in FGs to some extent; however, the large variation in µ84Sr values could reflect the variability in the FG formation processes. Importantly, REE-fractionated FGs, which were depleted in heavy REEs relative to light REEs, had relatively high µ84Sr values. This suggests that the formation of REE-fractionated FGs was triggered by rapid heating events, such as FU Orionis that occurred periodically in the early Solar System, and that at least two different heating events probably formed FGs with two different µ84Sr values.

Laboratory measurements of anhydrous minerals mixed with hyperfine hydrated minerals to support interpretation of infrared reflectance observations of planetary surfaces

1,2G.Poggiali,3S.Iannini Lelarge, 2J.R.Brucato, 1M.A.Barucci, 3,4M.Masotta ,2M.A.Corazzi, 2T.Fornaro, 5A.J.Brown, 6L.Mandon, 7N.Randazzo
Icarus (in Press) Link to Article []
1LESIA-Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92190 Meudon, France
2INAF-Astrophysical Observatory of Arcetri, Firenze, Italy
3Department of Earth Science, University of Pisa, Pisa, Italy
4CISUP, Centro per l’Integrazione della Strumentazione Università di Pisa, Pisa, Italy
5Plancius Research, Severna Park, MD 21146, USA
6Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
1Earth and Atmospheric Sciences, University of Alberta, Alberta, Canada
Copyright Elsevier

Identification of water in our Solar System is a key point to understanding the formation and evolution of planetary bodies as well as for astrobiological studies. Scientists identified hydrated minerals as a prime source of H2O in our Solar System. Minerals such as clays, serpentines and other phyllosilicates were discovered by orbiter and lander spacecraft and ground observations on a large variety of rocky surfaces from Mars to small asteroids using InfraRed (IR) spectroscopy as primary technique. It has already been observed that in the presence of large amounts of hydrated minerals in mixtures with anhydrous minerals, the IR spectra can be dominated by the features of hydrated minerals. However, it is still poorly studied how the IR spectra change in presence of different grain size of the two components.

The goal of this study was to investigate the infrared spectroscopic features of anhydrous mineral spectra in presence of low amounts of small grain size hydrated hyperfine particles. We prepared several mixtures using 1 wt% and 5 wt% of very small grain size (< 10 μm) hydrated minerals and 95 wt% and 99 wt% of larger grain size (200–500 μm) anhydrous minerals. We measured the IR reflectance spectrum of these mixtures in the range 8000–400 cm−1 (1.25–25 μm). Results presented here show how the presence of a very limited amount of hydrated minerals with grain size one order of magnitude smaller than the anhydrous component is sufficient to change the IR spectrum, especially in the Near-InfraRed (NIR) region where some of the major hydrated features manifest. On the contrary, the Mid-InfraRed (MIR) part of the spectrum (also identified as thermal infrared) is definitely less affected and anhydrous mineral features continue to be dominant with slight modifications. This result is of pivotal importance for correctly interpreting the IR reflectance observations of planetary bodies such as Mars or asteroids where a mixing of anhydrous and hydrated minerals can be observed. The presence of strong spectroscopic features due to hydrated minerals can be misinterpreted as a large abundance of this material instead of a spectroscopic effect.

Mass-independent Sn isotope fractionation and radiogenic 115Sn in chondrites and terrestrial rocks

1,2Alessandro Bragagni,1Frank Wombacher,1,3Maria Kirchenbaur,1,4Ninja Braukmüller,1Carsten Münker
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1Institut für Geologie und Mineralogie, Universität zu Köln, Zülpicher Str. 49b, 50674 Köln, Germany
2Dipartimento di Scienze della Terra, Università degli studi di Firenze, via La Pira 4, 50121 Firenze, Italy
3Institut für Mineralogie, Leibniz Universität Hannover, Callinstraße 3, 30167 Hannover, Germany
4Institut für Geologische Wissenschaften, Freie Universität, Malteserstr. 74-100, 12249, Berlin, Germany
Copyright Elsevier

Tin has ten stable isotopes, providing the opportunity to investigate and discriminate nucleosynthetic isotope anomalies from mass-dependent and mass-independent isotope fractionation. Novel protocols for chemical separation (based on TBP-resin) and MC-ICP-MS analyses are reported here for high precision Sn isotope measurements on terrestrial rocks and chondrites. Relative to the Sn reference standard (NIST SRM 3161a), terrestrial basalts and chondrites show isotope patterns that are consistent with mass-dependent and mass-independent isotope fractionation processes as well as with 115Sn radiogenic ingrowth from 115In.

Two different mass-independent isotope effects are identified, namely the nuclear volume (or nuclear field shift) and the magnetic isotope effect. The magnetic isotope effect dominates in the two measured ordinary chondrites, while repeated analyses of the carbonaceous chondrite Murchison (CM2) display a pattern consistent with a nuclear volume effect. Terrestrial basalts show patterns that are compatible with a mixture of nuclear volume and magnetic isotope effects. The ultimate origin of the isotope fractionation is unclear but a fractionation induced during sample preparation seems unlikely because different groups of chondrites show distinctly different patterns, hence pointing towards natural geo/cosmochemical processes. Only the carbonaceous chondrite Murchison (CM2) shows a Sn isotope pattern similar to what expected for nucleosynthetic variations. However, this pattern is better reproduced by nuclear volume effects. Thus, after considering mass-independent and mass-dependent effects, we find no evidence of residual nucleosynthetic anomalies, in agreement with observations for most other elements with similar half-mass condensation temperatures.

Most chondrites show a deficit in 115Sn/120Sn (typically −150 to −200 ppm) relative to terrestrial samples, with the exception of one ordinary chondrite that displays an excess of about +250 ppm. The 115Sn/120Sn data correlate with In/Sn, being consistent with the β− decay of 115In over the age of the solar system. This represents the first evidence of the 115In-115Sn decay system in natural samples. The radiogenic 115Sn signature of the BSE derives from a suprachondritic In/SnBSE, which reflects preferential partitioning of Sn into the Earth’s core.

Meteorites have inherited nucleosynthetic anomalies of potassium-40 produced in supernovae

1Nicole X. Nie,1,2Da Wang,1Zachary A. Torrano,1Richard W. Carlson,1Conel M. O’D. Alexander,1Anat Shahar
Science 379, 6630 Link to Article [DOI: 10.1126/science.abn178]
1Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA.
2International Center for Planetary Science, College of Earth Sciences, Chengdu University of Technology, 610059 Chengdu, China.
Reprinted with permission from AAAS

Meteorites record processes that occurred before and during the formation of the Solar System in the form of nucleosynthetic anomalies: isotopic compositions that differ from the Solar System patterns. Nucleosynthetic anomalies are rarely seen in volatile elements such as potassium at bulk meteorite scale. We measured potassium isotope ratios in 32 meteorites and identified nucleosynthetic anomalies in the isotope potassium-40. The anomalies are larger and more variable in carbonaceous chondrite (CC) meteorites than in noncarbonaceous (NC) meteorites, indicating that CCs inherited more material produced in supernova nucleosynthesis. The potassium-40 anomaly of Earth is close to that of the NCs, implying that Earth’s potassium was mostly delivered by NCs.

Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles

1Rayssa Martins,1Sven Kuthning,1Barry J. Coles,1Katharina Kreissig,1Mark Rehkämper
Science 379, 6630 Link to Article [DOI: 10.1126/science.abn1021]
1Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK.
Reprinted with permission from AAAS

Material inherited from different nucleosynthesis sources imparts distinct isotopic signatures to meteorites and terrestrial planets. These nucleosynthetic isotope anomalies have been used to constrain the origins of material that formed Earth. However, anomalies have only been identified for elements with high condensation temperatures, leaving the origin of Earth’s volatile elements unconstrained. We determined the isotope composition of the moderately volatile element zinc in 18 bulk meteorites and identified nucleosynthetic zinc isotope anomalies. Using a mass-balance model, we find that carbonaceous bodies, which likely formed beyond the orbit of Jupiter, delivered about half of Earth’s zinc inventory. Combined with previous constraints obtained from studies of other elements, these results indicate that ~10% of Earth’s mass was provided by carbonaceous material.

Studying the temperature dependence of NIR reflectance spectra of selected hydrated salts dissolved in water: The case of natron, mirabilite and epsomite as representative for icy-world surfaces

1Daniele Fulvio,1Ciprian Popa,1Vito Mennella,2Federico Tosi,2SimoneDe Angelis,2Mauro Ciarniello,2Alessandro Mura,2Gianrico Filacchione
Icarus (in Press) Link to Article []
1INAF, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, Naples 80131, Italy
2INAF, Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, Rome 00133, Italy
Copyright Elsevier

Hydrated salts are thought to be a surface component of many different solid bodies in the solar system such as the icy-world satellites, especially the large ones of Jupiter and Saturn. In this context, three hydrated salts of interest in planetary sciences – natron (Na2CO3·10H2O), mirabilite (Na2SO4·10H2O), and epsomite (MgSO4·7H2O) – were selected and their NIR (0.8–3.6 μm) reflectance properties were studied as a function of temperature after diluting them in water. The main goal of these experiments is to characterize the evolution induced in the hydrated salt NIR spectra by the mixing and melting with water followed by freezing of the samples down to 95 K. Our results show that mixing of hydrated salts with water induces a complex phenomenology characterized by the formation of new bonds and absorption features. In addition, the shape and minimum position of the NIR spectral features here analyzed are temperature-dependent. The present laboratory study will be extremely useful to interpret the high-resolution data of Jupiter’s icy satellites surfaces which will be available in the next future thanks to the MISE and MAJIS instruments aboard NASA Europa Clipper and ESA JUICE spacecraft, respectively.

The noble gas and nitrogen relationship between Ryugu and carbonaceous chondrites

1M.W.Broadley et al. (>10)
Geochimica et Cosmochimica Acta (in Press) Link to Article []
1Université de Lorraine, CNRS, CRPG
Copyright Elsevier

Carbonaceous chondrites are considered to have originated from C-type asteroids and represent some of the most primitive material in our solar system. Furthermore, since carbonaceous chondrites can contain significant quantities of volatile elements, they may have played a crucial role in supplying volatiles and organic material to Earth and other inner solar system bodies. However, a major challenge of unravelling the volatile composition of chondritic meteorites is distinguishing between which features were inherited from the parent body, and what may be a secondary feature attributable to terrestrial weathering. In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfully returned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now been classified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites. The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse the volatile composition of material that originated from a CI-type asteroid without the complications arising from terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventories of chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to terrestrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grains collected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into the formation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples is greater than the average composition of previously measured CI chondrites and are primarily derived from phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The large noble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests that the Ryugu samples may represent some of the most primitive unprocessed material from the early solar system. In contrast to the noble gases, the abundance of nitrogen and δ15N composition of the two Ryugu pellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances and δ15N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueous alteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shown large variations in nitrogen concentrations and δ15N indicating that alteration fluids heterogeneously interacted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gases to nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indicates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen, likely from soluble organic matter, without modification of the noble gas budget, which is primarily hosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueous alteration.