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Hydrogen in the high-temperature phases of chondrites : origin and contribution to the hydrogen budget of the rocky planets

Thesis subject - deadline for candidates June 17 2020

This is the English version of the original posting in French : Hydrogène des phases de hautes températures des chondrites : origine et contribution aux budgets en hydrogène des corps du Système Solaire interne. -http://www.crpg.cnrs-nancy.fr/spip....

Scientific context and objectives

Chondrules (millimeter-sized igneous spheroids containing silicates, metal, sulfides, and glass) are the major high-temperature components of chondrites, suggesting that most inner solar system materials were affected by their formation. However, the underlying mechanisms of chondrule formation remain a mystery (e.g., Connolly & Jones, 2016). In the past ten years, there have been growing evidences that chondrule formation occurred under high partial pressures of volatile and moderately volatile elements such as sulfur, sodium or silicon and that gas-melt interactions played a significant role in shaping the chondrule textures and chemical and isotopic compositions (e.g., Alexander et al., 2008 ; Nagahara et al., 2009 ; Piani et al., 2016 ; Libourel & Portail, 2018 ; Marrocchi et al., 2018, 2019).

Hydrogen is the most abundant element in the solar system. Nonetheless, the distribution and evolution of hydrogen in the protoplanetary disk and planetary materials remain poorly constrained (e.g., Alexander, 2017 ; Piani et al., 2018). This is partly due to the difficulty to obtain extraterrestrial samples that have escaped post-formation heating or alteration that could have modified their primordial hydrogen signature. Another technical difficulty is linked to the fact that the hydrogen-bearing phases are generally intertwined at a micro-to sub-micrometer scale.

A large number of studies were performed to characterize the main H-bearing phases of hydrated carbonaceous chondrites (CI-, CM-, CR-type) : the hydrated minerals and organic matter. However, thehydrogen-bearing phases of the non-carbonaceous chondrites (ordinary chondrites, enstatite chondrites and Rumurutite chondrites) have not been thoroughly investigated. In these non-carbonaceous chondrites, the high temperature components such as chondrules are very abundant and could contribute significantly to the hydrogen budgets of the whole rocks.

Determining the hydrogen distribution, concentration and isotopic composition in the non-carbonaceous chondrites would help understand the distribution of volatile elements in the inner Solar System and, especially, in the feeding zone of terrestrial planets.

The objectives of the thesis are of two kinds :

- To perform a detailed characterization of the hydrogen distribution and isotopic composition among the non-carbonaceous chondrite phases using in situ analytical techniques (secondary ion mass spectrometry, secondary electron microscopy and electron micro-probe analyzer, Raman and infrared spectroscopy). Chondrule minerals and glasseswill be of particular interest for this characterization.

To build and run high-temperature/low-pressure (≤ 1 bar) experiments to simulate the formation of chondruleunder high partial pressure of hydrogen to understand how chondrules could have acquired their hydrogen contents and isotopic compositions. This experimental study aims at (i) estimating the conditions in which volatile-rich chondrules formed and (ii) identifying the source(s) of hydrogen and the possible formation environment(s) for chondrules in the protoplanetary disk.

Through this project the student will develop expertise and skills in state of the art analytical instruments such as SIMS IMS-1280HR or experimental petrology devices.

Supervision and environment

The thesis will be supervised by Yves Marrocchi (CR-CNRS, HDR) and Laurette Piani (CR-CNRS) incollaboration with Laurent Tissandier, Nathalie Bolfan-Casanova, Thomas Rigaudier in the framework of the ANR HYDRaTE(PI Laurette Piani). The thesis tasks will mainly take place at CRPG in Nancy but some experiments or analyses could occasionally be performed in the collaborator’s laboratories, such as at LVM in Clermont-Ferrand(France). Advances and results of the thesis will be regularly presented in national and international meetings.The PhD student will be a member of the CRPG Formation and evolution of the Solar System and Planets research theme and will be highly encouraged to take part in the organization of seminars and other scientific discussions within the theme.The CRPG is a laboratory under the administrative supervision of bothCNRS and Lorraine University and specialized in Earth and Planetary Sciences. The PhD formation and diploma will be delivered by the SIReNA (Sciences et Ingénierie des Ressources Naturelles)doctoral school, which is located in Nancy and is associated to14 laboratories of Lorraine University, INRA, CNRS, AgroParisTech and IGN.

About the candidates

The Ph.D. candidates must have a M.Sc. (or equivalent) in Planetology or Earth Sciences and have a strong interest for planetology, geochemistry and/or cosmochemistry. Skills or experiences in cosmochemistry, experimental petrology, analytical sciences and/or data analysis will be appreciated. Proficiency in English is highly suitable ; knowledge of French is not mandatory.

Contacts

Laurette Piani : laurette.piani@univ-lorraine.fr

Yves Marrocchi : yvesm@crpg.cnrs-nancy.fr

References

Alexander, C.M.O’D. et al.The formation conditions of chondrules and chondrites. Science 320, 1617–1619 (2008).
Alexander, C.M.O’D. et al. The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial Planets. Science 337, 721–723 (2012)
Alexander, C.M.O’D. et al. Water Reservoirs in Small Planetary Bodies : Meteorites, Asteroids, and Comets. Space Sci. Rev. 214, (2018).
Connolly, H. C. & Jones, R. H. Chondrules : The canonical and noncanonical views. J. Geophys. Res. Planets 121, 1885–1899 (2016).
Libourel, G. & Portail, M. Chondrules as direct thermochemical sensors of solar protoplanetary disk gas. Sci. Adv. 4, (2018)
Nagahara, H., Kita, N. T., Ozawa, K. & Morishita, Y. Condensation of major elements during chondrule formation and its implication to the origin of chondrules. Geochim. Cosmochim. Acta 72, 1442–1465 (2008).
Marrocchi, Y. & Libourel, G. ScienceDirect Sulfur and sulfides in chondrules. Geochim. Cosmochim. Acta 119, 117–136 (2013).
Marrocchi, Y. et al. Formation of CV chondrules byrecycling of amoeboid olivine aggregate-like precursors. Geochim. Cosmochim. Acta 247, 121–141 (2019).
Marrocchi, Y., Villeneuve, J., Batanova, V., Piani, L. & Jacquet, E. Oxygen isotopic diversity of chondrule precursors and the nebular origin of chondrules. Earth Planet. Sci. Lett. (2018).
Piani, L., Marrocchi, Y., Libourel, G. & Tissandier, L. Magmatic sulfides in the porphyritic chondrules of EH enstatite chondrites. Geochim. Cosmochim. Acta 195, 84–99 (2016).
Piani, L., Yurimoto, H. & Remusat, L. A dual origin for water in carbonaceous asteroids revealed by CM chondrites. Nat. Astron. 2, 317–323 (2018).
Tissandier, L., Libourel, G. & Robert, F. Gas-melt interactions and their bearing on chondrule formation. Meteorit. Planet. Sci. 37, 1377–1389 (2002)




publié jeudi 28 mai 2020