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This bachelor thesis consists of two parts. The first part consists of a review of the theoretical background. It starts off with a shorter review on theories of the history of the early Solar System, from protostellar evolution to grain agglomeration. This is then followed by a brief summary of different kinds of meteorites, what their origins might be and the radiometric dating techniques used to determine their ages. The second part of the thesis consists of an investigation of the possible forming times of the early planetesimals by computer simulation. These planetesimals can later become the parent bodies for iron-rich meteorites. Factors studied are ambient temperature and the abundance of the short-lived radioactive isotope 26Al in the forming nebula. The study found that the parent bodies of iron meteorites had to accrete within the first few million years after the earliest solids in the Solar System, the CAI. It also found that changes in the studied boundary conditions did extend this period, but not further than around 2.8Myrs compared to the standard 2.1Myrs. This data compares well to other, similar, studies. / Denna kandidatuppsats består av två delar. Först sammanfattas teorier om hur solsystemet tros ha formats, från hur solens närområde kan ha sett ut till hur de första himlakroppsembryona kan ha börjat formas. Detta följs av en kortare sammanfattning av olika typer av meteoriter och var de kan ha kommit från. Dessutom sammanfattas några tekniker som används för att bestämma åldern på dessa meteoriter. Huvuddelen av uppsatsen består av en undersökning av hur och när de kroppar järnrika meteoriter kommer från kan ha bildats med hjälp av en datorsimulering, och hur olika parametrar såsom temperatur och mängd radioaktiva isotoper kan ha påverkat denna tid. Undersökningen kom fram till att himlakropparna måste ha bildats snart, inom ca 2 Mår, efter de tidigaste kända delarna av vårt solsystem, CAI. Förändringar i de undersökta parametrarna kunde ändra denna tid något, men inte till senare än ca 2.8 Mår efter CAI. Detta stämmer väl med andra, liknande, studier.

Iron meteorites are Fe-Ni alloys that are thought to represent samples of the cores of differentiated asteroids. A minority of the iron meteorites contain silicate inclusions, the so-called silicate-bearing or non-magmatic iron meteorites. The presence of chemically evolved silicate inclusions in a high-density Fe-Ni metal raises questions about their origin. The IIE group belongs to the non-magmatic iron meteorites and contains primitive as well as evolved silicate inclusions. The object of this thesis is to investigate the formation processes of the silicate-bearing iron meteorites by examination of the primitive IIE irons. The first chapter provides an overview of the state of the art of silicate-bearing iron meteorites and highlights the existing open questions. The second chapter discusses the most important analytical techniques that have been used during this thesis. The third chapter contains all the research conducted on the Mont Dieu meteorite, a new primitive member of the IIE group. This meteorite represents a unique member of the IIE group as it contains chondrules in its silicate inclusions. Together with the Netschaëvo meteorite, they are the only two IIE irons that show such a primitive texture. Based on the mineralogy, the major element composition and the oxygen isotope composition, we conclude that Mont Dieu originated as an H chondrite. The observation of a series of features, including silicate darkening, thick metal veins containing angular clasts, and the need for a heterogeneous heat source, led to an impact-based origin for Mont Dieu. The fourth chapter is dedicated to the investigation of two samples of the primitive Netschaëvo IIE meteorite, that show lithologies that are very different to those described in the literature. The investigated pieces of Netschaëvo can be classified as impact melt rocks (IMR) and we show that the precursor material of these IMR and the primitive clasts both originated from the same parent body. The occurrence of both lithologies in the same meteorite suggests that Netschaëvo itself is a breccia containing metamorphosed and IMR clasts and that the meteorite formed as the result of an impact event. The fifth chapter focuses on the fine-grained matrix material found in the silicate inclusions of Netschaëvo IIE. This study provides insights into core-mantle boundary environments and confirms the impact-origin of Netschaëvo by the presence of minerals and textures pointing to a very rapid cooling. The investigations show that the re-partitioning of phosphorus from the metal into the silicate material during cooling might be a general process during planetary differentiation. In the sixth chapter, the veins present in the silicate inclusions of Mont Dieu are described in detail, and compared to the veining structures found in Techado IIE silicate. The characteristics of the processes causing the formation of these veins are discussed. The seventh chapter summarizes the conclusions of this thesis. The detailed petrographic and geochemical examinations conducted on the investigated samples show that collisions played a major role in the formation of the IIE iron meteorites. The work performed in the framework of this thesis provides a significant contribution towards a more complete and in-depth understanding of the formation mechanisms of silicate-bearing iron meteorites. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

abstract: This study explores how bulk composition and oxygen fugacity (fO2) affect the partitioning of sulfur between the molten mantle and core of an early planetesimal. The model can be used to determine the range of potential sulfur concentrations in the asteroid (16) Psyche, which is the target of the National Aeronautics and Space Administration/Arizona State University Psyche Mission. This mission will be our visit to an M-type asteroid, thought to be dominantly metallic. The model looks at how oxygen fugacity (fO2), bulk composition, temperature, and pressure affect sulfur partitioning in planetesimals using experimentally derived equations from previous studies. In this model, the bulk chemistry and oxygen fugacity of the parent body is controlled by changing the starting material, using ordinary chondrites (H, L, LL) and carbonaceous chondrites (CM, CI, CO, CK, CV). The temperature of the planetesimal is changed from 1523 K to 1873 K, the silicate mobilization and total melting temperatures, respectively; and pressure from 0.1 to 20 GPa, the core mantle boundary pressures of Vesta and Mars, respectively. The final sulfur content of a differentiated planetesimal core is strongly dependent on the bulk composition of the original parent body. In all modeled cores, the sulfur content is above 5 weight percent sulfur; this is the point at which the least amount of other light elements is needed to form an immiscible sulfide liquid in a molten core. Early planetesimal cores likely formed an immiscible sulfide liquid, a eutectic sulfide liquid, or potentially were composed of mostly troilite, FeS. / Dissertation/Thesis / Masters Thesis Geological Sciences 2020

The aim of this work is to assess the feasibility of asteroid exploitation as a potential source of valuable elements for a future green energy society and achieving a long-term sustainable development of our society. This research is based on the compilation of chemical data of elements concentration of 13 groups of iron meteorites from literature. These data were used to feed mathematical models to fit the historical world production data of each element and predicts the peak year and the future trend of their world production until 2100. Eventually, this work aims to calculate the required mass of asteroids for reaching different productions, and identify the most suitable groups of iron meteorites for exploitation.

ELEMENTAL AND ISOTOPIC STUDY OF DIFFERENTIATED METEORITES AND IMPLICATIONS FOR THE ORIGIN AND EVOLUTION OF THEIR PARENT BODIES Iron meteorites are differentiated meteorites composed largely of Fe-Ni alloys. The metallic phase of many iron meteorites shows a texture called the Widmanstätten pattern, which develops as a two-phase intergrowth of kamacite (α-bcc, ferrite) and taenite (γ-fcc, austenite), and forms by nucleation and growth of kamacite from taenite during slow cooling of the parent body. Selected iron meteorites - octahedrites of different structural and chemical groups (Canyon Diablo, Toluca, Bohumilitz, Horh Uul, Alt Biela, Nelson County, Gibeon and Joe Wright Mountain) were studied with intention to evaluate the scale and extent of Fe isotopic heterogeneities in iron meteorites and to find the possible link between the isotopic variations and thermal histories of the respective meteorite parent bodies. The Fe isotopic compositions of kamacite and taenite in the studied meteorites, obtained by three independent analytical techniques with different spatial resolution capabilities (laser ablation and solution MC ICP-MS and SIMS) show significant variations of up to ~4.5‰ in δ56 Fe. The taenite is isotopically heavier compared to kamacite in all studied meteorites. There is no correlation...