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Petrology of the NWA 2737 Martian Meteorite and Its Carbonate

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Petrology of the NWA 2737 Martian Meteorite and Its Carbonate Université Pierre et Marie Curie MSc in Planetary Sciences Placement report Space Research Centre, University of Leicester, UK. Petrology of the NWA 2737 Martian meteorite and its carbonate © Bruno Fectay & Carine Bidaut Other project: Analysis of superconductor films By Manon Le Testu March-June 2009 Tutor: Dr John Bridges SRC Table of contents ABSTRACT .................................................................................................................................................... - 2 - RESUME ....................................................................................................................................................... - 3 - PART 1: PETROLOGY OF THE NWA 2737 MARTIAN METEORITE AND ITS CARBONATE.................................. - 4 - PROBLEMATIC ................................................................................................................................................. - 5 - I. SNC PRESENTATION AND CHARACTERISTICS OF NWA 2737 METEORITE ................................................... - 6 - I. 1. Martian meteorites ............................................................................................................................. - 6 - I. 2. NWA 2737 meteorite characteristics .................................................................................................. - 7 - II. SAMPLES AND ANALYTICAL TECHNIQUES .................................................................................................. - 9 - II. 1. Samples description ........................................................................................................................... - 9 - II.1.a. Samples preparation .................................................................................................................... - 9 - II.1.b. Carbon Coating ............................................................................................................................ - 9 - II. 2. Optic microscopy ................................................................................................................................ - 9 - II. 3. Electronic microscopy analyses ........................................................................................................ - 10 - II. 3. a. Working principle ..................................................................................................................... - 10 - II. 3. b. Samples analysed by SEM ........................................................................................................ - 11 - III. OBSERVATIONS AND DATA TREATMENTS ............................................................................................... - 13 - III. 1. Optic imagery .................................................................................................................................. - 13 - III.2. SEM analyses .................................................................................................................................... - 13 - III.2.a. Samples general aspect ............................................................................................................. - 13 - III.2.b. Carbonates ................................................................................................................................ - 14 - III.3. Data treatment ................................................................................................................................. - 15 - III.3.a. Mineral composition ................................................................................................................. - 15 - III.3.b. Calculation of a chemical formula for carbonate and phosphate ............................................. - 15 - III.3.c. Mineral composition diagrams .................................................................................................. - 16 - IV. RESULTS AND DISCUSSION ...................................................................................................................... - 17 - IV. 1. Results and comparisons ................................................................................................................. - 17 - IV.1.a. Olivine and Pyroxene ................................................................................................................ - 17 - IV.1.b. Feldspar .................................................................................................................................... - 18 - IV.1.c. Spinel ......................................................................................................................................... - 18 - IV.1.d. Phosphate ................................................................................................................................. - 19 - IV.1.e. Carbonate ................................................................................................................................. - 19 - IV. 2. Discussion ........................................................................................................................................ - 20 - IV.2.a. Mineral composition ................................................................................................................. - 20 - IV.2.b. About carbonates ..................................................................................................................... - 21 - CONCLUSION PART 1 .................................................................................................................................... - 23 - PART 2: ANALYSIS OF SUPERCONDUCTOR FILMS ....................................................................................... - 24 - INTRODUCTION............................................................................................................................................. - 25 - I. METHOD .................................................................................................................................................... - 25 - I.1. Samples preparation .......................................................................................................................... - 25 - I.2. Types of analyses made ...................................................................................................................... - 25 - II. RESULTS .................................................................................................................................................... - 26 - II.1. Optical images ................................................................................................................................... - 26 - II.2. SEM analyses ..................................................................................................................................... - 29 - III. DISCUSSION ............................................................................................................................................. - 32 - III.1. Samples preparation ........................................................................................................................ - 32 - III.2. Analyses techniques used ................................................................................................................ - 32 - III.3. Results .............................................................................................................................................. - 32 - CONCLUSION PART 2 .................................................................................................................................... - 33 - BIBLIOGRAPHY ........................................................................................................................................... - 34 - Acknowledgments ...................................................................................................................................... - 37 - - 1 - ABSTRACT This Master 2 placement subject, carried out at the Space Research Centre of Leicester University, UK entailed making precise quantitative analyses of NWA 2737 meteorite with the Scanning Electron Microscope (SEM). This meteorite, also known under the name of “Diderot”, is the second member of the Chassignite group, which is a sub-group of the Martian meteorites. It was discovered in 2000 in sands of the north west African desert, but its martian nature was recognized only in 2004. Thus, only a few petrologic and geochemical analyses have been carried out to date. In a first time, accurate quantitative analyses of principal minerals composing NWA 2737 meteorite, were carried out under the SEM by energy-dispersive X-ray spectrometry. Then, the results of these analyses were indexed and treated in order to be compared with the results obtained by preceding research on this stone (Beck et al. 2005, Mikouchi et al. 2005, Treiman et al. 2007), and also on other Martian meteorites. Previous studies of NWA 2737 have described its general petrology and geochemistry (Beck et al., 2005-2006), its noble gazes (Marty et al. 2005), its age using the Ar-Ar dating technique (Bogard et al. 2006), and its shock events history (Mikouchi et al. 2005, Treiman et al., 2007, Van de Moortele et al. 2007). We are particularly interested in the mineral origin carbonates that are present in NWA2737. All the studies undertaken on this meteorite show the presence of this mineral in interstices left between olivine crystals, or in veins. According to Beck et al. (2005), some of these
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