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Experiments. Analysis of Partial Melting ^ of CR and R Chondritic Meteorites. Courtney King, Kathryn Gardner-Vandy, Dante Lauretta Lunar and Planetary Laboratory, University of Arizona. Objectives.
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Experiments Analysis of Partial Melting ^ of CR and R Chondritic Meteorites Courtney King, Kathryn Gardner-Vandy, Dante Lauretta Lunar and Planetary Laboratory, University of Arizona
Objectives • The study of meteoritics is important in order to learn about materials and environments of the early Solar System • Understand the origin of oxidized (Fe2+) igneous meteorites • Brachinites • Other primitive achondrites
Background • Types of meteorites: • Chondrites (undifferentiated) • Primitive Achondrites • Achondrites (differentiated) • CR chondrite group • Aqueous alteration • R chondrite group • Highly oxidized: Olivines and sulfides • Brachinites • Sulfides and oxides present • Fe in Olivine
Steps for Analyzing a Meteorite • Receive sample from Meteorite Working Group (MWG) • Cut sample into pieces and weigh • Mount a piece in epoxy and polish until smooth • View/analyze the mounted sample using Electron Microprobe • Perform a partial melting experiment • Repeat mounting process to analyze partially melted sample using probe
Renazzo • CR2 • Type 2: Low grade aqueous alteration • Rim of metals/sulfides • Kamacite < 6% Ni • Taenite > 6% Ni • Chondrule • Kamacite next to Taenite • Kamacite next to sulfides Pyrrhotite, Troilite • Stoichiometric Equilibrium • Presence of a Sulfur gas mixture: sulfurization of FeNi alloy (FeS)
Experimental Set-up • Temperature Controller • Pyrometer • Induction Furnace • Thermocouple • Gas flow Ar • QMS • Close up: • Al2O3 crucible • Platinum
Experiments • Partially melted R chondrite • 1200º C, Ar gas • Found: veins of troilite (FeS) surrounding unmelted olivine (FeMg)2SiO4 • Texture: coagulated • Temperature calibrations • Halite, Troilite • Ag, Cu Photo courtesy: Kathryn Gardner-Vandy
Implications of the Data • Question: What happens when a meteorite containing reduced iron (Fe0) and aqueous alteration is heated? • Possibility of producing oxidized iron (Fe2+); Olivine • Metal/sulfide textures respond rapidly to melting • What to look at: • Kamacite < 6% Ni • Taenite > 6% Ni • Kamacite Troilite (FeS) • Sulfur gas, H2S
Thank you! Dante Lauretta Kathryn Gardner-Vandy Katrina Jackson