Analysis of Partial Melting ^ of CR and R Chondritic Meteorites
-
Upload
ronan-hodges -
Category
Documents
-
view
26 -
download
0
description
Transcript of Analysis of Partial Melting ^ of CR and R Chondritic Meteorites
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