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GEOL3045: Planetary Geology

GEOL3045: Planetary Geology. Lysa Chizmadia SNC Meteorites. Introduction. Shergotty. Currently 34 All igneous rocks Three classes: Shergotites Basalts (olivine, pyroxene & plag) 150-190 Ma Nakhlites Pyroxenites (mostly pyroxene) ~1.3 Ga Chassigny Dunites (mostly olivine). Nakhla.

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GEOL3045: Planetary Geology

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  1. GEOL3045: Planetary Geology Lysa Chizmadia SNC Meteorites

  2. Introduction Shergotty • Currently 34 • All igneous rocks • Three classes: • Shergotites • Basalts (olivine, pyroxene & plag) • 150-190 Ma • Nakhlites • Pyroxenites (mostly pyroxene) • ~1.3 Ga • Chassigny • Dunites (mostly olivine) Nakhla Chassigny Images from: http://www2.jpl.nasa.gov/snc/

  3. Martian Meteorites Los Angeles #1 • Are probably from Mars b/c: • Young & basaltic • Recent volcanism (154 to 1300 Ma) • Must come from relatively large body • O-isotopes: • Form distinct mixing line • Similar to TFL but higher in ∂17O • If one from Mars, all from Mars • Gas bubbles trapped in glass • Composition ~ Viking measurements • N2, CO2, H2, He, Ar, Kr, Xe & isotope ratios Los Angeles #2 Images from: http://www2.jpl.nasa.gov/snc/ Image from: http://www.psrd.hawaii.edu/July99/EETA79001.html

  4. Oxygen Isotopes

  5. Trapped Gas Bubbles EETA79001 Image from: http://en.wikipedia.org/wiki/Mars_meteorite Plot from: http://www.psrd.hawaii.edu/July99/EETA79001.html

  6. Life of Mars? • PAHs: • ~ Antarctic meltwater • Not spatially near carbonates • C-isotopes point to terrestrial contamination • Carbonates: • Microfossils: • Magnetites: • Etched Glass: Image from: http://en.wikipedia.org/wiki/Mars_meteorite

  7. Carbonates Image from: www.fas.org Orange: Ca, Mn-rich Inner Black: Mg-rich White: Fe-rich Outer Black: Fe, S-rich (where mt is) Carbonate Globbules ~900oC or <80oC ? Image from: www.ndsu.nodak.edu Image from: cmex.ihmc.us

  8. Microfossils • SEM preparation artifact? • Too small for DNA? • Probably terrestrial contamination Shergotty Image from: www.astrobiology.com/ adastra/images/deadjim02.jpg Image from: news.bbc.co.uk Image from: www.lpi.usra.edu

  9. Magnetites nai.nasa.gov zebu.uoregon.edu Terrestrial (Magnetotactic Bacteria) ALH84001 science.nasa.gov ciencia.nasa.gov

  10. Etched Volcanic Glass Nakhla Terrestrial Images from: http://www.lpi.usra.edu/meetings/lpsc2006/pdf/2039.pdf

  11. Summary • Probably from Mars b/c: • Young ages • Must be from relatively large body • O-isotopes • If one from Mars, all are from Mars • Trapped gases • Must be from body with atmosphere like that of Mars • Life of Mars? • PAHs: terrestrial contaminations • Carbonates: can form inorganically • “Microfossils”: preparation artifacts • Magnetites: crystallographically not from bacteria • Etched Volcanic Glass: no counter argument

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