Other
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p23a1695s&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P23A-1695
Other
[1039] Geochemistry / Alteration And Weathering Processes, [1041] Geochemistry / Stable Isotope Geochemistry, [3344] Atmospheric Processes / Paleoclimatology, [5704] Planetary Sciences: Fluid Planets / Atmospheres
Scientific paper
Carbonate minerals provide valuable record of the atmosphere in which they are formed. This work utilizes C and O triple isotopic compositions of the carbonate minerals found in ALH84001 to explore the interaction between atmosphere-hydrosphere and lithosphere. The origin of carbonates found in the Martian meteorite ALH84001 (<1%) is heavily debated with low temperature aqueous precipitation, biogenic production, evaporative processes, high temperature reactions, and impact induced melting and reprecipitation are all candidate processes. These carbonates are heterogeneous chemically (Mg, Ca and Fe-Mn rich) and isotopically (δ13CPDB = +27 to 46 %; δ18OVSMOW = +9.5 to 20.6%) on micrometer scales. Our stepped phosphoric acid dissolution experiments released CO2 from multiple phases of Martian carbonate in the rock (12h acid digestion at 25o C for Ca rich phase and 3h acid digestion at 150oC for Mg rich phase). Both Ca and Mg rich phases showed 0.7% excess 17O (Δ17O = δ17O - 0.52δ18O) in contrast to terrestrial carbonate minerals formed by surficial weathering of the meteorite with no oxygen isotopic anomaly Δ17O ≈ 0 (one hour acid digestion at 25o C). The newly identified Ca-rich carbonate phase is 18O enriched (δ18O = +25%) in contrast to all of the other Ca-rich carbonates previously described. It also contains excess 17O (Δ17O = 0.7%) indicating incorporation of oxygen from an atmospheric source of Martian origin. These oxygen isotope characteristics differentiate this phase from the more commonly described carbonate globules or rosettes and suggest formation from separate aqueous event. This is confirmed by the carbon isotope composition of this new carbonate phase (δ13C= +20%) which differs from the other Martian carbonates in the meteorite and from terrestrial sources. This difference may be an evidence of the long term evolution of carbon isotopes in the atmosphere of Mars. The discovery of highly enriched (O isotopes) Ca-rich phase of Martian carbonate in the meteorite suggests that the history of water-rock interaction preserved in ALH 84001 is even more complex than previously thought.
Chong K. K.
Niles Paul B.
Shaheen R.
Thiemens Mark H.
No associations
LandOfFree
The Hydrological Cycle on Mars as Inferred from the Multi O-isotopic Composition of Carbonates in ALH84001 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Hydrological Cycle on Mars as Inferred from the Multi O-isotopic Composition of Carbonates in ALH84001, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Hydrological Cycle on Mars as Inferred from the Multi O-isotopic Composition of Carbonates in ALH84001 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-869613