HR: 0800h
AN: P41A-0215    [Abstracts]
TI: Experimental simulation of organic matter alteration in carbonaceous chondrites under an in situ micro FTIR spectroscopy
AU: * Kebukawa, Y
EM: yoko.soleil@ess.sci.osaka-u.ac.jp
AF: Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
AU: Nakashima, S
EM: satoru@ess.sci.osaka-u.ac.jp
AF: Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
AU: Saiki, K
EM: ksaiki@ess.sci.osaka-u.ac.jp
AF: Department of Earth and Space Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
AU: Zolensky, M E
EM: michael.e.zolensky@nasa.gov
AF: Astromaterials Research and Exploration Science, KT, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX 77058, United States
AB: Carbonaceous chondrites contain organic matter up to a few weight percents, most of which consists of kerogen- like macromolecular material. Chondritic organic matter preserves signatures of various evolutional steps from presolar materials, through aqueous alteration and thermal metamorphism in the parent asteroid up to delivery to the Earth. The organic-mineral interactions during these processes are little known. We report here on the experimental simulation of organic matter alteration on carbonaceous chondrite parent body under micro FTIR spectroscopy with a heating stage. Leonardite humic acid (IHSS standard humic acid) and synthetic saponite or natural antigorite were used as the macromolecular organic matter and the matrix mineral. These powdered samples were dispersed by MilliQ water then dropped on a CaF₂ plate and dried. They were heated in the heating stage from room temperature to 600 ^oC with a heating rate of 10 ^oC/min in air, Ar gas, and H₂+CO₂ gas mixture (mixing ratio 1:1). H₂+CO₂ gas mixture enables controls of not only oxygen fugacity but also water vapor fugacity, and aqueous processing on chondrite parent bodies can be partly simulated. IR spectra were collected at every 20 ^oC under the micro FTIR spectroscopy. Aliphatic C-H increased from room temperature to approximately 250 ^oC then decreased. Aromatic C-H increased from room temperature to around 400-450 ^oC then decreased. These aliphatic C-H decrease and aromatic C-H increase are faster in air than in Ar or H₂+CO₂. These CH changes of leonardite humic acid are slower with the presence of saponite. These results indicate that organic matter transformation might be prevented by the clay mineral (saponite). Some carbonaceous chondrite samples mixed with the organic material (leonardite humic acid) will also be investigated by the same way. These results will elucidate interactions of chondritic macromolecular organic matter with matrix minerals during parent body processes.
DE: 5220 Hydrothermal systems and weathering on other planets
DE: 6240 Meteorites and tektites (1028, 3662)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting