TY - JOUR
T1 - The fate of organic matter during planetary accretion
T2 - Preliminary studies of the organic chemistry of experimentally shocked murchison meteorite
AU - Tingle, Tracy N.
AU - Tyburczy, James
AU - Ahrens, Thomas J.
AU - Becker, Christopher H.
PY - 1991/9
Y1 - 1991/9
N2 - It is possible that Earth's biologic precursors were delivered by late-impacting asteroids or comets, and it is possible that these objects were a source of Earth's volatile inventory. To understand the behavior of organic matter in carbonaceous meteorites during hypervelocity impact (1-2 km s-1), three samples of the Murchison (CM2) carbonaceous chondrite were shocked to 19, 20 and 36 GPa and analyzed by very sensitive thermal-desorption photoionization mass spectrometry (SALI). Thermal-desorption (25-800 °C) SALI mass spectra of unshocked Murchison reveal indigenous aliphatic, aromatic, sulfur and organosulfur compounds. Samples shocked to ≈20 GPa exhibit little or no loss of organic matter relative to the unshocked material. This is consistent with the earlier work of Tyburczy et al. (1986) which showed that incipient devolatilization of Murchison occurs at peak shock pressures near 20 GPa. The small amount of organic matter lost appears to have occurred by volatilization of elemental sulfur, amines and aliphatic compounds. In the sample shocked to 36 GPa, approximately 70% of the organic matter was volatilized as a result of impact. The residual organic matter desorbed at somewhat higher temperatures and displayed a different chemical signature. In particular, the shocked material has a lower alkene/alkane ratio than that of the starting material. The preliminary data suggest that it is unlikely that the indigenous organic matter in carbonaceous chondrite-like planetesimals could have survived impact on the Earth in the later stages of Earth's accretion. However, chemical reactions that produce organic compounds with greater thermal stabilities may occur during impact or subsequent to impact by condensation of the impact-produced vapor plume.
AB - It is possible that Earth's biologic precursors were delivered by late-impacting asteroids or comets, and it is possible that these objects were a source of Earth's volatile inventory. To understand the behavior of organic matter in carbonaceous meteorites during hypervelocity impact (1-2 km s-1), three samples of the Murchison (CM2) carbonaceous chondrite were shocked to 19, 20 and 36 GPa and analyzed by very sensitive thermal-desorption photoionization mass spectrometry (SALI). Thermal-desorption (25-800 °C) SALI mass spectra of unshocked Murchison reveal indigenous aliphatic, aromatic, sulfur and organosulfur compounds. Samples shocked to ≈20 GPa exhibit little or no loss of organic matter relative to the unshocked material. This is consistent with the earlier work of Tyburczy et al. (1986) which showed that incipient devolatilization of Murchison occurs at peak shock pressures near 20 GPa. The small amount of organic matter lost appears to have occurred by volatilization of elemental sulfur, amines and aliphatic compounds. In the sample shocked to 36 GPa, approximately 70% of the organic matter was volatilized as a result of impact. The residual organic matter desorbed at somewhat higher temperatures and displayed a different chemical signature. In particular, the shocked material has a lower alkene/alkane ratio than that of the starting material. The preliminary data suggest that it is unlikely that the indigenous organic matter in carbonaceous chondrite-like planetesimals could have survived impact on the Earth in the later stages of Earth's accretion. However, chemical reactions that produce organic compounds with greater thermal stabilities may occur during impact or subsequent to impact by condensation of the impact-produced vapor plume.
UR - http://www.scopus.com/inward/record.url?scp=34249836111&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34249836111&partnerID=8YFLogxK
U2 - 10.1007/BF01808309
DO - 10.1007/BF01808309
M3 - Article
AN - SCOPUS:34249836111
SN - 0169-6149
VL - 21
SP - 385
EP - 397
JO - Origins of life and evolution of the biosphere
JF - Origins of life and evolution of the biosphere
IS - 5-6
ER -