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The Nature, Origin and Modification of Insoluble Organic Matter

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The Nature, Origin and Modification of Insoluble Organic Matter University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln U.S. Navy Research U.S. Department of Defense 2017 The an ture, origin and modification of insoluble organic matter inchondrites, the major source of Earth’s C and N C. M. O'D. Alexander Carnegie Institution of Washington, [email protected] G. D. Cody Carnegie Institution of Washington B. T. De Gregorio U.S. Naval Research Laboratory L. R. Nittler Carnegie Institution of Washington R. M. Stroud U.S. Naval Research Laboratory Follow this and additional works at: http://digitalcommons.unl.edu/usnavyresearch Alexander, C. M. O'D.; Cody, G. D.; De Gregorio, B. T.; Nittler, L. R.; and Stroud, R. M., "The an ture, origin and modification of insoluble organic matter inchondrites, the major source of Earth’s C and N" (2017). U.S. Navy Research. 117. http://digitalcommons.unl.edu/usnavyresearch/117 This Article is brought to you for free and open access by the U.S. Department of Defense at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in U.S. Navy Research by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Chemie der Erde 77 (2017) 227–256 Contents lists available at ScienceDirect Chemie der Erde j ournal homepage: www.elsevier.de/chemer The nature, origin and modification of insoluble organic matter in chondrites, the major source of Earth’s C and N a,∗ b c a c C.M.O’D. Alexander , G.D. Cody , B.T. De Gregorio , L.R. Nittler , R.M. Stroud a Dept. Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, Washington, DC 20015, USA b Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road, Washington, DC 20015, USA c Materials Science and Technology Division, U.S. Naval Research Laboratory, Washington, DC 20375, USA a r t i c l e i n f o a b s t r a c t Article history: All chondrites accreted ∼3.5 wt.% C in their matrices, the bulk of which was in a macromolecular solvent Received 20 July 2016 and acid insoluble organic material (IOM). Similar material to IOM is found in interplanetary dust particles Received in revised form (IDPs) and comets. The IOM accounts for almost all of the C and N in chondrites, and a significant fraction 21 December 2016 of the H. Chondrites and, to a lesser extent, comets were probably the major sources of volatiles for the Accepted 12 January 2017 Earth and the other terrestrial planets. Hence, IOM was both the major source of Earth’s volatiles and a Editorial handling - Klaus Keil potential source of complex prebiotic molecules. 15 Large enrichments in D and N, relative to the bulk solar isotopic compositions, suggest that IOM or Keywords: Meteorites its precursors formed in very cold, radiation-rich environments. Whether these environments were in Chondrites the interstellar medium (ISM) or the outer Solar System is unresolved. Nevertheless, the elemental and Comets isotopic compositions and functional group chemistry of IOM provide important clues to the origin(s) Interplanetary dust of organic matter in protoplanetary disks. IOM is modified relatively easily by thermal and aqueous Organic matter processes, so that it can also be used to constrain the conditions in the solar nebula prior to chondrite Interstellar accretion and the conditions in the chondrite parent bodies after accretion. Solar nebula Here we review what is known about the abundances, compositions and physical nature of IOM in the Protoplanetary disk most primitive chondrites. We also discuss how the IOM has been modified by thermal metamorphism and aqueous alteration in the chondrite parent bodies, and how these changes may be used both as petrologic indicators of the intensity of parent body processing and as tools for classification. Finally, we critically assess the various proposed mechanisms for the formation of IOM in the ISM or Solar System. ﾩ 2017 Elsevier GmbH. All rights reserved. Contents 1. Introduction . 228 2. Classification of chondritic meteorites and IDPs . 229 3. The inventory of chondritic organics . 229 4. Where are the organics? . 230 5. The nature of the most primitive IOM in meteorites . 232 5.1. The physical nature of the IOM . 232 5.2. Elemental and isotopic compositions . 233 5.3. Functional group chemistry . 234 5.3.1. Chemical degradation . 234 5.3.2. Pyrolysis . 235 5.3.3. NMR . 237 5.3.4. EPR and related techniques . 238 ∗ Corresponding author. E-mail address: [email protected] (C.M.O’D. Alexander). http://dx.doi.org/10.1016/j.chemer.2017.01.007 0009-2819/ﾩ 2017 Elsevier GmbH. All rights reserved. 228 C.M.O’D. Alexander et al. / Chemie der Erde 77 (2017) 227–256 5.3.5. C, N, O and S XANES and EELS. .239 5.3.6. FTIR . 240 5.4. Conclusions about the nature of primitive chondritic IOM . 241 5.5. IOM in IDPs and UCAMMs . 241 6. The effects of parent body alteration. .243 6.1. Aqueous alteration . 243 6.1.1. Source(s) of water, alteration processes and conditions . 243 6.1.2. Effects of alteration on IOM . 243 6.2. Thermal metamorphism . 246 6.2.1. Conditions and processes . 246 6.2.3. Effects on the IOM. .246 6.3. Was there a common IOM precursor? . 247 7. Where and how did the IOM form? . ..
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