Most ureilites are melt residues from the partially melted Ureilite Parent Body. The Ureilite Parent Body was catastrophically disrupted at 5 Ma after Calcium-Aluminum rich Inclusions (CAI) while it was still hot and the ureilites provide a unique window into early solar system magmatic processing. One ureilitic trachyandesite, one cumulate, and 16 melt residue ureilites, all from the Almahata Sitta meteorite strewn field, were analyzed for their noble gas compositions and, when such data was unavailable, for oxygen isotopes and petrology. Additionally, ureilite noble gas data from the literature was compiled together with petrology and oxygen isotope data of the same samples, this data is available in the supplementary materials. The compositions of noble gases and oxygen, as well as petrological characteristics, are similar to previously analyzed ureilites. This includes variable 36Artr/132Xe ratios of 20-1000 correlated with variable 84Kr/132Xe ratios of 0.15-2.5 and Xe isotopic compositions similar to the Q gases but with somewhat lower 134,136Xe/132Xe ratios. The well-established correlation between Mg-Fe olivine core composition and Delta'17O, interpreted as material mixing, is corroborated. There is no correlation between noble gas compositions and petrology or Delta'17O. Therefore, it is unlikely that the variable noble gas elemental ratios are due to mixing of noble gases from different sources, as previously suggested. We suggest that compositional variability was established during implantation of noble gases into disordered carbon prior to accretion and possibly during later processing. We discuss that partial graphitization resulted in noble gas loss, with noble gases remaining in un-graphitized organics, which were converted to diamond during the catastrophic disruption. Noble gases released during graphitization may have entered the melt. Isotopic compositions of trapped noble gases in the cumulate and trachyandesitic rocks, which crystallized from the melt are similar to those in the melt residue ureilites. The elemental noble gas composition of the cumulate shows evidence of a degassing stage and that the concentrations of noble gases in the ureilites were higher before melting. The noble gases in the trachyandesite contains radiogenic noble gases from decay of K, I, Th, and U, which were not enriched in the cumulate, showing that the trachyandesite crystallized from a more evolved melt. The cosmic-ray exposure ages of 15-22 Ma, with mostly overlapping uncertainties, are similar to those previously determined for ureilites from the Almahata Sitta strewn field and display a limited spread in contrast to ages previously detected in Almahata Sitta chondrites.

The chondritic building blocks from which Earth formed contain most of their elemental carbon and other volatiles in organic macromolecular matter. This substance is essential to set the chemical composition of terrestrial planets and start the emergence of life, but how it formed is unknown. We demonstrate that this organic macromolecular matter can efficiently form in dust traps – a prominent planet formation mechanism – in the solar nebula. By combining a protoplanetary disk dust evolution model with radiative transfer, we confirm that dust traps host regimes where ice-coated grains receive exceptionally large doses of radiation of several 10’s of eV molecule -1 year -1 . This allows for the processing of approximately 4% of the total disk ice reservoir from simple molecules into complex macromolecular matter in a matter of decades. This finding shows that planet formation and the emergence of organic macromolecular matter that sets habitable conditions, are intimately linked.

Carbonaceous chondrites are considered to have originated from C-type asteroids and represent some of the most primitive material in our solar system. Furthermore, since carbonaceous chondrites can contain significant quantities of volatile elements, they may have played a crucial role in supplying volatiles and organic material to Earth and other inner solar system bodies. However, a major challenge of unravelling the volatile composition of chondritic meteorites is distinguishing between which features were inherited from the parent body, and what may be a secondary feature attributable to terrestrial weathering. In December 2020, the Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) successfully returned surface material from the C-type asteroid (162173) Ryugu to Earth. This material has now been classified as closely resembling CI-type chondrites, which are the most chemically pristine meteorites. The analysis of material from the surface of Ryugu therefore provides a unique opportunity to analyse the volatile composition of material that originated from a CI-type asteroid without the complications arising from terrestrial contamination. Given their highly volatile nature, the noble gas and nitrogen inventories of chondrites are highly sensitive to different alteration processes on the asteroid parent body, and to terrestrial contamination. Here, we investigate the nitrogen and noble gas signature of two pelletized grains collected from the first and second touchdown sites (Okazaki et al., 2022a), to provide an insight into the formation and alteration history of Ryugu. The concentration of trapped noble gas in the Ryugu samples is greater than the average composition of previously measured CI chondrites and are primarily derived from phase Q, although a significant contribution of presolar nanodiamond Xe-HL is noted. The large noble gas concentrations coupled with a significant contribution of presolar nanodiamonds suggests that the Ryugu samples may represent some of the most primitive unprocessed material from the early solar system. In contrast to the noble gases, the abundance of nitrogen and δ15N composition of the two Ryugu pellets are lower than the average CI chondrite value. We attribute the lower nitrogen abundances and δ15N measured in this study to the preferential loss of a 15N-rich phase from our samples during aqueous alteration on the parent planetesimal. The analyses of other grains returned from Ryugu have shown large variations in nitrogen concentrations and δ15N indicating that alteration fluids heterogeneously interacted with material now present on the surface of Ryugu. Finally, the ratio of trapped noble gases to nitrogen is higher than CI chondrites, and is closer to refractory phase Q and nanodiamonds. This indicates that Ryugu experienced aqueous alteration that led to the significant and variable loss of nitrogen, likely from soluble organic matter, without modification of the noble gas budget, which is primarily hosted in insoluble organic matter and presolar diamonds and is therefore more resistant to aqueous alteration.

Interplanetary dust particles (IDPs) were likely major sources of extraterrestrial organics to the early Earth. However, IDPs experience heating to > 500 ${\deg}$C for up to several seconds during atmospheric entry. In this study, we aim to understand the effects of atmospheric entry heating on the dominant organic component in IDPs by conducting flash heating experiments (4 s to 400 {\deg}C, 600 {\deg}C, 800 {\deg}C, and 1000 {\deg}C) on insoluble organic matter (IOM) extracted from the meteorite Cold Bokkeveld (CM2). For each of the experimental charges, the bulk isotopic compositions of H, N, and C were analyzed using IRMS, the H isotopic heterogeneities (occurrence of hotspots) of the samples were measured by NanoSIMS, and the functional group chemistry and ordering of the IOM was evaluated using FTIR and Raman spectroscopy, respectively. IOM in particles heated to > 600 {\deg}C experienced loss of isotopically heavy, labile H and N groups, resulting in decreases in bulk ${\delta}$D, ${\delta}$15N, H/C and, upon heating > 800 {\deg}C, in N/C. The H heterogeneity was not greatly affected by flash heating to < 600 {\deg}C, although the hotspots tended to be less isotopically anomalous in the 600 {\deg}C sample than in the 400 {\deg}C sample. However, the hotspots all but disappeared in the 800 {\deg}C sample. Loss of C=O groups occurred at 800 {\deg}C. Based on the Raman G-band characteristics, the heating resulted in increased ordering of the polyaromatic component of the IOM. The data presented in this study show that all aspects of the composition of IOM in IDPs are affected by atmospheric entry heating. Modelling and temperature estimates from stepwise release of He has shown that most IDPs are heated to > 500{\deg}C (Love and Brownlee, 1991; Nier and Schlutter, 1993), hence, atmospheric entry heating is expected to have altered the organic matter in most IDPs.

STUDIES OF CM CHONDRITES METEORITE HILLS 00639 AND AGUAS ZARCAS. J. Davidson1, C. M. O’D. Alexander2, A. J. King3,4, H. C. Bates4, D. I. Foustoukos5, D. L. Schrader1, E. S. Bullock5, H. Busemann6, M. E. I. Riebe6, M. Schönbächler6, and P. Clay7. 1Center for Meteorite Studies, Arizona State University, 781 East Terrace Road, Tempe, AZ 85287-6004, USA (jdavidson@asu.edu). 2Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road, Washington, DC 20015, USA. 3Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK. 4Department of Earth Science, Natural History Museum (London), Cromwell Road, London SW7 5BD, UK. 5Geophysical Laboratory, Carnegie Institution for Science, 5251 Broad Branch Road, Washington, DC 20015, USA. 6Institute of Geochemistry and Petrology, ETH Zürich, CH-8092 Zürich, Switzerland. 7School of Earth and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, M13 9PL, UK.

CLUES AND CAUTIONS FROM ASTEROID 2008 TC3 AND THE ALMAHATA SITTA METEORITE. C. A. Goodrich1, M.E. Zolensky2, A.M. Fioretti3, M.H. Shaddad4, H. Downes5, T. Hiroi6, I. Kohl7, E.D. Young7, N.T. Kita8, V.E. Hamilton9, M. Riebe10, H. Busemann10, R.J. Macke11, M. Fries2, M. Sanborn12, Q-Z. Yin12, D.K. Ross13, P. Jenniskens14. 1Lunar and Planetary Institute, USRA, Houston TX 77058 USA (goodrich@lpi.usra.edu); 2ARES, NASA-JSC, Houston TX USA; 3CNR, Padova Italy; 4Univ. Khartoum, Khartoum Sudan; 5Birkbeck Univ. London, London UK; 6Brown Univ., Providence, RI USA; 7UCLA, Los Angeles, CA USA; 8Univ. Wisconsin, Madison, WI USA; 9SwRI, Boulder, CO USA; 10ETH, Zürich Switzerland; 11Specola Vaticana, Vatican City State; 12UC Davis, Davis, CA USA; 13Jacobs-JETS, NASA-JSC, Houston TX USA; 14SETI, Mountain View, CA USA.

Introduction: Despite the abundant presence of N in the insoluble organic matter (IOM) isolated from carbonaceous chondrites [1], very little is known about the change in N isotope systematics and speciation during IOM hydrothermal metamorphism [2,3]. Previous experimental studies have suggested the presence of labile N-functional groups during hydrothermal alteration [4,5]. Here, we present experimental data to address the effects of synthesis, aqueous alteration and thermal metamorphism on the N chemical and isotopic systematics in IOM from primitive chondritic meteorites. Experimental methods: Cold-sealed pressure vessel hydrothermal experiments were conducted at temperatures ranging from 250 °C to 450 °C at 500 bars to constrain the impact of hydrothermal alteration on the N chemical and isotopic composition of IOM extracted from Murchison (CM2) [1]. Reaction times varied from 210 to 3905 hours. To better understand the extent of 15 N14 N isotopic exchange between dissolved NH3(aq) and IOM, a set of experiments was performed in the presence of 15 N-enriched NH4-bearing aqueous solutions (δ 15 N +300 ‰). Details of the experimental and analytical protocols adopted have been presented previously [6]. In addition, synthesis experiments of IOM-analog material were performed (150 250 °C) to determine the degree of N incorporation in the structure of the organic residue. IOM analog material was synthesized hydrothermally in our lab by dextrose carbonization under vapor saturation pressures [7]. Reaction times varied from 0.5 to 241 hours. The reactant H2O solutions were enriched with NH4Cl (0.05-0.1 M) or KNO3 (0.5 M). A set of NH4Cl-bearing experiments were also conducted under acidic conditions (0.08 M HCl). To further constrain the mechanisms of N incorporation, a suite of 15 N-labelled experiments involved the addition of an NH4Cl solution with  15 N = 1564 ‰. We also conducted flash pyrolysis of Cold Bokkeveld (CM2,[1]) IOM as a means to distinguish between the effects of aqueous alteration and shock heating on the N chemical and isotopic evolution of chondritic IOM. Samples were flash heated in Ar-flow using a CDS 1000 pyroprobe to 400 °C, 600 °C, 800 °C, and 1000 °C respectively for 4s with a temperature increase of 500 °C/s to simulate atmospheric entry conditions. The elemental and isotopic analyses of these samples were performed with a Thermo Scientific Delta V Plus mass spectrometer and CE Instruments NA 2500 series elemental analyzer. Results and Discussion: Murchison-IOM: Results show that the N/C ratios in IOM decrease with increasing temperature (Fig. 1a), suggesting that N-functional groups, most likely N-H/amine groups, were released from the IOM into the aqueous solution. The evolved IOM also became progressively depleted in δ 15 N following a strong correlation with the inverse of the square of absolute temperature (Fig. 1b). Dissolved NH3(aq) was detected in the aliquot samples with δ 15 N compositions that are significantly enriched relative to the IOM. Thus, the experiments support the loss of labile 15 N-enriched N-H groups during alteration. In

1195. [12] Nagao K. et al. (2014) 77th MetSoc, Abstract #5204. [13] Leya I. and Masarik J. (2009) Meteorit-5204. [13] Leya I. and Masarik J. (2009) Meteoritics & Planetary Science, 44, 1061–1086. [14] Lodders K. and Fegley B. (1998) The planetary scientist’s companion. 2295.pdf 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083)