Organic matter in carbonaceous chondrite lithologies of Almahata Sitta: Incorporation of previously unsampled carbonaceous chondrite lithologies into ureilitic regolith

Abstract

The Almahata Sitta (AhS) meteorite is a unique polymict ureilite. Recently, carbonaceous chondritic lithologies were identified in AhS. Organic matter (OM) is ubiquitously found in primitive carbonaceous chondrites. The molecular and isotopic characteristics of this OM reflect its origin and parent body processes, and are particularly sensitive to heating. The C1 lithologies AhS 671 and AhS 91A were investigated, focusing mainly on the OM. We found that the OM in these lithologies is unique and contains primitive isotopic signatures, but experienced slight heating possibly by short-term heating event(s). These characteristics support the idea that one or more carbonaceous chondritic bodies were incorporated into the ureilitic parent body. The uniqueness of the OM in the AhS samples implies that there were large variations in primitive carbonaceous chondritic materials in the solar system other than known primitive carbonaceous chondrite groups such as CI, CM, and CR chondrites.

The nucleosynthetic fingerprint of the outermost protoplanetary disk and early Solar System dynamics

“…These data points form a mixing line between two endmembers. One endmember is relatively D-rich, 13 C-depleted, and 15 N-depleted organic matter that falls on the line predicted for organic matter derived from cold ion-molecule reactions in the ISM (30). Moreover, this correlated D-rich and 13 C-depleted composition is also consistent with H and C isotope trends from chemical reaction networks in dense prestellar cores (32).…”

“…We show in Fig. 3 the distribution of 15 N, D, and 13 C in the bulk maps; the carbon-rich regions; and the most 15 N-and D-rich regions. We observe a general decrease in 15 N with increasing carbon content (using 12 C 14 N as a proxy) and show that the most 15 N-rich regions essentially coat the carbon-rich material.…”

“…Their Mg and Cr isotope compositions suggest a genetic link to comets (10). Moreover, in addition to potential outer disk xenolithic fragments from non-carbonaceous chondrites (11)(12)(13)(14)(15)(16), the material of outer disk origin has been previously identified in a CR chondrite (17). Thus, we conducted a systematic search for outer disk material in the primitive CR chondrite North West Africa (NWA) 14250, which contains abundant millimeter-to centimetersized dark clasts (i.e., pebble-shaped, chondritic material unrelated to the host body) (18).…”

Heterogeneous nature of the carbonaceous chondrite breccia Aguas Zarcas – Cosmochemical characterization and origin of new carbonaceous chondrite lithologies

“…On the other hand, particle-like OM could be synthesized in the parent body from simple molecules such as formaldehyde and ammonia in the presence of liquid water with moderate concentrations (Cody et al, 2011;Kebukawa et al, 2013). In this scenario, the δD and δ 15 N values of OM would depend on the isotopic compositions of the original molecules as well as of the liquid water (Kebukawa et al, 2021).…”

Prospects required for future light-source facilities: a case of UVSOR synchrotron facility

“…As part of developing the analysis and evaluation, spectroscopic imaging techniques have been developed internationally in various fields, and as a pioneer, scanning transmission x-ray microscopy (STXM) applicable to the soft matter has been developed in UVSOR. To meet the recent demand for operand measurement, STXM is being further enhanced to apply to complex and heterogeneous systems [7][8][9][10][11][12][13][14][15]. In FY2020, we started the development of imaging for photoelectron spectroscopy.…”