https://repository.kopri.re.kr/handle/201206/5225 2026-03-11T12:28:44Z https://repository.kopri.re.kr/handle/201206/6266 Title: A multielement isotopic study of refractory FUN and F CAIs: Mass-dependent and mass-independent isotope effects Authors: Levke Koop; Andrew M. Davis; Park, Changkun; Kazuhide Nagashima; Alexander N. Krot; Travis J.Tenner; Noriko T. Kita; Philipp R. Heck; Daisuke Nakashima Abstract: Calcium-aluminum-rich inclusions (CAIs) are the oldest dated objects that formed inside the Solar System. Among these are rare, enigmatic objects with large mass-dependent fractionation effects (F CAIs), which sometimes also have large nucleosynthetic anomalies and a low initial abundance of the short-lived radionuclide 26Al (FUN CAIs). We have studied seven refractory hibonite-rich CAIs and one grossite-rich CAI from the Murchison (CM2) meteorite for their oxygen, calcium, and titanium isotopic compositions. The 26Al-26Mg system was also studied in seven of these CAIs. We found mass-dependent heavy isotope enrichment in all measured elements, but never simultaneously in the same CAI. The data are hard to reconcile with a single-stage melt evaporation origin and may require isotopic reintroduction or reequilibration for magnesium, oxygen and titanium after evaporation for some of the studied CAIs. The initial 26Al/27Al ratios inferred from model isochrons span a range from approximately zero to canonical (~5×10？5). The CAIs show a mutual exclusivity relationship between inferred incorporation of live 26Al and the presence of resolvable anomalies in 48Ca and 50Ti. Further-more, a relationship exists between 26Al incorporation and ？17O (i.e., 26Al-free CAIs have re-solved variations in ？17O, while all CAIs with resolved 26Mg excesses have ？17O values close to ？23‰). We interpret these data as indicating that fractionated hibonite-rich CAIs formed over an extended time period and sampled multiple stages in the isotopic evolution of the solar nebula, including (1) an 26Al-poor nebula with large positive and negative anomalies in 48Ca and 50Ti and variable ？17O, (2) a stage of 26Al-admixture, during which anomalies in 48Ca and 50Ti had been largely diluted and a ？17O value of ~ ？23‰ had been achieved in the CAI formation region, and (3) a nebula with an approximately canonical level of 26Al and a ？17O value of ~ ？23‰ in the CAI formation region. 2018-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/7519 Title: Redistribution of Sr and rare earth elements in the matrices of CV3 carbonaceous chondrites during aqueous alteration in their parent body Authors: JOGOKAORI; Lee, Jong Ik; Sachio Kobayashi; Tomoki Nakamura; Motoo Ito Abstract: We measured the abundances of Sr and rare earth elements (REEs) in the matrices of five CV3 carbonaceous chondrites:;Meteorite Hills (MET) 00430, MET 01070, La Paz icefield (LAP) 02206, Asuka (A) 881317 and Roberts Massif (RBT) 04143. In the MET 00430 and MET 01074 matrices, the 23 Sr/CI and light REE (LREE, La-Nd)/CI ratios positively correlate with the amounts of Ca-rich secondary minerals, which formed during aqueous alteration in the CV3 chondrite parent body. In contrast, in the LAP 02206 and RBT 04143 matrices, although the Sr/CI ratios correlate with the amounts of Ca-rich secondary minerals, the LREE/CI ratios vary independently from the amounts of any secondary minerals. This suggests that the LREE/CI ratios in these matrices would bewere produced prior to the parent body alteration, probably in the solar nebula. The LREE/CI ratios of the LAP 02206 and RBT 04143 matrices reveal the mixing process of matrix minerals prior to the accretion of the CV3 chondrite parent body. The mixing degrees of matrix minerals might be different between these two matrices. Because solid materials would be mixed with over time according to the radial diffusion model of a turbulent disk, the matrix minerals consisting of LAP 02206 and RBT 04143 matrices might be incorporated into their parent body at with different timing. 2018-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12387 Title: Effect of Thermal Metamorphism on Noble Gas of Carbonaceous Chondrites: Comparison of Vigarano (CV3) and Maralinga (CK4). Authors: Choi, Jisu; Nagao, Keisuke; Baek, Jongmin; Lee, Jong Ik Abstract: Introduction: Noble gas isotopic and elemental compositions of meteorites are result of formation and evolution processes of solar system. Primitive chon-drites have various components of noble gases such as HL, G, and N from presolar grains, Q gas, solar gas, and in-situ components like radiogenic, fissiogenic, and cosmogenic noble gases. Otherwise, metamor-phosed chondrites lost their gases during thermal event, and most of noble gases including gases of presolar grains were disappeared at that time. Subsolar compo-nent is primordial noble gas that can be seen in some chondrites including metamorphosed ones [1-7]. It constrains formation process of parent body of meteorites affected by solar gases from Sun [4,5]. Example is enstatite chondrite whose noble gas component is represented as subsolar [6,7]. In carbonaceous chondrites, it is not well studied because it is not a major component unlike that in enstatite chondrites. We present noble gas compositions of Vigarano CV3 and Maralinga CK4 chondrites. Maralinga has 50:50 chondrules to matrix ratio similar with reduced CV3 chondrites [8]. In this study, changes of noble gas composition resulted from thermal metamorphism are discussed by comparing noble gases of the two carbo-naceous chondrites. Experimental method: Noble gas abundances and isotopic ratios of Vigarano and Maralinga were meas-ured with modified VG-5400 at Korea Polar Research Institute (KOPRI). Bulk samples weighing 22.34 mg of Vigarano and 313.5 mg of Maralinga were prepared for stepwise heating analyses from 400°C to 1800°C per increasing 100°C step. 500 and 1700°C steps of Maralinga were skipped. Released gases were purified by two Ti-Zr getters and two SAES getters before intro-ducing them into the mass spectrometer. All-noble gases were measured, and blank levels were lower than 1% of released noble gases of each heating step except 500 and 1800°C of Vigarano. 1800°C step of Vigarano is not presented as abundance of it is comparable with blank level in all noble gases. Results and discussion: Cosmogenic component of Xe in Vigarano and Maralinga is neglected in this study. Proportion of cosmogenic 130Xe and 132Xe is 0.3 and 0.04 percent of total 130Xe and 132Xe of Maralinga. In case of Vigarano, it is much smaller than that of Maralinga due to its high abundance of trapped com-ponents. Xe isotopic ratios and elemental ratios of trapped heavy noble gases. Fig. 1 is a plot of 130Xe/132Xe vs. 136Xe/132Xe of Vigarano and Maralinga. Xe of low heating steps of both samples is affected by Earth atmosphere, as clearly indicated in step 4 of Vigarano and steps 4-8 of Maralinga. Weathering of Maralinga was classified as Bx, indicating moderate degree of weathering with presence of carbonates derived from the local country rock [8]. Several steps of Maralinga showing atmospheric isotopic ratio coincides with ob-servation of terrestrial weathering. It is also can be seen in Fig. 2. Steps 4-10 of Maralinga show elementally fractionated air. Higher heating steps of Maralinga tend toward Q. Xe isotopic ratios of those steps are plotted between Q-HL-fission derived Xe with 136Xe/132Xe as 0.33-0.34 (Fig. 1). Xe isotope distribution of Maralinga (Fig. 1) represents that Xe-Q and Xe-HL are released together, and it is suggested that retrapping of HL gas on phase Q during thermal metamorphism [9]. Whereas 136Xe/132Xe of Vigarano ranges 0.32-0.39, and presolar diamond of Vigarano containing HL was separated by [15]. Heavy elements are less elementally fractionated from solar gases in steps 10-13 of Vigarano on Fig. 2, though Xe isotopic ratios of those steps are not different from Q for 11-13 steps, same with previous studies [5,7]. Release pattern of primordial 132Xe. Fig. 3 is re-leased pattern of primordial 132Xe of Vigarano and Maralinga. Primordial Xe is calculated by subtracting atmospheric contamination and fission derived Xe, and includes Q, subsolar, and HL. 2018-01-01T00:00:00Z https://repository.kopri.re.kr/handle/201206/12604 Title: Confocal Raman spectroscopic study on minerals in chondrite Authors: Park, Sun Young; Park, Changkun; Lee, Jong Ik Abstract: Confocal Raman spectroscopy has been effective in unveiling strucutres of local area of the sample using a pinhole aperture, which removes signals from out-of-focus. Raman is also among the non-destructive probes wihch provides information from surface to depth. If the surface to be analyzed is out of focus, the spectrum appears from surrounding and/or under surface minerals. In this study, we introduce the application of confocal Raman spectroscopy on minerals in meteorite. The Raman experiments were performed at Thermo Fisher Scientific Korea with a DXR2xi equipped with a spectra physics argon ion laser and using 532 nm excitation. The laser beam was focused on the samples by a 100 X objective, leading to a ~1 μm diameter spot. The power of the laser was tuned as 9.1 mW (on the sample surface, measured out of a 10 X objective). Acquisition consisted of ~0.2 s exposer time with 600 scans. We provide well-resolved spectrum of local area of sample using confocal Raman spectroscopy without overlap with other peaks. We also probe the phase of mineral under surface using depth profiling. While the Raman spectrum of plagioclase in chondrule of Antarctic chondrite show the complex peaks including that of olivine and pyroxene without confocal analysis, that of plagioclase are only observed with confocal analysis. The depth profiling results with 0.6 μm step size show that the peak intensity of pyroxene increases with increasing depth. The phase change with depth can be determined without damage of the samples using confocal Raman spectroscopy. 2018-01-01T00:00:00Z