TY - JOUR
T1 - Titanium and chromium isotopic compositions of calcium-aluminum-rich inclusions
T2 - Implications for the sources of isotopic anomalies and the formation of distinct isotopic reservoirs in the early Solar System
AU - Torrano, Zachary A.
AU - Brennecka, Gregory A.
AU - Mercer, Cameron M.
AU - Romaniello, Stephen J.
AU - Rai, Vinai K.
AU - Hines, Rebekah R.
AU - Wadhwa, Meenakshi
N1 - Funding Information:
We thank the Buseck Center for Meteorite Studies at ASU for providing the CAI samples studied here. We are especially grateful to Laurence Garvie for his assistance with the selection and acquisition of the samples from which these CAIs were obtained. This work was supported by NASA grant NNX15AH41G to M. W. The contributions of G. A. B. to this study were performed under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 with release number LLNL-JRNL-836804. We thank A. M. Davis and an anonymous reviewer for their constructive reviews and Liping Qin for her editorial handling during the review process.
Funding Information:
We thank the Buseck Center for Meteorite Studies at ASU for providing the CAI samples studied here. We are especially grateful to Laurence Garvie for his assistance with the selection and acquisition of the samples from which these CAIs were obtained. This work was supported by NASA grant NNX15AH41G to M. W. The contributions of G. A. B. to this study were performed under the auspices of the US DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 with release number LLNL-JRNL-836804. We thank A. M. Davis and an anonymous reviewer for their constructive reviews and Liping Qin for her editorial handling during the review process.
Publisher Copyright:
© 2023 Elsevier Ltd
PY - 2023/5/1
Y1 - 2023/5/1
N2 - As the earliest-dated solids in our Solar System, calcium-aluminum-rich inclusions (CAIs) provide a record of their formation environment near the young Sun and hold clues to the formation of planetary-scale isotopic reservoirs in the solar protoplanetary disk. Although CAIs from several CV, CK, CM, CO, and ordinary chondrites have been analyzed previously for their Ti isotopic compositions, CAIs from just three CV chondrites have been analyzed for their Cr isotopic compositions, and only a handful of CAIs have been measured for both their Ti and Cr isotopic compositions. We report mass-independent Ti and Cr isotopic anomalies in several CAIs from CV and CK chondrites; this is the first report of the Cr isotopic composition of a CAI from a CK chondrite. With these additional data, we aim to better constrain the compositional range of CAIs in ε50Ti versus ε54Cr space, thereby facilitating the isotopic characterization of the material inherited by the solar protoplanetary disk and the role of CAIs in the formation of distinct planetary-scale isotopic reservoirs in our early Solar System. The narrow range in isotopic anomalies in CAIs when compared to other early-formed refractory inclusions such as platy hibonite crystals (PLACs) and spinel-hibonite inclusions (SHIBs) suggests that CAIs record the mixing of these precursor materials and the averaging of their larger isotopic anomalies. The isotopic composition of CAIs is therefore likely the result of a combination of factors, including mixing of material inherited from their formation region, heterogeneous carrier phase distribution, and thermal processing in the disk. The ε50Ti and ε54Cr isotopic compositions of CAIs are not correlated, further demonstrating that these isotopic anomalies have different carrier phases. The Ti and Cr isotopic compositions of CAIs additionally show that CAIs alone cannot be responsible for the compositional difference between the non-carbonaceous chondritic (NC) and carbonaceous chondritic (CC) isotopic reservoirs but nevertheless do play a role in the formation of these large-scale isotopic reservoirs in the early Solar System.
AB - As the earliest-dated solids in our Solar System, calcium-aluminum-rich inclusions (CAIs) provide a record of their formation environment near the young Sun and hold clues to the formation of planetary-scale isotopic reservoirs in the solar protoplanetary disk. Although CAIs from several CV, CK, CM, CO, and ordinary chondrites have been analyzed previously for their Ti isotopic compositions, CAIs from just three CV chondrites have been analyzed for their Cr isotopic compositions, and only a handful of CAIs have been measured for both their Ti and Cr isotopic compositions. We report mass-independent Ti and Cr isotopic anomalies in several CAIs from CV and CK chondrites; this is the first report of the Cr isotopic composition of a CAI from a CK chondrite. With these additional data, we aim to better constrain the compositional range of CAIs in ε50Ti versus ε54Cr space, thereby facilitating the isotopic characterization of the material inherited by the solar protoplanetary disk and the role of CAIs in the formation of distinct planetary-scale isotopic reservoirs in our early Solar System. The narrow range in isotopic anomalies in CAIs when compared to other early-formed refractory inclusions such as platy hibonite crystals (PLACs) and spinel-hibonite inclusions (SHIBs) suggests that CAIs record the mixing of these precursor materials and the averaging of their larger isotopic anomalies. The isotopic composition of CAIs is therefore likely the result of a combination of factors, including mixing of material inherited from their formation region, heterogeneous carrier phase distribution, and thermal processing in the disk. The ε50Ti and ε54Cr isotopic compositions of CAIs are not correlated, further demonstrating that these isotopic anomalies have different carrier phases. The Ti and Cr isotopic compositions of CAIs additionally show that CAIs alone cannot be responsible for the compositional difference between the non-carbonaceous chondritic (NC) and carbonaceous chondritic (CC) isotopic reservoirs but nevertheless do play a role in the formation of these large-scale isotopic reservoirs in the early Solar System.
KW - CAIs
KW - Carbonaceous chondrites
KW - Chromium
KW - Early solar system
KW - Isotopes
KW - Nucleosynthetic anomalies
KW - Titanium
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U2 - 10.1016/j.gca.2023.03.018
DO - 10.1016/j.gca.2023.03.018
M3 - Article
AN - SCOPUS:85151877599
SN - 0016-7037
VL - 348
SP - 309
EP - 322
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -