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Titanium isotopes and rare earth patterns in CAIs: Evidence for thermal processing and gas-dust decoupling in the protoplanetary disk

Davis, Andrew M. and Zhang, Junjun and Greber, Nicolas D. and Hu, Jingya and Tissot, François L. H. and Dauphas, Nicolas (2018) Titanium isotopes and rare earth patterns in CAIs: Evidence for thermal processing and gas-dust decoupling in the protoplanetary disk. Geochimica et Cosmochimica Acta, 221 . pp. 275-295. ISSN 0016-7037. https://resolver.caltech.edu/CaltechAUTHORS:20180613-152623011

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Abstract

Titanium isotopic compositions (mass-dependent fractionation and isotopic anomalies) were measured in 46 calcium-, aluminum-rich inclusions (CAIs) from the Allende CV chondrite. After internal normalization to ^(49)Ti/^(47)Ti, we found that ε^(50)Ti values are somewhat variable among CAIs, and that ε^(46)Ti is highly correlated with ε^(50)Ti, with a best-fit slope of 0.162 ± 0.030 (95% confidence interval). The linear correlation between ε^(46)Ti and ε^(50)Ti extends the same correlation seen among bulk solar objects (slope 0.184 ± 0.007). This observation provides constraints on dynamic mixing of the solar disk and has implications for the nucleosynthetic origin of titanium isotopes, specifically on the possible contributions from various types of supernovae to the solar system. Titanium isotopic mass fractionation, expressed as δ′^(49)Ti, was measured by both sample-standard bracketing and double-spiking. Most CAIs are isotopically unfractionated, within a 95% confidence interval of normal, but a few are significantly fractionated and the range δ′^(49)Ti is from ∼−4 to ∼+4. Rare earth element patterns were measured in 37 of the CAIs. All CAIs with significant titanium mass fractionation effects have group II and related REE patterns, implying kinetically controlled volatility fractionation during the formation of these CAIs.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.gca.2017.07.032DOIArticle
ORCID:
AuthorORCID
Tissot, François L. H.0000-0001-6622-2907
Additional Information:© 2017 Elsevier Ltd. Received 25 February 2017, Accepted 19 July 2017, Available online 27 July 2017. This paper is dedicated to the memory of Ernst Zinner, who, among his many accomplishments, was a pioneer in studying titanium isotope anomalies in CAIs and presolar grains. We thank Curtis Williams and an anonymous reviewer for their careful and constructive reviews. This work was supported by the U.S. National Aeronautics and Space Administration, through grants NNX09AG39G and NNX15AF78G to AMD and NNX12AH60G to ND, and by the U.S. National Science Foundation, through grant EAR1144429 to ND.
Funders:
Funding AgencyGrant Number
NASANNX09AG39G
NASANNX15AF78G
NASANNX12AH60G
NSFEAR-1144429
Subject Keywords:Calcium-aluminum-rich inclusions (CAIs); Titanium isotopic composition; Heterogeneity; Supernovae; Protoplanetary disk
Record Number:CaltechAUTHORS:20180613-152623011
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180613-152623011
Official Citation:Andrew M. Davis, Junjun Zhang, Nicolas D. Greber, Jingya Hu, François L.H. Tissot, Nicolas Dauphas, Titanium isotopes and rare earth patterns in CAIs: Evidence for thermal processing and gas-dust decoupling in the protoplanetary disk, Geochimica et Cosmochimica Acta, Volume 221, 2018, Pages 275-295, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2017.07.032. (http://www.sciencedirect.com/science/article/pii/S0016703717304568)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87085
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:13 Jun 2018 22:38
Last Modified:03 Oct 2019 19:52

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