J/ApJ/758/45 Isotopic Sr abundances in meteorites (Moynier+, 2012)
Planetary-scale strontium isotopic heterogeneity and the age of volatile
depletion of early solar system materials.
Moynier F., Day J.M.D., Okui W., Yokoyama T., Bouvier A., Walker R.J.,
Podosek F.A.
<Astrophys. J., 758, 45 (2012)>
=2012ApJ...758...45M 2012ApJ...758...45M
ADC_Keywords: Abundances ; Solar system
Keywords: astrochemistry; meteorites, meteors, meteoroids;
primordial nucleosynthesis
Abstract:
Isotopic anomalies in planetary materials reflect both early solar
nebular heterogeneity inherited from presolar stellar sources and
processes that generated non-mass-dependent isotopic fractionations.
The characterization of isotopic variations in heavy elements among
early solar system materials yields important insight into the stellar
environment and formation of the solar system, and about initial
isotopic ratios relevant to long-term chronological applications. One
such heavy element, strontium, is a central element in the geosciences
due to wide application of the long-lived 87Rb-87Sr radioactive as
a chronometer. We show that the stable isotopes of Sr were
heterogeneously distributed at both the mineral scale and the
planetary scale in the early solar system, and also that the Sr
isotopic heterogeneities correlate with mass-independent oxygen
isotope variations, with only CI chondrites plotting outside of this
correlation. The correlation implies that most solar system material
formed by mixing of at least two isotopically distinct components: a
CV-chondrite-like component and an O-chondrite-like component, and
possibly a distinct CI-chondrite-like component. The heterogeneous
distribution of Sr isotopes may indicate that variations in initial
87Sr/86Sr of early solar system materials reflect isotopic
heterogeneity instead of having chronological significance, as
interpreted previously. For example, given the differences in
84Sr/86Sr between calcium aluminum inclusions and eucrites
(εg84Sr>2), the difference in age between these materials
would be ∼6 Ma shorter than previously interpreted, placing the Sr
chronology in agreement with other long- and short-lived isotope
systems, such as U-Pb and Mn-Cr.
Description:
We report new high-precision Strontium isotope data obtained for
unspiked samples using a static measurement routine on two
ThermoFisher Triton TIMS instruments at the University of Maryland
(UMD) and Tokyo Institute of Technology (TT).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 45 145 Strontium isotopic abundance ratios
table2.dat 101 36 Strontium isotopic composition of terrestrial
samples and meteorites
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See also:
J/ApJ/748/L25 : Li-Be-B measurements using SIMS (Wielandt+, 2012)
J/ApJ/743/L23 : 48Ca heterogeneity in differentiated meteorites (Chen+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Sample Sample name
15 I1 --- S [1/3] Session number
17- 21 A5 --- Loc Location (Tokyo or UMD=University of Maryland)
23- 33 F11.9 --- 87Sr/86Sr [0.69/0.77] The 87Sr to 86Sr isotopic
abundance
35- 45 F11.9 --- 84Sr/86Sr [0.0564/0.0565] The 84Sr to 86Sr isotopic
abundance
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 42 A42 --- Group Meteorite group (1)
44- 60 A17 --- Sample Sample name
62- 81 A20 --- Type Chondrite type
83- 88 A6 --- Loc Place of analysis (TT=Tokyo Tech, or
UMD=University of Maryland)
90- 94 F5.2 --- e84Sr [-0.5/2.1] ε84Sr value (3)
96- 99 F4.2 --- e_e84Sr [0.04/0.8] Standard Error (2xSE)
101 I1 --- N [1/7]? Number of replicated measurements
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Note (1): Weighted average of e84Sr for each meteorite group is highlited in
this column by the indication in parenthesis.
Note (3): ε = part per 10000 deviations from the terrestrial value.
ε84Sr=[(84Sr/86Sr)samples/(84Sr/86Sr)SRM-987-1]x10000.
84Sr/86Sr is normalized to 88Sr/86Sr=8.375209.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 03-Jul-2014