Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk

Kirsten Kolbjørn Larsen; Anne Marie-Pierre Emilie Trinquier; Chad Paton; Martin Schiller; Daniel Kim Peel Wielandt; Marina A. Ivanova; James Connelly; Åke Nordlund; Alexander N. Krot; Martin Bizzarro

doi:10.1088/2041-8205/735/2/L37

Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk

Kirsten Kolbjørn Larsen, Anne Marie-Pierre Emilie Trinquier, Chad Paton, Martin Schiller, Daniel Kim Peel Wielandt, Marina A. Ivanova, James Connelly, Åke Nordlund, Alexander N. Krot, Martin Bizzarro

Astrophysics and Planetary Science

197 Citations (Scopus)

Abstract

With a half-life of 0.73 Myr, the 26Al-to-26Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of 26Al–26Mg ages of meteorites and their components relies on the critical assumption that the canonical 26Al/27Al ratio of ~5 × 10-5 recorded by the oldest dated solids, calcium–aluminium-rich inclusions (CAIs), represents the initial abundance of 26 Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent 26Mg composition (µ26Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U–Pb and 26Al–26Mg ages of pristine solar system materials, we infer that the bulk of theµ26Mg* variability reflects heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk. We conclude that the canonical value of ~5 × 10-5 represents the average initial abundance of 26Al only in the CAI-forming region, and that large-scale heterogeneity—perhaps up to 80% of the canonical value—may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the 26Al–26Mg system as an accurate early solar system chronometer.

Original language	English
Article number	L37
Journal	The Astrophysical Journal Letters
Volume	735
Number of pages	7
DOIs	https://doi.org/10.1088/2041-8205/735/2/L37
Publication status	Published - 10 Jul 2011

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10.1088/2041-8205/735/2/L37

Cite this

@article{f4e81c7fdfe940ff8a7b3aca878ad209,

title = "Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk",

abstract = "With a half-life of 0.73 Myr, the 26Al-to-26Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of 26Al–26Mg ages of meteorites and their components relies on the critical assumption that the canonical 26Al/27Al ratio of ~5 × 10-5 recorded by the oldest dated solids, calcium–aluminium-rich inclusions (CAIs), represents the initial abundance of 26 Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent 26Mg composition (µ26Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U–Pb and 26Al–26Mg ages of pristine solar system materials, we infer that the bulk of theµ26Mg* variability reflects heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk. We conclude that the canonical value of ~5 × 10-5 represents the average initial abundance of 26Al only in the CAI-forming region, and that large-scale heterogeneity—perhaps up to 80% of the canonical value—may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the 26Al–26Mg system as an accurate early solar system chronometer.",

author = "Larsen, {Kirsten Kolbj{\o}rn} and Trinquier, {Anne Marie-Pierre Emilie} and Chad Paton and Martin Schiller and Wielandt, {Daniel Kim Peel} and Ivanova, {Marina A.} and James Connelly and {\AA}ke Nordlund and Krot, {Alexander N.} and Martin Bizzarro",

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doi = "10.1088/2041-8205/735/2/L37",

language = "English",

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TY - JOUR

T1 - Evidence for magnesium isotope heterogeneity in the solar protoplanetary disk

AU - Larsen, Kirsten Kolbjørn

AU - Trinquier, Anne Marie-Pierre Emilie

AU - Paton, Chad

AU - Schiller, Martin

AU - Wielandt, Daniel Kim Peel

AU - Ivanova, Marina A.

AU - Connelly, James

AU - Nordlund, Åke

AU - Krot, Alexander N.

AU - Bizzarro, Martin

PY - 2011/7/10

Y1 - 2011/7/10

N2 - With a half-life of 0.73 Myr, the 26Al-to-26Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of 26Al–26Mg ages of meteorites and their components relies on the critical assumption that the canonical 26Al/27Al ratio of ~5 × 10-5 recorded by the oldest dated solids, calcium–aluminium-rich inclusions (CAIs), represents the initial abundance of 26 Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent 26Mg composition (µ26Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U–Pb and 26Al–26Mg ages of pristine solar system materials, we infer that the bulk of theµ26Mg* variability reflects heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk. We conclude that the canonical value of ~5 × 10-5 represents the average initial abundance of 26Al only in the CAI-forming region, and that large-scale heterogeneity—perhaps up to 80% of the canonical value—may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the 26Al–26Mg system as an accurate early solar system chronometer.

AB - With a half-life of 0.73 Myr, the 26Al-to-26Mg decay system is the most widely used short-lived chronometer for understanding the formation and earliest evolution of the solar protoplanetary disk. However, the validity of 26Al–26Mg ages of meteorites and their components relies on the critical assumption that the canonical 26Al/27Al ratio of ~5 × 10-5 recorded by the oldest dated solids, calcium–aluminium-rich inclusions (CAIs), represents the initial abundance of 26 Al for the solar system as a whole. Here, we report high-precision Mg-isotope measurements of inner solar system solids, asteroids, and planets demonstrating the existence of widespread heterogeneity in the mass-independent 26Mg composition (µ26Mg*) of bulk solar system reservoirs with solar or near-solar Al/Mg ratios. This variability may represent heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk at the time of CAI formation and/or Mg-isotope heterogeneity. By comparing the U–Pb and 26Al–26Mg ages of pristine solar system materials, we infer that the bulk of theµ26Mg* variability reflects heterogeneity in the initial abundance of 26Al across the solar protoplanetary disk. We conclude that the canonical value of ~5 × 10-5 represents the average initial abundance of 26Al only in the CAI-forming region, and that large-scale heterogeneity—perhaps up to 80% of the canonical value—may have existed throughout the inner solar system. If correct, our interpretation of the Mg-isotope composition of inner solar system objects precludes the use of the 26Al–26Mg system as an accurate early solar system chronometer.

U2 - 10.1088/2041-8205/735/2/L37

DO - 10.1088/2041-8205/735/2/L37

M3 - Journal article

SN - 0004-637X

VL - 735

JO - Astrophysical Journal

JF - Astrophysical Journal

M1 - L37

ER -