Nucleosynthetic Tungsten Isotope Anomalies in Acid Leachates of the Murchison Chondrite: Implications for Hafnium-Tungsten Chronometry

Burkhardt, C.; Kleine, T.; Dauphas, N.; Wieler, R.

doi:10.1088/2041-8205/753/1/l6

Cited by 80 publications

(94 citation statements)

References 35 publications

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“…These two intercept values are distinct from the inferred Solar System initial μ 182 W value of -351 ± 10 ppm (18) 26 Al-poor FUN CAIs, is coeval with canonical CAIs within the uncertainty of our measurements. These results are consistent with the proposal that 182 Hf was homogeneously distributed in the solar protoplanetary disk at the time of formation of the Solar System's first solids (16)(17)(18).…”

Section: Resultssupporting

confidence: 91%

“…With a half-life of ∼9 Ma, the 182 Hf-to-182 W decay scheme is one of the most widely used chronometers to understand the timing of solid formation in the early Solar System (15). In addition, currently available data support the proposal that the 182 Hf nuclide was uniformly distributed in the early Solar System with an initial 182 Hf/ 180 Hf ratio of (9.85 ± 0.40) × 10 −5 (16)(17)(18). First, the 182 Hf-182 W isochron of canonical CAIs intersects the carbonaceous chondritic composition, suggesting that the precursor material of primitive asteroids that presumably accreted in the outer Solar System had similar initial 182 Hf content as CAIs (16).…”

Section: Resultsmentioning

confidence: 99%

“…Samples were analyzed only once, and the ratios are reported as relative deviations from the mass-bias corrected NIST 3163 tungsten reference material in the μ-notation (10 6 deviations). A blank correction (17,18,35,36).…”

Section: Methodsmentioning

confidence: 99%

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¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

Holst

Olsen

Paton

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Refractory inclusions [calcium–aluminum-rich inclusions, (CAIs)] represent the oldest Solar System solids and provide information regarding the formation of the Sun and its protoplanetary disk. CAIs contain evidence of now extinct short-lived radioisotopes (e.g., 26 Al, 41 Ca, and 182 Hf) synthesized in one or multiple stars and added to the protosolar molecular cloud before or during its collapse. Understanding how and when short-lived radioisotopes were added to the Solar System is necessary to assess their validity as chronometers and constrain the birthplace of the Sun. Whereas most CAIs formed with the canonical abundance of 26 Al corresponding to 26 Al/ 27 Al of ∼5 × 10 −5 , rare CAIs with fractionation and unidentified nuclear isotope effects (FUN CAIs) record nucleosynthetic isotopic heterogeneity and 26 Al/ 27 Al of <5 × 10 −6 , possibly reflecting their formation before canonical CAIs. Thus, FUN CAIs may provide a unique window into the earliest Solar System, including the origin of short-lived radioisotopes. However, their chronology is unknown. Using the 182 Hf– 182 W chronometer, we show that a FUN CAI recording a condensation origin from a solar gas formed coevally with canonical CAIs, but with 26 Al/ 27 Al of ∼3 × 10 −6 . The decoupling between 182 Hf and 26 Al requires distinct stellar origins: steady-state galactic stellar nucleosynthesis for 182 Hf and late-stage contamination of the protosolar molecular cloud by a massive star(s) for 26 Al. Admixing of stellar-derived 26 Al to the protoplanetary disk occurred during the epoch of CAI formation and, therefore, the 26 Al– 26 Mg systematics of CAIs cannot be used to define their formation interval. In contrast, our results support 182 Hf homogeneity and chronological significance of the 182 Hf– 182 W clock.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

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¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

Holst

Olsen

Paton

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…This marked change at A ∼ 140 suggests a fundamental difference between the creation mechanism of r-process isotopes A < 140 and isotopes A > 140. Additionally, another similar change may occur in heavier elements (A ∼ 180), as shown by apparent r-process excesses reported in W (26). These data provide physical evidence for the decoupling of r-process nucleosynthesis-in which the production of the r-process isotope is controlled by mass.…”

Section: Resultssupporting

confidence: 71%

Evidence for supernova injection into the solar nebula and the decoupling of r -process nucleosynthesis

Brennecka

Borg

Wadhwa

2013

Proc. Natl. Acad. Sci. U.S.A.

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The isotopic composition of our Solar System reflects the blending of materials derived from numerous past nucleosynthetic events, each characterized by a distinct isotopic signature. We show that the isotopic compositions of elements spanning a large mass range in the earliest formed solids in our Solar System, calcium-aluminum-rich inclusions (CAIs), are uniform, and yet distinct from the average Solar System composition. Relative to younger objects in the Solar System, CAIs contain positive r-process anomalies in isotopes A < 140 and negative r-process anomalies in isotopes A > 140. This fundamental difference in the isotopic character of CAIs around mass 140 necessitates (i) the existence of multiple sources for r-process nucleosynthesis and (ii) the injection of supernova material into a reservoir untapped by CAIs. A scenario of late supernova injection into the protoplanetary disk is consistent with formation of our Solar System in an active star-forming region of the galaxy.isotopic anomalies | early Solar System | H-Event | nebular disk O ur knowledge of the formation and evolution of our Solar System principally comes from (i) astrophysical observations, which provide views of other nascent stellar systems; (ii) theoretical models, which provide constraints in such systems; and (iii) direct evidence gathered from the study of meteorites that sample the earliest epoch of Solar System history. However, the details about the galactic environment in which our Solar System formed are still a matter of intense debate. Central to this effort is the study of short-lived radionuclides and nucleosynthetic anomalies found in meteorites, which constrain if, how much, and when our Solar System was injected with supernova material. This present work centers on the stable isotope signatures of the Solar System's earliest solids to unravel the earliest events that occurred after the birth of our Solar System.The elemental and isotopic composition of our Solar System reflects a mixture of materials derived from nucleosynthetic reactions in past generations of stellar environments. Isotopes of elements heavier than nickel are produced by three principal mechanisms: the p-, s-, and r-processes (1, 2). The p-process creates isotopes through photodisintegration, proton capture, and neutrino reactions in supernovae, forming neutron-deficient nuclei. The s-process occurs from slow neutron addition in asymptotic giant branch stars, in which isotope production moves up the "valley of stability" through neutron addition to create isotopes that are either stable or β-decay to stable isotopes. Rapid neutron addition, better known as the r-process, occurs in the extremely high neutron densities found in supernovae. The r-process creates neutron-rich, radioactive isotopes that β-decay to stability, resulting in neutron-rich stable isotopes. Thus, for elements heavier than Ni, the combination of the p-, s-, and r-processes of nucleosynthesis is ultimately responsible for the isotope abundances present in all Solar System materials. A...

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“…The intercept of the Burkhardt et al (2008) isochron was e 182 W 0 ¼ À3.28 AE 0.12. Burkhardt et al (2012) measured tungsten isotopic compositions of leachates from the Murchison CM chondrite. The covariation of isotope ratios in leachates provided a way to correct measured 182 W anomalies using 183 W/ 184 W ratios.…”

Section: Hafnium-182mentioning

confidence: 99%

Short-Lived Radionuclides and Early Solar System Chronology

Davis

McKeegan

2014

Treatise on Geochemistry

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Nucleosynthetic Tungsten Isotope Anomalies in Acid Leachates of the Murchison Chondrite: Implications for Hafnium-Tungsten Chronometry

Abstract: ABSTRACT

Cited by 80 publications

References 35 publications

¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

Evidence for supernova injection into the solar nebula and the decoupling of r -process nucleosynthesis

Short-Lived Radionuclides and Early Solar System Chronology

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Nucleosynthetic Tungsten Isotope Anomalies in Acid Leachates of the Murchison Chondrite: Implications for Hafnium-Tungsten Chronometry

Abstract: ABSTRACT

Cited by 80 publications

References 35 publications

182 Hf– 182 W age dating of a 26 Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

182 Hf– 182 W age dating of a 26 Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

Evidence for supernova injection into the solar nebula and the decoupling of r -process nucleosynthesis

Short-Lived Radionuclides and Early Solar System Chronology

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Product

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¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System

¹⁸² Hf– ¹⁸² W age dating of a ²⁶ Al-poor inclusion and implications for the origin of short-lived radioisotopes in the early Solar System