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Hu Y, Moynier F, Bizzarro M. Potassium isotope heterogeneity in the early Solar System controlled by extensive evaporation and partial recondensation. Nat Commun 2022; 13:7669. [PMID: 36509778 PMCID: PMC9744853 DOI: 10.1038/s41467-022-35362-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 11/28/2022] [Indexed: 12/14/2022] Open
Abstract
Volatiles are vital ingredients for a habitable planet. Angrite meteorites sample the most volatile-depleted planetesimal in the Solar System, particularly for the alkali elements. They are prime targets for investigating the formation of volatile-poor rocky planets, yet their exceptionally low volatile content presents a major analytical challenge. Here, we leverage improved sensitivity and precision of K isotopic analysis to constrain the mechanism of extreme K depletion (>99.8%) in angrites. In contrast with the isotopically heavy Moon and Vesta, we find that angrites are strikingly depleted in the heavier K isotopes, which is best explained by partial recondensation of vaporized K following extensive evaporation on the angrite parent body (APB) during magma-ocean stage. Therefore, the APB may provide a rare example of isotope fractionation controlled by condensation, rather than evaporation, at a planetary scale. Furthermore, nebula-wide K isotopic variations primarily reflect volatility-driven fractionations instead of presolar nucleosynthetic heterogeneity proposed previously.
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Affiliation(s)
- Yan Hu
- grid.9489.c0000 0001 0675 8101Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, UMR 7154, Paris, 75005 France
| | - Frédéric Moynier
- grid.9489.c0000 0001 0675 8101Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, UMR 7154, Paris, 75005 France
| | - Martin Bizzarro
- grid.9489.c0000 0001 0675 8101Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, UMR 7154, Paris, 75005 France ,grid.5254.60000 0001 0674 042XStarPlan - Centre for Star and Planet Formation, GLOBE Institute, University of Copenhagen, Øster Voldgade 5-7, Copenhagen, DK-1350 Denmark
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2
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Abstract
Recent isotopic and paleomagnetic data point to a possible connection between carbonaceous chondrites and differentiated planetary materials, suggesting the existence, perhaps ephemeral, of transitional objects with a layered structure whereby a metal-rich core is enclosed by a silicate mantle, which is itself overlain by a crust containing an outermost layer of primitive solar nebula materials. This idea has not received broad support, mostly because of a lack of samples in the meteoritic record that document incipient melting at the onset of planetary differentiation. Here, we report the discovery and the petrologic-isotopic characterization of UH154-11, a ferroan trachybasalt fragment enclosed in a Renazzo-type carbonaceous chondrite (CR). Its chemical and oxygen isotopic compositions are consistent with very-low-degree partial melting of a Vigarano-type carbonaceous chondrite (CV) from the oxidized subgroup at a depth where fluid-assisted metamorphism enhanced the Na content. Its microdoleritic texture indicates crystallization at an increasing cooling rate, such as would occur during magma ascent through a chondritic crust. This represents direct evidence of magmatic activity in a carbonaceous asteroid on the verge of differentiating and demonstrates that some primitive outer Solar System objects related to icy asteroids and comets underwent a phase of magmatic activity early in the Solar System. With its peculiar petrology, UH154-11 can be considered the long-sought first melt produced during partial differentiation of a carbonaceous chondritic planetary body, bridging a previously persistent gap in differentiation processes from icy cometary bodies to fully melted iron meteorites with isotopic affinities to carbonaceous chondrites.
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Gao T, Ke S, Li R, Meng X, He Y, Liu C, Wang Y, Li Z, Zhu JM. High-precision magnesium isotope analysis of geological and environmental reference materials by multiple-collector inductively coupled plasma mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2019; 33:767-777. [PMID: 30577069 DOI: 10.1002/rcm.8376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/17/2018] [Accepted: 12/17/2018] [Indexed: 06/09/2023]
Abstract
RATIONALE High-precision magnesium (Mg) isotopic analysis for geological and environmental reference materials is a prerequisite to ensure data quality before using Mg isotopes to trace geochemical and environmental processes. However, the Mg-isotopic ratios of many commonly used reference materials, especially sediments, have rarely been reported. Furthermore, published values for some commonly used reference materials exhibit a significant inconsistency across laboratories and thus need more data comparison. METHODS We developed different Mg purification schemes for silicate rocks, high-Ca carbonates and carbonatites, and high-Mn samples because of their significantly different matrices. We then used synthetic solutions to evaluate potential effects on measurement using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The accuracy and precision of our procedures were assessed by measurement on both synthetic solutions and well-studied geostandards. RESULTS The three different schemes for routine, high-Ca, and high-Mn samples can remove matrices efficiently with nearly 100% Mg yield. However, the presence of acid molarity and concentration mismatch, matrix elements, and fluctuations in room temperature can significantly affect the precision and accuracy of Mg isotope analysis, and must be avoided. The Mg isotopic ratios of reference materials obtained in this study are identical to the previously published values within ±0.06‰, verifying that our procedures are robust. CONCLUSIONS This study presented a thorough set of tests for high precision and accuracy of Mg isotope measurements using MC-ICP-MS, which demonstrate reproducibility and accuracy better than 0.05‰ for δ25 Mg values and 0.06‰ for δ26 Mg values. We reported high-quality Mg isotopic data for 16 geological and environmental reference materials to aid the inter-laboratory calibration of Mg isotope measurements in the future.
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Affiliation(s)
- Ting Gao
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shan Ke
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Ruiying Li
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Xu'nan Meng
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Yongsheng He
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Chengshuai Liu
- State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, 550081, China
| | - Yang Wang
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Zijian Li
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
| | - Jian-Ming Zhu
- State Key Laboratory of Geological Process and Mineral Resources, School of Earth Science and Resources, China University of Geosciences, Beijing, 100083, China
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4
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Bohlin MS, Misra S, Lloyd N, Elderfield H, Bickle MJ. High-precision determination of lithium and magnesium isotopes utilising single column separation and multi-collector inductively coupled plasma mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:93-104. [PMID: 29078008 PMCID: PMC5767758 DOI: 10.1002/rcm.8020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 09/10/2017] [Accepted: 10/16/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Li and Mg isotopes are increasingly used as a combined tool within the geosciences. However, established methods require separate sample purification protocols utilising several column separation procedures. This study presents a single-step cation-exchange method for quantitative separation of trace levels of Li and Mg from multiple sample matrices. METHODS The column method utilises the macro-porous AGMP-50 resin and a high-aspect ratio column, allowing quantitative separation of Li and Mg from natural waters, sediments, rocks and carbonate matrices following the same elution protocol. High-precision isotope determination was conducted by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) on the Thermo Scientific™ NEPTUNE Plus™ fitted with 1013 Ω amplifiers which allow accurate and precise measurements at ion beams ≤0.51 V. RESULTS Sub-nanogram Li samples (0.3-0.5 ng) were regularly separated (yielding Mg masses of 1-70 μg) using the presented column method. The total sample consumption during isotopic analysis is <0.5 ng Li and <115 ng Mg with long-term external 2σ precisions of ±0.39‰ for δ7 Li and ±0.07‰ for δ26 Mg. The results for geological reference standards and seawater analysed by our method are in excellent agreement with published values despite the order of magnitude lower sample consumption. CONCLUSIONS The possibility of eluting small sample masses and the low analytical sample consumption make this method ideal for samples of limited mass or low Li concentration, such as foraminifera, mineral separates or dilute river waters.
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Affiliation(s)
- Madeleine S. Bohlin
- Department of Earth SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EQUK
| | - Sambuddha Misra
- Department of Earth SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EQUK
- Centre for Earth SciencesIndian Institute of ScienceBangalore560012India
| | - Nicholas Lloyd
- Thermo Fisher ScientificHanna‐Kunath‐Str. 1128199BremenGermany
| | - Henry Elderfield
- Department of Earth SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EQUK
| | - Mike J. Bickle
- Department of Earth SciencesUniversity of CambridgeDowning StreetCambridgeCB2 3EQUK
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5
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Iron diapirs entrain silicates to the core and initiate thermochemical plumes. Nat Commun 2018; 9:71. [PMID: 29302028 PMCID: PMC5754369 DOI: 10.1038/s41467-017-02503-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 12/05/2017] [Indexed: 11/08/2022] Open
Abstract
Segregation of the iron core from rocky silicates is a massive evolutionary event in planetary accretion, yet the process of metal segregation remains obscure, due to obstacles in simulating the extreme physical properties of liquid iron and silicates at finite length scales. We present new experimental results studying gravitational instability of an emulsified liquid gallium layer, initially at rest at the interface between two glucose solutions. Metal settling coats liquid metal drops with a film of low density material. The emulsified metal pond descends as a coherent Rayleigh-Taylor instability with a trailing fluid-filled conduit. Scaling to planetary interiors and high pressure mineral experiments indicates that molten silicates and volatiles are entrained toward the iron core and initiate buoyant thermochemical plumes that later oxidize and hydrate the upper mantle. Surface volcanism from thermochemical plumes releases oxygen and volatiles linking atmospheric growth to the Earth's mantle and core processes.
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Percolative core formation in planetesimals enabled by hysteresis in metal connectivity. Proc Natl Acad Sci U S A 2017; 114:13406-13411. [PMID: 29203657 DOI: 10.1073/pnas.1707580114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The segregation of dense core-forming melts by porous flow is a natural mechanism for core formation in early planetesimals. However, experimental observations show that texturally equilibrated metallic melt does not wet the silicate grain boundaries and tends to reside in isolated pockets that prevent percolation. Here we use pore-scale simulations to determine the minimum melt fraction required to induce porous flow, the percolation threshold. The composition of terrestrial planets suggests that typical planetesimals contain enough metal to overcome this threshold. Nevertheless, it is currently thought that melt segregation is prevented by a pinch-off at melt fractions slightly below the percolation threshold. In contrast to previous work, our simulations on irregular grain geometries reveal that a texturally equilibrated melt network remains connected down to melt fractions of only 1 to 2%. This hysteresis in melt connectivity allows percolative core formation in planetesimals that contain enough metal to exceed the percolation threshold. Evidence for the percolation of metallic melt is provided by X-ray microtomography of primitive achondrite Northwest Africa (NWA) 2993. Microstructural analysis shows that the metal-silicate interface has characteristics expected for a texturally equilibrated pore network with a dihedral angle of ∼85°. The melt network therefore remained close to textural equilibrium despite a complex history. This suggests that the hysteresis in melt connectivity is a viable process for percolative core formation in the parent bodies of primitive achondrites.
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7
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High precision direct analysis of magnesium isotope ratio by ion chromatography/multicollector-ICPMS using wet and dry plasma conditions. Talanta 2017; 165:64-68. [DOI: 10.1016/j.talanta.2016.12.033] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/10/2016] [Accepted: 12/16/2016] [Indexed: 11/24/2022]
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8
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Horneck G, Walter N, Westall F, Grenfell JL, Martin WF, Gomez F, Leuko S, Lee N, Onofri S, Tsiganis K, Saladino R, Pilat-Lohinger E, Palomba E, Harrison J, Rull F, Muller C, Strazzulla G, Brucato JR, Rettberg P, Capria MT. AstRoMap European Astrobiology Roadmap. ASTROBIOLOGY 2016; 16:201-43. [PMID: 27003862 PMCID: PMC4834528 DOI: 10.1089/ast.2015.1441] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 01/27/2016] [Indexed: 05/07/2023]
Abstract
The European AstRoMap project (supported by the European Commission Seventh Framework Programme) surveyed the state of the art of astrobiology in Europe and beyond and produced the first European roadmap for astrobiology research. In the context of this roadmap, astrobiology is understood as the study of the origin, evolution, and distribution of life in the context of cosmic evolution; this includes habitability in the Solar System and beyond. The AstRoMap Roadmap identifies five research topics, specifies several key scientific objectives for each topic, and suggests ways to achieve all the objectives. The five AstRoMap Research Topics are • Research Topic 1: Origin and Evolution of Planetary Systems • Research Topic 2: Origins of Organic Compounds in Space • Research Topic 3: Rock-Water-Carbon Interactions, Organic Synthesis on Earth, and Steps to Life • Research Topic 4: Life and Habitability • Research Topic 5: Biosignatures as Facilitating Life Detection It is strongly recommended that steps be taken towards the definition and implementation of a European Astrobiology Platform (or Institute) to streamline and optimize the scientific return by using a coordinated infrastructure and funding system.
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Affiliation(s)
- Gerda Horneck
- European Astrobiology Network Association
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Köln, Germany
| | | | - Frances Westall
- Centre National de la Recherche Scientifique–Centre de Biophysique Moléculaire, Orleans, France
| | - John Lee Grenfell
- Institute for Planetary Research, German Aerospace Center (DLR), Berlin, Germany
| | - William F. Martin
- Institute of Molecular Evolution, Heinrich-Heine University of Düsseldorf, Düsseldorf, Germany
| | - Felipe Gomez
- INTA Centre for Astrobiology, Torrejón de Ardoz, Madrid, Spain
| | - Stefan Leuko
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Köln, Germany
| | - Natuschka Lee
- Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
- Department of Microbiology, Technical University München, München, Germany
| | - Silvano Onofri
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo, Italy
| | - Kleomenis Tsiganis
- Department of Physics, Section of Astrophysics, Astronomy and Mechanics, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Raffaele Saladino
- Department of Agrobiology and Agrochemistry, University of Tuscia, Viterbo, Italy
| | | | - Ernesto Palomba
- INAF–Institute for Space Astrophysics and Planetology, Rome, Italy
| | - Jesse Harrison
- Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - Fernando Rull
- Department of Condensed Matter Physics, Crystallography and Mineralogy, Valladolid University, Valladolid, Spain
| | | | | | | | - Petra Rettberg
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Köln, Germany
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9
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Boujibar A, Andrault D, Bolfan-Casanova N, Bouhifd MA, Monteux J. Cosmochemical fractionation by collisional erosion during the Earth's accretion. Nat Commun 2015; 6:8295. [PMID: 26395157 PMCID: PMC4667431 DOI: 10.1038/ncomms9295] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Accepted: 08/07/2015] [Indexed: 11/09/2022] Open
Abstract
Early in the Solar System's history, energetic collisions of differentiated bodies affected the final composition of the terrestrial planets through partial destruction. Enstatite chondrites (EC) are the best candidates to represent the primordial terrestrial precursors as they present the most similar isotopic compositions to Earth. Here we report that collisional erosion of >15% of the early Earth's mass can reconcile the remaining compositional differences between EC and the Earth. We base our demonstration on experimental melting of an EC composition at pressures between 1 bar and 25 GPa. At low pressures, the first silicate melts are highly enriched in incompatible elements Si, Al and Na, and depleted in Mg. Loss of proto-crusts through impacts raises the Earth's Mg/Si ratio to its present value. To match all major element compositions, our model implies preferential loss of volatile lithophile elements and re-condensation of refractory lithophile elements after the impacts.
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Affiliation(s)
- Asmaa Boujibar
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS UMR-6524, 5 rue Kessler, 63000 Clermont-Ferrand, France
| | - Denis Andrault
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS UMR-6524, 5 rue Kessler, 63000 Clermont-Ferrand, France
| | - Nathalie Bolfan-Casanova
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS UMR-6524, 5 rue Kessler, 63000 Clermont-Ferrand, France
| | - Mohamed Ali Bouhifd
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS UMR-6524, 5 rue Kessler, 63000 Clermont-Ferrand, France
| | - Julien Monteux
- Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS UMR-6524, 5 rue Kessler, 63000 Clermont-Ferrand, France
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10
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Johansen A, Low MMM, Lacerda P, Bizzarro M. Growth of asteroids, planetary embryos, and Kuiper belt objects by chondrule accretion. SCIENCE ADVANCES 2015; 1:e1500109. [PMID: 26601169 PMCID: PMC4640629 DOI: 10.1126/sciadv.1500109] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/15/2015] [Indexed: 05/06/2023]
Abstract
Chondrules are millimeter-sized spherules that dominate primitive meteorites (chondrites) originating from the asteroid belt. The incorporation of chondrules into asteroidal bodies must be an important step in planet formation, but the mechanism is not understood. We show that the main growth of asteroids can result from gas drag-assisted accretion of chondrules. The largest planetesimals of a population with a characteristic radius of 100 km undergo runaway accretion of chondrules within ~3 My, forming planetary embryos up to Mars's size along with smaller asteroids whose size distribution matches that of main belt asteroids. The aerodynamical accretion leads to size sorting of chondrules consistent with chondrites. Accretion of millimeter-sized chondrules and ice particles drives the growth of planetesimals beyond the ice line as well, but the growth time increases above the disc lifetime outside of 25 AU. The contribution of direct planetesimal accretion to the growth of both asteroids and Kuiper belt objects is minor. In contrast, planetesimal accretion and chondrule accretion play more equal roles in the formation of Moon-sized embryos in the terrestrial planet formation region. These embryos are isolated from each other and accrete planetesimals only at a low rate. However, the continued accretion of chondrules destabilizes the oligarchic configuration and leads to the formation of Mars-sized embryos and terrestrial planets by a combination of direct chondrule accretion and giant impacts.
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Affiliation(s)
- Anders Johansen
- Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, Sweden
- Corresponding author. E-mail:
| | - Mordecai-Mark Mac Low
- Department of Astrophysics, American Museum of Natural History, 79th Street at Central Park West, New York, NY 10024–5192, USA
| | - Pedro Lacerda
- Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
| | - Martin Bizzarro
- Centre for Star and Planet Formation and Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
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11
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Connelly JN, Bizzarro M, Krot AN, Nordlund Å, Wielandt D, Ivanova MA. The absolute chronology and thermal processing of solids in the solar protoplanetary disk. Science 2012; 338:651-5. [PMID: 23118187 DOI: 10.1126/science.1226919] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Transient heating events that formed calcium-aluminum-rich inclusions (CAIs) and chondrules are fundamental processes in the evolution of the solar protoplanetary disk, but their chronology is not understood. Using U-corrected Pb-Pb dating, we determined absolute ages of individual CAIs and chondrules from primitive meteorites. CAIs define a brief formation interval corresponding to an age of 4567.30 ± 0.16 million years (My), whereas chondrule ages range from 4567.32 ± 0.42 to 4564.71 ± 0.30 My. These data refute the long-held view of an age gap between CAIs and chondrules and, instead, indicate that chondrule formation started contemporaneously with CAIs and lasted ~3 My. This time scale is similar to disk lifetimes inferred from astronomical observations, suggesting that the formation of CAIs and chondrules reflects a process intrinsically linked to the secular evolution of accretionary disks.
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Affiliation(s)
- James N Connelly
- Centre for Star and Planet Formation and Natural History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark.
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12
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Ling MX, Sedaghatpour F, Teng FZ, Hays PD, Strauss J, Sun W. Homogeneous magnesium isotopic composition of seawater: an excellent geostandard for Mg isotope analysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:2828-2836. [PMID: 21913261 DOI: 10.1002/rcm.5172] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The magnesium (Mg) isotopic compositions of 40 seawater samples from the Gulf of Mexico and of one seawater sample from the southwest Hawaii area were determined by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) to investigate the homogeneity of Mg isotopes in seawater. The results indicate that the Mg isotopic composition of seawater from the Gulf of Mexico is homogeneous, both vertically and horizontally, with average values for δ(26)Mg = -0.832 ± 0.068 and δ(25)Mg = -0.432 ± 0.053 (n = 40, 2SD)--identical to those of seawater from Hawaii (average δ(26)Mg = -0.829 ± 0.037 and δ(25)Mg = -0.427 ± 0.033) and to the average literature values of seawater worldwide (δ(26)Mg = -0.83 ± 0.11 and δ(25)Mg = -0.43 ± 0.06, n = 49, 2SD). Collectively, global seawater has a homogeneous Mg isotopic composition with δ(26)Mg = -0.83 ± 0.09 and δ(25) Mg = -0.43 ± 0.06 (2SD, n = 90). The magnesium isotopic composition of seawater is principally controlled by river water input, carbonate precipitation and oceanic hydrothermal interactions. The homogeneous Mg isotopic composition of seawater indicates a steady-state budget in terms of Mg isotopes in oceans, consistent with a long Mg residence time (~13 Ma). Considering that seawater is homogeneous, readily available in large amounts, can be easily accessed and processed for isotopic analysis, and has an isotopic composition near the middle of the natural range of variation, it is an excellent geostandard for accuracy assessment to rule out analytical artifacts during high-precision Mg isotopic analysis.
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Affiliation(s)
- Ming-Xing Ling
- State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, P.R. China.
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13
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Trieloff M. 4.5 Chronology of the Solar System. SOLAR SYSTEM 2009:771-788. [DOI: 10.1007/978-3-540-88055-4_35] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
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14
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Jacobsen SB, Ranen MC, Petaev MI, Remo JL, O'Connell RJ, Sasselov DD. Isotopes as clues to the origin and earliest differentiation history of the Earth. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2008; 366:4129-4162. [PMID: 18826920 DOI: 10.1098/rsta.2008.0174] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Measurable variations in (182)W/(183)W, (142)Nd/(144)Nd, (129)Xe/(130)Xe and (136)XePu/(130)Xe in the Earth and meteorites provide a record of accretion and formation of the core, early crust and atmosphere. These variations are due to the decay of the now extinct nuclides (182)Hf, (146)Sm, (129)I and (244)Pu. The (l82)Hf-(182)W system is the best accretion and core-formation chronometer, which yields a mean time of Earth's formation of 10Myr, and a total time scale of 30Myr. New laser shock data at conditions comparable with those in the Earth's deep mantle subsequent to the giant Moon-forming impact suggest that metal-silicate equilibration was rapid enough for the Hf-W chronometer to reliably record this time scale. The coupled (146)Sm-(147)Sm chronometer is the best system for determining the initial silicate differentiation (magma ocean crystallization and proto-crust formation), which took place at ca 4.47Ga or perhaps even earlier. The presence of a large (129)Xe excess in the deep Earth is consistent with a very early atmosphere formation (as early as 30Myr); however, the interpretation is complicated by the fact that most of the atmospheric Xe may be from a volatile-rich late veneer.
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Affiliation(s)
- Stein B Jacobsen
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA.
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15
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Stern R, Jedrzejas MJ. Carbohydrate Polymers at the Center of Life’s Origins: The Importance of Molecular Processivity. Chem Rev 2008; 108:5061-85. [DOI: 10.1021/cr078240l] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Robert Stern
- Department of Pathology and Comprehensive Cancer Center, School of Medicine, University of California, San Francisco, California 94143, Microdesign Institute, 29 Kingwood Rd., Oakland, California 94619, and Center for Immunobiology and Vaccine Development, Children’s Hospital Oakland Research Institute, 5700 Martin Luther King, Jr. Way, Oakland, California 94609
| | - Mark J. Jedrzejas
- Department of Pathology and Comprehensive Cancer Center, School of Medicine, University of California, San Francisco, California 94143, Microdesign Institute, 29 Kingwood Rd., Oakland, California 94619, and Center for Immunobiology and Vaccine Development, Children’s Hospital Oakland Research Institute, 5700 Martin Luther King, Jr. Way, Oakland, California 94609
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16
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Bizzarro M, Ulfbeck D, Trinquier A, Thrane K, Connelly JN, Meyer BS. Evidence for a late supernova injection of 60Fe into the protoplanetary disk. Science 2007; 316:1178-81. [PMID: 17525336 DOI: 10.1126/science.1141040] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
High-precision 60Fe-60Ni isotope data show that most meteorites originating from differentiated planetesimals that accreted within 1 million years of the solar system's formation have 60Ni/58Ni ratios that are approximately 25 parts per million lower than samples from Earth, Mars, and chondrite parent bodies. This difference indicates that the oldest solar system planetesimals formed in the absence of 60Fe. Evidence for live 60Fe in younger objects suggests that 60Fe was injected into the protoplanetary disk approximately 1 million years after solar system formation, when 26Al was already homogeneously distributed. Decoupling the first appearance of 26Al and 60Fe constrains the environment where the Sun's formation could have taken place, indicating that it occurred in a dense stellar cluster in association with numerous massive stars.
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Affiliation(s)
- Martin Bizzarro
- Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350, Denmark.
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Lipschutz ME, Wolf SF, Culp FB, Kent AJR. Geochemical and Cosmochemical Materials. Anal Chem 2007; 79:4249-74. [PMID: 17477509 DOI: 10.1021/ac070648v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael E Lipschutz
- Department of Chemistry, Wetherill Laboratory, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907-2038, USA.
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Bottke WF, Nesvorný D, Grimm RE, Morbidelli A, O'Brien DP. Iron meteorites as remnants of planetesimals formed in the terrestrial planet region. Nature 2006; 439:821-4. [PMID: 16482151 DOI: 10.1038/nature04536] [Citation(s) in RCA: 219] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Accepted: 12/12/2005] [Indexed: 11/09/2022]
Abstract
Iron meteorites are core fragments from differentiated and subsequently disrupted planetesimals. The parent bodies are usually assumed to have formed in the main asteroid belt, which is the source of most meteorites. Observational evidence, however, does not indicate that differentiated bodies or their fragments were ever common there. This view is also difficult to reconcile with the fact that the parent bodies of iron meteorites were as small as 20 km in diameter and that they formed 1-2 Myr earlier than the parent bodies of the ordinary chondrites. Here we show that the iron-meteorite parent bodies most probably formed in the terrestrial planet region. Fast accretion times there allowed small planetesimals to melt early in Solar System history by the decay of short-lived radionuclides (such as 26Al, 60Fe). The protoplanets emerging from this population not only induced collisional evolution among the remaining planetesimals but also scattered some of the survivors into the main belt, where they stayed for billions of years before escaping via a combination of collisions, Yarkovsky thermal forces, and resonances. We predict that some asteroids are main-belt interlopers (such as (4) Vesta). A select few may even be remnants of the long-lost precursor material that formed the Earth.
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Affiliation(s)
- William F Bottke
- Southwest Research Institute, 1050 Walnut St, Suite 400, Boulder, Colorado 80302, USA.
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