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Wilson Kuhnel W, Jacobsen SB, Li Y, Ku Y, Petaev MI, Huang S, Wu Z, Wang (王昆) K. High-temperature inter-mineral potassium isotope fractionation: implications for K-Ca-Ar chronology. ACS EARTH & SPACE CHEMISTRY 2021; 5:2740-2754. [PMID: 35005332 PMCID: PMC8740525 DOI: 10.1021/acsearthspacechem.1c00147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent advances in high-precision potassium (K) isotopic analysis have found considerable isotopic variation in rock samples of the Earth's continental and oceanic crusts; however, it is still uncertain whether there is any resolvable inter-mineral and mineral-melt K isotopic fractionation during igneous and metamorphic processes. Here, we report K isotope compositions of mineral separates from three extremely well preserved igneous rocks (intrusive/extrusive and mafic/intermediate/felsic) in order to investigate possible inter-mineral and mineral-melt K isotopic fractionation at magmatic temperatures. For the first time, we found large inter-mineral fractionation of K isotopes in natural samples (up to 1.072‰), where plagioclase displays a significant enrichment of heavier K isotopes compared to potassium feldspar and biotite in a granite. In addition, we also observed smaller but measurable K isotope fractionation (0.280‰±0.030‰) between ternary feldspar phenocrysts and matrix in a trachyandesite, as well as a comparable isotope fractionation (0.331‰±0.010‰) between plagioclase and the bulk in a gabbroic intrusive rock. We also evaluated such results by comparing the theoretically calculated equilibrium K isotope fractionation factors between relevant igneous minerals in literature and this study. In general, the measured inter-mineral fractionations are consistent with the theoretical calculations (i.e., plagioclase is enriched in heavier isotopes compared to potassium feldspar). Specifically, the measured K isotope fractionation between phenocryst rim and matrix in the trachyandesite agrees well with the calculated equilibrium isotope fractionation. However, the measured K isotope fractionations between phenocryst core and matrix as well as between plagioclase and K-feldspar are significantly larger (by a factor of ~2-3) than the calculated isotope fractionations, which suggest isotopic disequilibrium due to kinetic processes. Using a range of plagioclase-melt isotope fractionation factors inferred from the theoretical calculations in this study, we modeled the K isotopic fractionation during the formation of lunar anorthositic crust, and the result shows a negligible effect on the K isotopic compositions in both lunar crust and mantle. The K isotopic difference between Earth and Moon, therefore, cannot be the result of Lunar Magma Ocean differentiation. Finally, we evaluate the effect of observed inter-mineral fractionations on K-Ar and 40Ar-39Ar dating. This study indicates the variation of 40K/K ratio would contribute a maximum 0.08% error to the K-Ar and 40Ar-39Ar age uncertainties. We propose a refined 40K/total K ratio as 0.00011664±0.00000011 (116.64±0.11ppm) instead of the conventional value, 0.0001167(2) for the present Earth. Because some minerals fractionate K isotopes, ultrahigh precision age dating with the K-Ca-Ar dating systems must measure the K isotope fractionation in the same mineral fractions used for age dating.
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Affiliation(s)
- W. Wilson Kuhnel
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
| | - Stein B. Jacobsen
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
| | - Yonghui Li
- Laboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Yaray Ku
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
| | - Michail I. Petaev
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
| | - Shichun Huang
- Department of Geoscience, University of Nevada, Las Vegas, NV 89154, USA
| | - Zhongqing Wu
- Laboratory of Seismology and Physics of Earth’s Interior, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - Kun Wang (王昆)
- Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, MA 02138, USA
- Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
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Zhu MH, Artemieva N, Morbidelli A, Yin QZ, Becker H, Wünnemann K. Reconstructing the late-accretion history of the Moon. Nature 2019; 571:226-229. [DOI: 10.1038/s41586-019-1359-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 05/23/2019] [Indexed: 11/10/2022]
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Righter K. Volatile element depletion of the Moon-The roles of precursors, post-impact disk dynamics, and core formation. SCIENCE ADVANCES 2019; 5:eaau7658. [PMID: 30746461 PMCID: PMC6357731 DOI: 10.1126/sciadv.aau7658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 12/10/2018] [Indexed: 06/09/2023]
Abstract
The compositional and isotopic similarity of Earth's primitive upper mantle (PUM) and the Moon supports the derivation of the Moon from proto-Earth, but the Moon's inventory of volatile lithophile elements-Na, K, Rb, and Cs-is lower than Earth's PUM by factors of 4 to 5. The abundances of 14 other volatile elements exhibit siderophile behavior [volatile siderophile elements (VSEs); i.e., P, As, Cu, Ag, Sb, Ga, Ge, Bi, Pb, Zn, Sn, Cd, In, and Tl] that can be used to evaluate whether the Moon was derived from proto-Earth and if core formation or volatility controlled their depletion. At lunar core formation conditions, As, Sb, Ag, Ge, Bi, and Sn are siderophile, whereas P, Cu, Ga, Pb, Zn, Cd, In, and Tl are weakly siderophile or lithophile. VSEs may help to discriminate between physical and chemical processes that formed the Moon such as low- versus high-energy impacts and gas-melt interactions.
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Affiliation(s)
- K Righter
- Mailcode XI2, NASA-JSC, 2101 NASA Parkway, Houston, TX 77058, USA.
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Steenstra ES, Lin Y, Dankers D, Rai N, Berndt J, Matveev S, van Westrenen W. The lunar core can be a major reservoir for volatile elements S, Se, Te and Sb. Sci Rep 2017; 7:14552. [PMID: 29109545 PMCID: PMC5673932 DOI: 10.1038/s41598-017-15203-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/23/2017] [Indexed: 11/21/2022] Open
Abstract
The Moon bears a striking compositional and isotopic resemblance to the bulk silicate Earth (BSE) for many elements, but is considered highly depleted in many volatile elements compared to BSE due to high-temperature volatile loss from Moon-forming materials in the Moon-forming giant impact and/or due to evaporative loss during subsequent magmatism on the Moon. Here, we use high-pressure metal-silicate partitioning experiments to show that the observed low concentrations of volatile elements sulfur (S), selenium (Se), tellurium (Te), and antimony (Sb) in the silicate Moon can instead reflect core-mantle equilibration in a largely to fully molten Moon. When incorporating the core as a reservoir for these elements, their bulk Moon concentrations are similar to those in the present-day bulk silicate Earth. This suggests that Moon formation was not accompanied by major loss of S, Se, Te, Sb from Moon-forming materials, consistent with recent indications from lunar carbon and S isotopic compositions of primitive lunar materials. This is in marked contrast with the losses of other volatile elements (e.g., K, Zn) during the Moon-forming event. This discrepancy may be related to distinctly different cosmochemical behavior of S, Se, Te and Sb within the proto-lunar disk, which is as of yet virtually unconstrained.
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Affiliation(s)
- Edgar S Steenstra
- Faculty of Sciences, VU Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands.
| | - Yanhao Lin
- Faculty of Sciences, VU Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Dian Dankers
- Faculty of Sciences, VU Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
| | - Nachiketa Rai
- Department of Earth and Planetary Sciences, Birkbeck University of London, London, UK
- Department of Earth Sciences, Mineral and Planetary Sciences Division, Natural History Museum, London, UK
| | - Jasper Berndt
- Institute of Mineralogy, University of Münster, Münster, Germany
| | - Sergei Matveev
- Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
| | - Wim van Westrenen
- Faculty of Sciences, VU Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, The Netherlands
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Johnson BC, Blair DM, Collins GS, Melosh HJ, Freed AM, Taylor GJ, Head JW, Wieczorek MA, Andrews-Hanna JC, Nimmo F, Keane JT, Miljković K, Soderblom JM, Zuber MT. Formation of the Orientale lunar multiring basin. Science 2016; 354:441-444. [PMID: 27789836 DOI: 10.1126/science.aag0518] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 09/08/2016] [Indexed: 11/02/2022]
Abstract
Multiring basins, large impact craters characterized by multiple concentric topographic rings, dominate the stratigraphy, tectonics, and crustal structure of the Moon. Using a hydrocode, we simulated the formation of the Orientale multiring basin, producing a subsurface structure consistent with high-resolution gravity data from the Gravity Recovery and Interior Laboratory (GRAIL) spacecraft. The simulated impact produced a transient crater, ~390 kilometers in diameter, that was not maintained because of subsequent gravitational collapse. Our simulations indicate that the flow of warm weak material at depth was crucial to the formation of the basin's outer rings, which are large normal faults that formed at different times during the collapse stage. The key parameters controlling ring location and spacing are impactor diameter and lunar thermal gradients.
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Affiliation(s)
- Brandon C Johnson
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
| | - David M Blair
- Massachusetts Institute of Technology Haystack Observatory, Route 40, Westford, MA 01886, USA
| | - Gareth S Collins
- Impacts and Astromaterials Research Centre, Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK
| | - H Jay Melosh
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Andrew M Freed
- Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - G Jeffrey Taylor
- Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, Honolulu, HI 96822, USA
| | - James W Head
- Department of Earth, Environmental and Planetary Sciences, Brown University, Providence, RI 02912, USA
| | - Mark A Wieczorek
- Institut de Physique du Globe de Paris, Sorbonne Paris Cité, Université Paris Diderot, Paris Cedex 13 75205, France
| | | | - Francis Nimmo
- Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA
| | - James T Keane
- Department of Planetary Science, Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
| | - Katarina Miljković
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jason M Soderblom
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maria T Zuber
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Canup RM, Visscher C, Salmon J, Fegley B. LUNAR VOLATILE DEPLETION DUE TO INCOMPLETE ACCRETION WITHIN AN IMPACT-GENERATED DISK. NATURE GEOSCIENCE 2015; 8:918-921. [PMID: 31360221 PMCID: PMC6662721 DOI: 10.1038/ngeo2574] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 09/29/2015] [Indexed: 05/25/2023]
Abstract
The Moon may have formed from an Earth-orbiting disk of vapor and melt produced by a giant impact.1 The Moon and Earth's mantles have similar compositions. However, it is unclear why lunar samples are more depleted in volatile elements than terrestrial mantle rocks2-3, given that an evaporative escape mechanism4 appears inconsistent with expected disk conditions.5 Dynamical models6-7 suggest that the Moon initially accreted from the outermost disk, but later acquired up to 60% of its mass from melt originating from the inner disk. Here we combine dynamical, thermal and chemical models to show that volatile depletion in the Moon can be explained by preferential accretion of volatile-rich melt in the inner disk to the Earth, rather than to the growing Moon. Melt in the inner disk is initially hot and volatile-poor, but volatiles condense as the disk cools. In our simulations, the delivery of inner disk melt to the Moon effectively ceases when gravitational interactions cause the Moon's orbit to expand away from the disk, and this termination of lunar accretion occurs prior to condensation of potassium and more volatile elements. Thus, the portion of the Moon derived from the inner disk is expected to be volatile depleted. We suggest that this mechanism may explain part or all of the Moon's volatile depletion, depending on the degree of mixing within the lunar interior.
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Affiliation(s)
- Robin M Canup
- Planetary Sciences Directorate, Southwest Research Institute, Boulder, CO, 80302
| | - Channon Visscher
- Planetary Sciences Directorate, Southwest Research Institute, Boulder, CO, 80302
- Chemistry and Planetary Sciences, Dordt College, Sioux Center, IA, 51250
| | - Julien Salmon
- Planetary Sciences Directorate, Southwest Research Institute, Boulder, CO, 80302
| | - Bruce Fegley
- Department of Earth and Planetary Sciences and McDonnell Center for Space Sciences, Washington University, St. Louis, MO, 63130
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