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1. Phase Decomposition upon Alteration of Radiation-Damaged Monazite–(Ce) from Moss, Østfold, Norway

Author

Lutz Nasdala, Katja Ruschel, Dieter Rhede, Richard Wirth, Ljuba Kerschhofer-Wallner, Allen K. Kennedy, Peter D. Kinny, Friedrich Finger, and Nora Groschopf

Subjects
Chemical alteration, Monazite-(ce), Radiation damage, Thorium silicate, Chemistry, QD1-999
Abstract

The internal textures of crystals of moderately radiation-damaged monazite–(Ce) from Moss, Norway, indicate heavy, secondary chemical alteration. In fact, the cm-sized specimens are no longer mono-mineral monazite but rather a composite consisting of monazite–(Ce) and apatite pervaded by several generations of fractures filled with sulphides and a phase rich in Th, Y, and Si. This composite is virtually a 'pseudomorph' after primary euhedral monazite crystals whose faces are still well preserved. The chemical alteration has resulted in major reworking and decomposition of the primary crystals, with potentially uncontrolled elemental changes, including extensive release of Th from the primary monazite and local redeposition of radionuclides in fracture fillings. This seems to question the general alteration-resistance of orthophosphate phases in a low-temperature, 'wet' environment, and hence their suitability as potential host ceramics for the long-term immobilisation of radioactive waste.

Published
2010
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2. Apatite Reference Materials for SIMS Microanalysis of Isotopes and Trace Elements

Author

Allen K. Kennedy, Jörn‐Frederik Wotzlaw, James L. Crowley, Mark Schmitz, Urs Schaltegger, Benjamin Wade, Laure Martin, Cristina Talavera, Bryant Ware, and Thi Hao Bui

Subjects
Geochemistry and Petrology, Geology
Abstract

Twelve apatite samples have been tested as secondary ion mass spectrometry (SIMS) reference materials. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis shows that the SLAP, NUAN and GR40 apatite gems are internally homogeneous, with most trace element mass fractions having 2 standard deviations (2s) ≤ 2.0%. BR2, BR5, OL2, AFG2 and AFB1, which have U > 63 μg g-1, 206Pb/204Pb > 283, and homogeneous SIMS U-Pb data, have respective isotope dilution thermal ionisation mass spectrometry (ID-TIMS) ages of 2053.90 ± 0.18 Ma, 2040.32 ± 0.14 Ma, 868.90 ± 0.22 Ma, 478.74 ± 0.20 Ma and 473.33 ± 0.19 Ma. Minor U-Pb heterogeneity exists and accurate SIMS results require correction with the 3D Concordia-constrained common Pb composition. Among the studied samples, AFG2 and BR5 are the most homogeneous U-Pb reference materials. The SIMS sulfur isotopic compositions of eight of the apatites shows they are homogeneous, with 2s for both 103δ34S and 103δ33S

Published
2022

3. Regolith breccia Northwest Africa 7533: Mineralogy and petrology with implications for early Mars

Author

Allen K. Kennedy, Hugues Leroux, Eric Lewin, Roger H. Hewins, Jeremy J. Bellucci, Marion Grange, Damien Deldicque, Martin J. Whitehouse, Christa Göpel, Sylvain Courrech du Pont, Jean-Pierre Lorand, Pierre Beck, Maya Marinova, Munir Humayun, Alexander A. Nemchin, Laurent Remusat, Brigitte Zanda, Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Earth, Ocean and Atmospheric Science [Tallahassee] (FSU | EOAS), Florida State University [Tallahassee] (FSU), Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de géologie de l'ENS (LGENS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut de Planétologie et d'Astrophysique de Grenoble (IPAG), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Unité Matériaux et Transformations - UMR 8207 (UMET), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Institut Michel Eugène Chevreul - FR 2638 (IMEC), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Géochimie, Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Department of Applied Physics Curtin University of Technology, Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), Laboratory for Isotope Geology, Swedish Museum of Natural History (NRM), ANR-16-CE31-0012,MARS-PRIME,Environnement Primitif de Mars(2016), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université d'Artois (UA)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centrale Lille Institut (CLIL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Minéralogie et Cosmochimie du Museum (LMCM), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), PSL Research University (PSL)-PSL Research University (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Earth, Ocean and Atmospheric Science [Tallahassee] (EOAS), Laboratoire de Planétologie et Géodynamique UMR6112 (LPG), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Nantes - Faculté des Sciences et des Techniques, Université de Nantes (UN)-Université de Nantes (UN)-Université d'Angers (UA), Laboratoire de géologie de l'ENS (LGE), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Laboratoire de Planétologie de Grenoble (LPG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Chevreul - FR2638, Université de Lille, Droit et Santé-Université d'Artois (UA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Ecole Centrale de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université de Lille, Sciences et Technologies, Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), and Institut de Chimie du CNRS (INC)-Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)

Subjects
010504 meteorology & atmospheric sciences, Geochemistry, Pyroxene, engineering.material, 010502 geochemistry & geophysics, Feldspar, 01 natural sciences, Geophysics, Augite, 13. Climate action, Space and Planetary Science, visual_art, Clastic rock, Breccia, Pigeonite, visual_art.visual_art_medium, engineering, Plagioclase, Petrology, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Zircon
Abstract

Northwest Africa 7533, a polymict Martian breccia, consists of fine‐grained clast‐laden melt particles and microcrystalline matrix. While both melt and matrix contain medium‐grained noritic‐monzonitic material and crystal clasts, the matrix also contains lithic clasts with zoned pigeonite and augite plus two feldspars, microbasaltic clasts, vitrophyric and microcrystalline spherules, and shards. The clast‐laden melt rocks contain clump‐like aggregates of orthopyroxene surrounded by aureoles of plagioclase. Some shards of vesicular melt rocks resemble the pyroxene‐plagioclase clump‐aureole structures. Submicron size matrix grains show some triple junctions, but most are irregular with high intergranular porosity. The noritic‐monzonitic rocks contain exsolved pyroxenes and perthitic intergrowths, and cooled more slowly than rocks with zoned‐pyroxene or fine grain size. Noritic material contains orthopyroxene or inverted pigeonite, augite, calcic to intermediate plagioclase, and chromite to Cr‐bearing magnetite; monzonitic clasts contain augite, sodic plagioclase, K feldspar, Ti‐bearing magnetite, ilmenite, chlorapatite, and zircon. These feldspathic rocks show similarities to some rocks at Gale Crater like Black Trout, Mara, and Jake M. The most magnesian orthopyroxene clasts are close to ALH 84001 orthopyroxene in composition. All these materials are enriched in siderophile elements, indicating impact melting and incorporation of a projectile component, except for Ni‐poor pyroxene clasts which are from pristine rocks. Clast‐laden melt rocks, spherules, shards, and siderophile element contents indicate formation of NWA 7533 as a regolith breccia. The zircons, mainly derived from monzonitic (melt) rocks, crystallized at 4.43 ± 0.03 Ga (Humayun et al. 2013) and a 147Sm‐143Nd isochron for NWA 7034 yielding 4.42 ± 0.07 Ga (Nyquist et al. 2016) defines the crystallization age of all its igneous portions. The zircon from the monzonitic rocks has a higher Δ17O than other Martian meteorites explained in part by assimilation of regolith materials enriched during surface alteration (Nemchin et al. 2014). This record of protolith interaction with atmosphere‐hydrosphere during regolith formation before melting demonstrates a thin atmosphere, a wet early surface environment on Mars, and an evolved crust likely to have contaminated younger extrusive rocks. The latest events recorded when the breccia was on Mars are resetting of apatite, much feldspar and some zircons at 1.35–1.4 Ga (Bellucci et al. 2015), and formation of Ni‐bearing pyrite veins during or shortly after this disturbance (Lorand et al. 2015).

Published
2017

4. Matrix-Matched Iron-Oxide Laser Ablation ICP-MS U–Pb Geochronology Using Mixed Solution Standards

Author

Allen K. Kennedy, Alexandre Raphael Cabral, Zhiyong Zhu, Liam Courtney-Davies, Nigel J. Cook, Benjamin P. Wade, Cristiana L. Ciobanu, and Kathy Ehrig

Subjects
lcsh:QE351-399.2, iron-oxide -- U–Pb geochronology -- matrix-matched standard -- LA-ICP-MS, Mineralogy, Fractionation, Standard solution, 010502 geochemistry & geophysics, Iron oxide copper gold ore deposits, 01 natural sciences, Matrix (chemical analysis), ddc:550, LA-ICP-MS, iron-oxide, U–Pb geochronology, matrix-matched standard, 0105 earth and related environmental sciences, lcsh:Mineralogy, 010401 analytical chemistry, article, Geology, Hematite, Geotechnical Engineering and Engineering Geology, 0104 chemical sciences, visual_art, Primary standard, Geochronology, visual_art.visual_art_medium, Zircon
Abstract

U–Pb dating of the common iron-oxide hematite (α-Fe2O3), using laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS), provides unparalleled insight into the timing and processes of mineral deposit formation. Until now, the full potential of this method has been negatively impacted by the lack of suitable matrix-matched standards. To achieve matrix-matching, we report an approach in which a U–Pb solution and ablated material from 99.99% synthetic hematite are simultaneously mixed in a nebulizer chamber and introduced to the ICP-MS. The standard solution contains fixed U- and Pb-isotope ratios, calibrated independently, and aspiration of the isotopically homogeneous solution negates the need for a matrix-matched, isotopically homogenous natural iron-oxide standard. An additional advantage of using the solution is that the individual U–Pb concentrations and isotope ratios can be adjusted to approximate that in the unknown, making the method efficient for dating hematite containing low (~10 ppm) to high (>1 wt %) U concentrations. The above-mentioned advantage to this solution method results in reliable datasets, with arguably-better accuracy in measuring U–Pb ratios than using GJ-1 Zircon as the primary standard, which cannot be employed for such low U concentrations. Statistical overlaps between 207Pb/206Pb weighted average ages (using GJ-1 Zircon) and U–Pb upper intercept ages (using the U–Pb mixed solution method) of two samples from iron-oxide copper-gold (IOCG) deposits in South Australia demonstrate that, although fractionation associated with a non-matrix matched standard does occur when using GJ-1 Zircon as the primary standard, it does not impact the 207Pb/206Pb or upper intercept age. Thus, GJ-1 Zircon can be considered reliable for dating hematite using LA-ICP-MS. Downhole fractionation of 206Pb/238U is observed to occur in spot analyses of hematite. The use of rasters in future studies will hopefully minimize this problem, allowing for matrix-matched data. Using the mixed-solution method in this study, we have validated a published hematite Pb–Pb age for Olympic Dam, and provide a new age (1604 ± 11 Ma) for a second deposit in the same province. These ages are further evidence that the IOCG mineralizing event is tied to large igneous province (LIP) magmatism in the region at ~1.6 Ga.

Published
2016

5. Nickeliferous pyrite tracks pervasive hydrothermal alteration in Martian regolith breccia: A study in NWA 7533

Author

Jean-Pierre Lorand, Allen K. Kennedy, Hugues Leroux, Marion Grange, Alexander A. Nemchin, Roger H. Hewins, Brigitte Zanda, Munir Humayun, Sylvain Pont, Laurent Remusat, Damien Jacob, Christa Göpel, Maya Marinova, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de minéralogie, de physique des matériaux et de cosmochimie (IMPMC), Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS), Unité Matériaux et Transformations - UMR 8207 (UMET), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Department of Physics [Thessaloniki], Aristotle University of Thessaloniki, Department of Earth, Ocean and Atmospheric Science [Tallahassee] (FSU | EOAS), Florida State University [Tallahassee] (FSU), Department of Applied Physics Curtin University of Technology, Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie du CNRS (INC)-Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de minéralogie du Muséum National d'Histoire Naturelle (LMMNHN), Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de recherche pour le développement [IRD] : UR206-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche pour le développement [IRD] : UR206-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Université Pierre et Marie Curie - Paris 6 (UPMC), Muséum national d'Histoire naturelle (MNHN), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut National de la Recherche Agronomique (INRA), and Department of Earth, Ocean and Atmospheric Science [Tallahassee] (EOAS)

Subjects
Mineral, 010504 meteorology & atmospheric sciences, Fracture (mineralogy), Geochemistry, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, Regolith, Hydrothermal circulation, Shock metamorphism, Geophysics, [SDU.STU.PL]Sciences of the Universe [physics]/Earth Sciences/Planetology, Meteorite, Space and Planetary Science, Breccia, engineering, Pyrite, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

Martian regolith breccia NWA 7533 (and the seven paired samples) is unique among Martian meteorites in showing accessory pyrite (up to 1% by weight). Pyrite is a late mineral, crystallized after the final assembly of the breccia. It is present in all of the lithologies, i.e., the fine-grained matrix (ICM), clast-laden impact melt rocks (CLIMR), melt spherules, microbasalts, lithic clasts, and mineral clasts, all lacking magmatic sulfides due to degassing. Pyrite crystals show combinations of cubes, truncated cubes, and octahedra. Polycrystalline clusters can reach 200 lm in maximum dimensions. Regardless of their shape, pyrite crystals display evidence of very weak shock metamorphism such as planar features, fracture networks, and disruption into subgrains. The late fracture systems acted as preferential pathways for partial replacement of pyrite by iron oxyhydroxides interpreted as resulting from hot desert terrestrial alteration. The distribution and shape of pyrite crystals argue for growth at moderate to low growth rate from just-saturated near neutral (6 FMQ + 2 log units. It is inferred from the maximum Ni contents (4.5 wt%) that pyrite started crystallizing at 400–500 °C, during or shortly after a short-duration, relatively low temperature, thermal event that lithified and sintered the regolith breccias, 1.4 Ga ago as deduced from disturbance in several isotope systematics.

Published
2015

6. Record of the ancient martian hydrosphere and atmosphere preserved in zircon from a martian meteorite

Author

Martin J. Whitehouse, Roger H. Hewins, Alexander A. Nemchin, Brigitte Zanda, C. Fieni, Jean-Pierre Lorand, Munir Humayun, Allen K. Kennedy, Marion Grange, and Damien Deldicque

Subjects
Martian, Atmosphere, Geochemistry, Meteorite, General Earth and Planetary Sciences, Martian soil, Mars Exploration Program, Geokemi, Regolith, Geology, Hydrosphere, Astrobiology, Zircon
Abstract

Mars exhibits ample evidence for an ancient surfacehydrosphere. The oxygen isotope compositions of carbonateminerals and alteration products in martian meteoritessuggest that this ancient hydrosphere was not in isotopicequilibrium with the martian lithosphere1–4. Martian meteoriteNWA 7533 is composed of regolith breccia from the heavilycratered terrains of ancient Mars and contains zircon grainsfor which U–Pb ages have been reported5. Here we reportvariations between the oxygen isotopic compositions offour zircon grains from NWA 7533. We propose that thesevariations can be explained if the mantle melts from whichthe zircon crystallized approximately 4.43Gyr ago hadassimiliated 17O-enriched regolith materials, and that someof the zircon grains, while in a metamict state, were lateraltered by low-temperature fluids near the surface less than1.7Gyr ago. Enrichment of the martian regolith in 17O beforethe zircon crystallized, presumably through exchange withthe 17O-enriched atmosphere or hydrosphere during surfacealteration, suggests that the thick primary atmosphere ofMars was lost within the first 120Myr after accretion. Weconclude that the observed variation of 17O anomalies in zirconfrom NWA 7533 points to prolonged interaction between themartian regolith, atmosphere and hydrosphere. Early Planetary Evolution

Published
2014

7. Two magma series and associated ore deposit types in the Permian Emeishan large igneous province, SW China

Author

Allen K. Kennedy, Mei-Fu Zhou, Christina Yan Wang, John Malpas, Nicolas T. Arndt, Department of Earth Sciences [Hong kong], The University of Hong Kong (HKU), Laboratoire de Géodynamique des Chaines Alpines (LGCA), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Department of Applied Physics, Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut des Sciences de la Terre (ISTerre), and Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut national des sciences de l'Univers (INSU - CNRS)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Institut de recherche pour le développement [IRD] : UR219-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)

Subjects
Basalt, Mineralization (geology), 010504 meteorology & atmospheric sciences, Permian, Large igneous province, Mafic-ultramafic rocks, Geochemistry, SW China, Geology, Gabbroic rocks, 010502 geochemistry & geophysics, 01 natural sciences, Mantle plume, Igneous rock, Geochemistry and Petrology, Syenite, Flood basalt, Petrology, Emeishan Large Igneous Province, 0105 earth and related environmental sciences, Zircon
Abstract

International audience; The Late Middle Permian (not, vert, similar 260 Ma) Emeishan large igneous province in SW China contains two magmatic series, one comprising high-Ti basalts and Fe-rich gabbroic and syenitic intrusions, the other low-Ti basalts and mafic-ultramafic intrusions. The Fe-rich gabbros are spatially and temporally associated with syenites. Each series is associated with a distinctive type of mineralization, the first with giant Fe-Ti-V oxide ore deposits such as Panzhihua and Baima, the second with Ni-Cu-(PGE) sulfide deposits such as Jinbaoshan, Limahe and Zhubu. New SHRIMP zircon U-Pb isotopic data yielded 263 ± 3 Ma for the Limahe intrusion, 261 ± 2 Ma for the Zhubu intrusion and 262 ± 2 Ma for a syenitic intrusion. These new age dates, together with previously reported SHRIMP zircon U-Pb ages, suggest that all these intrusions are contemporaneous with the Emeishan flood basalts and formed during a major igneous event at ca. 260 Ma. The oxide-bearing intrusions have higher Al2O3, FeO (as total iron) and total alkalis (Na2O + K2O) but lower MgO than the sulfide-bearing intrusions. All intrusions are variably enriched in LREE relative to HREE. The oxide-bearing intrusions display positive Nb- and Ti-anomalies and in certain cases negative Zr-Hf anomalies, whereas the sulfide-bearing intrusions have obvious negative Nb- and Ti-anomalies, a feature of crustal contamination. Individual intrusions have relatively small ranges of var epsilonNd(t) values. All the intrusions, however, have var epsilonNd(t) values ranging from − 3.9 to + 4.6, and initial 87Sr/86Sr ratios from 0.7039 to 0.7105. The syenites have very low MgO (< 2 wt.%) but highly variable Fe2O3 (2.5 to 13 wt.%) with initial 87Sr/86Sr ratios ranging from 0.7039 to 0.7089. Magmas from both series could have derived by melting of a heterogeneous mantle plume: the high-Ti series from a Fe-rich, more fertile source and the low-Ti series from a Fe-poor, more refractory source. In addition, the low-Ti series underwent significant crustal contamination. The two magma series evolved along different paths that led to distinct mineralization styles.

Published
2007

8. Zircons from Syros, Cyclades, Greece - Recrystallization and mobilization of zircon during high pressure metamorphism

Author

Allen K. Kennedy, Frank Tomaschek, Markus Lagos, Chris Ballhaus, Igor M. Villa, Tomaschek, F, Kennedy, A, Villa, I, Lagos, M, and Ballhaus, C

Subjects
geochronology, paragonite, zircon, petrology, eclogite, Recrystallization (geology), CYCLADES, Geochemistry, Metamorphism, Geophysics, Geochemistry and Petrology, Oceanic crust, GEO/08 - GEOCHIMICA E VULCANOLOGIA, 550 Earth sciences & geology, Fluid inclusions, Inclusion (mineral), Protolith, Geology, Zircon
Abstract

Zircons were studied from high-pressure/low-temperature metamorphosed meta-igneous lithologies from Syros. These rocks carry several zircon generations related to each other by dissolution---reprecipitation processes. One generation is pristine zircon that shows growth zoning, relatively elevated contents of trivalent cations and high Th/U ratios. The other end-member is a skeletal zircon generation with negligible trivalent cation contents and low Th/U ratios ( 0 1). Texturally between these two, there is a range of zircon crystals with complex inclusion populations of Y---HREE---Th phases and fluid inclusions, showing variable progress of replacement--recrystallization. Both end-members yield distinct sensitive high-resolution ion microprobe (SHRIMP) U---Pb ages. The pristine generation has an age of 80 2 1 6Ma from a metagabbro, and 76 4 2 1Ma from a meta-plagiogranite dyke. The skeletal, low-Th/U zircon generation yields an age of 52 4 0 8Ma. The older, Late Cretaceous, zircons are interpreted to date emplacement of the magmatic protoliths in a small segment of oceanic crust. The younger, Eocene, age, however, dates a zircon recrystallization event, which possibly coincides with high solubility and mobility of high field strength elements in a high-pressure aqueous fluid phase. Intergrowth relations between zircon and peak-metamorphic garnet, and excellent agreement of the U---Pb ages with white mica Ar---Ar ages for the same samples support the conclusion that Eocene is the true age of high-pressure metamorphism on Syros.

Published
2003

9. Zircons from Syros, Cyclades, Greece--Recrystallization and Mobilization of Zircon During High-Pressure Metamorphism.

Author

FRANK TOMASCHEK, ALLEN K. KENNEDY, IGOR M. VILLA, MARKUS LAGOS, and CHRIS BALLHAUS

Subjects
*ZIRCON, *METAMORPHISM (Geology)
Abstract

Zircons were studied from high-pressure/low-temperature metamorphosed meta-igneous lithologies from Syros. These rocks carry several zircon generations related to each other by dissolution-reprecipitation processes. One generation is pristine zircon that shows growth zoning, relatively elevated contents of trivalent cations and high Th/U ratios. The other end-member is a skeletal zircon generation with negligible trivalent cation contents and low Th/U ratios (≤0·1). Texturally between these two, there is a range of zircon crystals with complex inclusion populations of Y-HREE-Th phases and fluid inclusions, showing variable progress of replacement- recrystallization. Both end-members yield distinct sensitive high-resolution ion microprobe (SHRIMP) U-Pb ages. The pristine generation has an age of 80·2 ± 1·6 Ma from a metagabbro, and 76·4 ± 2·1 Ma from a meta-plagiogranite dyke. The skeletal, low-Th/U zircon generation yields an age of 52·4 ± 0·8 Ma. The older, Late Cretaceous, zircons are interpreted to date emplacement of the magmatic protoliths in a small segment of oceanic crust. The younger, Eocene, age, however, dates a zircon recrystallization event, which possibly coincides with high solubility and mobility of high field strength elements in a high-pressure aqueous fluid phase. Intergrowth relations between zircon and peak-metamorphic garnet, and excellent agreement of the U-Pb ages with white mica Ar-Ar ages for the same samples support the conclusion that Eocene is the true age of high-pressure metamorphism on Syros. [ABSTRACT FROM AUTHOR]

Published
2003
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