• UPb Isotopic Ages of the K/T Impact Event and its Target ...

    UPb isotopic results for individual zircon grains from the fire ball ejecta layer of the Cretaceous/Tertiary (K/T) boundary claystone, Raton Basin, Colorado, lie on a Pb loss line between 550 + 10 Ma and + 3 Ma. This implies that the target area is dominated by rocks of the older age, and that grains plotting near the younger end of the Pbloss line record a high .

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  • Shock deformation in zircon grains from the Mien impact ...

     · Impactgenerated granular texture in zircon generally forms at high temperatures, during or subsequent to shock decompression, following shock pressures in excess of 30 GPa (, Schmieder et al. 2015; Timms et al. 2017), and in some instances by the reversion from reidite to zircon if the zircon is subjected to postshock conditions corresponding to shock .

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  • Zircon Chronology: Dating the Oldest Material on Earth | AMNH

    Zircon contains the radioactive element uranium, which Dr. Mueller calls "the clock within the zircon" because it converts to the element lead at a specific rate over a long span of time. According to Mueller, this makes zircons "the most reliable natural chronometer that we have when we want to look at the earliest part of Earth history." He goes on to explain that there are .

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  • The formation of large neoblasts in shocked zircon and ...

    zircon incorporated into impactrelated melt. Based on insight from large neoblast growth in terrestrial settings, we suggest that the ca. Ga neoblasts recently reported in lunar zircon may imply a major basinforming event on the Moon at that time. New knowledge of the cratering environments in which large neoblasts form also raises the prospect of possibly linking ex situ granular ...

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  • Imbrium Age for Zircons in Apollo 17 South Massif Impact ...

     · The poikilitic impact melt breccias brought back to Earth by the Apollo 17 mission have been widely seen as ejecta from the Serenitatis impact basin and have been used to date its formation. We observe that zircons in Apollo 17 poikilitic impact melt breccia 73155,69 have age, textural, and geochemical characteristics linked to the younger, billionyearold .

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  • Single crystal U–Pb zircon age and Sr–Nd isotopic ...

    Single crystal U–Pb zircon age and Sr–Nd isotopic composition of impactites from the Bosumtwi impact structure, Ghana: Comparison with country rocks and Ivory Coast tektites Ludovic Ferrièrea,b,⁎,1, Christian Koeberla,c, Martin Thönia, Chen Liangb a Department of Lithospheric Research, University of Vienna, Althanstrasse 14, A1090 Vienna, Austria b State Key .

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  • Impact of air, laser pulse width and fluence on U–Pb ...

    The accuracy of zircon U–Pb dating by LAICPMS is limited by matrix effects related to differences in U–Pb fractionation between an unknown and the calibration standard. Zircon radiation dose has a strong influence on the ablation rate, which in turn affects the amount of U–Pb fractionation and subsequent ag

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  • Environmental Impact And Risk Assessment Of A Zircon ...

    Environmental impact and risk assessment of a zircon mineral plant emissions S. Righi1, C. Simonetto1, L. Bruzzi1, M. Andretta2 R. Serra2 1 Bologna University, Italy 2 Monteini Environmental Research Center, Montedison Group, Italy Abstract In this paper we present a study of the effects of particulate emissions of a zircon mineral processing plant on the air quality of an industrial area ...

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  • A terrestrial perspective on using ex situ shocked zircons ...

    An impact age of 1975 ± 39 Ma was detected in neoblasts within a granular zircon that also contains shock microtwins, which link neoblast formation to the impact. However, we show that granular texture can form during regional metamorphism, and thus is not unique to impact environments. These results demonstrate that dating an impact with ex situ shocked zircon requires identifying diagnostic ...

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  • Shock deformation in zircon grains from the Mien impact ...

     · Impactgenerated granular texture in zircon generally forms at high temperatures, during or subsequent to shock decompression, following shock pressures in excess of 30 GPa (, Schmieder et al. 2015; Timms et al. 2017), and in some instances by the reversion from reidite to zircon if the zircon is subjected to postshock conditions corresponding to shock stage IV (Erickson et al. 2017).

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  • ACCURATE AND PRECISE DATING OF IMPACT EVENTS BY UPb ...

    ZIRCON – A CASE STUDY FROM THE LAPPAJÄRVI IMPACT STRUCTURE G. G. Kenny1*, M. Schmieder2,3, ... ated with an impact event [, 4,5,6,7], and report the first highprecision UPb age for shocked zircon from a Phanerozoic impact crater. Furthermore, we compare our new results from the 23 kmindiameter Lappajärvi impact structure, Finland, with the preexisting 40Ar/39Ar framework for .

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  • Precise radiometric age establishes Yarrabubba, Western ...

     · The ~70 kmdiameter Yarrabubba impact structure in Western Australia is regarded as among Earth's oldest, but has hitherto lacked precise age constraints. Here we present U–Pb ages for impact ...

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  • Minerals | Free FullText | Properties of ImpactRelated ...

     · Isotopic dating was done on zircon, crystallized from impact melts, and yielded 2020 ± 3 Ma, which is presently accepted as the most accurate age . Since the impact event, the impact structure has been eroded to a depth of 8–10 km [13,14]. The central uplift of the structure consists of Archean basement granites in the core, with the overturned supracrustal sequence .

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  • Cubic Zirconia

    In 1937 Cubic Zirconia was discovered by two German mineralogists. It was found in a natural state in a Zircon. The Zircon contained tiny crystals that were in a cubic form of zirconium oxide. At the time the two mineralogists thought so little of their discovery that they did not give it a name. This is why it is still known by its scientific name cubic zirconia...

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  • Shockdeformed zircon from the Chicxulub impact crater and ...

    Shockdeformed zircon from the Chicxulub impact crater and impliions for cratering process Jiawei Zhao1, Long Xiao1,2*, Zhiyong Xiao2,3, Joanna V. Morgan4, Gordon R. Osinski5,6, Clive R. Neal7, Sean Gulick8,9, Ulrich Riller10, Philippe Claeys11, Shanrong Zhao1, Nils C. Prieur12, Alexander Nemchin 13, Shuoran Yu 14 and IODP 364 Science Party† 1State Key Laboratory of Geological ...

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  • Shock deformation in zircon grains from the Mien impact ...

     · We investigated zircon grains from the Mien impact structure in southern Sweden with the aim of characterizing shock deformation. The grains were found in two samples of impact melt rock with varying clast content, and in one sample of suevitic breccia. We report the first documentation of socalled "FRIGN zircon" (former reidite in granular neoblastic zircon) from .

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  • A SEARCH FOR SHOCKED ZIRCONS IN IMPACT HORIZONS .

    Methodology: Zircons from the three impact horizons and Fig Tree sandstone were hand picked and placed onto SEM stubs. Backstered electron (BSE) and secondary electrons (SE) imaging of grain surfaces were carefully studied for identifiion of microstuctures as well as grain morphology. Figure 1. Example of planar fractures (PFs) in zircon. The grain is a detrital shocked zircon from ...

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  • Shockmetamorphosed zircon in terrestrial impact craters

    Shockmetamorphosed zircon in terrestrial impact craters 435 Popigai Crater To characterize shock features in zircon from coherent impact melt rocks, we investigated two samples from the largest known Cenozoic impact structure, the Popigai crater in northern Siberia, which is Ma old and 100 km in diameter (Masaitis 1994; Bottomley et al. 1997; Vishnevsky and Montanari 1999; Whitehead et ...

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  • Geochemical signatures in zircons as probes of the impact ...

    Impactgenerated or altered lunar zircons at about 4000 and 4200 Ma coincide with "LHB" and "preLHB" events reported in other radiogenic systems, other zircon ages from lunar impact breccias, as well as the oldest terrestrial zircons. These results support a longer period of bombardment akin to the proposed dynamical "Sawtooth" model.

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  • Amorphization in zircon: evidence for direct impact damage

    Amorphization in zircon: evidence for direct impact damage SR´ıos†§,EKHSalje†, M Zhang† and R C Ewing‡ † Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK ‡ Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI, USA Received 26 November 1999, in .

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