Results 151 to 160 of about 1,365 (198)

Synthesis and purification of 205Pb for UPb geochronology

Chemical Geology: Isotope Geoscience section, 1987
Abstract 205Pb is a synthetic isotope of great utility in UPb geochronology, but it has never been widely available in a purified, useable form. We have successfully completed two production runs with a total yield of ∼100μg 205Pb. The isotope was produced by 24–27-MeV proton irradiation using cyclotron facilities of Atomic Energy of Canada Limited
Randall R. Parrish, Tom E. Krogh
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UPb geochronology of the Sri Lankan basement

Precambrian Research, 1994
Abstract UPb ages of zircons and monazites from ortho- and paragneisses representing the major crystalline basement units of Sri Lanka establish a new geochronological framework, which is consistent with previously published work on SmNd model ages, RbSr whole-rock ages, and UPb mineral ages.
S. Hölzl, A.W. Hofmann, W. Todt, H. Köhler   +3 more
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Bastnaesite: a promising U-Pb geochronological tool

Doklady Earth Sciences, 2010
One of the most complex problems in geochrono logical studies is dating endogenous ore processes. The application of the U–Pb method in solving this prob lem is constrained by the sufficiently narrow range of traditional mineral geochronometers, which, if present in ores, are strongly altered.
E. B. Sal’nikova, S. Z. Yakovleva, A. V. Nikiforov, A. B. Kotov, V. V. Yarmolyuk, I. V. Anisimova, A. M. Sugorakova, Yu. V. Plotkina   +7 more
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Zircon U–Pb geochronology of paragneisses and biotite

2011
Sensitive high-resolution ion microprobe U–Th–Pb age determinations on detrital and inherited zircon from the E ´ vora Massif (SW Iberian Massif, Portugal) provide direct evidence for the provenance of the Ossa–Morena Ediacaran basins (Se´rie Negra) and a palaeogeographical link with the West African craton.
Pereira, M. Francisco, Chichorro, Martim, Williams, Ian S., Silva, Jose B.   +3 more
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U-Pb geochronology of exposed basement rocks in Oklahoma

Geological Society of America Bulletin, 1979
U-Pb measurements on zircons separated from Precambrian basement rocks from Oklahoma yield the following: (1) the Spavinaw Granite, which appears in outcrops in Mayes County, northeastern Oklahoma, is 1,370 ± 20 m.y. old; (2) the ages of rocks exposed in the eastern Arbuckle Mountains in southeastern Oklahoma are: Tishomingo Granite, 1,374 ± 15 m.y ...
M. E. BICKFORD, RICHARD D. LEWIS
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U–Pb geochronology: its development and importance in Canada

Canadian Journal of Earth Sciences, 2023
This article presents a history of the development of U–Pb geochronology with emphasis on the role of Canadian researchers and some of its applications to Canadian geology. Modern U–Pb dating is the result of work by many individuals over the past 60 years, but the most important was Tom Krogh, who established methods that allowed determination of ...
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U–Pb geochronological constraints of the late Svecofennian leucogranites of southern Finland

Precambrian Research, 2011
Abstract The ∼500 km long zone of late Svecofennian leucogranites in southern Finland is characterized by felsic, in places migmatitic magmatism that crosscuts older Paleoproterozoic crustal segments. SIMS and ID-TIMS U–Pb isotopic data on zircon and monazite from 15 granite and migmatite samples show that the emplacement of individual leucogranite ...
Matti Kurhila, Irmeli Mänttäri, Matti Vaasjoki, O. Tapani Rämö, Mikko Nironen   +4 more
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U/Pb Zircon Geochronology and Tempo of the End-Permian Mass Extinction

Science, 1998
The mass extinction at the end of the Permian was the most profound in the history of life. Fundamental to understanding its cause is determining the tempo and duration of the extinction. Uranium/lead zircon data from Late Permian and Early Triassic rocks from south China place the Permian-Triassic boundary at 251.4 ± 0.3 million years ago.
S. A. Bowring, D. H. Erwin, Y. G. Jin, M. W. Martin, K. Davidek, W. Wang   +5 more
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Revolution and Evolution: 100 Years of U-Pb Geochronology

Elements, 2013
U–Pb geochronology has its roots in a spectacular decade of discovery. Within about ten years of the discovery of radioactivity in 1896, old ideas about the nature of matter were overthrown and the seeds of geochronology were planted. After giants of physics like Ernest Rutherford moved on to other research, Arthur Holmes nurtured the new field of ...
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U–Pb ID-TIMS geochronology using ATONA amplifiers

Journal of Analytical Atomic Spectrometry, 2020
New low noise, large dynamic range amplifiers applied to Faraday measurements of small loads of Pb and U for geochronology.
Dawid Szymanowski, Blair Schoene
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