Results 271 to 280 of about 68,798 (308)
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Air abrasion experiments in U-Pb dating of zircon
Chemical Geology, 1986Abstract Air abrasion of zircon grains can remove metamict material that has lost radiogenic Pb and zircon overgrowths that were added during younger events and thereby improve the precision of the age measurements and permit closer estimates of the original age.
S.S. Goldich, Lynn B. Fischer
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U–Pb dating of andradite-rich garnet by SIMS
Journal of Analytical Atomic Spectrometry, 2022The SIMS U–Pb dating method for andradite-rich garnet with the andradite composition ranging from 52 to 95 mol% was developed.
Yong-Shu Huang +8 more
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NanoSIMS imaging method of zircon U-Pb dating
Science China Earth Sciences, 2016We report an imaging method of zircon U-Pb dating with NanoSIMS 50L, which overcomes the significant U-Pb fractionation as the pit was sputtered deeper during conventional spot mode analysis and can be applied to irregular small grains or heterogeneous areas of zircon.
Sen Hu +6 more
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Rb–Sr and U–Pb dating of bentonites
Canadian Journal of Earth Sciences, 1983A 6 in. (15 cm) bentonite in the Z coal (Cretaceous–Tertiary boundary) in eastern Montana was sampled at four different places, and biotite, sanidine, and zircon were separated from the clay. U–Pb analyses of purified zircons yielded small systematic variations from concordant U–Pb dates.
H. Baadsgaard, J. F. Lerbekmo
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U‐Pb zircon dating of Stockholm granite at Frescati
GFF, 1995Abstract U‐Pb zircon dating of a sample of grey Stockhohn granite from Frescati just north of Stockholm yielded an upper intercept age of 1803+23 ‐19 Ma, similar to earlier age determinations, and interpreted as the age of crystallization of the granite. Ivarsson, C. & Johansson, A., 1995: U‐Pb zircon dating of Stockholm granite at Frescati.
Carin Ivarsson, Åke Johansson
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U-Pb dating of skarn garnets from Bulgarian deposits
2020<p>Calcic garnets from grossular-andradite (grandite) series have proven their ability to record the conditions and timing of their formation processes. Typically these minerals occur in skarn systems, together with other calc-silicates (diopside, epidote) and commonly host economic Cu, Zn-Pb-Ag, Au, Sn, W or Mo mineralization ...
Rossitsa Vassileva +4 more
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U-Pb dating of a speleothem of Quaternary age
Geochimica et Cosmochimica Acta, 1998We demonstrate that U-Pb dating is a promising method for secondary carbonate materials of Quaternary age and older by obtaining a 206Pb∗/238U age for a speleothem with high U (>10 μg g−1) and very low Pb (
Richards, DA +4 more
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UPb dating of a carbonate subaerial exposure event
Earth and Planetary Science Letters, 1995Ten samples of the dolomite fraction from the Lower Ordovician Oneota Formation, directly below the Sauk-Tippecanoe unconformity in Wisconsin, define a 238U206Pb age of 504 ± 14 Ma (MSWD = 190, 206Pb204Pb = 27–85, 238U204Pb = 84–795), which is in agreement with the 500 ± 4 Ma depositional age based on conodont biostratigraphy.
Bryce L. Winter, Clark M. Johnson
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Geochemistry: does U-Pb date Earth's core formation?
Nature, 2006Constraining the timing of the formation of Earth's core, which defines the birth of our planet, is essential for understanding the early evolution of Earth-like planets. Wood and Halliday and Halliday discuss the apparent discrepancy between the U-Pb (60-80 Myr) and Hf-W clocks (30 Myr) in determining the timescale of Earth's accretion and core ...
Qing-zhu, Yin, Stein B, Jacobsen
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Identifying Geologically Meaningful U-Pb Dates in Fossil Teeth
2017Dating attempts on fossil material have thus far yielded mixed results. While successes have been reported on single specimens, most fossils are thought to have experienced a complex history that obscures a simple determination of age. For this thesis, transects along the cross-sections of 14 fossil alligorid teeth from the Arroyo Chijuillita Member of
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