Search Results - "Ludwig, Kenneth R"

Age and Timing of the Permian Mass Extinctions: U/Pb Dating of Closed-System Zircons by Mundil, Roland, Ludwig, Kenneth R., Metcalfe, Ian, Renne, Paul R.

“…The age and tinning of the Permian-Triassic mass extinction have been difficult to determine because zircon populations from the type sections are typically…”
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On the Treatment of Concordant Uranium-Lead Ages by Ludwig, Kenneth R.

“…Uranium-lead analyses that yield arguably concordant U/Pb and Pb/Pb ages are highly reliable and often very precise; however, there is no generally accepted…”
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Continuous 500,000-Year Climate Record from Vein Calcite in Devils Hole, Nevada by Winograd, Isaac J., Coplen, Tyler B., Landwehr, Jurate M., Riggs, Alan C., Ludwig, Kenneth R., Szabo, Barney J., Kolesar, Peter T., Revesz, Kinga M.

“…Oxygen-18 ($\delta^{18}$O) variations in a 36-centimeter-long core (DH-11) of vein calcite from Devils Hole, Nevada, yield an uninterrupted 500,000-year…”
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Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia by White, Tim D, Clark, J. Desmond, Beyene, Yonas, WoldeGabriel, Giday, Hart, William K, Renne, Paul R, Gilbert, Henry, Defleur, Alban, Suwa, Gen, Katoh, Shigehiro, Ludwig, Kenneth R, Boisserie, Jean-Renaud, Asfaw, Berhane

“…Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult,…”
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Decay constant errors in U–Pb concordia-intercept ages by Ludwig, Kenneth R

“…Although almost universally ignored, the effect of errors in the uranium decay-constants on U–Pb concordia-intercept ages (and Pb–Pb ages) are significant, and…”
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Timing of the Permian–Triassic biotic crisis: implications from new zircon U/Pb age data (and their limitations) by Mundil, Roland, Metcalfe, Ian, Ludwig, Kenneth R., Renne, Paul R., Oberli, Felix, Nicoll, Robert S.

“…The most profound biotic crisis in the Earth’s history, causing the near extinction of both terrestrial and marine life, occurred at the end of the Permian…”
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Response to the comment by W.H. Schwarz et al. on “Joint determination of 40K decay constants and 40Ar ∗/ 40K for the Fish Canyon sanidine standard, and improved accuracy for 40Ar/ 39Ar geochronology” by P.R. Renne et al. (2010) by Renne, Paul R., Balco, Greg, Ludwig, Kenneth R., Mundil, Roland, Min, Kyoungwon

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Joint determination of 40K decay constants and 40Ar∗/ 40K for the Fish Canyon sanidine standard, and improved accuracy for 40Ar/ 39Ar geochronology by Renne, Paul R., Mundil, Roland, Balco, Greg, Min, Kyoungwon, Ludwig, Kenneth R.

“…40Ar/ 39Ar and K–Ar geochronology have long suffered from large systematic errors arising from imprecise K and Ar isotopic data for standards and imprecisely…”
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Eliminating mass-fractionation effects on U-Pb isochron ages without double spiking by Ludwig, Kenneth R.

“…The utility of uranium-lead isochrons for dating rocks with a restricted range in U/Pb is limited by any uncertainty in the mass fractionation of the analysis…”
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A cool eastern Pacific Ocean at the close of the Last Interglacial complex by Muhs, Daniel R., Simmons, Kathleen R., Kennedy, George L., Ludwig, Kenneth R., Groves, Lindsey T.

“…New high-precision thermal ionization mass-spectrometric (TIMS) U-series ages of solitary corals ( Balanophyllia elegans) from several marine terrace…”
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Absolute Ages Aren't Exactly by Renne, Paul R., Karner, Daniel B., Ludwig, Kenneth R.

“…Uncertainty in the decay constants has caused accuracy to lag behind precision in many radioisotopic dating methods This decay constant uncertainty causes…”
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Thorium-230 Ages of Corals and Duration of the Last Interglacial Sea-Level High Stand on Oahu, Hawaii by Szabo, Barney J., Ludwig, Kenneth R., Muhs, Daniel R., Simmons, Kathleen R.

“…Thorium-230 ages of emergent marine deposits on Oahu, Hawaii, have a uniform distribution of ages from ∼114,000 to ∼131,000 years, indicating a duration for…”
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A test for systematic errors in 40Ar/ 39Ar geochronology through comparison with U/Pb analysis of a 1.1-Ga rhyolite by Min, Kyoungwon, Mundil, Roland, Renne, Paul R., Ludwig, Kenneth R.

“…Important sources of systematic error in 40Ar/ 39Ar dating arise from uncertainties in the 40K decay constants and K/Ar isotopic data for neutron fluence…”
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U-Pb dating of uranium deposits in collapse breccia pipes of the Grand Canyon region by Ludwig, Kenneth R, Simmons, K. R

“…Two major periods of uranium mineralization are indicated by U-Pb isotope dating of uranium ores from collapse breeeia pipes in the Grand Canyon region,…”
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Joint determination of super(40)K decay constants and super(40)Ar/ super(40)K for the Fish Canyon sanidine standard, and improved accuracy for super(40)Ar/ super(39)Ar geochronology by Renne, Paul R, Mundil, Roland, Balco, Greg, Min, Kyoungwon, Ludwig, Kenneth R

“…super(40)Ar/ super(39)Ar and K-Ar geochronology have long suffered from large systematic errors arising from imprecise K and Ar isotopic data for standards and…”
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Evolution of volcanic rocks and associated ore deposits in the Marysvale volcanic field, Utah by Cunningham, Charles G, Steven, Thomas A, Rowley, Peter D, Naeser, Charles W, Mehnert, Harald H, Hedge, Carl E, Ludwig, Kenneth R

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Mass-Spectrometric $^{230}$Th-$^{234}$U-$^{238}$U Dating of the Devils Hole Calcite Vein by Ludwig, Kenneth R., Simmons, Kathleen R., Szabo, Barney J., Winograd, Isaac J., Landwehr, Jurate M., Riggs, Alan C., Hoffman, Ray J.

“…The Devils Hole calcite vein contains a long-term climatic record, but requires accurate chronologic control for its interpretation. Mass-spectrometric…”
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U-Pb isotope systematics and age of uranium mineralization, Midnite Mine, Washington by Ludwig, Kenneth R, Nash, J. T, Naeser, C. W

“…Uranium ores at the Midnite mine, near Spokane, Washington, occur in phyllites and calcsilicates of the Proterozoic Togo Formation, near the margins of an…”
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Age of uranium mineralization at the Highland Mine, Powder River basin, Wyoming, as indicated by U-Pb isotope analyses by Santos, Elmer S, Ludwig, Kenneth R

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Optimization of multicollector isotope-ratio measurement of strontium and neodymium by Ludwig, Kenneth R.

“…For isotope-ratio analyses of Sr and Nd whose precisions are constrained by amplifier and ion-counting noise, significant improvements in efficiency/precision…”
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