Reassessing the uranium decay constants for geochronology using ID-TIMS U–Pb data

Schoene, Blair; Crowley, James L.; Condon, Daniel J.; Schmitz, Mark D.; Bowring, Samuel A.

doi:10.1016/j.gca.2005.09.007

Cited by 449 publications

(294 citation statements)

References 81 publications

(152 reference statements)

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“…Taken together, these data suggest that the Norian Stage has a duration of approximately 20 Ma, two-fifths the length of the entire Triassic Period. The end of the Rhaetian (Triassic-Jurassic boundary) is well constrained to between 202 and 201 Ma by U-Pb ages and magnetostratigraphic data (e.g., Kent and Olsen, 1999;Schoene et al, 2006;Schaltegger et al, 2008;Jourdan et al, 2009), with an estimated age of 201.3 Ma based on cyclostratigraphy (Whiteside et al, 2010).…”

Section: Dating the Origin Of Dinosaursmentioning

confidence: 99%

The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

240

214

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Dinosaurs were remarkably successful during the Mesozoic and one subgroup, birds, remain an important component of modern ecosystems. Although the extinction of non-avian dinosaurs at the end of the Cretaceous has been the subject of intense debate, comparatively little attention has been given to the origin and early evolution of dinosaurs during the Late Triassic and Early Jurassic, one of the most important evolutionary radiations in earth history. Our understanding of this keystone event has dramatically changed over the past 25 years, thanks to an influx of new fossil discoveries, reinterpretations of long-ignored specimens, and quantitative macroevolutionary analyses that synthesize anatomical and geological data. Here we provide an overview of the first 50 million years of dinosaur history, with a focus on the large-scale patterns that characterize the ascent of dinosaurs from a small, almost marginal group of reptiles in the Late Triassic to the preeminent terrestrial vertebrates of the Jurassic and Cretaceous. We provide both a biological and geological background for early dinosaur history. Dinosaurs are deeply nested among the archosaurian reptiles, diagnosed by only a small number of characters, and are subdivided into a number of major lineages. The first unequivocal dinosaurs are known from the late Carnian of South America, but the presence of their sister group in the Middle Triassic implies that dinosaurs possibly originated much earlier. The three major dinosaur lineages, theropods, sauropodomorphs, and ornithischians, are all known from the Triassic, when continents were joined into the supercontinent Pangaea and global climates were hot and arid. Although many researchers have long suggested that dinosaurs outcompeted other reptile groups during the Triassic, we argue that the ascent of dinosaurs was more of a matter of contingency and opportunism. Dinosaurs were overshadowed in most Late Triassic ecosystems by crocodile-line archosaurs and showed no signs of outcompeting their rivals. Instead, the rise of dinosaurs was a two-stage process, as dinosaurs expanded in taxonomic diversity, morphological disparity, and absolute faunal abundance only after the extinction of most crocodile-line reptiles and other groups.

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Section: Dating the Origin Of Dinosaursmentioning

confidence: 99%

The origin and early radiation of dinosaurs

Brusatte

Nesbitt

Irmis

et al. 2010

Earth-Science Reviews

240

214

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“…3) (Pringle et al 1974;Greenough and Papezik 1987;Wade and Jansa 1994;McHone 2011). Correlative basalt on the south shore of the Bay of Fundy in Nova Scotia yielded 40Ar/39Ar dates of 199 ± 1 Ma and 201 ± 1 Ma, and a U-Pb zircon date of 201.3 ± 0.3 Ma indicative of a Late Triassic (Rhaetian) age (Kontak and Archibald 2003;Schoene et al 2006;Cirilli et al 2009;Jourdan et al 2009). The development of the Fundy rift basin is related to the initial opening stages of the Atlantic Ocean (Nadon and Middleton 1984;Cirilli et al 2009).…”

Section: Fundy Basinmentioning

confidence: 99%

A Review of Proterozoic to Early Paleozoic Lithotectonic Terranes in New Brunswick, Canada and their Tectonic Evolution during Penobscot, Taconic, Salinic and Acadian Orogenesis

Fyffe

Johnson²,

Staal

2012

atgeol

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Geological relationships preserved in the New Brunswick segment of the Appalachian orogen are key to deciphering the complex tectonic events that occurred during the closing of the Paleozoic Iapetus Ocean. These events can be explained in terms of geodynamic interactions between eight lithotectonic terranes. The first, the Caledonia terrane, comprises Neoproterozoic volcanic arc sequences and comagmatic plutons considered to form part of the microcontinent of Avalonia. The seven other terranes are associated with the microcontinent of Ganderia and consist of (1) Brookville terrane-Mesoproterozoic to Neoproterozoic platformal carbonates and Neoproterozoic to Early Cambrian plutonic rocks, (2) New River terrane-Neoproterozoic volcanic arc sequences and comagmatic plutons overlain by a Cambrian Penobscot volcanic arc sequence, In New Brunswick, closure of the Iapetus Ocean is attributed to four major tectonic episodes: (1) the Penobscot orogeny, which accreted the Miramichi, Annidale, and St. Croix terranes to the New River terrane on the trailing edge of Ganderia by closing a Penobscot backarc basin in the Early Ordovician, (2) the Taconic orogeny, which accreted the Popelogan terrane on the leading edge of Ganderia to the Laurentian margin in the Late Ordovician and effectively closed the main tract of the Iapetus Ocean, (3) the Salinic orogeny, which accreted the Elmtree and Miramichi terranes to the Laurentian margin by closing the Tetagouche backarc basin in the Silurian, and (4) the Acadian orogeny, which accreted the Caledonia terrane (Avalonia) to the Brookville and New River terranes on the trailing edge of Ganderia in the latest Silurian to earliest Devonian and in the process closed the last remaining oceanic tract in the northeastern Appalachians. RÉSUMÉLes corrélations géologiques préservées dans la partie du Nouveau-Brunswick de l'orogène des Appalaches sont essentielles pour bien comprendre le déroulement des événements tectoniques complexes survenus au moment de la fermeture de l'océan Iapetus, pendant le Paléozoïque. Il est possible d'expliquer ces événements par des interactions géodynamiques entre huit terranes lithotectoniques. Le premier, soit le terrane calédonien, comprend des séquences d'arc volcanique et des plutons comagmatiques du Néoprotérozoïque dont on estime qu'ils faisaient partie du microcontinent Avalonia. Les sept autres terranes sont associés au microcontinent Ganderia et comprenaient les terranes que voici : (1)

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“…For these cases, the ability to trace the U-Pb system back to SI units means that these other decay systems can also be traced back, within limits, through assumptions about the samples used for inter-calibration. For the U-Pb system, the same approach can be taken to inter-calibrate 238 U/ 206 Pb and 235 U/ 207 Pb dates (Mattinson, 2000(Mattinson, , 2010Schoene et al, 2006), for instance by re-determining the 235 U decay constant (relative to the 238 U decay constant), exploiting the closed-system U-Pb systematics of zircons and assumed equivalence of 206 Pb/ 238 U and 207 Pb/ 235 U dates. Similarly, estimates for the 234 U and 230 Th decay constants have been determined relative to the 238 U decay constant using isotope dilution analyses of closed system secular equilibrium materials using gravimetrically calibrated U-Th tracers (Cheng et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

Condon¹,

Schoene²,

McLean³

et al. 2017

Preprint

Self Cite

116

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Mixed 235 U-233 U-205 Pb (-202 Pb) tracers for U-Pb isotope-dilution isotope ratio mass spectrometry have been prepared under the auspices of the EARTHTIME Initiative. The methods and results for the preparation and calibration of the U/Pb ratio and isotopic abundances are given, and the various sources of uncertainty are discussed and quantified. The accuracy of the EARTHTIME U-Pb tracer isotopic composition can be traced back to SI units via a series of assay and isotopic composition reference materials combined with the experiments described herein. The parameters used in calculating U/Pb ratios (and inferentially U-Pb dates) have correlated uncertainties that result in a total uncertainty contribution to 206 Pb/ 238 U dates of ± < 0.03% (95% confidence). For suitable terrestrial materials such as zircon, when other sources of uncertainty have been minimised (e.g., open-system behaviour, 238 U/ 235 U variation, intermediate daughter product disequilibrium, common Pb, etc.) the U-Pb tracer calibration uncertainty is a limiting factor in the accuracy of U-Pb geochronology -but less so than the uncertainty in the 238 U and 235 U decay constants (±0.11 and 0.14% 2r). The calibration approach of the mixed EARTHTIME 235 U-233 U-205 Pb (-202 Pb) tracers, in addition to updated values for reference materials (e.g., mixed gravimetric reference solutions), and parameters (e.g., Pb reference material assay), can be applied to other laboratory-specific U-Pb tracers and will facilitate the generation of accurate and directly inter-comparable U-Pb data.

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Reassessing the uranium decay constants for geochronology using ID-TIMS U–Pb data

Cited by 449 publications

References 81 publications

The origin and early radiation of dinosaurs

The origin and early radiation of dinosaurs

A Review of Proterozoic to Early Paleozoic Lithotectonic Terranes in New Brunswick, Canada and their Tectonic Evolution during Penobscot, Taconic, Salinic and Acadian Orogenesis

Metrology and Traceability of U-Pb Isotope Dilution Geochronology (EARTHTIME Tracer Calibration Part I)

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