4 results on '"Cirilli, S."'
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2. 40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias
- Author
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Jourdan, F., primary, Marzoli, A., additional, Bertrand, H., additional, Cirilli, S., additional, Tanner, L.H., additional, Kontak, D.J., additional, McHone, G., additional, Renne, P.R., additional, and Bellieni, G., additional
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- 2009
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3. 40Ar/39Ar ages of CAMP in North America: Implications for the Triassic–Jurassic boundary and the 40K decay constant bias
- Author
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Jourdan, F., Marzoli, A., Bertrand, H., Cirilli, S., Tanner, L.H., Kontak, D.J., McHone, G., Renne, P.R., and Bellieni, G.
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ARGON isotopes , *POTASSIUM isotopes , *TRIASSIC stratigraphic geology , *JURASSIC stratigraphic geology , *MAGMAS , *GEOLOGICAL time scales , *RADIOACTIVE decay - Abstract
Abstract: The Central Atlantic magmatic province (CAMP) is one of the largest igneous provinces on Earth (>107 km2), spanning four continents. Recent high-precision 40Ar/39Ar dating of mineral separates has provided important constraints on the age, duration, and geodynamic history of CAMP. Yet the North American CAMP is strikingly under-represented in this dating effort. Here we present 13 new statistically robust plateau, mini-plateau and isochron ages obtained on plagioclase and sericite separates from lava flows from the Fundy (n =10; Nova Scotia, Canada), Hartford and Deerfield (n =3; U.S.A.) basins. Ages mostly range from 198.6±1.1 to 201.0±1.4 Ma (2σ), with 1 date substantially younger at 190.6±1.0 Ma. Careful statistical regression shows that ages from the upper (199.7.0±1.5 Ma) and bottom (200.1±0.9 Ma) units of the lava pile in the Fundy basin are statistically indistinguishable, confirming a short duration of emplacement (≪1.6 Ma; ≤1 Ma). Three ages obtained on the Hartford (198.6±2.0 Ma and 199.8±1.1 Ma) and Deerfield (199.3±1.2 Ma) basins were measured on sericite from the upper lava flow units. We interpret these dates as reflecting syn-emplacement hydrothermal activity within these units. Collectively, CAMP ages gathered so far suggest a short duration of the main magmatic activity (2–3 Ma), but also suggest the possibility of a temporal migration of the active magmatic centers from north to south. Such a migration challenges a plume model that would postulate a radial outward migration of the magmatism and is more compatible with other models, such as the supercontinent global warming hypothesis. When compared to the age of the Triassic–Jurassic boundary, the filtered CAMP age database suggests that the onset of the magmatic activity precedes the limit by at least few hundred thousand years, thereby suggesting a causal relationship between CAMP and the end of Triassic mass extinction. An age at 191 Ma possibly suggests a minor CAMP late tailing activity (190–194 Ma) which has been observed already for dykes and sills in Africa and Brazil. We speculate that, if genuine, this late activity can be due to a major extensional event, possibly heralding the oceanization process at ~190 Ma. Comparison between high quality U/Pb and 40Ar/39Ar ages of pegmatite lenses from the North Mountain basalts confirms a ~1% bias between the two chronometers. This discrepancy is likely attributed to the miscalibration of the 40K decay constants, in particular the electron capture branch. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
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4. Timing and duration of the Central Atlantic magmatic province in the Newark and Culpeper basins, eastern U.S.A
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Fred Jourdan, Simonetta Cirilli, Giuliano Bellieni, Hervé Bertrand, Tiberio Cuppone, John H. Puffer, Angelo De Min, Lawrence H. Tanner, Andrea Marzoli, Robert E. Weems, Dipartimento di Geoscienze [Padova], Universita degli Studi di Padova, Western Australian Argon Isotope Facility, Department of Applied Geology & JdL-CMS, Curtin University [Perth], Planning and Transport Research Centre (PATREC)-Planning and Transport Research Centre (PATREC), Department of Earth and Environmental Science [Newark], Rutgers University [Newark], Rutgers University System (Rutgers)-Rutgers University System (Rutgers), Department of Biological Sciences [Syracuse], Le Moyne College, Paleo Quest, Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement [Lyon] (LGL-TPE), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), Dipartimento di Scienze della Terra, Università degli Studi di Perugia (UNIPG), Università degli studi di Trieste, CARIPARO agency, PRIN agency, Marzoli, A., Jourdan, F., Puffer, J. H., Cuppone, T., Tanner, L. H., Weems, R. E., Bertrand, H., Cirilli, S., Bellini, G., DE MIN, Angelo, Università degli Studi di Padova = University of Padua (Unipd), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Università degli Studi di Perugia = University of Perugia (UNIPG), and Università degli studi di Trieste = University of Trieste
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basalt ,010506 paleontology ,[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph] ,Lava ,[SDE.MCG]Environmental Sciences/Global Changes ,Geochemistry ,Geocronology ,Triassic-Jurassic ,NE american basins ,[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph] ,Diachronous ,Structural basin ,engineering.material ,010502 geochemistry & geophysics ,01 natural sciences ,40Ar/39Ar age ,Sill ,[SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry ,Geochemistry and Petrology ,Plagioclase ,Lava flow correlation ,lava flow correlation ,0105 earth and related environmental sciences ,Basalt ,geography ,geography.geographical_feature_category ,Geology ,40Ar/39Ar ,Central Atlantic magmatic province ,Volcano ,13. Climate action ,engineering ,Phenocryst ,[SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy - Abstract
International audience; New major and trace element data and (40)Ar/(39)Ar plateau ages constrain the timing, duration and time-related geochemical evolution of the Central Atlantic magmatic province in the U.S.A. (Newark and Culpeper basins) and refine correlations with basaltic lava flows from other Late Triassic-Early Jurassic circum-Atlantic basins. The precise, statistically robust (40)Ar/(39)Ar plateau ages were obtained on biotite and on fresh plagioclase and calculated using the latest (40)K decay constants. These ages are supported by a general consistency of the Ca/K calculated from (37)Ar/(39)Ar of the plateau steps and the Ca/K obtained by detailed electron microprobe analyses on plagioclase phenocrysts. The ages of five analyzed basalt lava flows, from all three lava flow units in the Newark basins, and the ages of two sill samples are indistinguishable, indicating a brief magmatic peak phase at 201.8 +/- 0.7 Ma. Recalibrated (40)Ar/(39)Ar plateau ages from the entire province indicate a near-synchronous onset and peak volcanic activity at the Triassic-Jurassic boundary within the circum-Atlantic basins from the U.S.A., Canada and Morocco. The early erupted magmas (Moroccan Lower to Upper basalts, the Fundy basin North Mountain Basalt, and Orange Mountain and equivalent U.S.A. flows) yield an enriched geochemical signature (e.g., with relatively high La/Yb), whereas late magmas in the U.S.A. (Hook Mountain and Hampden basalts) and Morocco (Recurrent basalt) yield relatively depleted geochemical compositions (low La/Yb). A slight, but significant age difference for eruption of Hook Mountain and Hampden basalts (200.3 +/- 0.9 Ma) and Recurrent basalts (198.2 +/- 1.1 Ma) is interpreted as evidence of a diachronous northward rift-drift transition during break-up of Pangea. Our data indicate also a prolonged intrusive sequence that continued until about 195 Ma at the Palisades sill and is consistent with sporadic late CAMP magmatism for dykes from the south-eastern U.S.A. and for intrusions from Guinea.
- Published
- 2011
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