Cyclostratigraphic calibration of the Frasnian (Late Devonian) time scale (western Alberta, Canada)

Abstract

Until now, the duration of the Frasnian Stage has remained very poorly constrained, hampering a detailed understanding of sedimentation processes and environmental and evolutionary change. In this study, timeseries analyses of high-resolution (10-20 k.y.) magnetic susceptibility data identify sixteen 405 k.y. eccentricity cycles in the magnetic susceptibility stratigraphy of the Frasnian (Late Devonian), derived from carbonate-platform and surrounding slope and basin deposits in western Alberta, Canada. Previous studies demonstrated the generally consistent pattern of magnetic susceptibility change across the Alberta basin and thus demonstrated the utility of magnetic susceptibility stratigraphy as a refi ned regional correlation tool compared to biostratigraphy. In the present study, we show that the magnetic susceptibility stratigraphy of the Frasnian interval in western Alberta has been signifi cantly infl uenced by astro nomical forcing. Using the sixteen 405 k.y. eccentricity cycles as a geochronometer, we constructed a Frasnian astronomical time scale. This time scale indicates a duration of 6.5 ± 0.4 m.y. for the Frasnian. Calibrating this duration to the best available Devonian chronology, the absolute age of the Givetian-Frasnian boundary is recalculated to 383.6 ± 3.0 Ma, and the age of the Frasnian-Famennian boundary is recalculated to 376.7 ± 3.0 Ma. These new absolute ages take into account the astronomically derived duration of the Frasnian, but they also yield a narrowing of the error margins of the absolute ages by several hundreds of thousands of years.

Stratigraphic Completeness of Carbonate-Dominated Records From Continental Interiors Versus Continental Margins: Stratigraphic Thinning Occurs Via Condensation and Omission At Multiple Scales

“…A more precise approximation is not warranted because these durations could represent an under-estimate or overestimate, due to entire cycles missing at bounding surfaces or failure to identify cycles. Nonetheless, attributing these cycles to fourth-order to fifth-order sea-level change is consistent with sea-level oscillations documented in other Devonian records of North America and globally (Elrick 1995(Elrick , 1996Whalen and Day 2008;Tucker and Garland 2010;Brett et al 2011;De Vleeschouwer et al 2012;McClung et al 2013).…”

The astronomical calibration of the Givetian (Middle Devonian) timescale (Dinant Synclinorium, Belgium)

“…Lourens et al 2004;Meyers 2008;Meyers et al 2012). Only a few astrochronological studies have addressed Palaeozoic greenhouse periods such as the Devonian (Bai 1995;House 1995;Chlupáč 2000;Chen & Tucker 2003;Ellwood et al 2011a, b;Garcia-Alcalde et al 2012;De Vleeschouwer et al 2012b, 2013. Two of these studies estimated the duration of the Givetian by counting astronomically forced sedimentary cycles: House (1995) estimated the Givetian duration at 6.5 Myr, assuming that the dominant microcyclicity at the Pic de Bissous (southern France) is forced by climatic precession.…”

Middle Paleozoic Basaltic and Kimberlitic Magmatism in the Northwestern Shoulder of the Vilyui Rift, Siberia: Relations in Space and Time

“…Нюрбинская не может быть древнее возраста 383.6 ± 3.0 млн лет [Vleeschouwer et al, 2012], отвеча-ющего границе между живетским и франским ярусами девона.…”

“…Нюрбинская однозначно сидетельствует о том, что ее возраст не может быть древнее возраста грани-цы между живетским и франским ярусами, который оценивается в 383.6 ± 3.0 млн лет [Vleeschouwer et al, 2012]. Полученный в нашем исследовании возраст долеритов 374.4 ± 3.5 млн лет из дайки, прорыва-ющей кимберлиты, может являться верхним возрастным ограничением времени ее формирования.…”