Abstract
The Pennine Basin of northern England contains a comparatively complete Serpukhovian– Moscovian succession characterized by high-resolution ammonoid zonation and cyclic paralic sedimentation. Two new isotope dilution thermal ionization mass spectrometry zircon ages from a bentonite deposited during the Arnsbergian (mid-Serpukhovian) regional substage and tonstein of earliest Bolsovian (early Moscovian) regional substage have been determined. The weighted mean 206 Pb/ 238 U ages of 328.34 ± 0.55 and 314.37 ± 0.53 Ma (total uncertainty), respectively, require modification of the time scale for the Western Europe regional chronostratigraphy. The areal extent of acme ammonoid facies is used as a proxy for the magnitude of 47 discrete flooding events. Incised valleys (major sequence boundaries) are used as a proxy for the magnitude of sea-level falls. The frequency of these events, in the light of the new radiometric dating, indicates the following: (1) there is temporal coincidence between major glaciations in Gondwana and phases of increased frequency of sequence boundaries in the Pennine Basin; (2) high-amplitude flooding surfaces have an average frequency of c . 400 ka; (3) average cycle durations during the Pendleian–early Arnsbergian and Chokierian–Bolsovian, of c . 111 and c . 150 ka, respectively, reflect short-duration eccentricities; (4) multiple flooding surfaces with the same ammonoid assemblages may equate with sub-100 ka precession or obliquity frequencies. Supplementary material: U–Pb method description and data, procedure for the calculation of the areal extent of marine bands, and tables showing a full listing of biostratigraphical data used in the study are available at www.geolsoc.org.uk/SUP18505 .
Highlights
Zircons were analysed using CA-isotope dilution thermal ionization mass spectrometry (ID-TIMS) methodologies employed at NERC Isotope Geoscience Laboratory (NIGL), details of which are outlined in an online supplemental material along with the tabulated results of the analytical programme
This study provides two new high-precision U/Pb ages of 328.34 ± 0.55 Ma 522 for the Arnsbergian regional substage and 314.37 ± 0.53 Ma for the earliest Bolsovian regional substage
These ages are somewhat older than existing published ages for these successions and require modification of the current timescale for the Western Europe regional chronostratigraphy, but align with recent dates provided by Davydov et al (2010) for the Donetz Basin
Summary
Hess & Lippolt (1986) and Berger et al (1997) derived 40Ar/39Ar sanidine plateau dates from German and Czech tonsteins which suggested that the combined duration of the Namurian and Westphalian (broadly Serpukhovian to Moscovian) was about 21 Ma. Claoué-Long et al (1995) determined 39 measurements of 37 zircons from the Z1 tonstein, with a mean U–Pb SHRIMP age of 311.0 ± 3.4 Ma (2σ)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.