New high-precision U–Pb dates from western European Carboniferous tuffs; implications for time scale calibration, the periodicity of late Carboniferous cycles and stratigraphical correlation

Abstract

We present three new high-precision U–Pb zircon chemical abrasion–isotope dilution–thermal ionization mass spectrometry (CA-ID-TIMS) dates from western European Carboniferous diagenetically altered volcanic ash layers (bentonites and tonsteins) that occur interbedded with cyclic siliciclastic sedimentary rocks. The dates constrain the average periodicity of western European late Carboniferous (Arnsbergian to early Langsettian) cyclic sedimentation to between 89 and 124 ka per cycle. This is consistent with the 100 ka ‘short’ eccentricity Milankovitch cycle and supports previous suggestions that the cycles are the product of glacio-eustasy. Cyclostratigraphic tuning of Namurian cycles to the 100 ka eccentricity cycle revises the timing of the global Mississippian–Pennsylvanian boundary to c . 323.9 Ma. CA-ID-TIMS dates also facilitate correlation between different facies belts where biostratigraphical correlations are difficult. Correlation between eastern and western European sequences confirms that the base of the Moscovian stage is located within the Duckmantian (Westphalian B) western European regional substage. Supplementary materials: Zircon separation and concentration procedures, U–Pb zircon CA-ID-TIMS methods and data table, average periodicity calculations for western and central European Namurian and Westphalian sedimentary cycles, and procedures for recalibrating legacy 40 Ar/ 39 Ar dates are available at www.geolsoc.org.uk/SUP18547 .

Re-assessment of lithostratigraphy, biostratigraphy, and volcanic activity of the Late Paleozoic Intra-Sudetic, Krkonoše-Piedmont and Mnichovo Hradiště basins (Czech Republic) based on new U-Pb CA-ID-TIMS ages

“…4). Its Bolsovian age (312.39 ± 0.10 Ma) is in agreement with both macrofloras (Šetlík 1977) and the published numerical age of this sub-stage (Gradstein et al 2012, Pointon et al 2012, Opluštil et al 2016 and contrasts with its previously determined 40 Ar/ 39 Ar sanidine plateau age of 309.3 ± 4.6 Ma (Lippolt et al 1986). Flora of the lower part of the Petrovice Member is similar to that of the Prkenný Důl-Žďárky Member, however, in its upper part Annularia sphenophylloides, A. stellata and Linopteris obliqua appear (Fig.…”

“…We, however, prefer the late Duckmantian based on a 313.78 ± 0.08 Ma CA-ID-TIMS age for the Z1 tonstein in the Ruhr Basin, Germany (Pointon et al 2012), which is located~10 m below the regionally widespread Aegiranum Marine Band, the base of which defines the Duckmantian/Bolsovian boundary (Owens et al 1985). The radioisotopic age of the 3 rd Strážkovice coal tonstein is thus in agreement with late Duckmantian macroflora of the Prkenný Důl-Žďárky Member (Šimůnek in Pešek et al 2001).…”

“…Although these data are still relatively rare, where available, they help to calibrate local lithostratigraphic units, identify hiatuses, and via numerical ages correlate local lithostratigraphic units and biozones to Global Chart (e.g. Davydov et al 2010, Pointon et al 2012, Schmitz & Davydov 2012, Michel et al 2015, Opluštil et al 2016. Such an approach can be very useful in continental basins, where floral and faunal biozones are difficult to correlate to marine zones and, in turn, to global stages.…”

Castle Conglomerate Unit of the Upper Silesian Basin (Czech Republic and Poland): a record of the onset of Late Mississippian C2 glaciation?

“…Although we do not have sufficient reliable geochronological data, orbital climatic forcing appears to be the simplest explanation of the cyclothems' driving mechanism (Davydov et al 2010, Pointon et al 2012, Sweet & Soreghan 2012. The two major coarse-grained and most laterally persistent units of the Ostrava Formation are correlated with two major glacieustatic sea level drops (Haq & Schutter 2008): the Castle Conglomerate Unit at 323 Ma and the stratigraphic level of the Main Ostrava Whetstone at 327.4 Ma (see Fig.…”

“…This study has implication for sequence stratigraphic analysis of the Late Palaeozoic cyclothems and paleoclimatic analysis of the Late Palaeozoic, a topic of long-term interest (e.g., Hampson et al 1999, Bishop et al 2010, Davydov et al 2010, Jerrett et al 2011, Pointon et al 2012, Sweet & Soreghan 2012.…”