Integrated biomagnetochronology for the Palaeogene of ODP Hole 647A: implications for correlating palaeoceanographic events from high to low latitudes

Abstract

Lower Eocene to Oligocene microfossil-rich hemipelagic sediments in ODP Hole 647A, southern Labrador Sea, provide a strategic section for resolving the early history of high North Atlantic climates and ocean circulation, and for correlating with carbonate-poor lower Cenozoic sediments in the Arctic and Nordic seas. Our new, integrated palaeomagneto-and multigroup biostratigraphy (63 dinoflagellate cyst, calcareous nannofossil, planktonic foraminifer and diatom datums) significantly improves Site 647 chronostratigraphy and provides a framework for future studies. This new age model, coupled with provisional d 18 O analyses, provides greater confidence in the location of significant ocean-climate events at this site, including the Eocene-Oligocene transition and the Middle Eocene Climatic Optimum. Early Eocene hyperthermals may also be present near the base of the section. Palaeomagnetic age control is significantly improved in the Eocene, but not in the Oligocene. Revised estimates of sedimentation and biogenic flux indicate changes in supply and preservation that may be climatically controlled. A Lower to Middle Eocene hiatus is more precisely constrained, with a c. 4 million year duration. Age and depth errors quantify the age uncertainties throughout the section. Our revised age model will play an important role in stratigraphic correlation between very high latitude and lower latitude sites. Supplementary material: All tables with ages and age-derived calculations based on the Gradstein et al. (2004) timescale used herein are reproduced as supplementary tables using both the Gradstein et al. (2004) and the Cande & Kent (1995) timescales (Tables DS1-DS6). Discrete sample and shipboard pass-through cryomagnetometer palaeomagnetic data, planktonic foraminifer and fine fraction (,20 mm) stable isotope data, raw and processed core GRA density data, and specifications and results of GRA density spectral analyses are also provided as supplementary tables (Tables DS7-DS11). These tables are available at www.geolsoc.org.uk/SUP18546. Downloaded from J. V. FIRTH ET AL. J. V. FIRTH ET AL. J. V. FIRTH ET AL. } HO Nannotetrina spp.; LO of D. hesslandii (equivalent to R. bisecta). 1 HO Nannotetrina fulgens. 2 LO R. bisecta between top and base of C18r.

Comment on ‘Wetzeliella and its allies – the ‘hole’ story: a taxonomic revision of the Paleogene dinoflagellate subfamily Wetzelielloideae’ by Williams et al. (2015)

“…There are, however, numerous examples where species within the Wetzelielloideae, well defined within the original taxonomic framework, represent clear, unambiguous stratigraphical markers, such as; Apectodinium augustum at the PaleoceneEocene Thermal Maximum (e.g. Sluijs et al 2007); Charlesdowniea edwardsii, Dracodinium waipawaense and Wetzeliella samlandica in the early Eocene (Hollis et al 2009;Hollis et al 2012;Bijl et al 2013a, b;Dallanave et al 2016); Dracodinium rhomboideum, Dracodinium pachydermum and Charlesdowniea columna in the middle Eocene (Eldrett et al 2004;Eldrett & Harding 2009;Firth et al 2013); and Wetzeliella gochtii and Rhombodinium perforatum in the Oligocene (e.g. Pross 2001;Fensome et al 2008;Pross et al 2010;Sliwinska et al 2012;Egger et al in press).…”

Dinoflagelados del Eoceno medio a superior de las cuencas Punta Del Este y Colorado, latitudes medias del Atlántico sudoccidental

“…Esta información se puede extrapolar a las cuencas de latitudes medias del Atlántico Sudoccidental permitiendo asignar la sección analizada en el Pozo Gaviotín al Eoceno medio (Luteciano superior a Bartoniano inferior). La edad mínima coincide con la presencia de Diphyes colligerum, cuyo registro más joven está datado a los 39,8 Ma (Firth et al, 2013). Asimismo, la presencia de Enneadocysta arcuata en todas las asociaciones del intervalo analizado sugiere una edad no más antigua que 41,5 Ma (Firth et al, 2013).…”

“…La edad mínima coincide con la presencia de Diphyes colligerum, cuyo registro más joven está datado a los 39,8 Ma (Firth et al, 2013). Asimismo, la presencia de Enneadocysta arcuata en todas las asociaciones del intervalo analizado sugiere una edad no más antigua que 41,5 Ma (Firth et al, 2013). De acuerdo con Williams et al (2015) los registros más antiguos de Wetzeliella, caracterizado por un arqueopilo soleiforme, corresponden al Luteciano tardío.…”

“…El intervalo entre 1195 y 1275 m tiene una muy alta representación de Enneadocysta distyostila, por lo que puede ser asignado al Luteciano superior-Bartoniano inferior. Asimismo, la presencia de Cleistosphaeridum polypetellum a los 1195 m, cuyo biocrón se extiende desde el Eoceno inferior al Eoceno medio y de Phthanoperidinium comatum a los 1235 m confirma una edad no mayor a los 41.4 Ma (Firth et al, 2013). Los dos niveles inferiores (1295 y 1320) carecen de indicadores bioestratigráficos relevantes, excepto por la presencia de pocos ejemplares de la asociación endémica-antártica.…”

Magnetic methods and the timing of geological processes

“…We introduce applications that use magnetic direction and geomagnetic polarity reversals to infer geodynamo processes, tectonics, diagenesis and climate change. (Firth et al 2012;Savian et al 2013;Jovane et al 2013), and a composite integrated magnetostratigraphic sequence from Italy is provided for the entire Palaeogene Period (Coccioni et al 2012).…”