A new Miocene biostratigraphy for the northeastern North Atlantic: an integrated foraminiferal, bolboformid, dinoflagellate and diatom zonation

Abstract

This study presents a new Miocene biostratigraphic synthesis for the high-latitude northeastern North Atlantic region. Via correlations to the bio-magnetostratigraphy and oxygen isotope records of Ocean Drilling Program and Deep Sea Drilling Project Sites, the ages of shallower North Sea deposits have been better constrained. The result has been an improved precision and documentation of the age designations of the existing North Sea foraminiferal zonal boundaries of King (1989) and Gradstein and Bäckström (1996). All calibrations have been updated to the Astronomically Tuned Neogene Time Scale (ATNTS) of Lourens et al. (2004). This improved Miocene biozonation has been achieved through: the updating of age calibrations for key micro fossil bioevents, identification of new events, and integration of new biostratigraphic data from a foramini feral analysis of commercial wells in the North Sea and Norwegian Sea. The new zonation has been successfully applied to two commercial wells and an onshore research borehole. At these high latitudes, where standard zonal markers are often absent, integration of microfossil groups significantly improves temporal resolution. The new zonation comprises 11 Nordic Miocene (NM) Zones with an average duration of 1 to 2 million years. This multi-group combination of a total of 92 bioevents (70 foraminifers and bolboformids; 16 dinoflagellate cysts and acritarchs; 6 marine diatoms) facilitates zonal identification throughout the Nordic Atlantic region. With the highest proportion of events being of calcareous walled microfossils, this zonation is primarily suited to micropaleontologists. A correlation of this Miocene biostratigraphy with a re-calibrated oxygen isotope record for DSDP Site 608 suggests a strong correlation between Miocene planktonic microfossil turnover rates and the inferred paleoclimatic trends. Benthic foraminifera zonal boundaries appear to often coincide with Miocene global sequence boundaries. The biostratigraphic record is punctuated by four main stratigraphic hiati which show variation in their geographic and temporal extent. These are related to the following regional unconformities: basal Neogene, Lower/Middle Miocene ("mid-Miocene unconformity"), basal Upper Miocene and basal Messinian unconformities. Further coring of Neogene sections in the North Sea and Norwegian Sea may better constrain their extent and their effect on the biostratigraphic record.

An updated and revised stratigraphic framework for the Miocene and earliest Pliocene strata of the Roer Valley Graben and adjacent blocks

“…This type of analysis has led to significant improvements in age-dating of Neogene successions in NW Europe and beyond and in understanding their palaeoenvironmental setting (e.g. Powell, 1986Powell, , 1992Head et al, 1989;Brinkhuis, 1992Brinkhuis, , 1994Zevenboom, 1995;De Verteuil and Norris, 1996;Head 1998;Dybkjaer and Rasmussen, 2000;Louwye, 2002;Louwye et al, 2004;Köthe, 2007;Köthe et al, 2008;De Schepper and Head, 2009;Dybkjaer and Piasecki, 2010;Anthonissen, 2012;Quaijtaal et al, 2014;De Schepper et al, 2015Dybkjaer et al, 2018). The potential of dinoflagellate cyst analyses in (bio)stratigraphic differentiation for Neogene intervals in the Netherlands has been proven as well (e.g.…”

The Oligocene/Miocene boundary in the ON-Mol-1 and Weelde boreholes along the southern margin of the North Sea Basin, Belgium

“…Organic-walled dinoflagellate cysts (dinocysts) analysis has led to significant improvements in the age assessment of the late Paleogene-Neogene successions in NW Europe and in understanding their palaeoenvironmental setting (e.g. Powell, 1986 and1992;Head et al, 1989;Brinkhuis et al, 1992;Zevenboom, 1995;de Verteuil & Norris, 1996;Head, 1998;Dybkjaer & Rasmussen, 2000;Köthe, 2007;Köthe et al, 2008;De Schepper & Head, 2009;Dybkjaer & Piasecki, 2010;Anthonissen, 2012;Quaijtaal et al, 2014;De Schepper et al, 2015. The potential of dinoflagellate cyst analyses in (bio)stratigraphic differentiation has also been confirmed for the late Paleogene and Neogene intervals in Belgium and the Netherlands (e.g.…”

A revised core-seismic integration in the Molloy Basin (ODP Site 909): Implications for the history of ice rafting and ocean circulation in the Atlantic-Arctic gateway

“…This may be explained by the low and isolated occurrences of the stratigraphic marker species that might have been caused by reworking. Nonetheless, these species disappear in the Langhian to Serravallian (Anthonissen, 2012).…”

“…However, G. bulloides is also present close to the base of Hole 909C in Sample 103R-2, 3-7 at 1059.53 mbsf where it co-occurs with Globorotalia scitula. Anthonissen (2012) compiled stratigraphic information from a number of DSDP and ODP sites in the northern North Atlantic and Nordic Seas and gives an age of 14.7 Ma for the LO of G. bulloides. Globorotalia scitula appeared also in sediments younger than base middle Miocene (planktonic foraminifer zone N9; Spiegler, 1996) but Anthonissen (2012) (Myhre et al, 1995b).…”

“…Anthonissen (2012) compiled stratigraphic information from a number of DSDP and ODP sites in the northern North Atlantic and Nordic Seas and gives an age of 14.7 Ma for the LO of G. bulloides. Globorotalia scitula appeared also in sediments younger than base middle Miocene (planktonic foraminifer zone N9; Spiegler, 1996) but Anthonissen (2012) (Myhre et al, 1995b). If these species were considered reworked, the early Miocene marker species may also be indicative for younger sediments.…”