Palaeomagnetic correlation and dating of Plio/Pleistocene sediments at the southern margins of the North Sea Basin

Abstract

A series of discontinuous sediment sequences, of Plio/Pleistocene age, occur onshore around the southern North Sea margins, notably in the East Anglian region of Britain. Intensive lithological and palaeontological analyses of these sediments have shown that they record both major and minor oscillations in climate, sea level and environmental conditions. However, significant uncertainties exist regarding the absolute and relative chronostratigraphies of many of these sequences, hindering understanding of the relative impacts of climatic, eustatic and tectonic changes on the palaeogeographic development of the southern North Sea basin. Here, a number of key East Anglian Plio/Pleistocene sites are subjected to robust palaeomagnetic and mineralogical examination, in order to determine those sediments which display reliable, syn-depositional magnetic polarities, which are thus of use in ascribing a palaeomagnetically determined age from comparison with the Geomagnetic Polarity Timescale (GPTS). Based on a range of palaeomagnetic and complementary mineralogical methods, reliable palaeomagnetic directions were obtained from eight sites, with reversed polarities displayed by sediments from three sites. These polarity determinations can be used to infer absolute ages and test published, between-site correlations.

A striated, far travelled clast of rhyolitic tuff from Thames river deposits at Ardleigh, Essex, England: evidence for early Middle Pleistocene glaciation in the Thames catchment

“…Palaeomagnetism is appropriate and the site at Ardleigh has been studied. The results have been published (Maher and Hallam, 2005) indicating normal polarity with the inference that the gravels are younger than 780 ka.…”

A consistent magnetic polarity stratigraphy of late Neogene to Quaternary fluvial sediments from the Heidelberg Basin (Germany): A new time frame for the Plio–Pleistocene palaeoclimatic evolution of the Rhine Basin

“…As already noted by Rolf et al (2008), this worldwide climate change is marked by the initiation of Northern Hemisphere glaciation and is well documented in deep-sea sediments (Shackleton et al, 1984) and loess deposits in China (Heller and Liu, 1982). Further advances in the knowledge of superregional geological and palaeoclimatic developments can be expected from, for example, the correlation with the Plio/Pleistocene sites in the North Sea Basin (Zagwijn, 1985;Maher and Hallam, 2005b;Westerhoff et al, 2008), the Pannonian Basin (Nádor et al, 2003) and the Po-Basin (Scardia et al, 2006;Muttoni et al, 2007).…”

“…He studied sedimentary successions in the North Sea Basin and correlated a number of stratigraphic levels with the geomagnetic polarity time scale (GPTS). In the following years, magnetic polarity stratigraphy became an important age determination tool for geologically young, onshore strata worldwide (e.g., Keller et al, 1977;Heller and Liu, 1982;Johnson et al, 1986;Appel et al, 1991;Biswas et al, 1999;Maher and Hallam, 2005b;Scardia et al, 2006). However, the current chronostratigraphic system for the Quaternary and the late Neogene in central and north-western Europe is based primarily on pollen-analysis investigations from the Netherlands and the Lower Rhine Embayment (i.e., Zagwijn, 1957Zagwijn, , 1963Zagwijn, , 1985Kemna, 2008;Westerhoff et al, 2008).…”

Magnetic carriers and remanence mechanisms in magnetite‐poor sediments of Pleistocene age, southern North Sea margin

“…Recent work has shown that some of the sedimentary units can be reliably dated using reversal magnetostratigraphy (e.g. Hallam and Maher, 1994;Maher and Hallam, 2005). However, compared with the more complete Pleistocene sediments in the Netherlands (van Montfrans, 1971), the East Anglian sediments display very few reversed polarity intervals.…”