Age limits on Middle Pleistocene glacial sediments from OSL dating, north Norfolk, UK

Abstract

The lowland region of north Norfolk contains some of the best preserved evidence for glacial deposition during the Middle Pleistocene in northwest Europe.Despite the importance of these deposits, there is limited chronological control and it is debated whether they belong to a single glaciation, equated to the Anglian glaciation (Marine Isotope Stage 12), or represent deposition over a number of Middle Pleistocene cold stages. In order to develop an improved chronology for glaciation in this region, we obtained 18 samples for optical stimulated luminescence (OSL) dating from glacial outwash facies. Samples of coarse-grained quartz sand were measured using the SAR (single aliquot regenerative-dose) protocol. The low radioactive isotope concentrations in sediments of this region enable the traditionally accepted age limit of luminescence dating to be extended. The form of the dose response curves, pre-heat plateaux tests, and dose recovery experiments also indicate that laboratory doses can be reliably measured in these samples. Age overestimation due to partial bleaching is thought to be insignificant. The OSL ages suggest that the glacial sediments studied were deposited during MIS 12 rather than in different post MIS 12 stages.

A polyphase glacitectonic model for ice-marginal retreat and terminal moraine development: the Middle Pleistocene British Ice Sheet, northern Norfolk, UK

“…The southern limit of this advance was marked by the development of a large composite moraine topped by outwash sands and gravels that forms the area of elevated ground between Trimingham and Fakenham known locally as the 'Cromer Ridge' (Boulton et al, 1984;Hart, 1990;Pawley et al, 2005) together with a range of more localised northerly-developed glacitectonic structures (Ehlers et al, 1987). The outwash, collectively known as the Briton's Lane Formation (dated by OSL to Marine Isotope Stage (MIS) 12 (Anglian) by Pawley et al, 2008), extends southwards from the 'Cromer Ridge' as a highly-degraded sheet that drapes over the pre-existing glacial deposits and topography (Straw, 1973;Moorlock et al, 2002). To the north of the 'Cromer Ridge', further sands and gravels Lee, J.R., Phillips, E., Booth, S.J., Rose, J., Jordan, H.M., Pawley, S.M., Warren, M., Lawley, R.S.…”

“…The absolute chronology of the A6 event in north Norfolk is a controversial issue with several different models indicating glaciation during the Anglian glaciation (Lunkka, 1994;Banham et al, 2001;Pawley et al, 2008;Preece et al, 2009) or during a later Middle Pleistocene glaciation possibly equivalent to MIS 6 (Saalian) (Straw, 1973;Hamblin et al, 2000Hamblin et al, , 2005Rose, 2009). A detailed critique of the evidence and arguments behind this debate is beyond the scope of this paper (see Rose, 2009 for an overview of this debate) although 'dated' stratigraphic levels within the glacitectonised succession enable a chronostratigraphy to be applied to parts of the succession.…”

The problem of dating quartz 1: Spectroscopic ionoluminescence of dose dependence

“…Numerous OSL dating applications to sediments of different ages (e.g. Ballarini et al, 2003;Pawley et al, 2008), provenances (e.g. Preusser et al, 2006) and depositional environments (e.g.…”

Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK

“…As a source of dissolved calcium carbonate to groundwater is required, it is most likely that reworked chalk in the overlying glacial tills of the Sheringham Cliffs Formation was the dominant source: the observed relationship between presence of crust and overlying chalk-rich tills supports this interpretation. As these tills were probably deposited during MIS 12 (Pawley et al 2008), the cementation is unlikely to be older than c. 480 ka (much younger than the timing proposed by Burnaby, 1950). This is strongly supported by the nearby presence of groundwater calcretes at the contact between the Sheringham Cliffs Formation tills and the Wroxham Crag (Fig.…”

“…Although the study site is close to the Devensian ice margin, there is no proof positive that solution was a Devensian event. Indeed the nearby glacial outwash deposits of the Briton's Lane Sand and Gravel Member appear to be of MIS 12 age (Pawley et al 2008), so solution could have been related to these outwash events. We can be more certain, due to the isotopic constraints, that cementation was not related to glacial melt-water or subglacial waters.…”