A scanning system for measuring the age-related luminescence of split sediment cores

This article describes the development and performance of an integrated optical sensor system that has been designed for rapid analysis of split sediment cores. The primary aim of the system is to obtain information based on optically stimulated luminescence (OSL) techniques; these provide a record of the accrued radiation dose of material since deposition. Particularly after suitable normalization, the luminescence signal recorded along the length of the core will provide information on the relative age of the sediment. Two wavelengths of stimulation are used (infra-red and green) and these probe the feldspar, and combined feldspar and quartz components of the sediment respectively; the ratio of the two signals can thus provide some indication of relative changes in the silicate mineralogy. A secondary use of the system is for optical reflectance measurements. With the addition of a monochromator, optical reflectance spectroscopy can be applied to obtain additional information on down-core mineralogical changes. In this article we describe technical aspects of the sensor system, discuss measurement techniques and consider the relevance of data obtained. Two examples of sediment cores are presented, which demonstrate the applicability of the instrument.     

Aeolian stratigraphy and thermoluminescence dating of sediments of late Holocene age from Sola, southwest Norway

Thermoluminescence age determinations were performed on four aeolian sand samples of late Holocene scenceagesediments from Stavanger airport, Sola, in southwest Norway. The locality is well suited for testing thermoluminescence dating because of a good agreement between radiocarbon ages and age information based on archaeological typology and sea level changes. The conclusion from a comparison of thermoluminescence and archaeologicaltypologyradiocarbon dates is that it is possible to date well bleached sediments as young as 1600 years with thermoluminescence (TL). The TL dates for the aeolian deposits are in accord with expected ages. Six formal, diachronous aeolian/non-aeolian phases are defined and grouped together as the Sola Episode. The first phase onousaeolian/non-aeolianof aeolian activity was short-lasting and took place in the middle Subboreal chronozone. A second and lianactivitywaslong-lasting period, dominated by aeolian activity, took place from the transition between the Subboreal and Subatlantic chronozones until the present. We conclude that human activities were the releasing factor for the aeolian activity recorded in sand sheets.     

Luminescence dating of Late Quaternary sediments from East Greenland

Luminescence dating based on K-feldspars and using both TL and OSL methods have been performed on 94 sediment samples from East Greenland. The ages go back more than 380 ka, but are mainly from the last interglaciation and the subsequent period and include both shallow-marine/coastal-fluvial and ice proximal meltwater sediments. Independent age control indicates that the dates in the first group generally fall within ± 15% of the expected age, although a few samples show larger deviations. The ice proximal sediments, on the other hand, show a much larger spread and exaggerated ages, probably owing to incomplete bleaching. OSL may give better results than TL in these sediments.     

Three frost wedge casts from Jutland (Denmark) and TL dating of their infill

Excavations for an oil pipeline in western Jutland provided the opportunity to study geological features in the trenches. Among these were ice wedge casts, composite wedge casts, and wedges with primary infilling of eolian sand. In this paper the characteristics of three wedges with a high proportion of primary infill of eolian sand are described in some detail. Thermoluminescence (TL) dating was made on the eolian sand using 0.1–0.3 mm grains of quartz and potassium feldspar. The TL ages are: 39,000 ± 5,000, 24,000 ± 3,000, and 17,000 ± 3,000 years B.P. These ages are discussed and compared with indirect datings. Palaeoenvironmental conditions at the time of maximum cold during the upper part of the Weichselian are briefly considered.