Thermoluminescence (TL) and optically stimulated luminescence (OSL) sensitivities, and IRSL/OSL measurements for core GL-1248 (off Parnaíba River drainage basin, northern northeastern Brazil)

Abstract

Marine sediment core GL-1248 was collected from the continental slope off northern northeastern Brazil by Petrobras oil company. Sediment samples (154 in total) were collected with 2 cm wide scoops at every 10 cm from the uppermost 16 m (covering the the last 113 thousand years) of the marine sediment core GL-1248. Samples were oven‐dried at 60°C, precisely weighted to 0.5 g and treated with H2O2 27% and HCl 10% to remove organic matter and calcium carbonate, respectively. The remaining content was diluted in alcohol and three aliquots per sample were mounted on stainless steel discs with four drops of the homogenized solution of alcohol and silt/clay sediments. GL-1248 luminescence measurements were performed on an automated Lexsyg Smart TL/OSL reader equipped with blue and infrared LEDs, Hoya U-340 filters for light detection in the ultraviolet band (270-390 nm) using a photomultiplier and beta radiation sources (90Sr/90Y) with doses rate of 0.116 Gy s-1 at the Luminescence and Gamma Spectrometry Laboratory of the Institute of Geosciences, University of São Paulo, Brazil. The sensitivity representative of the 110°C thermoluminesce (TL) peak of quartz considered the 80–120°C integration range from the TL curve. The 80-120°C TL sensitivity was calculated as a percentage of the total TL emission (0-250°C) and using the background TL curve. The mean of three measured aliquots represents the TL sensitivity of each sample. The OSL sensitivity was calculated by integrating the first second of light emission and the last ten seconds as background. GL-1248 TL sensitivity data were compared to previously published data obtained from marine sediment core GeoB16206-1 (https://doi.org/10.1594/PANGAEA.904357). Marine sediment core GeoB16206-1 was analyzed in a different luminescence reader (i.e. RisØ OSL/TL DA-20 reader) and using different regeneration dose. In order to avoid machine artifacts and the influence of dose size on sensitivity, we normalized the TL data output from both marine sediment cores and produced a composite record. Name of the Campaign: collected by the Petrobras oil company Event Label: GL1248 (GL-1248) Method: quarzt luminescence sensitivity Latitude: -0.920000 Longitude: -43.401667 Elevation: -2,264

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