IRSL Signals from Maar Lake Sediments Stimulated at Various Temperatures

Abstract

Optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) have been measured from seven fine-grained samples from core JW3 from the dry maar of Jungfernweiher (West Eifel /Germany). Two different elevated temperature post-IR IRSL protocols in the blue detection were applied to polymineral fine grains (4-11 μm). These protocols involve stimulation with IR for up to 200s at 50°C prior to elevated temperature stimulation with IR for 100s at 225°C or 200s at 290°C. Quartz OSL saturates at doses of 260-300 Gy, and the De values obtained using IRSL at 50°C (IR50) do not increase with depth indicating that this signal is also in field saturation at ∼500 Gy. However, the post-IR IRSL signals at 225°C (pIRIR225) and 290°C (pIRIR290) increase with depth from ∼800 Gy to ∼1400 Gy, suggesting a minimum (fading uncorrected) age of ∼200 ka for the youngest sediments. Mean laboratory fading rates are 4.09 ± 0.02%/decade for IR50 and 2.55 ± 0.14%/decade for polymineral pIRIR225. For sample JWS1 a g-value of 0.52 ± 1.12%/decade for the pIRIR290 was obtained. Both fading corrected pIRIR225 and uncorrected pIRIR290 De values from the youngest sample (∼16 m below modern surface) indicate an age estimate of ∼250 ka for the uppermost sample increasing up to ∼400 ka for the oldest samples taken ∼94 m below modern surface. Copyright: