IRSL DATING OF A DEEP WATER CORE FROM PYLOS, GREECE; COMPARISON TO POST IR BLUE OSL AND TL DATING RESULTS

Abstract

The ‘double SAR’ protocol procedure permits the determination of two equivalent dose (De) values for each polymineral aliquot; an IRSL De resulting mostly from feldspars along with a post‐IR OSL De for a mixed signal for quartz (mostly) and feldspar grains. The objective of the present study is to test for the first time its usefulness for polymineral, coarse silt, closely‐spaced deep‐sea sediment samples. A new, ‘double SAR’ IRSL dataset is presented for the sedimentation ages of a deep‐sea sediment core of the Hellenic Trench, drilled from a water depth of 4 km, near the deepest site of the Mediterranean Sea, outside Pylos, Greece. Post IR quartz‐based optical dating was previously proved to be consistent with AMS radiocarbon ages, obtained from planktonic foraminifera from the same core. IRSL De values are, with one exception, always much greater than the corresponding (post‐IR) OSL results. This result suggests that for the present study ‘double SAR’ protocol procedure was proved to be extremely effective method for separating the luminescence signals from quartz and feldspars. Furthermore, De values obtained after infra‐red stimulation and thermoluminescence generally agree within errors. This quantitative equivalence of those two sets of De values implies that as in the case of IRSL, TL signal is also feldspar‐dominated. IRSL ages vary between 3.5 and 7.8 ka with associated errors up to 9%. Application of ‘double SAR’ protocol to coarse silt, closely‐spaced deep‐sea sediment samples seems advisable, despite the fact that the post‐IR blue OSL signal is the most stable signal, and is preferred for dating.