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Development of a red TL detection system for a single grain of quartz

Development of a red TL detection system for a single grain of quartz

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc)

Subsequently, Berger (1992) showed that TL signals from 4 to 11 ?m grains of glass separated from tephra beds can be used to accurately date volcanic deposits spanning the Holocene to middle Pleistocene age range. Attempts have been made to date Quaternary volcanic events in the Chaine-des-Puys by using the red thermoluminescence signal from quartz in pyroclastic ash layers, and sediments heated by lava flows (Pilleyre et al., 1992). With regard to anomalous fading, additional work is required to determine whether storage at elevated temperatures can assist in removal of the fading component of the luminescence signals.

The results of experiments which characterise the optically stimulated luminescence (OSL) signals of an ash sample (BI07-TL-05) from Barren Island are presented. The infrared stimulated luminescence signal decreases to 5% of its initial value when preheated at 150 °C for 10 s, suggesting that the infrared stimulated luminescence signal associated with the 290–390 nm emission in this sample arises from a single trap evicted by heating to 150 °C. The post-IR blue stimulated luminescence emission has greater thermal stability and arises from traps which are emptied by heating to temperatures between 120 °C and 240 °C. Dose recovery experiments demonstrate that a laboratory dose can be reliably determined to within 5% for the post-IR blue stimulated luminescence signal. However, the fading rate for the post-IR blue stimulation is high, and the g-value is estimated to be (9.6 ± 3.5)% per logarithmic decade for BI07-TL-05.