Santorini: Luminescence dating of a volcanic province using quartz?

We have investigated the application of luminescence dating to the palaeoso l underlying the Cape Riva ignimbrite from the volcanic island of Santorini (36.40 degreesN, 25.40 degreesE) in the Aegean Sea. The history of volcani sm in this area is of intrinsic interest, and is also of importance to arch aeology in the eastern Mediterranean - a flourishing late Bronze Age settle ment was buried under the volcanic products of the Minoan Eruption (1640 BC ). Volcanic provinces are notoriously difficult to date using luminescence techniques, because volcanic feldspars almost invariably show anomalous fad ing (which can lead to age underestimates of more than 50%). Quartz does no t show anomalous fading, but unfortunately it is rare or non-existent in vo lcanic sediments, and so it is usually not considered as a potential chrono meter. We have studied the luminescence characteristics of material extract ed from the Cape Riva palaeosol, with good independent age control. All sam ples contain detectable quartz, but usually < 0.01% of the bulk deposit; th e quartz is identified primarily by the ability to sensitize the characteri stic 110<degrees>C TL peak, and by the absence of significant regenerated r esponse to intense infra-red illumination from an IR laser. It may be that this quartz is of aeolian origin, perhaps from North Africa or from local s ources. If the former, quartz is only accumulated during the period of soil development. Blue-light (470 nm) stimulated luminescence signal levels are highly variable, and despite chemical and physical concentration, some ali quots show no significant natural luminescence or laboratory dose-response. The single-aliquot regenerative-dose protocol has been used to estimate th e equivalent dose in the remainder. Despite our identification of the lumin escent material as quartz, all aliquots grossly underestimate the known age , by 90% on average. (C) 2000 Elsevier Science Ltd. All rights reserved.