Daniel Fernández Mosquera

TL and OSL Dating of Sediment and Pottery from Two Syrian Archaeological Sites

TL and OSL Dating of Sediment and Pottery from Two Syrian Archaeological Sites Luminescence dating is widely applied nowadays, mainly for archaeological material and artefacts and sediments of all types and origins. However, optically stimulated luminescence (OSL) from archaeological sediment, originated from mud brick buildings has been hardly studied. The archaeological sites of Tall Abu Fahd and Tall Qsubi are located in the Middle Euphrates Valley, Deir ez-Zor district, Syria. These two Bronze Age sites were recently discovered by a Spanish-Syrian team from the Directorate General of Antiquities and Museums (Damascus) and the University of Coruña. Both sites were dated (about 3.5 ka BC) by typological pottery classification. Sediment and pottery samples from these archaeological sites were collected for luminescence dating. Several analytical procedures for obtaining equivalent doses were tested on the sediment samples. Blue OSL from quartz subsamples and IRSL, post IRSL Blue OSL from feldspar contaminated quartz and polymineral subsamples were performed to obtain OSL ages. For the pottery samples, additive dose TL on a coarse grain feldspar contaminated quartz subsample was performed as well. Results have shown agreement among all the luminescence procedures tested on the Tall Abu Fahd site samples after fading correction, showing ages around 2.7 ka BP. Obtained ages from the other site samples show disagreement among quartz blue OSL and the other subsamples. Fading ratios allow correcting age underestimations from the polymineral post-IR OSL signal. However, the polymineral IRSL signal still shows underestimation. Final sediment and pottery ages have shown good agreement. Older 14C independent age (3.32 ka BP) corresponds to occupational periods of the site while sediment ages are attributed to a post occupation phase.

A SIMPLE METHOD TO SEPARATE QUARTZ AND FELDSPAR AND ITS APPLICATION TO TL/OSL METHODS

A Simple Method to Separate Quartz and Feldspar and its Application to TL/OSL Methods In the dating of sediments by luminescence methods, to obtain a sample the purest possible as to its mineralogy determines the rest of the analytical procedures. The isolation of the sample minerals is a critical stage due to the impossibility of quantifying the relative contributions to the dose from the different minerals. In this paper we propose a non chemical method to isolate quartz from feldspar extracted from different aeolian and fluvial sediments. Grinding together quartz and feldspar grains in an agate mortar results in crushing the feldspar fraction due to its smaller hardness. Later sieving of the grinded mixture enables simple separation of both fractions. Then it is possible to save the feldspar fraction for later analyses instead of losing it as it occurs when using acid etching. Also, we study the evolution of the feldspar abundance along different purification steps with acid etching or grinding with two numerical indexes. We conclude that the grinding procedure can be introduced in the purification methods as an effective way to separate quartz from feldspar. Nonetheless, it is not an standalone procedure to obtain pure quartz and must be combined with chemical methods when the sample is rich in feldspar minerals.