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The Roman amphitheatre in Mérida, Spain ˗Augustan or Flavian? Radiocarbon dating results on mortar carbonate

Lindroos Alf, Heinemeier Jan, Ringbom Åsa, Schrøder Daugbjerg Thomas, Hajdas Irka

Geochronometria

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2020

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Vol. 47, no.1

187--195

EN

Four lime mortar samples from the Mérida amphitheatre in Spain were dated in 2001 and re-dated in 2019 with refined dating methods and focus on carbon dioxide that was released in late CO2 fractions when dissolved in phosphoric acid. The samples were difficult to date because they contained highly soluble, young carbonate contamination that dominated the carbon dioxide from the early stages of the reaction with the acid in the hydrolysis process. They were also rather hydraulic and rich in magnesium, which could have caused delayed hardening. However, there was very little dead carbon contamination so that late carbon dioxide fraction gave uniform 14C ages, pointing to a late 1st c. AD Flavian, or later age of the amphitheatre.

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Historical building dating: A multidisciplinary study of the Convento de São Francisco (Coimbra, Portugal)

Stella G., Almeida L., Basílio L., Pasquale S., Dinis J., Almeida M., Gueli A. M.

Geochronometria

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2018

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Vol. 45, no. 1

119--129

EN

Cross-dating of bricks and mortars from historical building, through thermal (TL) and optically stimulated (OSL) luminescence have achieved good accuracy and precision. However this approach is, in many cases, not exhaustive especially for buildings with different construction phases closely temporally spaced to each other. The uncertainties of experimental data added to the reuse of old bricks and/or the presence of mortars applied on restorations represent the main limits to obtain the complete chronology. In the case of the Convento de S. Francisco (Coimbra, Portugal), the dating results were crossed with the stratigraphic study of the building, mineralogical characterization by XRD and colorimetric data of the mortar samples. Thanks to luminescence ages, mineralogical composition and color specification, two phases of construction were identified: the first from the 17th century and the first half of the 18th century and the second from the second half of the 18th century to the first half of the 19th century. These results were confirmed by mineralogical characterization and colorimetric measurements of mortars that identify two different types of materials in aggregate/binder ratio terms and superficial optical characteristics.

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Application of different protocols and age-models in OSL dating of earthen mortars

Panzeri L., Cantù M., Martini M., Sibilia E.

Geochronometria

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2017

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Vol. 44, no. 1

341--351

EN

In this study, OSL dating was applied to earthen mortars, consisting in a quartz-rich aggregate dispersed in silty-clayey matrix. The samples were taken from two independently dated structures in Cremona, Northern Italy (Palazzo Raimondi, 1495–1499 AD and Palazzo Soldi, 1770–1790 AD). The evaluation of the equivalent dose (De) was attempted with both the multigrain and the single grain protocols using the 150–250 μm quartz fraction. The reliability and effectiveness of the various statistical methods in identifying the well-bleached samples were tested. The use of the multi-grain technique gave unreliable results, due to the high amount of poorly bleached grains. With the single-grain technique, more promising results were obtained: in particular, the un-log MAM3 and IEU models allowed an accurate evaluation of the mortar expected age in most cases, even if the precision is still relatively low.

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Cretaceous aggregate and reservoir effect in dating of binding materials

Michalska D., Pazdur A., Czernik J., Szczepaniak M., Żurakowska M.

Geochronometria

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2013

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Vol. 40, no. 1

33-41

EN

Lime mortars may contain carbon from different origins. If the mortars are made of totally burnt lime, radiocarbon dating yields the true age of building construction. The presence of carbona-ceous aggregates gives the so-called dead carbon effect, which may generate older ages. Another source of carbon is charcoal present in mortars. An attempt has been made to apply the radiocarbon method to mortars of archaeologically estimated age from the Dead Sea region. Petrographical anal-yses of these samples show the carbonaceous character of the binder and large amounts of limestone aggregate. Determination of the mineral composition of the mortars and comparison with the geology of the surrounding, allows the provenance of the raw materials to be identified. They probably repre-sent the Cretaceous rocks of the Judea Group. Separate radiocarbon dates were made on bulk mortar samples, binder, charcoal fragments and sepa-rated fractions from mortars. In the case of binder-aggregate mixture the reservoir effect correction has been applied.