Browsing by Author "Mattielli, Nadine"

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    Black pitch, carved histories: radiocarbon dating, wood species identification and strontium isotope analysis of prehistoric wood carvings from Trinidad's Pitch Lake
    (Elsevier, 2017-11-06) Ostapkowicz, Joanna; Brock, Fiona; Widenhoeft, Alex C.; Snoeck, Christophe; Pouncett, John; Baksh-Comeau, Yasmin; Schulting, Rick J.; Claeys, Philippe; Mattielli, Nadine; Richards, Mike; Boomert, Arie
    We report on the results of a multi-disciplinary project (including wood identification, radiocarbon dating and strontium isotope analysis) focused on a collection of pre-Columbian wooden carvings and human remains from Pitch Lake, Trinidad. While the lake's unusual conditions are conducive to the survival of organic artefacts, they also present particular challenges for analysis. There is a loss of any contextual association beyond that of the lake, and specific methodologies are required to deal with pitch contamination. A surprising taxonomic range of woods was employed for the various utilitarian and ceremonial items recovered. The 14C results range from ca. 3200 BCE to ca. 700 CE, and include the earliest known wooden carvings in the entire Caribbean. The strontium isotope results - interpreted with the aid of an isoscape developed for the project, based on extensive samples of modern trees across Trinidad and Tobago - indicate that most carvings are consistent with the site's immediate environs; however, a ‘weaving tool’ came from a more radiogenic region that is unlikely to be found on Trinidad, suggesting links with the South American mainland.
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    Testing various pre-treatments on artificially waterlogged and pitch-contaminated wood for strontium isotope analyses
    (Frontiers, 2021-01-12) Snoeck, Christophe; Schulting, Rick J.; Brock, Fiona; Rodler, Alexandra S.; van Ham-Meert, Alicia; Mattielli, Nadine; Ostapkowicz, Joanna
    Strontium isotope ratios (87Sr/86Sr) are commonly used in archeological and forensic studies to assess if humans and fauna are local to the place they were found or not. This approach is largely unexplored for wooden artifacts recovered in archeological contexts, as wood – in the rare instances it does survive – is often poorly preserved. One of the most common ways wood is preserved is through the anoxic conditions found in waterlogged contexts. A more unusual form of preservation is through submergence in natural pitch. These depositional media contribute their own strontium values to the in vivo 87Sr/86Sr wood values, which needs to be removed prior to analysis. Here we test several pre-treatment methods to remove potential strontium contamination from wood samples that were artificially immersed in seawater and pitch from Trinidad’s Pitch Lake. Water rinses and acid-leaching tests were carried out with hydrochloric acid and acetic acid to remove exogenous strontium from experimentally waterlogged wood. These tests removed large amounts of strontium from the samples and did not enable the recovery of the endogenous 87Sr/86Sr signal. For samples artificially immersed in pitch, the pre-treatments tested were based on radiocarbon dating procedures and carried out with and without the aqueous-based acid-base-acid (ABA) step. The use of organic solvents alone (methanol and toluene) removed exogenous strontium originating from the pitch. However, the ABA step eliminates large amounts of in vivo strontium from the samples. These tests show that 87Sr/86Sr values of wood are altered by the presence of pitch and water. With adequate pre-treatment using exclusively organic solvents, it may be possible to remove this contamination for samples immersed in pitch. However, the aqueous-based ABA pre-treatment should be avoided. The removal of contamination from waterlogged samples was unsuccessful with the current pre-treatment protocols and more research is needed. More importantly, and unexpectedly, 87Sr/86Sr values may extend outside of the mixing line between the wood’s endogenous strontium and the water. These results indicate the need for extreme caution when attempting to determine the provenance of waterlogged wood.