For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar. The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age). This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO2 and then for data interpretation.

中文翻译：

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MODIS2 比对框架中用于放射性碳测年的砂浆样品的表征和选择：两个比较程序

几十年来，人们一直致力于提高砂浆放射性碳测年的准确性，并评估有关所检查标本类型的结果的可靠性。该方法应用的几个基本假设在许多情况下可能无法满足，例如（a）在煅烧过程中原生石灰石完全解离，（b）钙质聚集体中所含的地源碳的有效分离，（c）碳酸化时间短，和 (d) 不存在次生方解石。世界各地的许多实验室提出了不同的方法来选择合适的砂浆比例。第一次比对尝试于 2016 年组织，涉及八个国际实验室，旨在对不同实验室采用各自的表征和预处理方法在相同材料上获得的结果进行比较和统计处理（Hajdas 等人，2017 年；Hayen 等人，2017 年）。 2017）。继第一步之后，在 2018 年砂浆约会国际会议（法国波尔多）期间提出并建立了一项新的比对实验。选择了一组新的三个砂浆样品，注意标准化材料的选择（均匀性、已知的矿物成分、不存在外源夹杂物、已知的预期年龄）。这项工作描述了参与比较的两个研究小组的结果。根据每个实验室策略对样品进行表征、选择和测定日期。结果强调了原材料表征的重要性，以更好地了解样品的矿物学和岩相成分。这些信息可以支持选择最合适的二氧化碳提取策略2然后进行数据解释。